Genetic diversity and species richness patterns in Baetidae (Ephemeroptera) in the Montseny Mountain range (North-East Iberian Peninsula)

This study aimed to describe patterns of diversity of Baetidae (Ephemeroptera) at the ommunity and population levels within the Montseny Mountain range (North-East Iberian Peninsula). We studied both the distribution of 4 species of baetids in 20 sites among three catchments along the altitudinal gradient (350-1700 masl); and the genetic diversity of the mtDNA cytochrome c oxidase subunit I (cox1) gene of the two common species Baetis alpinus and Baetis rhodani. We found a gradual replacement of the dominant species along the altitudinal gradient. Baetis alpinus inhabited sites at high-altitudes, and this species was replaced by B. rhodani when the altitude decreased. Baetis melanonyx and Alainites muticus attained low abundance at all river sections, and no clear altitudinal trend appeared. Our hypothesis at the population level was that genetic structuring is associated with geographic distance and limited by drainage boundaries among the three studied catchments because of the short-time dispersion of adults. Unexpectedly, analyses of molecular variance (AMOVA) and isolation-bydistance (IBD) showed genetic diversity was unstructured by distance for both species, which may be explained by the relatively short spatial scale studied and small topographic barriers among the three catchments. The Generalized Mixed Yule-Coalescent (GMYC) model showed that B. rhodani had two differentiated genetic lineages that co-occurred in all sites. Overall, diversity of baetids was structured at the community level along the altitudinal gradient, whereas it was unstructured at the population level within the Montseny Mountain range.

Genetic diversity and species richness patterns in Baetidae (Ephemeroptera) in the Montseny Mountain range (North-East Iberian Peninsula)

This study aimed to describe patterns of diversity of Baetidae (Ephemeroptera) at the ommunity and population levels within the Montseny Mountain range (North-East Iberian Peninsula). We studied both the distribution of 4 species of baetids in 20 sites among three catchments along the altitudinal gradient (350-1700 masl); and the genetic diversity of the mtDNA cytochrome c oxidase subunit I (cox1) gene of the two common species Baetis alpinus and Baetis rhodani. We found a gradual replacement of the dominant species along the altitudinal gradient. Baetis alpinus inhabited sites at high-altitudes, and this species was replaced by B. rhodani when the altitude decreased. Baetis melanonyx and Alainites muticus attained low abundance at all river sections, and no clear altitudinal trend appeared. Our hypothesis at the population level was that genetic structuring is associated with geographic distance and limited by drainage boundaries among the three studied catchments because of the short-time dispersion of adults. Unexpectedly, analyses of molecular variance (AMOVA) and isolation-bydistance (IBD) showed genetic diversity was unstructured by distance for both species, which may be explained by the relatively short spatial scale studied and small topographic barriers among the three catchments. The Generalized Mixed Yule-Coalescent (GMYC) model showed that B. rhodani had two differentiated genetic lineages that co-occurred in all sites. Overall, diversity of baetids was structured at the community level along the altitudinal gradient, whereas it was unstructured at the population level within the Montseny Mountain range.

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.

Sexual foraging segregation in South American sea lions increases during the pre-breeding period in the La Plata River plume

Stable carbon and nitrogen isotopes in skin and bone of South American sea lions from Brazil and Uruguay were analysed to test the hypothesis that trophic overlap between the sexes is lower during the pre-breeding season than throughout the rest of the year. The isotopic values of skin and bone were used to infer the trophic relationships between the sexes during the pre-breeding period and year round, respectively. Prey species were also analysed to establish a baseline necessary for interpreting the stable isotope ratios of skin and bone. Standard ellipse areas, estimated using Bayesian inference in the SIBER routine of the SIAR package in R, suggested that males and females used a wide diversity of foraging strategies throughout the year and that no differences existed between the sexes. However, the diversity of foraging strategies was largely reduced during the pre-breeding period, with all the individuals of each sex adopting similar strategies, but with the two sexes differing considerably in stable isotope values and the ellipse areas of males and females not overlapping at all. Nevertheless, the results revealed a general increase in the consumption of pelagic prey by both sexes during the pre-breeding period. The progressive crowding of individuals in the areas surrounding the breeding rookeries during the pre-breeding period could lead to an increase in the local population density, which could explain the above reported changes.

The Problem of Invasive Species in River Ecosystems

Invasive nonnative species are a major problem in river ecosystems, and have large ecological and economic costs. Few ecosystems can resist invasions. The species that tend to invade most readily are those that humans. Introduce the most, and the ecosystems they invade are those with the most human activity. Most invasions are irreversible, and control is expensive, so efforts should be focused on prevention of future invasions

Concluding Remarks on River Conservation

We have pragmatic and ethical obligations to conserve rivers and their biodiversity. This chapter outlines how and why river conservation is important. To make a difference, we must act as individuals and groups, using water wisely and protecting vulnerable assets such as water quality, riparian zones and aquatic biodiversity

Catalase in fluvial biofilms: a comparison between different extraction methods and example of application in a metal-polluted river

