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Sant Carles de la Ràpita, Spain

Couturier T.,EPHE Paris | Cheylan M.,EPHE Paris | Bertolero A.,IRTA Aquatic Ecosystems | Astruc G.,EPHE Paris | Besnard A.,EPHE Paris
Journal of Wildlife Management | Year: 2013

Assessing population trends is a basic prerequisite to carrying out adequate conservation strategies. Selecting an appropriate method to monitor animal populations can be challenging, particularly for low-detection species such as reptiles. This study compares 3 detection-corrected abundance methods (capture-recapture, distance sampling, and N-mixture) used to assess population size of the threatened Hermann's tortoise. We used a single dataset of 432 adult tortoise observations collected at 118 sampling sites in the Plaine des Maures, southeastern France. We also used a dataset of 520 tortoise observations based on radiotelemetry data collected from 10 adult females to estimate and model the availability (g0) needed for distance sampling. We evaluated bias for N-mixture and capture-recapture, by using simulations based on different values of detection probabilities. Finally, we conducted a power analysis to estimate the ability of the 3 methods to detect changes in Hermann's tortoise abundances. The abundance estimations we obtained using distance sampling and N-mixture models were respectively 1.75 and 2.19 times less than those obtained using the capture-recapture method. Our results indicated that g0 was influenced by temperature variations and can differ for the same temperature on different days. Simulations showed that the N-mixture models provide unstable estimations for species with detection probabilities <0.5, whereas capture-recapture estimations were unbiased. Power analysis showed that none of the 3 methods were precise enough to detect slow population changes. We recommend that great care should be taken when implementing monitoring designs for species with large variation in activity rates and low detection probabilities. Although N-mixture models are easy to implement, we would not recommend using them in situations where the detection probability is very low at the risk of providing biased estimates. Among the 3 methods allowing estimation of tortoise abundances, capture-recapture should be preferred to assess population trends. © The Wildlife Society, 2013. Source

Vicente J.,CSIC - Institute of Environmental Assessment And Water Research | Bertolero A.,IRTA Aquatic Ecosystems | Meyer J.,CSIC - Institute of Environmental Assessment And Water Research | Viana P.,Instituto Da Agua Ip | Lacorte S.,CSIC - Institute of Environmental Assessment And Water Research
Science of the Total Environment | Year: 2012

This study is aimed to evaluate the presence and distribution of Perfluorinated Compounds (PFCs) in Yellow-legged gull eggs (Larus michahellis) collected from 8 National or Natural Parks from the Iberian Peninsula. In each colony, 12 eggs were randomly collected and pooled from 3 areas of the colony and analyzed using liquid-solid extraction and liquid chromatography coupled to tandem mass spectrometry. Perfluorooctanate sulfonate (PFOS) was the only compound detected in the eggs and its presence was higher in the colonies situated in NE Iberian Peninsula due to the more industrial and mass urbanization in this area compared to the SW Mediterranean or Atlantic colonies. Accordingly, the Medes site, followed by the Ebro Delta and Columbretes, all situated in the NW Mediterranean coast, contained the highest PFOS levels (40.5-54.0. ng/g-ww). In all other colonies, PFOS was detected at levels of 10.1-18.6. ng/g-ww. Egg shell biometry was studied and it was found that the presence of PFOS did not affect the development of the egg. © 2011 Elsevier B.V. Source

Maceda-Veiga A.,University of Barcelona | Monleon-Getino A.,University of Barcelona | Caiola N.,IRTA Aquatic Ecosystems | Casals F.,University of Lleida | de Sostoa A.,University of Barcelona
Freshwater Biology | Year: 2010

