The Andean Biotic Index (ABI): revised tolerance to pollution values for macroinvertebrate families and index performance evaluation.

Score-based biotic indices are widely used to evaluate the water quality of streams and rivers. Few adaptations of these indices have been done for South America because there is a lack of knowledge on mac-roinvertebrate taxonomy, distribution and tolerance to pollution in the region. Several areas in the Andes are densely populated and there is need for methods to assess the impact of increasing human pressures on aquatic ecosystems. Considering the unique ecological and geographical features of the Andes, macroinvertebrate indices used in other regions must be adapted with caution. Here we present a review of the literature on mac-roinvertebrate distribution and tolerance to pollution in Andean areas above 2 000masl. Using these data, we propose an Andean Biotic Index (ABI), which is based on the BMWP index. In general, ABI includes fewer macroinvertebrate families than in other regions of the world where the BMWP index has been applied because altitude restricts the distribution of several families. Our review shows that in the high Andes, the tolerance of several macroinvertebrate families to pollution differs from those reported in other areas. We tested the ABI index in two basins in Ecuador and Peru, and compared it to other BMWP adaptations using the reference condi-tion approach. The ABI index is extremely useful for detecting the general impairment of rivers but class quality boundaries should be defined independently for each basin because reference conditions may be different. The ABI is widely used in Ecuador and Peru, with high correlations with land-use pressures in several studies. The ABI index is an integral part of the new multimetric index designed for high Andean streams (IMEERA). Rev. Biol. Trop. 62 (Suppl. 2): 249-273. Epub 2014 April 01.

Modelling nitrogen and phosphorus loads in a Mediterranean river catchment (La Tordera, NE Spain)

Human activities have resulted in increased nutrient levels in many rivers all over Europe. Sustainable management of river basins demands an assessment of the causes and consequences of human alteration of nutrient flows, together with an evaluation of management options. In the context of an integrated and interdisciplinary environmental assessment (IEA) of nutrient flows, we present and discuss the application of the nutrient emission model MONERIS (MOdelling Nutrient Emissions into River Systems) to the Catalan river basin, La Tordera (north-east Spain), for the period 1996–2002. After a successful calibration and verification process (Nash-Sutcliffe efficiencies E=0.85 for phosphorus and E=0.86 for nitrogen), the application of the model MONERIS proved to be useful in estimating nutrient loads. Crucial for model calibration, in-stream retention was estimated to be about 50 % of nutrient emissions on an annual basis. Through this process, we identified the importance of point sources for phosphorus emissions (about 94% for 1996–2002), and diffuse sources, especially inputs via groundwater, for nitrogen emissions (about 31% for 1996–2002). Despite hurdles related to model structure, observed loads, and input data encountered during the modelling process, MONERIS provided a good representation of the major interannual and spatial patterns in nutrient emissions. An analysis of the model uncertainty and sensitivity to input data indicates that the model MONERIS, even in data-starved Mediterranean catchments, may be profitably used by water managers for evaluating quantitative nutrient emission scenarios for the purpose of managing river basins. As an example of scenario modelling, an analysis of the changes in nutrient emissions through two different future scenarios allowed the identification of a set of relevant measures to reduce nutrient loads.

20 Myr of eccentricity paced lacustrine cycles in the Cenozoic Ebro Basin

Long-period orbital forcing is a crucial component of the major global climate shifts during the Cenozoic as revealed in marine pelagic records. A complementary regional perspective of climate change can be assessed from internally drained lake basins, which are directly affected by insolation and precipitation balance. The Ebro Basin in northeastern Iberia embraces a 20 Myr long continuous sedimentary record where recurrent expansions and retractions of the central lacustrine system suggest periodic shifts of water balance due to orbital oscillations. In order to test climatic (orbital) forcing a key-piece of the basin, the Los Monegros lacustrine system, has been analyzed in detail. The cyclostratigraphic analysis points to orbital eccentricity as pacemaker of short to long-term lacustrine sequences, and reveals a correlation of maxima of the 100-kyr, 400-kyr and 2.4-Myr eccentricity cycles with periods of lake expansion. A magnetostratigraphy-based chronostratigraphy of the complete continental record allows further assessing long-period orbital forcing at basin scale, a view that challenges alternate scenarios where the stratigraphic architecture in foreland systems is preferably associated to tectonic processes. We conclude that while the location of lacustrine depocenters reacted to the long-term tectonic-driven accommodation changes, shorter wavelenght oscillations of lake environments, still million-year scale, claims for a dominance of orbital forcing. We suggest a decoupling between (tectonic) supply-driven clastic sequences fed from basin margins and (climatic) base level-driven lacustrine sequences in active settings with medium to large sediment transfer systems.

