Research Center for Mediterranean Wetlands

Azay-le-Rideau, France

Research Center for Mediterranean Wetlands

Azay-le-Rideau, France
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Bouahim S.,Hassan II University | Bouahim S.,Montpellier University | Bouahim S.,Research Center for Mediterranean Wetlands | Rhazi L.,Hassan II University | And 12 more authors.
Comptes Rendus - Biologies | Year: 2010

The impact of grazing on the vegetation of Moroccan temporary pools has been studied at 2 scales: regional (inter-pools) and local (intra-pools). Half of the 16 forest pools studied is located in a reserve and ungrazed. The other half, located within public forest, is grazed. Vegetation relevés coupled to water-depths measurements were carried out in each pool. The results showed a significant effect of grazing on both scales of analysis. This effect was found in the species composition of the vegetation, which differed between the 2 types of pools, and in the lower species richness and abundance of plant species in the grazed pools. These differences are interpreted as resulting from the selection by herbivores and the differential tolerance of species to disturbance. These impacts are likely to expose certain species to local extinction by reducing their populations. © 2010 Académie des sciences. Published by Elsevier Masson SAS. All rights reserved.

Waterkeyn A.,Charles University | Waterkeyn A.,Research Center for Mediterranean Wetlands | Vanschoenwinkel B.,Charles University | Elsen S.,Charles University | And 3 more authors.
Aquatic Conservation: Marine and Freshwater Ecosystems | Year: 2010

1. Several human activities, such as actions for nature conservation, research and recreational activities, are closely associated with inland aquatic habitats that are usually considered as isolated island habitats. In this study, the possibility of unintentional dispersal of aquatic invertebrates among water bodies via footwear and motor vehicles was investigated. 2. Mud samples collected from boots and from the tyres and wheel cases of cars used for field work by biologists (Camargue, Southern France) were hatched under laboratory conditions and also checked for the presence of unhatched propagules. A large number of organisms hatched and invertebrate propagules from a wide range of taxa were encountered (including Artemia, freshwater large branchiopods, Cladocera, Ostracoda, Rotifera, Turbellaria, Nematoda, etc.). The results also demonstrated that different research groups tend to transport the aquatic invertebrates typical for their respective study systems. 3. Human dispersal of aquatic invertebrates has been studied mainly on large continental scales, such as in the case of transoceanic transport via ballast water in ships. This study provides evidence that dispersal via footwear and motor vehicles may result in frequent dispersal of aquatic invertebrates on a local scale, and we presume also occasionally over longer distances. Given the rapid spread of invasive zooplankton species (e.g. Artemia franciscana encountered in this study), we promote caution and recommend cleaning before transport of any equipment which comes in contact with water or aquatic sediment. © 2010 John Wiley & Sons, Ltd.

Waterkeyn A.,Charles University | Waterkeyn A.,Research Center for Mediterranean Wetlands | Pineau O.,Research Center for Mediterranean Wetlands | Grillas P.,Research Center for Mediterranean Wetlands | Brendonck L.,Charles University
Hydrobiologia | Year: 2010

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. © 2010 Springer Science+Business Media B.V.

Rhazi L.,Hassan II University | Grillas P.,Research Center for Mediterranean Wetlands | Saber E.-R.,Aix - Marseille University | Rhazi M.,Moulay Ismaï University | And 3 more authors.
Hydrobiologia | Year: 2012

Although Mediterranean temporary pools are of great value for conservation, they are in rapid decline under the impact of various forms of anthropogenic pressure. Their disappearance from the landscape may result in a weakening of the biological connections between pools due to increasing isolation and the impoverishment of their communities. In Western Morocco (province of Benslimane), temporary pools have undergone severe regression over the past decades. The quantification of these losses and the impact on the richness of plant communities remain, however, unstudied. Since this is of vital importance for the conservation of the biodiversity of these habitats, a study has been undertaken associating (1) an assessment of the pool losses (both in density and surface area) between 1955 and 2001 using remote sensing, (2) surveys of vegetation and water depth (in 2006) in 48 pools, and (3) an assessment of the density and surface area of pools occurring within a 3 km radius around each of the sampled pools. The results show a loss of 23% in number and 61% in surface area of pools in the province over a period of 47 years. This decline, promoted by their small size and shallowness, is probably related to socio-economic changes (intensification of agricultural practices and population growth). The richness in characteristic and rare species of the pools was related to both local (water depth) and regional features (land use, pool density and total water surface area in the surrounding landscape). The significant impact of the current density of pools and their total surface area on the conservation value of the studied pools suggests a weakening of the metacommunity dynamics between pools. Given the rapid socio-economic changes in the province and the current rate of pool disappearance (0.5% per year) we predict a continuing reduction in pool density with a high risk of the widespread loss of their unique flora in the long term. © 2011 Springer Science+Business Media B.V.