North-eastern Spain is a hot spot for the introduction of alien fish species, and its native fish fauna is one of the most endangered worldwide. We used an extensive data set from 2002 to 2003 and historical information from the area to characterize fish diversity and establish conservation priorities in river catchments. Diversity indices were used to characterize fish diversity at the basin scale. An index of conservation status was applied for each species, which considers the occurrence, abundance and endemicity of each taxon. We used indirect ordination methods to test the relationship among basin features and to identify those variables most correlated with each other. To identify physical, biotic and environmental characteristics that seem to make a basin particularly susceptible to invasion, we performed a step-wise multiple regression to examine the relationship between the number of native, translocated and introduced fish species (including the original native species richness of each basin), and landscape variables. Over a period of approximately 50 years, the mean range size of native fish species has decreased by 60%. The greatest decline occurred in Gasterosteus gymnurus, Anguilla anguilla and Salaria fluviatilis, for which species over 75% of the original distribution area has been lost. The species with the highest conservation index were Gasterosteus gymnurus and Salaria fluviatilis. Basin area and the catchment type explained 70% of variation in native species richness, whereas the number of dams and basin area accounted for more than 80% of variation in the number of introduced species. The original native species richness and the number of introduced species at basin scale were not related, and thus there was no evidence of " biotic resistance" to invasion. The restoration of natural hydrologic processes and the development of specific management tools to protect native species, such as the prioritization of areas for fish conservation and the eradication of local populations of exotic species, are required to restore native fish fauna in these catchments. © 2010 Blackwell Publishing Ltd. Source

Prado P.,IRTA Aquatic Ecosystems | Caiola N.,IRTA Aquatic Ecosystems | Ibanez C.,IRTA Aquatic Ecosystems
Estuaries and Coasts | Year: 2013

Rice cultivation in the Ebro Delta (Catalonia, Spain) has inverted the natural hydrological cycles of coastal lagoons and decreased water salinities for over 150 years. Adjustments in the water management practices-in terms of source and amount of freshwater inputs-have resulted in changes in the diversity, distribution and productivity of submerged angiosperms. Between the 1970s and late 1980s, a massive decline of the aquatic vegetation occurred in the Encanyissada-Clot and Tancada lagoons, but little information on the status is available after the recovery of macrophytes in the 1990s. Here, we evaluate the influence of salinity regimes resulting from current water management practices on the composition, distribution, seasonal abundance and flowering rates of submersed macrophytes, as well as on the occurrence of epiphyte and drift macroalgae blooms in three coastal lagoons. Our results show that Ruppia cirrhosa is the dominant species in the Encanyissada lagoon (185. 97 ± 29. 74 g DW m-2 year-1; 12-27 ‰ salinity) and the only plant species found in the Tancada lagoon (53. 26 ± 10. 94 g DW m2 year-1; 16-28 ‰ salinity). Flowering of R. cirrhosa (up to 1,011 ± 121 flowers m-2) was only observed within the Encanyissada and suggests that mesohaline summer conditions may favor these events. In contrast, low salinities in Clot lagoon (~3-12 ‰) favor the development of Potamogeton pectinatus (130. 53 ± 13. 79 g DW m2 year-1) with intersperse R. cirrhosa (8. 58 ± 1. 71 g DW m-2) and mixed stands of P. pectinatus and Najas marina (up to ~57 g DW m-2 year-1) in some reduced areas. The peak biomasses observed during the study are 88 to 95 % lower than maximum values reported in the literature at similar salinities, and there is also little or no recovery in some areas compared to last reports more than 20 years ago. The main management actions to restore the natural diversity and productivity of submersed angiosperms, such as the recovering of the seagrass Zostera noltii, should be the increase of salinity during the period of rice cultivation, by reducing freshwater inputs and increasing flushing connections with the bays. © 2012 Coastal and Estuarine Research Federation. Source

Alcaraz C.,IRTA Aquatic Ecosystems | Caiola N.,IRTA Aquatic Ecosystems | Ibanez C.,IRTA Aquatic Ecosystems
Science of the Total Environment | Year: 2011

In the Flix Reservoir (Ebro River, Spain), ca. 300,000. tons of industrial waste were dumped because of the activity of a factory plant in Flix. Within the recovery program implemented, this exceptional situation provides a unique opportunity to test the value of zebra mussel as sentinel organism. Ten metal concentrations were measured in mussels from different sites to assess spatial redistribution of metals and bioavailability to the food web. Our results showed an important metal uptake by mussels; metal concentrations (except As) measured in impacted sites were up to 10 times higher than in control sites, and Mn and Hg exceeded several times the levels previously reported for polluted waters. Concentrations increased downstream showing the metal mobilization from polluted sediments in Flix Reservoir. The higher metal concentrations measured in zebra mussel individuals clearly indicated their bioavailability to the food web, allowing the toxics transfer to predators and occasionally to humans. Thus, zebra mussel is a valuable sentinel organism to identify highly polluted waters, transport routes and trophic transfer. © 2010 Elsevier B.V. Source

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