Les articles de Patrick Grillas

Experimental effects of 2,4-D on aquatic plant communities in Mediterranean temporary ponds in Northwestern Morocco

Tue, 21 Jul 2026 14:45:38

de Abdessadeq Boudjaj, Laïla Rhazi, Jamie Kneitel, Mouhssine Rhazi, Said Moukrim, Mohammed El Madihi, Mohamed Ben Bammou, Imane Wahby, Jorge García Girón, Dan Cogalniceanu, et al.
In Ecologies, 7(3) (September, 2026), 71
En ligne : www.mdpi.com[...]

Increased herbicide use in agriculture is a major threat to adjacent aquatic and wetland ecosystems. In Morocco, the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) poses a risk to temporary ponds found in agricultural landscapes. This study used mesocosm experiments to assess the effects of 2,4-D concentration (0, 0.10, 0.20, and 0.30 mg·L−1) and application timing (early vs. late in the hydrological cycle) on water quality and aquatic plant communities from forest ponds not previously exposed to herbicides. At the highest concentration (0.30 mg·L−1), conductivity increased from 206 to 274 µS and pH from 7.5 to 8.4 under early application. At the same time, species richness and total abundance significantly decreased with increasing 2,4-D concentrations, with the strongest effects observed under early application. Community composition shifted markedly in response to 2,4-D, with annual and submerged species showing greater sensitivity, whereas perennial and emergent species were relatively tolerant. These findings highlight the need to adopt more sustainable agricultural practices to conserve pond biodiversity. Specifically, herbicide applications should be avoided near ponds, at high application rates, and during periods early in the hydroperiod. Lastly, land-use strategies should balance agricultural productivity with the conservation of biodiversity in temporary pond ecosystems.

Assessment of soil carbon stock in Mediterranean temporary ponds under a semi-arid climate in NW Morocco

Tue, 5 May 2026 09:56:16

de Abdessadeq Boudjaj, Laïla Rhazi, Said Moukrim, Saida Ourraisse, Abdelmjid Zouahri, Mohammed El Madihi, Mouhssine Rhazi, Said Lahssini, Mohamed Ben Bammou, Imane Wahby, et al.
In Hydrobiologia, (en ligne) (April, 2026)
En ligne : doi.org[...]

The role of temporary ponds in carbon budgets remains poorly understood, particularly in arid regions. This study quantified soil organic carbon (SOC) stocks in 15 temporary ponds in Morocco, across three land use types (agricultural, reserve, forest). In each pond, one soil core was collected in each of the three topographic zone (peripheral, intermediate, and central) and divided in three soil depth (0–15, 15–30, 30–45 cm) with sub-samples (3) averaged by layer. Relationship with vegetation abundance and plant diversity (aquatic and terrestrial), hydrological and soil properties were also assessed. SOC content was measured, and factorial ANOVAs with Tukey’s tests were used for statistical analysis. SOC density was significantly higher in agricultural and reserve ponds than in forest ponds. Total SOC stock was positively correlated with hydrology, soil nutrients, and vegetation attributes, while topographic zone, soil depth, or their interaction showed no significant effects. Extrapolation to all 672 ponds in the 2760 km2 study area estimated a total SOC stock of 153,878 metric tons. These results highlight the importance of conserving agricultural ponds and creating new reserves in pond-rich forest areas to maximize carbon sequestration in semi-arid regions.

Vegetation trajectories over 150 years of temporary ponds created in the Camargue delta (Southern France)

Wed, 18 Mar 2026 15:40:14

de Hugo Fontes, Patrick Grillas, Thierry Dutoit, Antoine Gazaix, Elie Gaget, François Mesléard
In Restoration Ecology, (en ligne) (March, 2026), e70372
En ligne : onlinelibrary.wiley.com[...]

Temporary ponds in the Mediterranean climate have a high conservation value, but many have been severely destroyed or degraded. Pond restoration and new pond creation have been engaged widely. Evaluations of the success of such operations are generally carried out over 10–15 years and show divergent results over this timeframe. In the Camargue (Rhône delta, South of France), several temporary ponds were created with various objectives since the second half of the 19th century.
Study the long-term trajectory of plant communities in created temporary ponds and compare them with those of reference temporary ponds.
We carried out vegetation surveys and measured environmental parameters in 25 ponds created in the 19th, 20th, and 21st centuries, as well as in 27 natural reference ponds (space-for-time substitution approach).
Submerged macrophyte communities (composition, abundance, and species-richness) converged toward the reference communities after one or several decades. Emergent plant communities (terrestrial plants and helophytes) converged more slowly toward the reference communities (composition and abundance). Even after 150 years, the emergent plant communities with the highest conservation interest (in particular Natura 2000 habitat) were not found in created ponds.
The creation of temporary ponds in the Camargue is of conservation interest but cannot compensate for the loss of natural temporary ponds.

Phenotypic plasticity in amphibious plants across a latitudinal (climatic) gradient

Wed, 4 Feb 2026 15:33:35

de Mohammed El Madihi, Laïla Rhazi, Abdessadeq Boudjaj, Maarten Van den Broeck, Mouhssine Rhazi, Bouabid Badaoui, Said Moukrim, Mohamed Ben Bammou, Imane Wahby, Aline Waterkeyn, et al.
In Oikos, (en ligne) (February, 2026), e11804
En ligne : onlinelibrary.wiley.com[...]

Temporary ponds are vital ecosystems in the Mediterranean basin, supporting many specialized species. Plants must endure significant interannual fluctuations in pond hydrology and may face increased stress from climate change. While research has largely focused on community-level dynamics, we still lack a clear understanding of how species respond to hydrology and the relative roles of plasticity versus adaptation in their responses. We studied selected vegetative (height, number of leaves, leaf area) and reproductive (number of fruits, number of seeds/spores per fruit, number of seeds/spores per plant, seed/spore size and seed mass) traits of six characteristic species (of the genera; Baldellia, Damasonium, Elatine and Isoetes) in 20 temporary ponds along a 750 km north–south latitudinal (climate) gradient (31°–35°N) in Morocco (mean annual precipitation range 264 to 856 mm). Traits were assessed on both field-collected specimens and those grown from seeds/spores in mesocosms under uniform experimental conditions. Our results showed a significant correlation between latitude and plant traits in the field. From north (humid) to south (dry), plants became shorter, with fewer and smaller leaves, fewer fruits, smaller seeds/spores, lower mass per fruit/sporangium, and fewer seeds per plant. Reduced growth and fecundity along the gradient likely result from limited and variable flooding in the south, increasing plant stress. However, these differences in traits were not observed when the plants were grown under common garden conditions. This pattern strongly suggests that differences in plant traits across the six species are mainly due to phenotypic plasticity to local hydrological conditions, although potential genetic differentiation cannot be excluded. In conclusion, phenotypic plasticity, likely favored by large interannual variations in hydrological conditions, may enhance species resilience to climate change and may aid in population transfers for restoration projects.

Long-Time Dynamics in a North African Coastal Ramsar Site, the Sidi Boughaba Lake

Fri, 16 Jan 2026 15:52:35

de Said Moukrim, Jihane Tellal, Said Lahssini, Abdessadeq Boudjaj, Mouhssine Rhazi, Mohammed El Madihi, Mohamed Ben Bammou, Mustapha Moukrim, Er-riyahi Saber, Imane Wahby, et al.
In Ekológia (Bratislava), 44(2) (Decembre, 2025), 147-159
En ligne : www.sciendo.com[...]

Coastal wetlands host a large part of the world’s biodiversity and provide various ecosystem services with a known economic value. However, they experience many pressures due to anthropogenic and natural drivers, causing periodic changes in their structure and functioning. Earth Observation provides opportunities for monitoring water surface dynamics and understanding the impacts of different drivers on wetland degradation. This study had two objectives: to assess the spatiotemporal dynamic of the Sidi Boughaba Lake surface area (Mediterranean and North African coastal Ramsar site, Morocco) over 38 years (1984–2021) and to identify natural and anthropogenic drivers of this dynamic, mainly land-use and land-cover changes and policies. This work focused on the use of multiple datasets based on remote sensing images within a cloud-based computing platform. Time series of satellite images were classified and used after a series of processing procedures to assess the land use and land cover and water extent dynamics. Results reveal that over 38 years, the lake shows intra- and inter-annual variations, including significant losses of permanent water impacting its dynamic and extent. Those trends call into question the urban and agricultural policies adopted. Pressure on resources and the regressive trend recorded in the dynamic of the lake are likely to increase further in future years if effective protection measures are not implemented. The results of this study help authorities, civil society, and decision makers to make decisions and call for action to protect these areas and maintain their capacity to provide ecosystem services and address global concerns such as biodiversity conservation and climate change mitigation.

Assessing methane emissions and soil carbon stocks in the Camargue coastal wetlands: Management implications for climate change regulation

Wed, 21 Aug 2024 14:29:14

de Maite Martínez-Eixarch, Pere Masqué, Anna Lafratta, Paul Lavery, Samuel Hilaire, Lluís Jornet, Cyrille Thomas, Arnaud Boisnard, Néstor Pérez-Méndez, Carles Alcaraz, et al.
In Science of The Total Environment, 950 (November, 2024), 175224
En ligne : www.sciencedirect.com[...]

Coastal wetlands are crucial in climate change regulation due to their capacity to act as either sinks or sources of carbon, resulting from the balance between greenhouse gas (GHG) emissions, mainly methane (CH4), and soil carbon sequestration. Despite the paramount role of wetlands in climate regulation few studies investigate both aspects. The Camargue is one of the largest wetlands in Europe, yet the ways in which environmental and anthropic factors drive carbon dynamics remain poorly studied. We examined GHG emissions and soil organic carbon (SOC) stocks and accumulation rates in twelve representative wetlands, including two rice fields, to gain insights into the carbon dynamics and how it is influenced by hydrology and salinity. Mean CH4 rates ranged between – 87.0 and 131.0 mg m−2 h−1and the main drivers were water conductivity and redox, water table depth and soil temperature. High emission rates were restricted to freshwater conditions during summer flooding periods whereas they were low in wetlands subjected to summer drought and water conductivity higher than 10 mS cm−1. Nitrous oxide emissions were low, ranging from – 0.5 to 0.9 mg N2O m−2 h−1. The SOC stocks in the upper meter ranged from 17 to 90 Mg OC ha−1. Our research highlights the critical role of low-saline wetlands in carbon budgeting which potentially are large sources of CH4 but also contain the largest SOC stocks in the Camargue. Natural hydroperiods, involving summer drought, can maintain them as carbon sinks, but altered hydrology can transform them into sources. Artificial freshwater supply during summer leads to substantial CH4 emissions, offsetting their SOC accumulation rates. In conclusion, we advocate for readjusting the altered hydrology in marshes and for the search of management compromises to ensure the compatibility of economic and leisure activities with the preservation of the inherent climate-regulating capacity of coastal wetlands.

The Distance to Reference Communities Index (DRCI): a new tool to assess communities' restoration success

Mon, 27 May 2024 15:18:01

de Hugo Fontes, Christian Marquis, Franck Torre, Patrick Grillas, Thierry Dutoit, François Mesléard
In Restoration Ecology, (Online version) (May, 2024), e14194
En ligne : onlinelibrary.wiley.com[...]

The concept of a reference ecosystem is fundamental in restoration ecology, especially in assessing the success of ecological restoration projects. In response to criticism, it has undergone conceptual evolutions in its definition and use in the last decades. Even though there is still a need to develop statistical methods and analyses to account for reference variability. Here, we focus on two original and one literature-based calculation methods for designed indexes, which all aim to compare a community to be assessed (undergoing restoration) with a variable set of reference communities. These methods either use the average reference situation (species composition and abundance) as the restoration target or on the contrary, allow any reference site to be considered a relevant target. We compare the results of these methods by analyzing a simulated dataset. We then illustrate the application of the most relevant index by a real case study that compared a created Mediterranean temporary pond to a panel of 27 reference ponds located in the south of France. The results show that the Distance to Reference Communities Index (DRCI) correctly measures differences in species composition and abundance between an assessed and a reference panel of communities. It takes into account the variability of the reference communities, while the use of other indexes focuses on unrealistic average and fixed reference values. DRCI is complementary to a detailed ecological interpretation and to the use of other commonly used indexes, by giving a synthetic metric.

Compositional breakpoints of freshwater plant communities across continents

Tue, 10 Oct 2023 10:00:42

de Jorge García-Girón, Jani Heino, Lars Baastrup-Spohr, John Clayton, Mary de Winton, Tõnu Feldmann, Camino Fernandez-Alaez, Frauke Ecke, Patrick Grillas, Mark V. Hoyer, et al.
In Limnetica, 42(2) (March, 2023), 1
En ligne : www.limnetica.net[...]