Antioxidant enzymes are involved in important processes of cell detoxification during oxidative stress and have, therefore, been used as biomarkers in algae. Nevertheless, their limited use in fluvial biofilms may be due to the complexity of such communities. Here, a comparison between different extraction methods was performed to obtain a reliable method for catalase extraction from fluvial biofilms. Homogenization followed by glass bead disruption appeared to be the best compromise for catalase extraction. This method was then applied to a field study in a metal-polluted stream (Riou Mort, France). The most polluted sites were characterized by a catalase activity 4–6 times lower than in the low-polluted site. Results of the comparison process and its application are promising for the use of catalase activity as an early warning biomarker of toxicity using biofilms in the laboratory and in the field

Persistent organic pollutants in two reservoirs along the Paraíba do Sul-Guandu River system, Rio de Janeiro, Brazil

Sediment contamination is evaluated by determining organic micropollutants (organochlorine compounds - OCs and polycyclic aromatic hydrocarbons - PAHs) in two important Brazilian water reservoirs. Trace levels of OCs were observed in the Santana reservoir (44.8 ng g-1 d.w. of p,p'-DDT), while in the Funil reservoir the levels were below detection level. Forty-eight percent of the found sigmaocs were polychlorinated biphenyls, 29% dichlorodiphenyltrichloroethane (DDT), 18% Drins, and 5% other pesticides (HCB, Heptachlor, Heptachlor-epoxide, gamma-HCH and a-Endosulfan). We observed lower levels of sigmaPAH in the Funil reservoir (1 to 275 ng g-1d.w.) than in the Santana reservoir (2.2 to 26.7 µg g-1 d.w.).

Pharmaceuticals occurrence in a WWTP with significant industrial contribution and its input into the river system

Occurrence and removal of 81 representative Pharmaceutical Active Compounds (PhACs) were assessed in a municipal WWTP located in a highly industrialized area, with partial water reuse after UV tertiary treatment and discharge to a Mediterranean river. Water monitoring was performed in an integrated way at different points in the WWTP and river along three seasons. Consistent differences between therapeutic classes were observed in terms of influent concentration, removal efficiencies and seasonal variation. Conventional (primary and secondary) treatment was unable to completely remove numerous compounds and UV-based tertiary treatment played a complementary role for some of them. Industrial activity influence was highlighted in terms of PhACs presence and seasonal distribution. Even if global WWTP effluent impact on the studied river appeared to be minor, PhACs resulted widespread pollutants in river waters. Contamination can be particularly critical in summer in water scarcity areas, when water flow decreases considerably

River Conservation: Going against the Flow to Meet Global Challenges

Rivers are among the most diverse and threatened ecosystems on Earth, as they are impacted by increasing human pressures. Because rivers provide essential goods and services, conservation of these ecosystems is a requisite for sustainable development. Therefore, we must seek ways to conserve healthy rivers and to restore degraded ones

María Zambrano y Georges Bataille: variaciones de lo imposible

[spa]La intención de este artículo es explorar la relación entre poesía, filosofía y el concepto de "lo imposible". Para ello, me propongo revisar no sólo ciertos textos de Zambrano, sino también algunos momentos de la obra de Georges Bataille, en los que estos autores estudiaron, desde dos perspectivas muy distintas, la categoría mencionada.

Maraé

Digitoitu 15. 10. 2005.

Organochlorine pesticides in Piracicaba river basin (São Paulo/Brazil): a survey of sediment, bivalve and fish

The main objective of this paper was to evaluate the level of occurrence of the organochlorine compounds in samples of sediments, bivalves and two fish species collected in the Piracicaba River basin (São Paulo, Brazil). The isomers alpha and gamma of HCH and Heptachlor were most frequently detected in samples of sediments and specimens of bivalve and fish. Therefore, although the levels of these compounds found were not critically high, they are still found in the environment. This fact suggests that they are still being used, despite the fact that the use of these compounds was outlawed more than twenty years ago.

Daño oxidativo en la microalga Pseudokirchneriella subcapitata expuesta a aguas receptoras de un efluente minero en del Río Blanco (V Región, Chile)

In this investigation antioxidant response and toxicity of metals in receiving water effluent miner in the Blanco river in Pseudokirchneriella subcapitata was assessed. The catalase activity, lipid damage through Tbars, the growth rate of was determined. The result showed an inhibition of the growth rate of P. subcapitata which correlated with increased catalase activity and the lipid liperoxidation. These responses were correlated with the concentrations of copper and iron.

Evaluación de la toxicidad de cobre en suelos a través de biomarcadores de estrés oxidativo en eisenia foetida

Copper toxicity in soil was evaluated using biomarkers of oxidative stress (catalase enzyme activity, superoxide dismutase and lipid peroxidation) in the earthworm Eisenia foetida. Agricultural topsoils from mining areas of the Aconcagua river basin were collected. Total copper concentrations were in the range of 94-959 mg kg-1, while the exchangeable copper concentrations were in the range of 46-2225 µg kg-1. Earthworms exposed to soil with exchangeable copper concentrations above 32 µg kg-1 showed an increase in catalase activity. Parameters of antioxidant activity were more sensitive than the weight change and thus can be used as appropriate biomarkers in Eisenia foetida.