IRTA Aquatic Ecosystems

Sant Carles de la Ràpita, Spain

IRTA Aquatic Ecosystems

Sant Carles de la Ràpita, Spain
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Ibanez C.,IRTA Aquatic Ecosystems | Caiola N.,IRTA Aquatic Ecosystems | Rovira A.,IRTA Aquatic Ecosystems | Real M.,United Research Services Espana
Science of the Total Environment | Year: 2012

The lower Ebro River (Catalonia, Spain) has recently undergone a regime shift from a phytoplankton to a macrophyte-dominated system. Macrophytes started to spread at the end of the 1990s and since 2002 artificial floods (flushing flows) of short duration (1-2 days) are released from the Riba-roja dam once or twice a year in order to reduce macrophyte density. The aim of this study was to analyse the spatiotemporal trends of the submerged macrophytes in two stretches of the lower Ebro River using high-resolution hydroacoustic methods, in order to elucidate the effects of artificial floods and natural floods on its distribution and abundance. Results showed that the mean cover in the two studied stretches (Móra and Ginestar) was not reduced after a flushing flow (from 36.59% to 55.85% in Móra, and from 21.18% to 21.05% in Ginestar), but it was greatly reduced after the natural flood (down to 9.79% in Móra and 2.04% in Ginestar); surprisingly the cover increased in Móra after the artificial flood. In order to increase the efficiency of floods in controlling macrophyte spreading, the magnitude and frequency of them should largely increase, as well as the suspended sediment load, approaching as much as possible to the original flood pattern before dam construction. Hydroacoustic methods combined with geostatistics and interpolation in GIS can accurately monitor spatiotemporal trends of submerged macrophytes in large rivers. This is the first article to apply this monitoring system to submerged macrophytes in rivers. © 2012 Elsevier B.V.

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.

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.

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.

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.

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.

In the Ebro Delta coastal lagoons, one of the main anthropogenic pressures is the artificial freshwater input. Each coastal lagoon has different water management schemes causing profound changes in its physicochemical characteristics. The main objective of this water management is to favour some bird species with interest either for conservation or hunting activities. The present study assesses the influence of hydrological alteration on the fish assemblages of three coastal lagoons in the Ebro Delta. The small-bodied fish fauna was mainly composed of five families: Gobiidae, Poecilidae, Cyprinodontidae, Atherinidae and Mugilidae. Salinity was found to be the main factor structuring fish community in the lagoons. The dominant species was the common goby (Pomatochistus microps) when the lagoons reached higher salinity values, whereas the invasive eastern mosquitofish (Gambusia holbrooki) dominated during the period of higher freshwater inputs. The juveniles of the family Mugilidae showed low catch per unit effort, especially during the period of lower salinity. This same pattern was found for the endangered Spanish toothcarp (Aphanius iberus). Overall, introduced species were favoured by low salinity, which highlights the importance of changing the present water management by reducing the freshwater inputs in order to maintain suitable levels of salinity to favour native species that are important for both commercial and conservation purposes.

Rovira A.,IRTA Aquatic Ecosystems | Alcaraz C.,IRTA Aquatic Ecosystems | Ibanez C.,IRTA Aquatic Ecosystems
Water Research | Year: 2012

Suspended load dynamics were analyzed for the period 2007-2009 in a semi-meandering cross-section under different hydrological conditions. Samples were collected at four different points of the cross-section. During " low discharges" (≤600 m 3/s) suspended load samples were collected at-a-monthly basis, whereas at " high discharges" (>600 m 3/s) sampling was conducted intensively (at-a-daily basis during the first stages of the flood event). Results indicated that during low discharges, both organic and inorganic suspended load concentrations tended to be uniformly distributed across the fluvial section; but during high discharges, two distinct areas were found: an area extending from the " Inner-bank" to the " Channel centre" (Area-I) with higher suspended concentrations (organic and inorganic) than those recorded in the " Outer bank" (Area-II). This phenomenon was likely related to the formation of secondary flow velocity cells and the activation of new sources of sediment. In addition, a non-significant relationship between organic suspended load and water flow was observed in the outer-bank. At-a-monthly basis, the analysis of the suspended load showed the existence of an intra-annual cycle of the inorganic concentrations, with a progressive increase from October to March followed by a decrease from March to September. Nevertheless, the organic suspended load did not show any trend, being equally distributed along the year, suggesting that other sources of organic matter besides phytoplankton are predominant. © 2012 Elsevier Ltd.

Nebra A.,IRTA Aquatic Ecosystems | Caiola N.,IRTA Aquatic Ecosystems | Ibanez C.,IRTA Aquatic Ecosystems
Scientia Marina | Year: 2011

The community composition and spatial distribution of benthic macroinvertebrates were studied along the Ebro estuary, a highly stratified estuary located in the NE Iberian Peninsula. During the last decade the oligotrophication process occurring in the lower Ebro River and its estuary has allowed a complex benthic macroinvertebrate community to become established; these results contrast with the poor community found there in the early nineties. A total of 214 taxa were identified, and polychaetes dominated the community both in abundance and species richness. The results showed spatial differences in the structure and composition of macroinvertebrates, which suggests that there are two distinct communities along the estuary. Each community was found in a specific stretch (upper and lower estuary) in function of the presence of the salt wedge. The macrobenthos of the upper estuary was dominated by freshwater taxa, but some euryhaline species were also found. The lower estuary showed a marine community typical of shallow Mediterranean environments. The transition between these two communities fits an ecotone model. The highest abundances, richness and diversities were recorded at the lower estuarine stations, especially those closer to the river mouth, whereas the lowest values corresponded to the stations adjacent to the tip of the salt wedge.

Rovira L.,IRTA Aquatic Ecosystems | Trobajo R.,IRTA Aquatic Ecosystems | Ibanez C.,IRTA Aquatic Ecosystems
Marine Pollution Bulletin | Year: 2012

Diatom indices are used to evaluate the ecological status of rivers but they have been rarely applied in estuaries. This study aimed to identify the diatom species indicating the main environmental gradients and pressures in a highly stratified estuary; and to evaluate the applicability of existing freshwater diatom indices. Marine influence due to salt-wedge intrusion and sea water mixing appeared as the main factor affecting diatom community. Three diatom assemblages were identified: indicators of riverine conditions (without marine influence), indicators of estuarine conditions (heterogeneous conditions with higher conductivities due to marine influence) and those specifically indicating well-established salt-wedge situations. Nowadays, the main human pressure affecting diatom community in the Ebro Estuary is the hydrological alteration resulting from flow regulation and abstraction. Several limitations were encountered in the application of diatom indices (e.g. inverse response with nutrients; ecologically important species not considered). Therefore, their use in estuaries should be done cautiously. © 2012 Elsevier Ltd.

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