Compositional breakpoints of freshwater plant communities across continents unravelling patterns and mechanisms of biogeographical transitions is crucial if we are to understand compositional gradients at large spatial extents, but no studies have thus far examined breakpoints in community composition of freshwater plants across continents. Using a dataset of almost 500 observations of lake plant community composition from six continents, we examined, for the first time, if such breakpoints in geographical space exist for freshwater plants and how well a suite of ecological factors (including climatic and local environmental variables) can explain transitions in community composition from the subtropics to the poles. Our combination of multivariate regression tree (MRT) analysis and k-means partitioning suggests that the most abrupt breakpoint exists between temperate to boreal regions on the one hand and freshwater plant communities harbouring mainly subtropical or Mediterranean assemblages on the other. The spatially structured variation in current climatic conditions is the most likely candidate for controlling these latitudinal patterns, although one cannot rule out joint effects of eco-evolutionary constraints in the harsher high-latitude environments and post-glacial migration lags after Pleistocene Ice Ages. Overall, our study supports the foundations of global regionalisation for freshwater plants and anticipates further biogeographical research on freshwater plant communities once datasets have been harmonised for conducting large-scale spatial analyses.

Scientific Reports of Port-Cros National Park, n°37. Stratégie scientifique 2023-2032 du Parc national de Port-Cros (Provence, France) (2023)

Wed, 21 Feb 2024 15:53:42

de Marion Peirache, Alain Barcelo, Annie Aboucaya, Magalie Alaphilippe, Franck Alary, Violaine Arnaud, Sophie Arnaud-Haond, Guillelme Astruc, Giulia Azzolini, Rémi Beau, et al.
[S.l.] : Parc National de Port-Cros Hyères, 2023

La stratégie scientifique du Parc national de Port-Cros (PNPC), espace protégé terrestre et marin situé en Provence (France, Méditerranée), est un document cadre permettant de disposer d’une définition des besoins dans le domaine scientifique au sein du PNPC, et de retenir les axes prioritaires d’action pour l'ensemble des disciplines scientifiques (biologie, écologie, économie, droit, géographie, histoire, sociologie, etc.) durant la période 2023-2032, dans le cadre d’une vision à long terme. Elle déborde largement de la simple définition du programme des actions scientifiques du PNPC puisqu’elle intègre l'ensemble de la chaîne de production de la connaissance, depuis sa genèse jusqu'à sa diffusion.

Commemorating the 50th anniversary of the Ramsar Convention on Wetlands

Mon, 19 Sep 2022 11:24:41

de C. Max Finlayson, S. Fennessy, Patrick Grillas, R. Kumar
In Marine and Freshwater Research, 73(10) (September, 2022), i-v
En ligne : doi.org[...]

This issue of Marine and Freshwater Research celebrates 50 years of the Ramsar Convention on Wetlands, which was signed in 1971. It contains papers that describe the development of the Convention and its implementation, including the listing of wetlands of international importance and maintenance of their ecological character. The latter is a fundamental issue for wetland management as illustrated in papers that address a range of management issues, including the impact of climate change, and approaches for building awareness about their values, and concludes with a forward view for potentially reframing human–wetland relationships.

The genus Callitriche (Plantaginaceae, Callitricheae) in Morocco

Thu, 21 Jul 2022 15:57:03

de Richard V. Lansdown, Laïla Rhazi, Er-riyahi Saber, Mohammed El Madihi, Patrick Grillas
In Phytotaxa, 555(1) (July, 2022), 53-72
En ligne : www.biotaxa.org[...]

This article presents information on the distribution and ecology of Callitriche species in Morocco, based on field survey, literature review, and examination of herbarium specimens. Taxa reported erroneously from the country are discussed and new information is presented on the morphology of C. mathezii and C. truncata subsp. truncata.

Mediterranean Temporary Lagoon: proposal for a definition of this endangered habitat to improve its conservation

Fri, 20 May 2022 18:18:44

de Mathilde Latron, Aubin Allies, Olivier Argagnon, Nadine Bosc, Karine Faure, Hugo Fontes, Patrick Grillas, James Molina, Rutger de Wit, Guillaume Papuga
In Journal for Nature Conservation, Online (May, 2022), 126193
En ligne : www.sciencedirect.com[...]

Coastal lagoons have been recognised as a priority habitat for conservation and have benefited from several conservation plans. Under the Mediterranean climate, some of these lagoons might dry out during summer due to drought events. We propose the term Mediterranean Temporary Lagoons (MTLs) for these ephemeral water bodies and discuss their definition and characteristics. This term emerged in France among its coastal zone managers, who now commonly use it for conservation purposes. It is used in both natural systems as well as most artificial salt ponds in abandoned saltworks. In Europe, two directives have integrated lagoons as key targets to be preserved. Nonetheless, a certain discrepancy in the different definitions of lagoons has constrained joint actions. Indeed, while institutional definitions were originally derived from the scientific concept, their legislative and managerials meanings have been gradually modified and nowadays often differ from the original concept to create difficulties in the field. In addition, while it has been recommended to consider MTLs as a coastal lagoon habitat in the European Habitat Directive, its interpretation among EU member states is unsettled. Thus, clarifying lagoon habitats' terminology is required to ensure better management, monitoring and planning, and coordinate conservation actions. We discuss the inclusion of MTLs in habitat 1150 by confronting scientific and institutional literature and propose a new framework to better delimitate lagoon habitat around the Mediterranean basin, integrating MTLs. MTLs represent a specific habitat that hosts a pool of stenoecious macrophytes of conservation interest like Althenia filiformis, Riella helicophylla or Tolypella salina.

The future of temporary wetlands in drylands under global change

Thu, 18 Nov 2021 17:44:01

de Gema Parra, Francisco Guerrero, Javier Armengol, Luc Brendonck, Sandra Brucet, C. Max Finlayson, Luciana Gomes-Barbosa, Patrick Grillas, Erik Jeppesen, Fernando Ortega, et al.
In Inland Waters, Online (November, 2021), 1-12
En ligne : www.tandfonline.com[...]

The Andalusian International University held a workshop entitled Temporary wetlands’ future in drylands under the projected global change scenario in March 2020 in Baeza, Spain, with 26 participants from 10 countries. The workshop objectives were to promote international cooperation and scientific exchange on the conservation and protection of temporary wetlands. The participants highlighted the extreme conditions that temporary and permanent wetlands, ponds, and shallow lakes are currently facing and predicted a dismal future for these systems due to climate change. To foster a holistic view of these ecosystems, the workshop included wetland watersheds. It was concluded that the main threats are those affecting water quality and quantity as well as egg-seed banks, species population dynamics, and food webs. The inherent characteristics of waterbodies in drylands, including high resilience and resistance to harsh conditions, are already negatively impacted by direct human actions and climate change. Another threat is the time lag between scientific warnings about threats and the social and political concern leading to mitigating actions. Thus, more effective actions to protect and conserve temporary wetlands are essential. Research networks could help stimulate the necessary conservation actions, but the global recession due to the COVID-19 pandemic will pose a challenge as economies are burdened with urgent expenditure. This special issue of the journal Inland Waters is the outcome of the workshop presentations and is composed of the ensuing papers on wetlands in drylands.

Effect of inter-annual meteorological fluctuations and wild boar disturbance on the vegetation of Mediterranean temporary ponds

Thu, 16 Dec 2021 10:47:33

de Maria Carmela Caria, Patrick Grillas, Giovanni Rivieccio, Simonetta Bagella, Péter Török
In Applied Vegetation Science, 24(4) (October, 2021)
En ligne : onlinelibrary.wiley.com[...]

Which are the effects of inter-annual meteorological fluctuations on plant species richness and vegetation dynamics in Mediterranean temporary ponds, shallow wetlands characterized by alternating phases of drought and flooding? Which are the effects of wild boar disturbance? How do the responses of specialist or non-specialist species of the habitat differ?
Location: NW Sardinia Island (Italy).
Methods: We assessed plant cover during six years within one 60 cm × 60 cm quadrat in each of five areas. To measure the effect of inter-annual meteorological fluctuations on vegetation, we used two indices: the evapotranspiration and the synthetic agrometeorological indicator. To quantify the effect of disturbance by boars, we compared two treatments: disturbed and non-disturbed (located outside and inside 1.5 m × 1.5 m exclosures respectively). As a whole, we monitored 60 plots (6 years × 2 treatments × 5 replications). We analyzed data using ANOVA, PERMANOVA and BIO-ENV.
Results: Plant species richness and composition showed significant differences between years and treatments. Species composition was correlated with the evapotranspiration before the vegetative peak during the last period and with the agrometeorological indicator during the whole vegetative period. Specialist species showed much weaker growth, quantified as cover, in the drier years. Starting from the third survey year, plant richness and cover of specialist species were significantly higher in disturbed than in not-disturbed plots. The extent of bare soil generally was not affected by the treatment.
Conclusion: Meteorological fluctuations affect plant species composition and vegetation dynamics in Mediterranean temporary ponds. The sensitivity of specialist species could make them particularly vulnerable to climate change. Nevertheless, they are resilient to unpredictable disturbances such as burrowing by wild boar. However, our results concerning the positive impact of wild boar disturbance on the vegetation cannot be generalized. Elsewhere, the lack of hunting activity could also be a problem for these habitats.

Foreseen impact of climate change on temporary ponds located along a latitudinal gradient in Morocco

Mon, 27 Sep 2021 09:36:30

de Patrick Grillas, Laïla Rhazi, Gaëtan Lefebvre, Mohammed El Madihi, Brigitte Poulin
In Inland Waters, Online (Septembre, 2021), 1-16
En ligne : www.tandfonline.com[...]

Wetlands have been declining worldwide, with an estimated 64–71% loss over the last century. Climate change is increasing pressure on wetlands, aﬀecting their hydrology, and Mediterranean temporary ponds could be particularly vulnerable to these changes. We studied the expected changes in hydrology and plant community according to climatic change scenarios in 18 temporary ponds distributed in 6 areas along a latitudinal and climatic gradient in Morocco (750 km; 4° latitudinal gradient). Richness of pond species was signiﬁcantly correlated with water level and pond hydroperiod and showed a strong decline from north to south along with increased water stress. Using the Mar-O-Sel software (mar-o-sel.net), we simulated the future evolution of water balance and wetland hydroperiod (duration and frequency of ﬂooding) in these ponds for mid- and late-21st century. Climate projections were estimated based on 2 Representative Concentration Pathway (RCP) scenarios assuming a stabilization (RCP4.5) or increase (RCP8.5) in greenhouse gas emissions. The mean water deﬁcit of the ponds currently ranges between −1380 and −1812 mm/yr and would increase by 16–67% in 2100 under the RCP8.5 scenarios. Pond richness is expected to decrease by 8–15 species in 2100, depending on area, as a result of shorter projected hydroperiods. Severity of change was not related to location of the ponds along the latitudinal (aridity) gradient, but rather to the interaction between the size of their catchment area and the thickness of the permeable soil layer.

Estimation of Bathymetry and Benthic Habitat Composition from Hyperspectral Remote Sensing Data (BIODIVERSITY) Using a Semi-Analytical Approach

Fri, 21 May 2021 09:16:30

de Audrey Minghelli, Sayoob Vadakke-Chanat, Malik Chami, Mireille Guillaume, Emmanuelle Migne, Patrick Grillas, Olivier Boutron
In Remote Sensing, 13(10) (May, 2021), 17
En ligne : www.mdpi.com[...]

The relevant beneﬁts of hyperspectral sensors for water column determination and seabed features mapping compared to multispectral data, especially in coastal areas, have been demonstrated in recent studies. In this study, we used hyperspectral satellite data in the accurate mapping of the bathymetry and the composition of water habitats for inland water. Particularly, the identiﬁcation of the bottom diversity for a shallow lagoon (less than 2 m in depth) was examined. Hyperspectral satellite data were simulated based on aerial hyperspectral imagery acquired above a lagoon, namely the Vaccarès lagoon (France), considering the spatial and spectral resolutions, and the signal-to-noise ratio of a satellite sensor, BIODIVERSITY, that is under study by the French space agency (CNES). Various sources of uncertainties such as inter-band calibration errors and atmospheric correction were considered to make the dataset realistic. The results were compared with a recently launched hyperspectral sensor, namely the DESIS sensor (DLR, Germany). The analysis of BIODIVERSITY-like sensor simulated data demonstrated the feasibility to satisfactorily estimate the bathymetry with a root-mean-square error of 0.28 m and a relative error of 14% between 0 and 2 m. In comparison to open coastal waters, the retrieval of bathymetry is a more challenging task for inland waters because the latter usually shows a high abundance of hydrosols (phytoplankton, SPM, and CDOM). The retrieval performance of seabed abundance was estimated through a comparison of the bottom composition with in situ data that were acquired by a recently developed imaging camera (SILIOS Technologies SA., France). Regression coefﬁcients for the retrieval of the fractional species abundances from the theoretical inversion and measurements were obtained to be 0.77 (underwater imaging camera) and 0.80 (in situ macrophytes data), revealing the potential of the sensor characteristics. By contrast, the comparison of the in situ bathymetry and macrophyte data with the DESIS inverted data showed that depth was estimated with an RSME of 0.38 m and a relative error of 17%, and the fractional species abundance was estimated to have a regression coefﬁcient of 0.68.