Homogenization Dynamics and Introduction Routes of Invasive Freshwater Fish in the Iberian Peninsula

Nonnative invasive species are one of the main global threats to biodiversity. The understanding of the traits characterizing successful invaders and invasion-prone ecosystems is increasing, but our predictive ability is still limited. Quantitative information on biotic homogenization and particularly its temporal dynamics is even scarcer. We used freshwater fish distribution data in the Iberian Peninsula in four periods (before human intervention, 1991, 1995, and 2001) to assess the temporal dynamics of biotic homogenization among river basins. The percentage of introduced species among fish faunas has increased in recent times (from 41.8% in 1991 to 52.5% in 2001), leading to a clear increase in the similarity of community composition among basins. The mean Jaccard's index increase (a measure of biotic homogenization) from the pristine situation to the present (17.1%) was similar to that for Californian fish but higher than for other studies. However, biotic homogenization was found to be a temporally dynamic process, with finer temporal grain analyses detecting transient stages of biotic differentiation. Introduced species assemblages were spatially structured along a latitudinal gradient in the Iberian Peninsula, with species related to sport fishing being characteristic of northern basins. Although the comparison of fish distributions in the Iberian Peninsula and France showed significant and generalized biotic homogenization, nonnative assemblages of northeastern Iberian basins were more similar to those of France than to those of the rest of the Iberian Peninsula, indicating a main introduction route. Species introduced to the Iberian Peninsula tended to be mainly piscivores or widely introduced species that previously had been introduced to France. Our results indicate that the simultaneous analysis of the spatial distribution of introduced assemblages (excluding native species that reflect other biogeographical patterns) and their specific traits can be an effective tool to detect introduction and invasion routes and to predict future invaders from donor regions

First record of the common bream (Abramis brama) introduced to the Iberian Peninsula

This is the first record of the common bream, Abramis brama (Linnaeus, 1758), introduced into the Iberian Peninsula. Eight individuals of this cyprinid fish species were captured (of a total of 978 fish) in the Boadella Reservoir (Catalonia, Spain) on August 18, 2004. This reservoir is only 14 km away from France, where the bream is native, and contains several exotic freshwater fish that are still not widespread in Spain. The further introduction of species and the illegal translocation of the bream by anglers to other Iberian river basins should be controlled by the Spanish administration

Estimation of Water Circulation in a Mediterranean Salt Marsh and its Relationship with Flooding Causes

Variations in water volume in small depressions in Mediterranean salt marshes in Girona (Spain) are described and the potential causes for these variations analysed. Although the basins appear to be endorrheic, groundwater circulation is intense, as estimated from the difference between water volume observed and that expected from the balance precipitation / evaporation. The rate of variation in volume (VR = AV / VAt) may be used to estimate groundwater supply ('circulation'), since direct measurements of this parameter are impossible. Volume.conductivity figures can also be used to estimate the quantity of circulation, and to investigate the origin of water supplied to the system. The relationships between variations in the volume of water in the basins and the main causes of flooding are also analysed. Sea storms, rainfall levels and strong, dry northerly winds are suggested as the main causes of the variations in the volumes of basins. The relative importance assigned to these factors has changed, following the recent regulation of freshwater flows entering the system

Organic carbon and nutrient (P, N) concentrations of water and sediment in several aquatic environment types of a Mediterranean coastal wetland (Empordà Wetlands, NE Iberian Peninsula)

Total sediment and water organic carbon and nutrient (nitrogen and phosphorus) concentrations of different environment types of a Mediterranean coastal wetland (temporary and brackish, temporary and freshwater, semi-permanent and brackish, and permanent and brackish basins) were analysed during two hydroperiods. A nitrogen limitation was found for both sediment and water. The total organic carbon concentration of the water was significantly related to the water level, which varies throughout the hydroperiods. In contrast, the total organic carbon concentration of the sediment was not related to water level. However, significant differences in total organic carbon of the sediment were found between hydroperiods. On the other hand, total organic carbon of the sediment varied spatially, being higher in temporary brackish basins with lower sand content, and lower in permanent and semi-permanent brackish basins with higher sand content

Population structure in a highly pelagic seabird, the Cory's shearwater (Calonectris diomedea): an examination of genetics, morphology and ecology

Increasing evidence suggests oceanic traits may play a key role in the genetic structuring of marine organisms. Whereas genetic breaks in the open ocean are well known in fishes and marine invertebrates, the importance of marine habitat characteristics in seabirds remains less certain. We investigated the role of oceanic transitions versus population genetic processes in driving population differentiation in a highly vagile seabird, the Cory"s shearwater, combining molecular, morphological and ecological data from 27 breeding colonies distributed across the Mediterranean (Calonectris diomedea diomedea) and the Atlantic (C. d. borealis). Genetic and biometric analyses showed a clear differentiation between Atlantic and Mediterranean Cory"s shearwaters. Ringing-recovery data indicated high site fidelity of the species, but we found some cases of dispersal among neighbouring breeding sites (<300 km) and a few long distance movements (>1000 km) within and between each basin. In agreement with this, comparison of phenotypic and genetic data revealed both current and historical dispersal events. Within each region, we did not detect any genetic substructure among archipelagos in the Atlantic, but we found a slight genetic differentiation between western and eastern breeding colonies in the Mediterranean. Accordingly, gene flow estimates suggested substantial dispersal among colonies within basins. Overall, genetic structure of the Cory"s shearwater matches main oceanographic breaks (Almería-Oran Oceanic Front and Siculo-Tunisian Strait), but spatial analyses suggest that patterns of genetic differentiation are better explained by geographic rather than oceanographic distances. In line with previous studies, genetic, phenotypic and ecological evidence supported the separation of Atlantic and Mediterranean forms, suggesting the 2 taxa should be regarded as different species.