Waterkeyn A.,Charles University | Waterkeyn A.,Research Center for Mediterranean Wetlands | Grillas P.,Research Center for Mediterranean Wetlands | Anton-Pardo M.,University of Valencia | And 2 more authors.
Marine and Freshwater Research | Year: 2011

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 (0.52.5gL -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. © 2011 CSIRO.

Bouahim S.,Hassan II University | Bouahim S.,Research Center for Mediterranean Wetlands | Bouahim S.,Montpellier University | Rhazi L.,Hassan II University | And 13 more authors.
Marine and Freshwater Research | Year: 2014

Identifying the respective role of environmental, landscape and management factors in explaining the patterns in community composition is an important goal in ecology. Using a set of 32 temporary ponds in northern Morocco we studied the respective importance of local (within the pond) and regional (density of ponds in landscape) factors and the impacts of different land uses on the plant species assemblages, separating pond and terrestrial species. The main hypotheses tested were that (1) species assemblages respond to both local and regional environmental factors, (2) anthropogenic pressure has a negative influence on the number of pond species, and that (3) human activities differ in their impact on pond biodiversity. The results showed that (1) local factors explain most of the variation in plant community composition, and (2) land use impacts the communities through changing local environmental conditions, leading to a loss of typical pond species. Aside from recreation, all other activities (grazing, drainage, agriculture and partial urbanisation) significantly reduced the number of pond species. The conservation strategy for rare pond species should focus on maintaining networks of oligotrophic ponds, while allowing only low-impact activities. © CSIRO 2014.

Sahib N.,Hassan II University | Sahib N.,Research Center for Mediterranean Wetlands | Rhazi L.,Hassan II University | Grillas P.,Research Center for Mediterranean Wetlands
Botany | Year: 2011

Mediterranean temporary pools are frequently visited habitats where domestic livestock and wild herbivores generate numerous physical soil disturbances. Using two sizes of experimental plots (large, 1.20 m × 1.20 m; small, 0.3 m × 0.3 m), the effects of soil disturbances on vegetation dynamics and the vertical distribution of seeds were studied in one Moroccan temporary pool. Results show a very rapid regeneration of temporary wetland vegetation in disturbed plots. The speed of regeneration depends on the size of disturbance and hydrology. There was an almost complete return of vegetation to the reference state in the small disturbed plots by the end of the 1st year. This fast restoration was mainly due to seed banks, which play a key role in the resilience of pools to the different sizes of disturbances frequently generated by herbivores, but also to lateral colonization by perennials.

Tuytens K.,Catholic University of Leuven | Vanschoenwinkel B.,Catholic University of Leuven | Vanschoenwinkel B.,Vrije Universiteit Brussel | Waterkeyn A.,Catholic University of Leuven | And 2 more authors.
Freshwater Biology | Year: 2014

Future moderate changes in evaporation and precipitation regimes could have pronounced effects on zooplankton populations in small and temporary aquatic habitats, by causing higher salinity and a shorter wet phase and by reducing passive dispersal via hydrological connections between pools and increasing it by exposing propagules to the wind. Using a hydrological model, we simulated various climate change scenarios in a natural cluster of temporary rock pools in South Africa. In our simulations, a shift towards a drier climate was associated with reduced permanence and increased conductivity, resulting in a lower percentage of inundations sufficient for the hatching, growth and reproduction of aquatic organisms (up to a 21% decline for a fairy shrimp). Connections between pools by overflowing occurred less frequently (by up to 28%). However, more frequent desiccation events (by up to 15%) led to increased exposure of dormant propagules to wind, possibly promoting dispersal within the pool cluster but also leading to losses from the propagule bank. Our results suggest that environmental change might not only affect local (within-pool) selection pressures but also regional dynamics in rock pool metapopulations and communities. © 2014 John Wiley & Sons Ltd.

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