Seventeen ‘extinct’ plant species back to conservation attention in Europe

Wed, 10 Mar 2021 16:46:39

de Thomas Abeli, Giulia Albani Rocchetti, Zoltán Barina, Ioannis Bazos, David Draper, Patrick Grillas, José María Iriondo, Emilio Laguna, Juan Carlos Moreno-Saiz, Fabrizio Bartolucci
In Nature Plants, 7 (March, 2021)
En ligne : www.nature.com[...]

Seventeen European endemic plant species were considered extinct, but improved taxonomic and distribution knowledge as well as ex situ collecting activities brought them out of the extinct status. These species have now been reported into a conservation framework that may promote legal protection and in situ and ex situ conservation.

Ramsar Wetlands of International Importance–Improving Conservation Outcomes

Wed, 24 Mar 2021 10:27:42

de R. T. Kingsford, G. Bino, C. M. Finlayson, D. Falster, J. A. Fitzsimons, D. E. Gawlik, N. J. Murray, Patrick Grillas, R. C. Gardner, T. J. Regan, et al.
In Frontiers in Environmental Science, 9 (March, 2021)
En ligne : www.frontiersin.org[...]

The Ramsar Convention, signed in 1971, was one of the first international conservation agreements, promoting global wise use of wetlands. It has three primary objectives: national designation and management of wetlands of international importance; general wise use of wetlands; and international cooperation. We examined lessons learnt for improving wetland conservation after Ramsar’s nearly five decades of operation. The number of wetlands in the Ramsar Site Network has grown over time (2,391 Ramsar Sites, 2.5 million km2, as at 9/6/20) but unevenly around the world, with decreasing rate of growth in recent decades. Ramsar Sites are concentrated in countries with a high GDP and human pressure (e.g. western Europe) but, in contrast, Ramsar sites with the largest wetland extent are in central-west Africa and South America. We identified three key challenges for improving effectiveness of the Ramsar Site Network: increasing wetland area; improved representation (functional, geographical and biological) and effective management and reporting. Increasing area in the Ramsar network could benefit from targets, implemented at national scales. Knowledge of representativeness is inadequate, requiring analyses of functional ecotypes, geographical and biological representativeness. Finally, most countries have inadequate management planning and reporting on the Ecological Character of their Ramsar Sites, requiring more focused attention on a vision and objectives, with regular reporting of key indicators to guide management. There are increasing opportunities to rigorously track ecological character, utilizing new tools and available indicators (e.g. remote sensing). It is critical that the world protect its wetlands, with an effective Ramsar Convention at the core.

Ecological niche differentiation among six annual Lythrum species in Mediterranean temporary pools (2021)

Wed, 3 Nov 2021 10:19:06

de Antoine Gazaix, Patrick Grillas, Guillaume Papuga, Hugo Fontes, Florent Sabatier, Virginie Pons, Perrine Gauthier, John D. Thompson
2021, 13
En ligne : link.springer.com[...]

The ecological niche defines the favourable range of a species in a multidimensional space of ecological factors that determine the presence and function of individuals. This fundamental concept in ecology is widely used to understand plant species coexistence and segregation. In this study, we test for ecological differentiation among six annual Lythrum species that are characteristic of temporary pools in the South of France, where they either coexist or occur separately. We first analysed the co-occurrence of species at two different geographical scales: cluster analyses of species presence in 10 km grid cells and coexistence in 0.25 m2 quadrats within populations of each species. Second, for three to nine populations of each species, we quantified a range of biotic and abiotic parameters using point contacts and soil measurements in five 0.25 m2 quadrats per population. We performed PCA on all variables and analysed each variable separately to compare the ecological niche features of the six species. A phenological index was assessed for the plant community of each site. We detected highly localized niche differentiation in terms of soil pH (all species) and for a range of variables among pairs of species. The six species also showed marked differences in the flowering period relative to the mean and variability of flowering time in their local community. These fine-scaled niche differences are associated with phylogenetic distances among species and may contribute to species’ coexistence. These results are integrated in a conservation management plan for the habitat of the rarest species in this group.

The future for Mediterranean wetlands: 50 key issues and 50 important conservation research questions

Wed, 27 Jan 2021 10:11:49

de Nigel G. Taylor, Patrick Grillas, Hazem Al Hreisha, Özge Balkız, Maud Borie, Olivier Boutron, Ana Catita, Jocelyn Champagnon, Semia Cherif, Kerim Cicek, et al.
In Regional Environmental Change, Online (2021), 25

Wetlands are critically important for biodiversity and human wellbeing, but face a range of challenges. This is especially true in the Mediterranean region, where wetlands support endemic and threatened species and remain integral to human societies, but have been severely degraded in recent decades. Here, in order to raise awareness of future challenges and opportunities for Mediterranean wetlands, and to inform proactive research and management, we identified (a) 50 key issues that might affect Mediterranean wetlands between 2020 and 2050, and (b) 50 important research questions that, if answered, would have the greatest impact on the conservation of Mediterranean wetlands between 2020 and 2050. We gathered ideas through an online survey and review of recent literature. A diverse assessment panel prioritised ideas through an iterative, anonymised, Delphi-like process of scoring, voting and discussion. The prioritised issues included some that are already well known but likely to have a large impact on Mediterranean wetlands in the next 30 years (e.g. the accumulation of dams and reservoirs, plastic pollution and weak governance), and some that are currently overlooked in the context of Mediterranean wetlands (e.g. increasing desalination capacity and development of antimicrobial resistance). Questions largely focused on how best to carry out conservation interventions, or understanding the impacts of threats to inform conservation decision-making. This analysis will support research, policy and practice related to environmental conservation and sustainable development in the Mediterranean, and provides a model for similar analyses elsewhere in the world.

Languedoc lagoon environments and man: Building a modern analogue botanical macroremain database for understanding the role of water and edaphology in sedimentation dynamics of archaeobotanical remains at the Roman port of Lattara (Lattes, France)

Mon, 22 Jun 2020 11:18:07

de Bigna L. Steiner, Natàlia Alonso, Patrick Grillas, Christophe Jorda, Gaël Piquès, Margaux Tillier, Núria Rovira
In PLOS ONE, 15(6) (18 juin 2020), e0234853
En ligne : journals.plos.org[...]

A new method to evaluate archaeological wetland sites in a more objective way was tested. Different wetland environments have been sampled in areas of a nature reserve and their macroremain content analysed to build a modern analogue dataset. This dataset was then used to characterise archaeological samples from a navigation channel from the Roman port city Lattara. In the modern analogue samples, the different wetland types (saline/brackish or fresh water) could be differentiated in the correspondence analysis. Within these groups, the sampled area of the littoral (submerged, shoreline, unsubmerged) could also be differentiated. This dataset can therefore provide a basis for the interpretation of the nature and degree of aquatic influence and layer formation processes in archaeobotanical records of coastal sites. In the tested archaeological samples from the navigation channel of Lattara, changes in space and time could be tracked using the modern analogue dataset and geoarchaeological information. The channel lost its fresh water supply and silted up over a short period of time (approx. 100 years).

A history of discoveries and disappearances of the rare annual plant Lythrum thesioides M.Bieb.: new insights into its ecology and biology

Mon, 20 Apr 2020 19:02:13

de Antoine Gazaix, Mario Klesczewski, Michel-Ange Bouchet, Manuel Cartereau, James Molina, Henri Michaud, Serge D. Muller, Lionel Pirsoul, Perrine Gauthier, Patrick Grillas, et al.
In Botany Letters, 167(2) (April, 2020), 201-211
En ligne : doi.org[...]

Mediterranean temporary pools are threatened ecosystems that host a unique plant community, mostly composed of annual species with large and long-lived seed banks. The longevity of their seed bank, the scarcity of their habitat, the small size of their populations and the low frequency of above-ground vegetation result in a low probability of detection of these species. The discovery of new populations of such rare species are thus important for our understanding of the ecology of the temporary pool ecosystem. Lythrum thesioides M.Bieb., 1808 is a very rare annual species of temporary pools and river banks which was thought to be extinct in the South of France until 1998. Here, we review the distribution of the species and report the recent discovery of a population during a targeted search combining historical data on wetland occurrence on a particular geological substrate. We present new information on its autecology, pollen morphology and the karyotype. Only three populations are currently known worldwide for Lythrum thesioides, and only one of these has favorable management conditions. Thus, we outline new conservation perspectives in the context of a targeted search project and the conservation management of one population.

Limonium mucronatum: plant communities and cytogenetic characterization of an endemic of the Moroccan Atlantic coast

Wed, 11 Mar 2020 18:14:05

de Laïla Rhazi, Ana Rita Rebelo, Ana S. Róis, Sílvia Castro, João Loureiro, Mohammed El Madihi, Ana Paula Paes, Patrick Grillas, Mohammed Ibn Tattou, Ana D. Caperta
In Plant Biosystems, Online (April, 2020), 1-22
En ligne : doi.org[...]

Limonium mucronatum (L.f.) Chaz. (Plumbaginaceae), a strict endemic of Morocco, has a restricted range in the littoral zone between Rabat and Tan Tan (Draa valley). This coastal region at the junction of Mediterranean, Canary and Saharan influences is of considerable biogeographical interest. However, little information exists on L. mucronatum communities and its relationship with bioclimatology or chromosome polymorphisms, which may have an impact in the context of plant conservation. In this study, we analysed L. mucronatum communities and performed a cytometric and karyological characterization of this rare species. Results showed two plant communities associated to this species related with a latitudinal and bioclimatic gradient along the surveyed region. Our study provided for the first time new data regarding nuclear DNA amount and about the numbers, positions and organization of 45S rDNA loci in L. mucronatum. Remarkably, cytogenetic analyses revealed homogeneous ploidy across all studied populations with all individuals with 2n = 12 chromosomes. The results obtained are discussed in the context of the originality of flora and the threats to L. mucronatum communities, and in the perspective of a conservation strategy for this endemic species.

Global patterns and determinants of lake macrophyte taxonomic, functional and phylogenetic beta diversity

Mon, 23 Mar 2020 11:43:24

de Jorge García-Girón, Jani Heino, Lars Baastrup-Spohr, Claudia P. Bove, John Clayton, Mary de Winton, Tõnu Feldmann, Margarita Fernández-Aláez, Frauke Ecke, Patrick Grillas, et al.
In Science of The Total Environment, Online (March 19, 2020), 138021
En ligne : www.sciencedirect.com[...]

Documenting the patterns of biological diversity on Earth has always been a central challenge in macroecology and biogeography. However, for the diverse group of freshwater plants, such research program is still in its infancy. Here, we examined global variation in taxonomic, functional and phylogenetic beta diversity patterns of lake macrophytes using regional data from six continents. A data set of ca. 480 lake macrophyte community observations, together with climatic, geographical and environmental variables, was compiled across 16 regions worldwide. We (a) built the very first phylogeny comprising most freshwater plant lineages; (b) exploited a wide array of functional traits that are important to macrophyte autoecology or that relate to lake ecosystem functioning; (c) assessed if different large-scale beta diversity patterns show a clear latitudinal gradient from the equator to the poles using null models; and (d) employed evolutionary and regression models to first identify the degree to which the studied functional traits show a phylogenetic signal, and then to estimate community-environment relationships at multiple spatial scales. Our results supported the notion that ecological niches evolved independently of phylogeny in macrophyte lineages worldwide. We also showed that taxonomic and phylogenetic beta diversity followed the typical global trend with higher diversity in the tropics. In addition, we were able to confirm that species, multi-trait and lineage compositions were first and foremost structured by climatic conditions at relatively broad spatial scales. Perhaps more importantly, we showed that large-scale processes along latitudinal and elevational gradients have left a strong footprint in the current diversity patterns and community-environment relationships in lake macrophytes. Overall, our results stress the need for an integrative approach to macroecology, biogeography and conservation biology, combining multiple diversity facets at different spatial scales.

A review of the adequacy of reporting to the Ramsar Convention on change in the ecological character of wetlands

Wed, 4 Dec 2019 13:46:03

de N. C. Davidson, L. Dinesen, S. Fennessy, C. M. Finlayson, Patrick Grillas, A. Grobicki, R. J. McInnes, D. A. Stroud
In Marine and Freshwater Research, 71 (December, 2019), 10
En ligne : www.publish.csiro.au[...]

We review the mechanisms established by the Ramsar Convention for reporting on the status and change in the ecological character of wetlands. We assess the extent of their implementation and compliance, but not issues of the adequacy of their design nor the consequences of their extent of implementation. We conclude that, with the exception of qualitative national-scale reporting in triennial Contracting Party National Reports, there is inadequate implementation and compliance with most of these mechanisms, notably concerning required reporting under Article 3.2 of the Convention and the updating of the Information Sheet on Ramsar Wetlands (RIS). This limits the ability of the Convention to assess the status, and trends in status, of designated Wetlands of International Importance (Ramsar Sites), and to inform future decision-making and priority-setting for the wise use of all wetlands. As has been recognised by the Ramsar Convention, unless compliance with these mechanisms is improved, sufficient information will not be gathered through the mechanisms of Ramsar Convention to assess fully the Sustainable Development Goal 6.6.1 indicator supported by the Convention on change in the extent of water-related ecosystems over time.

Trends in the ecological character of the world’s wetlands

Wed, 4 Dec 2019 13:45:53

de N. C. Davidson, L. Dinesen, S. Fennessy, C. M. Finlayson, Patrick Grillas, A. Grobicki, R. J. McInnes, D. A. Stroud
In Marine and Freshwater Research, 71 (December, 2019), 10
En ligne : www.publish.csiro.au[...]

We assessed trends in the ecological character of wetlands generally and of Ramsar Sites reported in 2011, 2014 and 2017 by the Contracting Parties to the Ramsar Convention on Wetlands in their national reports. There was more widespread deterioration than improvement in the ecological character of wetlands generally, with deterioration increasingly more widespread between 2011 and 2017. The ecological-character trends in Ramsar Sites were significantly better than those of wetlands generally, but an increasingly more widespread deterioration of ecological character was reported between 2011 and 2017. Trends in the ecological character of wetlands generally, and of Ramsar Sites were worst in Africa and Latin America and the Caribbean, and recently also in Oceania, and better in North America and Europe. Deterioration in the ecological character of Ramsar Site was more widespread in countries with a large average area of their Ramsar Sites. This information on trends of wetland ecological character can contribute to assessing the achievement of the 2030 Sustainable Development Goal Target 6.6 and Aichi Biodiversity Target 5. Our analysis indicated that the 1971 aim of the Ramsar Convention to stem the degradation of wetlands has not yet been achieved.

Estimating biodiversity changes in the Camargue wetlands: An expert knowledge approach

Mon, 28 Oct 2019 11:50:23

de Sara Fraixedas, Thomas Galewski, Sofia Ribeiro-Lopes, Jonathan Loh, Jacques Blondel, Hugo Fontes, Patrick Grillas, Philippe Lambret, Delphine Nicolas, Anthony Olivier, et al.
In PLOS ONE, 14(10) (24 oct. 2019), e0224235
En ligne : journals.plos.org[...]

Mediterranean wetlands are critical strongholds for biodiversity and the provision of ecosystem functions and services; yet, they are being severely degraded by a number of socio-economic drivers and pressures, including climate change. Moreover, we still lack comprehensive understanding of the extent to which biodiversity loss in Mediterranean wetlands will accelerate change in ecosystem processes. Here, we evaluate how changes in biodiversity can alter the ecosystem of the Camargue (southern France). We collected data on species presence/absence, trends and abundance over a 40-year period by combining observations from the scholarly literature with insights derived from expert knowledge. In total, we gathered more than 1500 estimates of presence/absence, over 1400 estimates of species abundance, and about 1400 estimates of species trends for eight taxonomic groups, i.e. amphibians, reptiles, breeding birds, fish, mammals, dragonflies (odonates), orthopterans and vascular plants. Furthermore, we used information on recently arrived species and invasive species to identify compositional changes across multiple taxa. Complementing targeted literature searches with expert knowledge allowed filling important gaps regarding the status and trends of biodiversity in the Camargue. Species trend data revealed sharp population declines in amphibians, odonates and orthopterans, while birds and plants experienced an average increase in abundance between the 1970s and the 2010s. The general increasing trends of novel and invasive species is suggested as an explanation for the changing abundance of birds and plants. While the observed declines in certain taxa reflect the relative failure of the protection measures established in the Camargue, the increasing exposure to novel and invasive species reveal major changes in the community structure of the different taxonomic groups. This study is the first attempt to assess changes in biodiversity in the Camargue using an expert knowledge approach, and can help manage the uncertainties and complexities associated with rapid social-ecological change in other Mediterranean wetlands.

A synthesis of evidence for the effects of interventions to conserve peatland vegetation: overview and critical discussion

Thu, 26 Sep 2019 10:49:33

de Nigel G. Taylor, Patrick Grillas, M.S. Fennessy, E. Goodyer, L.L.B. Graham, E. Karofeld, R.A. Lindsay, D.A. Locky, N. Ockendon, A. Rial, et al.
In Mires and Peat, 24 (June, 2019), 1-21
En ligne : www.repository.cam.ac.uk[...]

Peatlands are valuable but threatened ecosystems. Intervention to tackle direct threats is often necessary, but should be informed by scientific evidence to ensure it is effective and efficient. Here we discuss a recent synthesis of evidence for the effects of interventions to conserve peatland vegetation - a fundamental component of healthy, functioning peatland ecosystems. The synthesis is unique in its broad scope (global evidence for a comprehensive list of 125 interventions) and practitioner-focused outputs (short narrative summaries in plain English, integrated into a searchable online database). Systematic literature searches, supplemented by recommendations from an international advisory board, identified 162 publications containing 296 distinct tests of 66 of the interventions. Most of the articles studied open bogs or fens in Europe or North America. Only 36 interventions were supported by sufficient evidence to assess their overall effectiveness. Most of these interventions (85 %) had positive effects, overall, on peatland vegetation although this figure is likely to have been inflated by publication bias. We discuss how to use the synthesis, critically, to inform conservation decisions. Reflecting on the content of the synthesis we make suggestions for the future of peatland conservation, from monitoring over appropriate timeframes to routinely publishing results to build up the evidence base.

Dynamics of the seagrass Zostera noltei in a shallow Mediterranean lagoon exposed to chemical contamination and other stressors

Tue, 7 May 2019 11:27:11

de Diane Espel, Noël J. Diepens, Olivier Boutron, Evelyne Buffan-Dubau, Yves Chérain, Eric Coulet, Patrick Grillas, Anne Probst, Jérôme Silvestre, Arnaud Elger
In Estuarine, Coastal and Shelf Science, 222 (June, 2019), 1-12
En ligne : linkinghub.elsevier.com[...]

Seagrass decline due to a variety of stressors has been observed worldwide. In the shallow Vaccarès lagoon, Camargue, France, the dominant macrophyte species, Zostera noltei, has suﬀered two major declines since 1996. The ﬁrst decline was well explained by salinity and turbidity variations, while the second one could not be explained by these parameters. Other stressors such as chemical contamination, eutrophication or temperature increase could be explanatory variables for this most recent decline. The aim of our study was to understand, via scientiﬁc monitoring from 2011 to 2015, the inﬂuence of chemical contamination and its possible interactions with other biological and environmental pressures, on seagrass physiology and population dynamics in the Vaccarès lagoon.

Livestock disturbances in Mediterranean temporary ponds

Thu, 11 Apr 2019 11:22:08

de Maarten Van den Broeck, Laïla Rhazi, Aline Waterkeyn, Mohammed El Madihi, Patrick Grillas, Jamie M. Kneitel, Luc Brendonck
In Freshwater Biology, 64(5) (May, 2019), 856-869
En ligne : onlinelibrary.wiley.com[...]

The number and quality of temporary wetlands are declining worldwide and many of the remaining habitats are used as pastures and drinking sites for livestock. Livestock can impact wetlands through a combination of herbivory (defoliation), trampling (physical disturbance), and defecation (nutrient input), but how these influence community structure is still poorly understood. It is nonetheless generally accepted that wetland management can include some grazing, and that properly managed livestock can play a major role in wetland conservation. In Mediterranean temporary ponds, however, it is suggested that grazing might negatively affect macrophyte biodiversity within the pond basin. The impact of livestock on the characteristic freshwater fauna also remains understudied. Using an outdoor mesocosm experiment, we focused on two effects of sheep livestock (trampling and defecation) and their combination, on water quality and on faunal and floral communities from Moroccan temporary ponds. Communities from forested and agricultural sites (pond type) were also compared in a factorial design with treatments. We found that sheep-simulated trampling and nutrient input decreased hatching invertebrate and plant richness, while lasting effects on water quality and actively colonising communities were limited. Temporary pond communities from forested and agricultural sites differed in species composition and interacted with treatments in their effects on hatching crustaceans and macrophyte species composition. Treatments had a larger effect on the species composition of forest ponds compared to agricultural ponds. These results highlight the complex effects livestock may have on aquatic communities. Water quality, taxonomic groups, and trophic levels responded negatively to trampling and waste treatments and these responses changed with pond type. With worldwide declines of seasonal wetland habitat, the effects of land use (i.e. livestock grazing) on these ecosystems and their biota are important to consider for integrated and sustainable management.

A More Effective Ramsar Convention for the Conservation of Mediterranean Wetlands

Fri, 15 Feb 2019 10:48:59

de Ilse R. Geijzendorffer, Coralie Beltrame, Laurent Chazee, Elie Gaget, Thomas Galewski, Anis Guelmami, Christian Perennou, Nadège Popoff, Carlos A. Guerra, Roxanne Leberger, et al.
In Frontiers in Ecology and Evolution, 7 (February, 2019)
En ligne : www.frontiersin.org[...]

The Ramsar Convention is the multilateral agreement aimed at protecting wetlands globally. Wetlands are particularly recognized for their role in the Mediterranean biodiversity hotspot by providing key habitats for endemic and migratory species, directly contributing benefits to the lives of people and being an integral part of their culture. In response to this importance, the Mediterranean Wetlands Observatory publishes Mediterranean Wetland Outlooks on the state and trends of Mediterranean wetlands; the first edition in 2012 (MWO1) and the second edition in 2018 (MWO2). In this paper, we used the results of the two Mediterranean Wetland Outlooks to highlight ways to increase the impact of the Ramsar Convention by identifying the spatial dimensions of detected biodiversity trends as well as the societal developments and estimated impacts of global change and protection status.

Global patterns in the metacommunity structuring of lake macrophytes: regional variations and driving factors

Tue, 6 Nov 2018 10:16:26

de Janne Alahuhta, Marja Lindholm, Claudia P. Bove, Eglantine Chappuis, John Clayton, Mary de Winton, Tõnu Feldmann, Frauke Ecke, Esperança Gacia, Patrick Grillas, et al.
In Oecologia, 188(4) (October, 2018), 16
En ligne : link.springer.com[...]

We studied community–environment relationships of lake macrophytes at two metacommunity scales using data from 16 regions across the world. More specifically, we examined (a) whether the lake macrophyte communities respond similar to key local environmental factors, major climate variables and lake spatial locations in each of the regions (i.e., within-region approach) and (b) how well can explained variability in the community–environment relationships across multiple lake macrophyte metacommunities be accounted for by elevation range, spatial extent, latitude, longitude, and age of the oldest lake within each metacommunity (i.e., across-region approach). In the within-region approach, we employed partial redundancy analyses together with variation partitioning to investigate the relative importance of local variables, climate variables, and spatial location on lake macrophytes among the study regions. In the across-region approach, we used adjusted R2 values of the variation partitioning to model the community–environment relationships across multiple metacommunities using linear regression and commonality analysis. We found that niche filtering related to local lake-level environmental conditions was the dominant force structuring macrophytes within metacommunities. However, our results also revealed that elevation range associated with climate (increasing temperature amplitude affecting macrophytes) and spatial location (likely due to dispersal limitation) was important for macrophytes based on the findings of the across-metacommunities analysis. These findings suggest that different determinants influence macrophyte metacommunities within different regions, thus showing context dependency. Moreover, our study emphasized that the use of a single metacommunity scale gives incomplete information on the environmental features explaining variation in macrophyte communities.

Oviposition plant choice maximizes offspring fitness in an aquatic predatory insect

Fri, 8 Jun 2018 12:18:40

de Philippe Lambret, Imogen Rutter, Patrick Grillas, Robby Stoks
In Hydrobiologia, 10.1007/s10750-018-3507-1 (May 2018), 1-12
En ligne : link.springer.com[...]

Evidence for the adaptive value of oviposition site selection in terms of increased offspring fitness is rare in predatory insects. We tested this in the damselfly Lestes macrostigma that prefers the plant Bolboschoenus maritimus. We carried out two experiments with shoots containing eggs: we flooded (1) some shoots of the same type (i.e. combination of species and desiccation state) at different dates and (2) different shoot types at the same date. Earlier flooding increased hatching success. Because B. maritimus grows in deeper parts of temporary ponds, it is flooded before other plants after the drought season, suggesting that adult oviposition site selection is driven by lower egg desiccation risk. Independently of flooding date, hatching success was higher and larvae hatched earlier when eggs were laid in B. maritimus. Faster embryonic development enhances chances to complete larval development before pond desiccation and reduces costs associated with time stress. Offspring higher fitness was more constant between shoots of B. maritimus compared to the other types of shoot, suggesting that laying eggs in one shoot of this plant leads offspring to high fitness more surely. Our results indicate that adults choose oviposition plants maximizing offspring fitness (higher hatching success and faster embryonic development).

Diversity and Distribution of Characeae in the Maghreb (Algeria, Morocco, Tunisia)

Tue, 29 Aug 2017 15:58:46

de Serge D. Muller, Laïla Rhazi, Ingeborg Soulie-Märsche, Mohamed Benslama, Marion Bottollier-Curtet, Amina Daoud-Bouattour, Gérard De Belair, Zeineb GHRABI-GAMMAR, Patrick Grillas, Laure Paradis, et al.
In Cryptogamie, Algologie, 38(3) (August 1, 2017), 201-251
En ligne : www.bioone.org[...]

Characeae are macroscopic green algae present in the Maghreb (Morocco, Algeria, Tunisia) that are known since the 19 century works of Desfontaines (1800) and Braun (1868). Feldmann (1946) published the first regional synthesis, and this study provides a new Maghreb-wide synthesis of all collections made since 1784 (570 observations distributed over 464 sites). Each of the 31 reported species is described in detail with its diagnostic features, ecology and distribution in the three Maghrebian countries. Distribution maps distinguish between the three collection periods: 1780–1939, 1940–1979, and 1980–2016. An illustrated key is provided to help botanists working in the Maghreb to identify the taxa. From a biogeographical perspective, the Characean flora of the Maghreb is dominated by elements originating from northern (European) countries (61.3%) that include regionally very rare species such as Chara strigosa and C. tomentosa. The Mediterranean-Atlantic element is also well represented (32.3%), with some Mediterranean endemics (Chara imperfecta, C. oedophylla, C. vulgaris var. gymnophylla). Finally, two taxa that have an affinity for tropical conditions (Chara zeylanica and Lamprothamnium succinctum) extend to the southern Sahara. In North Africa, 14 species (7 Chara, 2 Lamprothamnium, 4 Nitella and 1 Sphaerochara) are threatened and raise issues about their conservation; three of these are particularly endangered: Chara imperfecta, C. oedophylla and Lamprothamnium papulosum.

Global variation in the beta diversity of lake macrophytes is driven by environmental heterogeneity rather than latitude

Fri, 11 Aug 2017 09:19:00

de Janne Alahuhta, Sarian Kosten, Munemitsu Akasaka, Dominique Auderset, Mattia M. Azzella, Rossano Bolpagni, Claudia P. Bove, Patricia A. Chambers, Eglantine Chappuis, John Clayton, et al.
In Journal of Biogeography, 44(8) (AUG 2017), 1758-1769
En ligne : doi.org[...]

We studied global variation in beta diversity patterns of lake macrophytes using regional data from across the world. Specifically, we examined (1) how beta diversity of aquatic macrophytes is partitioned between species turnover and nestedness within each study region, and (2) which environmental characteristics structure variation in these beta diversity components. Location Global. Methods We used presence-absence data for aquatic macrophytes from 21 regions distributed around the world. We calculated pairwise-site and multiple-site beta diversity among lakes within each region using SOrensen dissimilarity index and partitioned it into turnover and nestedness coefficients. Beta regression was used to correlate the diversity coefficients with regional environmental characteristics. Results Aquatic macrophytes showed different levels of beta diversity within each of the 21 study regions, with species turnover typically accounting for the majority of beta diversity, especially in high-diversity regions. However, nestedness contributed 30-50% of total variation in macrophyte beta diversity in low-diversity regions. The most important environmental factor explaining the three beta diversity coefficients (total, species turnover and nestedness) was elevation range, followed by relative areal extent of freshwater, latitude and water alkalinity range. Main conclusions Our findings show that global patterns in beta diversity of lake macrophytes are caused by species turnover rather than by nestedness. These patterns in beta diversity were driven by natural environmental heterogeneity, notably variability in elevation range (also related to temperature variation) among regions. In addition, a greater range in alkalinity within a region, likely amplified by human activities, was also correlated with increased macrophyte beta diversity. These findings suggest that efforts to conserve aquatic macrophyte diversity should primarily focus on regions with large numbers of lakes that exhibit broad environmental gradients.

Plant community patterns in Moroccan temporary ponds along latitudinal and anthropogenic disturbance gradients

Tue, 29 Aug 2017 15:57:17

de Mohammed El Madihi, Laïla Rhazi, Maarten Van den Broeck, Mouhssine Rhazi, Aline Waterkeyn, Er-riyahi Saber, Siham Bouahim, Moustapha Arahou, Abdelmajid Zouahri, Anis Guelmami, et al.
In Plant Ecology & Diversity, 10(1) (2017-07-24), 1-19
En ligne : www.tandfonline.com[...]

Background: Temporary ponds, an abundant habitat in the Maghreb region and notably in Morocco, have a high conservation value. However, they are mainly known from the north of the country.
Aims: The aim of this work was to characterise the vegetation of Moroccan temporary ponds along a combined gradient of latitude and anthropogenic pressure.
Methods: Eighty-five ponds distributed along a north–south gradient of 750 km were sampled. For each pond, all vegetation was surveyed (flooded and dry parts) and the local abiotic characteristics were measured during two successive hydrological cycles. The prevailing anthropogenic pressures were also identified and were attributed an impact score.
Results: Eighty-one characteristic pond species (including 17 rare species) were recorded, with several new distribution data in the southern part of the latitudinal gradient. Plant communities were related to climatic and anthropogenic factors, but mostly to local factors, such as maximum water depth and soil pH. The northern ponds (wettest macroclimate) were rich in characteristic species and rare species, while the southern (driest macroclimate) ponds were more species poor.
Conclusions: In addition to the direct impact of increasing human activity, a further reduction of the floristic richness of temporary ponds is expected due to climatic changes. This is particularly the case for characteristic species which have a high conservation value.

Experimental test of the ecosystem impacts of the keystone predator Triops cancriformis (Branchiopoda: Notostraca) in temporary ponds

Fri, 14 Oct 2016 14:38:41

de Aline Waterkeyn, Patrick Grillas, Luc Brendonck
In Freshwater Biology, 61(9) (September 2016), 1392-1404
En ligne : onlinelibrary.wiley.com[...]

Keystone species can influence an ecosystem through a series of trophic (both direct and indirect) and non-trophic effects. In temporary ponds, tadpole shrimps were recently identified as keystone predators, but the full extent of their ecosystem impact is still poorly known.
Using a large-scale mesocosm experiment, we quantified the impact of different Triops cancriformis densities on ecosystem properties: water quality (including chlorophyll a as measure for phytoplankton biomass) and the diversity and structure of macrophyte and zooplankton communities. Mesocosms of 400 L (1 m2 surface) were lined with natural pond sediment of two study ponds differing in their natural Triops densities (Triops-rich and Triops-poor pond) and inundated to allow hatching from the egg bank. Afterwards, four Triops density treatments were established in the mesocosms: 0 (control), 5, 25 and 100 Triops per m2.
After 13 weeks, the two highest Triops densities significantly influenced the ecosystem functioning not only by triggering changes in the diversity and composition of the pond communities but also by affecting water quality through bioturbation.
These results confirm that tadpole shrimp can function as ecosystem engineers in temporary ponds and could promote a shift from a clear water to a turbid state through a series of trophic and non-trophic level effects.

Assessing the ecological integrity of endorheic wetlands, with focus on Mediterranean temporary ponds

Fri, 29 Nov 2019 16:04:37

de Maarten Van den Broeck, Aline Waterkeyn, Laïla Rhazi, Patrick Grillas, Luc Brendonck
In Ecological Indicators, 54 (July, 2015), 1-11
En ligne : linkinghub.elsevier.com[...]

EU countries are required to perform an assessment of all freshwater habitats larger than 50 ha by 2015 to meet the requirements set by the Water Framework Directive (2000). To achieve this, an array of indicators and multimetric indices has been developed to monitor European waters. In general, these indicators are developed for large water bodies, while they are still largely lacking for smaller wetlands. This is in contrast with the conservation value, valuable ecosystem services and the often unique biodiversity of these systems, and the fact that like large (>50 ha) wetlands they are also covered by the Ramsar Convention. In (semi) arid regions, such as the Mediterranean basin, small water bodies are often of a temporary nature, are abundant and provide an important source of water for the local people, their livestock and agriculture. The quantity and quality of temporary wetlands are, however, decreasing at an alarming rate worldwide. Although some monitoring techniques were recently proposed, there is still an urgent need for a consistent policy and a user friendly set of monitoring tools for temporary wetlands that can be applied in different regions. In the following review, we present a whole range of indicators used to monitor different types of freshwater habitats, and discuss how some of these methods could be applied to temporary wetlands. Finally, we formulate some recommendations for temporary wetland monitoring and conservation.

Unravelling the impact of anthropogenic pressure on plant communities in Mediterranean temporary ponds (2014)

Mon, 26 Oct 2015 10:02:30

de S. Bouahim, Laïla Rhazi, B. Amami, A. Waterkeyn, M. Rhaszi, Patrick Grillas
2014

Expected and unexpected effects of waterbirds on Mediterranean aquatic plants (2012)

Mon, 26 Oct 2015 10:05:24

de G. Gayet, N. Croce, Patrick Grillas, C. Nourry, Clemence Deschamps, P. Defos Du Rau
2012

Long-term trends in the abundance of Mediterranean wetland vertebrates: From global recovery to localized declines

Thu, 26 Oct 2017 11:18:14

de Thomas Galewski, Ben Collen, Louise McRae, Jonathan Loh, Patrick Grillas, Michel Gauthier-Clerc, Vincent Devictor
In Biological Conservation, 144(5) (MAY 2011), 1392-1399

Biodiversity loss is unevenly distributed in space and time. Species have reached critically low population sizes in some areas, and remain abundant in others. Similarly, some species may benefit from successful conservation plans, while others still experience severe population depletions driven by negative impacts of human activities. Although several indicators have been proposed to measure the fate of biodiversity, they are generally only implemented globally so their relevance for regional assessment is still unclear. Here, we calculated the first regional trend in the Living Planet Index for the Mediterranean wetlands (Med LPI), an indicator that summarizes the fate of global biological diversity based on the temporal trends in abundance of vertebrate populations. The Med LPI was based on 1641 vertebrate populations of 311 species recorded in Mediterranean wetlands from 1970-2008, in 27 different countries. We investigated whether trends in the Med LPI differed between eastern and western Mediterranean countries, which have different socio-economic contexts. Finally, we assessed whether and how the trend in the Med LPI was robust to changes in the number and identity of species considered. We found that, at the Mediterranean scale, the Med LPI increased steeply, which could be taken at first sight, as a general recovery of wetland biodiversity in this biogeographical region. However, we found highly contrasting spatial trends within the Mediterranean region: the average trend was positive for western and negative for eastern countries. Moreover, we showed that depending on the method used to estimate the trend in Med LPI, it can be sensitive to the number and identity of the species considered. We suggest that understanding the regional discrepancies of the trend in biodiversity indicators as well as their robustness to the species represented in the index will enhance progress assessment towards global and regional conservation strategies. (C) 2011 Elsevier Ltd. All rights reserved.

Can large branchiopods shape microcrustacean communities in Mediterranean temporary wetlands?

Fri, 9 Apr 2021 18:18:04

de Aline Waterkeyn, Patrick Grillas, Maria Anton-Pardo, Bram Vanschoenwinkel, Luc Brendonck, Aline Waterkeyn, Patrick Grillas, Maria Anton-Pardo, Bram Vanschoenwinkel, Luc Brendonck
In Marine and Freshwater Research, 62(1) (February, 2011), 46-53
En ligne : www.publish.csiro.au[...]

It was recently suggested that large branchiopods may play a keystone role in temporary aquatic habitats. Using a microcosm experiment manipulating microcrustacean communities of Mediterranean temporary wetlands (Camargue, Southern France), we tested the following hypotheses: (i) large branchiopods (the notostracan Triops cancriformis and the anostracan Chirocephalus diaphanus) can limit microcrustacean densities through both competition and predation; (ii) notostracans create high suspended-matter concentrations through bioturbation, which can negatively impact microcrustaceans; and (iii) the outcome of these biotic interactions is more detrimental at high salinities. We found a strong predatory impact of T. cancriformis on active microcrustacean populations, but also on dormant populations through the consumption of resting eggs. They also preyed on anostracans and their conspecifics and can indirectly have a negative effect on microcrustaceans through bioturbation, probably by impeding filtering capacities. The presence of C. diaphanus also limited most microcrustacean groups, probably through competition and/or predation. We did not find a significant effect of the tested salinity range (0.5–2.5 g L–1) on the biotic interactions. Our study shows that large branchiopods can shape microcrustacean communities under a wide range of environmental conditions and confirms their potential for a keystone role, especially one of notostracans as top predators.

Post-disturbance dynamics of plant communities in a Mediterranean temporary pool (Western Morocco): Effects of disturbance size (2011)

Mon, 26 Oct 2015 10:03:19

de N. Sahib, Laïla Rhazi, Patrick Grillas
2011

Long-term effects of salinity and disturbance regime on active and dormant crustacean communities (2011)

Mon, 26 Oct 2015 10:02:43

de A. Waterkeyn, B. Vanschoenwinkel, H. Vercampt, Patrick Grillas, L. Brendonck
2011

Invertebrate dispersal by aquatic mammals: a case study with nutria Myocastor coypus (Rodentia, Mammalia) in Southern France

Fri, 8 Jun 2018 12:12:17

de Aline Waterkeyn, Olivier Pineau, Patrick Grillas, Luc Brendonck
In Hydrobiologia, 654(1) (OCT 2010), 267-271

Many freshwater invertebrates rely on vectors for their passive dispersal. A wide array of vectors has already been investigated, but dispersal mediated by aquatic mammals remains largely unknown. Since nutria (Myocastor coypus Molina, 1782) live in a variety of aquatic habitats and frequently move around between these water bodies, they have the opportunity to transport hitch-hiking aquatic invertebrates along with them. We investigated the presence of aquatic invertebrates in their fur to evaluate this hypothesis. This study demonstrates the feasibility of ectozoochory in a broad array of freshwater invertebrates by nutria on a local scale. More than 800 invertebrates of 14 different taxa were retrieved from the fur of 10 nutria specimens, including cladocerans, copepods, ostracods, rotifers, bryozoans, dipterans, nematodes, annelids and collembolans. Many of these freshwater invertebrates could survive at least 30 min in the moist fur of nutria. Therefore, we can state that besides modifying aquatic habitats physically by clearing vegetation or digging, nutria may also alter invertebrate communities by introducing new species or genotypes.

Numerical modelling of vertical suspended solids concentrations and irradiance in a turbid shallow system (Vaccares, Se France)

Fri, 8 Jun 2018 12:15:52

de Bertrand Millet, Christian Robert, Patrick Grillas, Clare Coughlan, Damien Banas
In Hydrobiologia, 638(1) (JAN 2010), 161-179

In shallow ecosystems, the short temporal variability of available underwater irradiance is considered a major process controlling submerged macrophytes development. Mechanistic models that estimate photosynthetically available radiation (PAR) in shallow ecosystems at very short time scales are needed for use in predicting submerged macrophyte growth and persistence. We coupled a 2D horizontal circulation model with, first, a 1D vertical numerical model of suspended solid (SS) re-suspension, diffusion and settling, and next, with a model of vertical extinction of irradiance, previously validated at the same site. The study site was the VaccarSs lagoon (France) where a large data set of high frequency bottom irradiance and SS concentration were available. SS and irradiance measurements were conducted at a vertical study station, monitored over a 6 month period (from December 1995 to May 1996) characterized by wide-ranging wind velocities (1.5-18 ms(-1)). In addition, grain-size analyses conducted over the whole lagoon, allowed adaptation of the 1D numerical model to the silt-sized (7 mu m) and clay-sized (0.3 mu m) fractions that prevail in the local sediment. First, model results showed that about 60% of the variance in bottom irradiance time series can be explained by our deterministic formulations, thus representing the same level of efficiency than those already obtained by a stochastic model previously developed with the same data set. Second, model results showed that the fit of the model to the field data (SS concentrations and bottom irradiance) depended mainly on storm occurrence and season (winter or spring). Finally, model results suggested that the underwater irradiance regime was controlled by seasonal succession of the horizontal circulation of turbid water in the lagoon, with increased solids concentrations in winter, followed by submerged canopy development and decreased solids concentrations in spring.

Recolonisation of disturbed micro-sites in temporary ponds in Western Morocco (2010)

Mon, 26 Oct 2015 10:07:09

de B. Amami, Laïla Rhazi, S. Bouahim, Patrick Grillas, Mouhssine Rhazi
2010

Impact of grazing on the species richness of plant communities in Mediterranean temporary pools (western Morocco) (2010)

Mon, 26 Oct 2015 10:06:37

de S. Bouahim, Laïla Rhazi, B. Amami, N. Sahib, Mouhssine Rhazi, A. Waterkeyn, A. Zouahri, François Mesléard, Serge D. Muller, Patrick Grillas
2010

A preliminary assessment of Important Areas for Ponds (IAPs) in the Mediterranean Basin and Alpine Arc (2010)

Mon, 26 Oct 2015 10:05:38

de N. Ewald, P. Nicolet, B. Oertli, V. Della Bella, Laïla Rhazi, A.S. Reymond, E. Minssieux, E. Saber, Mouhssine Rhazi, J. Biggs, et al.
[S.l.] : European Pond Conservation Network EPCN Genève, 2010, 41p ill

Floristic richness and human activities in the temporary pools of Western Morocco (2010)

Mon, 26 Oct 2015 10:03:26

de Laïla Rhazi, Patrick Grillas, Mouhssine Rhazi
2010

Focus on temporary ponds in North Africa (2010)

Mon, 26 Oct 2015 10:03:26

de Laïla Rhazi, Patrick Grillas, Mouhssine Rhazi
2010

Inventory of temporary ponds in Western Morocco: a first in North Africa (2010)

Mon, 26 Oct 2015 10:03:20

de E.R. Saber, Mouhssine Rhazi, Laïla Rhazi, Patrick Grillas, J.L. Ballais
2010

Impacts of physical soil disturbance on plant communities in temporary ponds in Morocco (2010)

Mon, 26 Oct 2015 10:03:19

de N. Sahib, Laïla Rhazi, Patrick Grillas, Mouhssine Rhazi
2010

Effect of salinity on seasonal community patterns of Mediterranean temporay wetlands crustaceans: a mesocosm study (2010)

Mon, 26 Oct 2015 10:02:43

de A. Waterkeyn, B. Van Schoenwinkel, Patrick Grillas, L. Brendonck
2010

Unintentional dispersal of aquatic invertebrates via footwear and motor vehicles in a Mediterranean wetland area (2010)

Mon, 26 Oct 2015 10:02:43

de A. Waterkeyn, B. Vanschoenwinkel, S. Elsen, M. Anton-pardo, Patrick Grillas, L. Brendonck
2010

Vegetation recolonisation of a Mediterranean temporary pool in Morocco following small-scale experimental disturbance

Fri, 8 Jun 2018 14:50:40

de Btissam Amami, Laïla Rhazi, Siham Bouahim, Mouhssine Rhazi, Patrick Grillas
In Hydrobiologia, 634(1) (NOV 2009), 65-76

Disturbances are key factors in the dynamics and species richness of plant communities. They create regeneration niches allowing the growth of new individuals in patches submitted to lower intensity of competition. In Mediterranean temporary pools, the intense summer drought constitutes for communities a large-scale disturbance whose intensity varies along the topographical and hydrological gradient between the centre and the edges. In this context, the importance of small-scale disturbance, such as those created by trampling and rooting herbivores in temporary pools, is poorly known. The recolonisation of small bare patches of a woodland temporary pool in western Morocco was studied experimentally in the field. The experiment was carried out using nine small control plots and nine experimental plots (sterilisation of the soil) distributed along the topographical gradient (centre, intermediate and edge zones). The area covered by plant species, and the water levels, were recorded for the plots over two successive hydrological cycles (2006/2007 and 2007/2008). The effects of natural history traits (size of seeds, presence or absence of dispersal mechanisms and annual/perennial) on the success of recolonisation of individual species were analysed. The results show that the experimental plots were rapidly recolonised. The community composition apparently was affected by the very dry conditions during the first year of the experiment, when annual species were largely absent and the clonal perennial species (Bolboschoenus maritimus and Eleocharis palustris) were dominant in the centre and intermediate zones, whilst not a single species colonised the edge zone. In the second year, less dry hydrological conditions allowed annual plants to appear in all three zones. After 2 years, the species composition of the vegetation in the experimental plots was similar to that of the unsterilised (control) plots. The abundance of plants in the centre zone was identical for experimental and control plots; in the intermediate and edge zones, the species' abundance was lower in the experimental plots than in the control plots, suggesting an incomplete return to the reference condition (control state). Differences in abundance of species were uncorrelated with the size of seeds or to the annual/perennial nature of the plants, but were particularly dependent on the hydrological conditions, which favoured lateral colonisation by perennials (runners, rhizomes). These results show that recovery from the minor disturbances can be rapid in Mediterranean temporary pools.

Ten-year dynamics of vegetation in a Mediterranean temporary pool in western Morocco

Fri, 8 Jun 2018 14:45:37

de Laïla Rhazi, Patrick Grillas, Mouhssine Rhazi, Jean-Christophe Aznar
In Hydrobiologia, 634(1) (NOV 2009), 185-194

The aim of this work was to test the hypotheses that the species composition of the vegetation of one pool in Morocco change continuously along with rainfall fluctuations, that among the vegetation can be recognized Pool species and Opportunistic species with distinct dynamics in time. We expected the Pool species to show lower inter-annual variation than the Opportunistic species. This hypothesis was tested in a 10-year study of the species composition of the vegetation along two permanent transects. The results showed high cumulative species richness (95 species) with large differences between years and a predominance of annual species (77). The proportion of Pool species during these 10 years was low (39%) when compared to opportunists (61%). In dry years the Opportunistic species were dominant and declined during wet years. The number of Pool species was correlated with the amount of rainfall. A large number of these species revealed a preference for wet years. No negative interaction between annuals/perennials and pools/non-pools species was found, suggesting that competition was not a major process during the survey. The intensity of the drought and flood stress, related to climate fluctuations, seems to be the main factors controlling the species composition of the vegetation of this unstable habitat. However, beyond the inter-annual fluctuation of the species composition of the vegetation a directional change was noticed. This directional change could result from a recovery process of the vegetation during the first years of the study after a severe flood which extirpated most of the Opportunistic species of the pool. In the last years this directional change of the species composition of the vegetation is less clear and random recruitment of the Opportunistic species from the surrounding forested habitats could contribute to explain inter-annual changes. The data collected over these 10 years led to the speculation of hypotheses on the consequences of climate change. The expected reduction of humid years and of rainfall regionally may lead to important changes in the species composition of the vegetation of the temporary pools in Morocco.

Experimental study of the effect of hydrology and mechanical soil disturbance on plant communities in Mediterranean temporary pools in Western Morocco

Fri, 8 Jun 2018 14:43:40

de Nargis Sahib, Laïla Rhazi, Mouhssine Rhazi, Patrick Grillas
In Hydrobiologia, 634(1) (NOV 2009), 77-86

Physical soil disturbance and the hydrology of temporary pools affect the biomass, species composition and richness of plant communities. Disturbance liberates sites for the random recruitment of new individuals. The addition of seeds modifies the structure of the communities. In order to verify these hypotheses concerning the vegetation of temporary pools, an experiment was carried out using 72 soil samples collected from a pool in Western Morocco and placed in containers. Three types of laboratory treatments were applied, each combined with control treatments: soil disturbance (control/disturbed), hydrology (flooded, saturated and dry) and seed addition (sowing/no sowing). The total biomass, the annual and perennial species richness were calculated for each sample to test the effects of disturbance, hydrology and seed addition on the biomass and species richness of the various plant communities. The results show that disturbance reduces the total biomass, especially of perennials, but without significantly increasing the richness of annuals. Seed addition does not affect the total biomass and reduces total richness only in saturated soil, where biomass production is high. The most extreme stress conditions (drought and flooding) limit the abundance of species and therefore competition.

Competition in microcosm between a clonal plant species (Bolboschoenus maritimus) and a rare quillwort (Isoetes setacea) from Mediterranean temporary pools of southern France

Fri, 8 Jun 2018 14:41:57

de Mouhssine Rhazi, Patrick Grillas, Laïla Rhazi, Anne Charpentier, Frederic Medail
In Hydrobiologia, 634(1) (NOV 2009), 115-124

Bolboschoenus maritimus, a clonal species, is locally invasive in Mediterranean temporary pools where it threatens endangered rare plant species such as Isoetes setacea. The combination of management modifications (grazing) and of the progressive accumulation of fine sediments in the pools contributed to the establishment of competitive perennial plants such as B. maritimus. The competitive advantage of B. maritimus on I. setacea has been studied in controlled conditions. The goal of this experiment was to assess the role of environmental conditions in the output of the competition between Bolboschoenus and Isoetes, notably hydrology and soil richness. For this purpose, Isoetes was cultivated alone (three individuals/pot) and with Bolboschoenus (three individuals of both species). The experiment was run with five replicates on six types of sediment (gradient of richness in sand/silt/clay) combined with three hydrological treatments (flooded, wet. and dry). The competitive advantage of Bolboschoenus was measured as the ratio of the production of Isoetes in mixture versus monoculture. The results showed that Isoetes was always outcompeted by Bolboschoenus. However, the competitive advantage of Bolboschoenus on Isoetes, was more related to hydrology than to soil richness. The competitive advantage of Bolboschoenus was very high in wet and flooded conditions and very low in dry conditions. This situation may lead to the extinction, medium-term, of the populations of I. setacea. The introduction of ovine grazing or of cut back practices in temporary pools could reduce the B. maritimus biomass and help toward the conservation of I. setacea populations.

Ten-years dynamics of vegetation in a Mediterranean temporary pool in western Morocco (2009)

Mon, 26 Oct 2015 10:03:26

de Laïla Rhazi, Patrick Grillas, Mouhssine Rhazi, C. Aznar
2009

Rice fields regulate organochlorine pesticides and PCBs in lagoons of Nature Reserve of Camargue (2009)

Mon, 26 Oct 2015 10:03:24

de H. Roche, Y. Vollaire, E. Martin, C. Rouer, E. Coulet, Patrick Grillas, D. Banas
2009

Assemblage structure and dynamics of large branchiopods in Mediterranean temporary wetlands: patterns and processes (2009)

Mon, 26 Oct 2015 10:02:44

de A. Waterkeyn, Patrick Grillas, E.R.M. De Roeck, L. Boven, L. Brendonck
2009

Recolonisation des micro-sites perturbés dans les mares temporaires du Maroc occidental (2008)

Mon, 26 Oct 2015 10:07:09

de B. Amami, Laïla Rhazi, S. Bouahim, Patrick Grillas, Mouhssine Rhazi
2008

La perception des mares temporaires par la population locale du Maroc occidental (2008)

Mon, 26 Oct 2015 10:06:37

de S. Bouahim, Laïla Rhazi, B. Amami, Raphael Mathevet, Lisa Ernoul, Patrick Grillas, A. Khattabi
2008

Les zones humides temporaires méditerranéennes et les changements climatiques (2008)

Mon, 26 Oct 2015 10:05:13

de Patrick Grillas
2008

Pond conservation in Europe: the European Pond Conservation Network (EPCN) (2008)

Mon, 26 Oct 2015 10:04:46

de N. Indermuehle, B. Oertli, J. Biggs, R. Cereghino, Patrick Grillas, A. Humm, P. Nicolet, O. Scher
2008

Long-term dynamics of a Mediterranean alkaline vernal pool (Rhône delta, southern France) (2008)

Mon, 26 Oct 2015 10:03:54

de Serge D. Muller, H. Bruneton, I. Soulie-märsche, T. Rey, A. Thiery, A. Waterkeyn, L. Brendonck, P. Schevin, Nicole Yavercovski, Patrick Grillas
2008

Les mares temporaires du Maroc et les changements climatiques (2008)

Mon, 26 Oct 2015 10:03:27

de Laïla Rhazi, Patrick Grillas, Mouhssine Rhazi
2008

Richesse floristique et activités humaines dans les mares temporaires du Maroc occidental (2008)

Mon, 26 Oct 2015 10:03:27

de Laïla Rhazi, Patrick Grillas, Mouhssine Rhazi
2008

Zoom sur les mares temporaires d'Afrique du Nord (2008)

Mon, 26 Oct 2015 10:03:27

de Laïla Rhazi, Patrick Grillas, Mouhssine Rhazi
2008

Les mares temporaires du Maroc et les changements climatiques (2008)

Mon, 26 Oct 2015 10:03:26

de Laïla Rhazi, Patrick Grillas, Mouhssine Rhazi
2008

Impact des perturbations physiques du sol sur les communautés de plantes dans les mares temporaires du Maroc occidental (2008)

Mon, 26 Oct 2015 10:03:19

de N. Sahib, Laïla Rhazi, Patrick Grillas, Mouhssine Rhazi
2008

Dispersal of freshwater invertebrates by large terrestrial mammals: a case study with wild boar (Sus scrofa) in Mediterranean wetlands (2008)

Mon, 26 Oct 2015 10:02:49

de B. Vanschoenwinkel, A. Waterkeyn, T. Vandecaetsbeek, Olivier Pineau, Patrick Grillas, L. Brendonck
2008

Invertebrate community patterns in Mediterranean temporary wetlands along hydroperiod and salinity gradients (2008)

Mon, 26 Oct 2015 10:02:44

de A. Waterkeyn, Patrick Grillas, B. Vanschoenwinkel, L. Brendonck
2008

Richness and structure of plant communities in temporary pools from western Morocco: influence of human activities (2006)

Mon, 26 Oct 2015 10:03:26

de Laïla Rhazi, Mouhssine Rhazi, Patrick Grillas, D. El Khyari
2006

Short time scale changes in underwater irradiance in a wind-exposed lagoon (Vaccarès lagoon, France): efficiency of infrequent field measurements of water turbidity or weather data to predict irradiance in the water column (2005)

Mon, 26 Oct 2015 10:06:58

de D. Banas, Patrick Grillas, I. Auby, F. Lescuyer, E. Coulet, J.C. Moreteau, B. Millet
2005

Spatio-temporal dynamics of a Zostera noltii dominated community over a period of fluctuating salinity in a shallow lagoon, Southern France (2005)

Mon, 26 Oct 2015 10:06:18

de Anne Charpentier, Patrick Grillas, F. Lescuyer, E. Coulet, I. Auby
2005

Conservation and monitoring of pond biodiversity: introduction (2005)

Mon, 26 Oct 2015 10:03:49

de B. Oertli, J. Biggs, R. Cereghino, Patrick Grillas, P. Joly, J.B. Lachavanne
2005

Consequences of shrub clearing on the richness of aquatic vegetation in oligotrophic seasonal pools in Southern France (2005)

Mon, 26 Oct 2015 10:03:26

de Mouhssine Rhazi, Patrick Grillas, F. Medail, Laïla Rhazi
2005

Conséquences des changements hydrologiques sur le fonctionement biologique d'une lagune (2004)

Mon, 26 Oct 2015 10:05:13

de Patrick Grillas, Anne Charpentier, P. Chauvelon, Alain Jean Crivelli, A. Sandoz, F. Lescuyer, E. Coulet
2004

Experimental management of Mediterranean temporary pools for conservation of the rare quillwort Isoetes setacea (2004)

Mon, 26 Oct 2015 10:03:26

de Mouhssine Rhazi, Patrick Grillas, Anne Charpentier, F. Medail
2004

Association between aquatic vegetation and landscape indicators of human pressure (2003)

Mon, 26 Oct 2015 10:07:01

de J.C. Aznar, A. Dervieux, Patrick Grillas
2003

Deposition, germination and spatio-temporal patterns of charophyte propagule banks: a review (2002)

Mon, 26 Oct 2015 10:06:39

de A. Bonis, Patrick Grillas
2002

Flore des plantes vasculaires de Camargue: résultat d'observations réalisées au printemps 2001 (2002)

Mon, 26 Oct 2015 10:04:08

de M. Mary, L. Desnouhes, H. Michaud, N. Yaverkovski, Patrick Grillas
2002

Quels objectifs de restauration pour un ancien polder de la basse vallée du Vistre? (2002)

Mon, 26 Oct 2015 10:04:06

de André Mauchamp, Patrick Grillas
2002

Restoration of floodplain wetlands: opening polders along a coastal river in Mediterranean France, Vistre marshes (2002)

Mon, 26 Oct 2015 10:04:06

de André Mauchamp, P. Chauvelon, Patrick Grillas
2002

Multilocus genetic structure at contrasted spatial scales of the endangered water fern Marsilea strigosa Willd. (Marsieaceae, Pteridophyta) (2002)

Mon, 26 Oct 2015 10:02:47

de R. Vitalis, M. Riba, B. Colas, Patrick Grillas, I. Olivieri
2002

The seed bank and the between years dynamics of the vegetation of a Mediterranean temporary pool (NW Morocco)

Thu, 7 Jun 2018 09:43:31

de L. Rhazi, Patrick Grillas, L. Tan Ham, D. El Khyari
In Ecologia Mediterranea, 27(1) (2001), 69-88
En ligne : ecologia-mediterranea.univ-avignon.fr[...]

Effects of submergence on the growth of Phragmites australis seedlings (2001)

Mon, 26 Oct 2015 10:04:06

de André Mauchamp, S. Blanch, Patrick Grillas
2001

Impact of land use in catchment and human activities on water, sediment and vegetation of Mediterranean temporary pools (2001)

Mon, 26 Oct 2015 10:03:26

de Laïla Rhazi, Patrick Grillas, A.M. Toure, L. Tan Ham
2001

La végétation et les caractéristiques de l’eau et du sédiment ont été étudiées au Maroc pendant deux cycles hydrologiques (1997–1998 et 1998–1999), dans dix mares temporaires soumises à des perturbations anthropiques variées. Les résultats des analyses multivariées et paramétriques montrent que les perturbations avaient un impact significatif sur l’eau et le sédiment. L’agriculture dans le bassin versant conduisait à des teneurs fortes en azote et l’utilisation de lessives à des teneurs fortes en phosphore dans l’eau et le sédiment. L’extraction de minéraux conduisait à des profondeurs et des durées d’inondation supérieures. Les caractéristiques de la végétation étaient mieux corrélées aux variables hydrologiques (durée et hauteur d’inondation) qu’aux variables trophiques. Ces résultats suggèrent que l’agriculture dans le bassin versant contribue à modifier le sédiment mais son impact sur la conservation est limité. Toutefois l’attention devrait porter sur les effets à long terme de l’agriculture à travers les effets cumulatifs et sur les conséquences possibles des changements dans les pratiques agricoles.

The effects of population size limitation on fecundity in mosaic populations of the clonal macrophyte Scirpus maritimus (Cyperaceae) (2000)

Mon, 26 Oct 2015 10:06:18

de Anne Charpentier, Patrick Grillas, J.D. Thompson
2000

Spatial dynamics of Zostera noltii over a 5-year period of fluctuating salinity in the Vaccarès lagoon, France (2000)

Mon, 26 Oct 2015 10:05:13

de Patrick Grillas, Anne Charpentier, I. Auby, F. Lescuyer, E. Coulet
2000

Effects of seasonal flooding and grazing on the vegetation of former ricefields in the Rhône delta (Southern France) (1999)

Mon, 26 Oct 2015 10:04:00

de François Mesléard, J. Lepart, Patrick Grillas, André Mauchamp
1999

Dynamique intra- et inter-annuelIe de la végétation dans les mares de la Réserve NaturelIe de Roque-Haute (Hérault, France): programme d'étude et résultats préliminaires

Thu, 7 Jun 2018 09:47:46

de Patrick Grillas, L. Tan Ham
In Ecologia Mediterranea, 24(2) (1998), 215-222
En ligne : ecologia-mediterranea.univ-avignon.fr[...]

Les mares temporaires méditerranéennes sont caractérisées par une grande richesse floristique et par la présence d'espèces rares. La végétation des mares temporaires a largement été décrite par de nombreux auteurs mais la dynamique et la dépendance de cette dynamique aux facteurs physiques et biotiques du milieu ont été peu étudiées. Les objectifs de ce projet sont d'étudier sur les mares de la Réserve Naturelle de Roque-Haute (1) la composition spécifique de la végétation des mares en relation avec le fonctionnement hydrologique intra- et inter-annuel des mares et (2) d'étudier l'impact de diverses perturbations sur la dynamique inter-annuelle de la végétation. La réserve contient environ 200 mares avec des caractéristiques hydrologiques et écologiques variées. Pendant la première phase de ce projet (3 ans), la dynamique intra- et inter-annuelle de la végétation sera étudiée sur un échantillon de 21 mares sur la Réserve Naturelle de Roque-Haute accompagnée par une étude hydrologique détaillée des mares et la mise au point d'un modèle hydrologique. La première phase a débuté en 1996 avec une mesure mensuelle de la végétation entre mai et août sur un échantillon de 21 mares sélectionnées en fonction d'une classification antérieure. Les résultats de la première année montrent que la richesse totale des mares n'était pas corrélée avec la longueur des transects ou avec le nombre de quadrats. La classification de Molina a été confirmée par l'analyse statistique multivariée des données floristiques. La composition spécifique de la végétation vivante s'est modifiée durant la période d'étude pendant que les mares s'asséchaient. La dynamique de la végétation et les facteurs de perturbation doivent être pris en compte dans la gestion du site afin de maintenir sa richesse floristique.

The role of water level and salinity in the regulation of Juncus gerardi populations in former ricefields in Southern France (1998)

Mon, 26 Oct 2015 10:06:18

de Anne Charpentier, François Mesléard, Patrick Grillas
1998

Restauration de la fonction de gagnage pour les anatidés (Anatidae) hivernants dans les friches rizicoles de Camargue (1998)

Thu, 1 Jan 1998 00:00:00

de C. Tourenq, François Mesléard, D. Roux, J.L. Lucchesi, Patrick Grillas
1998

Effects of drought and flooding on the reproduction of an amphibious plant, Ranunculus peltatus (1997)

Mon, 26 Oct 2015 10:02:46

de A. Volder, A. Bonis, Patrick Grillas
1997

Seed bank dynamics and coexistence of annual macrophytes in a temporary and variable habitat (1995)

Mon, 26 Oct 2015 10:06:39

de A. Bonis, J. Lepart, Patrick Grillas
1995

Effects on fisheries and waterbirds of raising water levels at Kerkini Reservoir, a Ramsar site in Northern Greece (1995)

Mon, 26 Oct 2015 10:06:02

de Alain Jean Crivelli, Patrick Grillas, H. Jerrentrup, T. Nazirides
1995

A new, higher dam was installed at Kerkini Reservoir in 1982, causing habitat and landscape disruption. A decrease in the area of grassland and shallow water areas, the rapid disappearance of reedbeds, the appearance of beds ofNymphaea, and the disappearance of half the forest area were all observed between 1982 and 1991. With the new hydrological regime, a lacustrine system was created, with an extensive, rather deep (4–8 m), pelagic zone favorable for the development of coarse fish species throughout the year. After 1982, an increase in fishing effort and a change in the relative abundance of fish species in the catch, including the disappearance of eels and wels, were observed. The impact of the rise in the water level of breeding aquatic birds led to a general decline in species typical of marshy habitats in favor of species preferring deeper open water habitats. A decrease was recorded in bird species that feed largely on invertebrates and to a lesser extent fish (e.g., glossy ibis) and that require extensive shallow feeding areas. There was a decline in geese, whose nests were regularly flooded, and a major increase in piscivorous birds, particularly diving birds (e.g., cormorants), which prefer deeper open water and benefitted directly from the large increase in coarse fish biomass. The disappearance of birds breeding in flooded meadows (e.g., black-winged stilts) and of those restricted to reedbeds (e.g., marsh harrier) occurred from 1983. Over the same period, the changes in populations of wintering birds at Kerkini were different from those occurring in other wetlands in northern Greece. The changes recorded in the populations of wintering birds at Kerkini did not therefore result from overall regional trends but from the major habitat modifications that occurred to this wetland. As for breeding birds, strictly piscivorous species increased greatly as a result of the increased availability of fish, but also due to the appearance of many suitable night roosting sites (flooded trees) and to the great increase in the area of open water greater than 2 m deep. Today, Kerkini has become the most important breeding site in Greece for a majority of colonial waterbirds. In contrast, wintering shorebirds practically disappeared. The many changes recorded in the status of breeding and wintering birds at Kerkini can mostly be explained by the changes that occurred in the functioning of the ecosystem and in the habitat structure following the inauguration of the new hydrological regime. These changes did not all occur at the same time: some were immediate and others required a delay before they could be detected.

Responses of vegetation to a rise in water level at Kerkini Reservoir (1982-1991), a Ramsar site in Northern Greece (1995)

Mon, 26 Oct 2015 10:06:02

de Alain Jean Crivelli, Patrick Grillas, B. Lacaze
1995

The floodplain of the river Strymon at Kerkini (northern Greece) was transformed into an irrigation reservoir by the construction of a dam in 1932 and subsequently enlarged in 1982. The aims of this study were to quantify the changes occurring in the various habitat types following raising of the waterlevel and to assess the stability of the plant communities present at this Ramsar site. The current hydrological regime, which has been stable since 1986, is typified by an increase in mean annual reservoir level of 2.2 m and by an increase in the annual range in level of 1.3 m. Landsat (1980, 1981, 1984, 1986, and 1988) and SPOT (1990) satellite images show a decrease in the area of grassland and shallow water areas, the very rapid disappearance of reedbeds, the appearance of beds ofNymphaea and the disappearance of half the forest area.

The flooded forest, dominated bySalix alba, is a key habitat contributing to the biological richness of this wetland of international importance. The decrease in the forested area will continue because of the death of standing trees, the absence of regeneration under the new regime, the felling of trees and grazing. Management could be undertaken to ensure the survival of forested habitat and reedbeds at Kerkini, but this would require that the authorities take into account nature conservation and the protected status of the site and not raise the water level again.

Restoration of seasonally-flooded marshes in abandoned ricefields in the Camargue (southern France). Preliminary results on vegetation and use by ducks (1995)

Sun, 1 Jan 1995 00:00:00

de François Mesléard, Patrick Grillas, L. Tan Ham
1995, 95-106
En ligne : www.sciencedirect.com[...]

Six management regimes (two artificially flooded for 6 months and a control irregularly flooded by rain, with or without grazing) were tested in 18 abandoned ricefields each of 1 ha, dominated by halophytic species in the Camargue in southern France. In 2 years the vegetation developed towards different communities depending on the treatments. Flooding treatments led to improved grazing conditions with Scirpus maritimus and Juncus gerardi as the dominant plant species. The winter following the beginning of the experiment, the number of teal (Anas recca) and mallard (A. platyrhynchos) using the plots depended chiefly on flooding. During the second winter the number of the two duck species was determined mainly by the volume (cover x height) of the vegetation. The results indicate that wildlife conservation can be improved along with pastoral quality by managing abandoned ricefields as seasonally flooded shallow marshes.

Etude des herbiers de Zostera noltii dans le Vaccarès en 1993 et 1994 (1994)

Mon, 26 Oct 2015 10:05:13

de Patrick Grillas, F. Lescuyer, Anne Charpentier
1994

A review of habitat changes in the Camargue: an assessment of the effects of the loss of biological diversity on the wintering waterfowl community (1994)

Mon, 26 Oct 2015 10:03:00

de Alain Tamisier, Patrick Grillas
1994

For the last 50 years, drastic changes have occurred in the Camargue. The loss of c. 40,000 ha of natural areas (33,000 ha of wetlands) was related to the extension of agriculture, salt exploitation and industry. On most of the remaining wetlands (mostly private hunting estates), management involved division of the marshes into smaller dyked units and large inputs of freshwater, resulting in a decrease in mean water salinity and an increase in duration of flooding. The original unpredictable variations in water level and water salinity, a characteristic of Mediterranean seasonal marshes, has been replaced by a tendency towards predictable permanent freshwater marshes. Consequently the species composition of aquatic habitats has changed from diversified Mediterranean to monospecific continental-type communities. The higher plant biomass favours use by wintering waterfowl which are, in turn, probably limited by high hunting pressure. These changes result in losses of biological diversity at the intra- and inter-habitat, as well as at the Mediteranean and continental, levels. New concepts of conservation should be proposed which take into consideration the biodiversity of the delta as a whole, including private properties instead of isolated management plans for reserves only.

A comparison between the biomass production of Potamogeton pectinatus L. and Myriophyllum spicatum L. in the Camargue (southern France) in relation to salinity and sediment characteristics (1994)

Mon, 26 Oct 2015 10:02:49

de C. Van Wijck, Patrick Grillas, C.J. De Groot, L. Tan Ham
1994

The effect of salinity on the reproduction of coastal submerged macrophytes in experimental communities (1993)

Mon, 26 Oct 2015 10:06:39

de A. Bonis, Patrick Grillas, C. Van Wijck, J. Lepart
1993

Polymorphisme enzymatique et morphologique comparé chez Chara aspera et C. galioides (Charophyceae) en Camargue (1993)

Mon, 26 Oct 2015 10:06:39

de A. Bonis, P. Gemayel, Patrick Grillas
1993

Submergerd macrophyte seed bank in a Mediterranean temporary marsh: Abundance and relationship with established vegetation (1993)

Mon, 26 Oct 2015 10:05:13

de Patrick Grillas, P. Garcia-murillo, O. Geertz-hansen, N. Marba, C. Montes, C.M. Duarte, L. Tan Ham, A. Grossmann
1993

The effect of salinity on the dominance-diversity relations of experimental coastal macrophyte communities (1993)

Mon, 26 Oct 2015 10:05:12

de Patrick Grillas, C. Van Wijck, A. Bonis
1993

Competition between an introduced and an indigenous species: The case of Paspalum paspalodes (Michx) Schribner and Aeluropus littoralis (Gouan) in the Camargue (southern France) (1993)

Mon, 26 Oct 2015 10:04:00

de François Mesléard, L. Tan Ham, V. Boy, C. Van Wijck, Patrick Grillas
1993

Distribution de Ludwigia en France. Etude des causes de l'expansion récente en Camargue. In: 15° Conférence COLUMA. Journées Internationales sur la Lutte contre les Mauvaises Herbes, Versailles (FRA) 2-4/12/92 (1992)

Mon, 26 Oct 2015 10:05:13

de Patrick Grillas, L. Tan Ham, Alain Dutartre, François Mesléard
[S.l.] : COLUMA Paris, 1992, p1083-1090

Transferring sediment containing intact seed banks: A method for studying plant community ecology (1992)

Mon, 26 Oct 2015 10:05:12

de Patrick Grillas, C. Van Wijck, V. Boy
1992

Experimental management of shallow wetlands: Preliminary results on vegetation structure and use by waterbirds (1992)

Mon, 26 Oct 2015 10:04:00

de François Mesléard, Patrick Grillas, D. Roux, J.L. Lucchesi
1992

The effect of anaerobic sediment on the growth of Potamogeton pectinatus L.: The role of organic matter, sulphide and ferrous iron (1992)

Mon, 26 Oct 2015 10:02:49

de C. Van Wijck, C.J. De Groot, Patrick Grillas
1992

The influence of sediment organic matter content on biomass production of Potamogeton pectinatus L. was investigated using nine Camargue sediments ranging from 8 to 66 mg C g−1. The biomass production of P. pectinatus was found to increase with increasing sediment organic matter content up to 26 mg C g−1. Biomass production was low on some sediments with a high organic matter content. Further experiments showed that the increase in biomass production was probably owing to increased availability of nitrogen which is released during the mineralization of organic matter. Modification of the water content and/or structure of the sediments by the addition of sand had no influence on biomass production. The relatively low biomass production observed on some sediments rich in organic matter could not be explained by a lack of available nitrogen, but presumably by anoxic conditions caused by the high quantities of organic matter present. The addition of iron and sulphide had a negative effect on biomass production, presumably owing to the presence of Fe2+ and S2− in the interstitial water. Concentrations of Fe2+ and S2− in the interstitial water of the sediments of some marshes in the Camargue were found to be sufficiently high to be of ecological importance to submerged macrophytes.

Life history traits: A possible cause for the higher frequency of occurence of Zannichellia pedunculata than of Zannichellia obtusifolia in temporary marshes (1991)

Mon, 26 Oct 2015 10:05:12

de Patrick Grillas, C. Van Wijck, A. Bonis
1991

Zannichellia pedunculata Reichenb. andZannichellia obtusifolia Talavera, Garcia-Murillo & Smit have been recorded in the marshes of the Camargue (south of France). Of these species,Z. pedunculata is very common, butZ. obtusifolia is rare. In three neighbouring marshes,Z. pedunculata andZ. obtusifolia occur regularly together. These two species have a similar morphology. Some of their life history traits were compared experimentally in natural and artificial habitats.
At the two concentrations of Cl− studied (0 and 2 g l−1), the percentage germination ofZ. obtusifolia (100% and 96%, respectively) is equal to or higher than that ofZ. pedunculata (100% and 38%, respectively) when the seeds are not allowed to dry out. In contrast, when the seeds have undergone desiccation, the percentage germination ofZ. pedunculata is higher (94% and 64%, respectively) than that ofZ. obtusifolia (88% and 56%, respectively at the two concentrations of Cl−, 0 and 2 g l−1). Salinity and the date of flooding were found to affect the biomass of both species ofZannichellia similarly. After flooding in autumn,Zannichellia pedunculata is capable of producing fruit before the winter, butZ. obtusifolia does not do so until the following spring.
The inability to reproduce in the autumn, and the negative influence of desiccation on the rate of germination and percentage germination, can explain whyZ. obtusifolia is uncommon in the Camargue marshes which are s

Plant community succession in a coastal wetland after abandonment of cultivation: The example of the Rhône delta (1991)

Mon, 26 Oct 2015 10:04:01

de François Mesléard, Patrick Grillas, J. Lepart
1991

The use of domestic herbivores in the conservation of the biological richness of European wetlands (1990)

Mon, 26 Oct 2015 10:05:17

de I.J. Gordon, Patrick Duncan, Patrick Grillas, T. Lecomte
1990

Distribution of submerged macrophytes in the Camargue in relation to environmental factors (1990)

Mon, 26 Oct 2015 10:05:14

de Patrick Grillas
1990
En ligne : onlinelibrary.wiley.com[...]

Le genre Zannichellia en Camargue (1990)

Mon, 26 Oct 2015 10:05:13

de Patrick Grillas, C. Van Wijck
1990

Un nouveau mode de gestion des friches rizicoles: Le marais artificiel (1990)

Mon, 26 Oct 2015 10:05:12

de P. Gros, Patrick Grillas
1990

Haemonia appendiculata Panzer (Chrysomelidae, Donaciinae) and its impact on Potamogeton pectinatus L. and Myriophyllum spicatum L. beds in the Camargue (France) (1988)

Mon, 26 Oct 2015 10:05:14

de Patrick Grillas
1988

Haemonia appendiculata Panzer (Chrysomelidae, Donaciinae), known in the 1950s as a rare species, has recently become very common in some marshes of the Camargue; it is present in most of the permanent freshwater marshes. This insect is able to damage Potamogeton pectinatus L. and Myriophyllum spicatum L. on the scale of hectares. On one site of great abundance, the density of the larvae, pupae and imagos of H. appendiculata was measured, and the impact on vegetation was evaluated. An hypothesis as to the cause of the recent increase in the abundance of the insect in Camargue marshes is proposed.

La réserve volontaire de la Tour du Valat (1987)

Mon, 26 Oct 2015 10:05:13

de Patrick Grillas, Heinz Hafner, Lukas Hoffmann
1987

La réserve volontaire de la Tour du Valat (1986)

Mon, 26 Oct 2015 10:05:13

de Patrick Grillas, Heinz Hafner, Lukas Hoffmann
1986