Freshwater fish diversity hotspots for conservation priorities in the Amazon Basin

Conserving freshwater habitats and their biodiversity in the Amazon Basin is a growing challenge in the face of rapid anthropogenic changes. We used the most comprehensive fish-occurrence database available (2355 valid species; 21,248 sampling points) and 3 ecological criteria (irreplaceability, representativeness, and vulnerability) to identify biodiversity hotspots based on 6 conservation templates (3 proactive, 1 reactive, 1 representative, and 1 balanced) to provide a set of alternative planning solutions for freshwater fish protection in the Amazon Basin. We identified empirically for each template the 17% of sub-basins that should be conserved and performed a prioritization analysis by identifying current and future (2050) threats (i.e., degree of deforestation and habitat fragmentation by dams). Two of our 3 proactive templates had around 65% of their surface covered by protected areas; high levels of irreplaceability (60% of endemics) and representativeness (71% of the Amazonian fish fauna); and low current and future vulnerability. These 2 templates, then, seemed more robust for conservation prioritization. The future of the selected sub-basins in these 2 proactive templates is not immediately threatened by human activities, and these sub-basins host the largest part of Amazonian biodiversity. They could easily be conserved if no additional threats occur between now and 2050.     

Hydrocarbon biodegradation and dynamic laser speckle for detecting chemotactic responses at low bacterial concentration

We report on the biodegradation of pure hydrocarbons and chemotaxis towards these compounds by an isolated chlorophenol degrader,Pseudomonas strain H.The biochemical and phylogenetic analysis of the 16S rDNA sequence identified Pseudomonas strain H as having 99.56% similarity with P.aeruginosa PA01.This strain was able to degrade n-hexadecane,1-undecene,1-nonene,1-decene,1-dodecene and kerosene.It grew in the presence of 1-octene,while this hydrocarbons is toxic to other hydrocarbons degraders.Pseudomonas strain H was also chemotactic towards n-hexadecane,kerosene,1-undecene and 1-dodecene.These results show that this Pseudomonas strain H is an attractive candidate for hydrocarbon-containing wastewater bioremediation in controlled environments.Since the classical standard techniques for detecting chemotaxis are not efficient at low bacterial concentrations,we demonstrate the use of the dynamic speckle laser method,which is simple and inexpensive,to confirm bacterial chemotaxis at low cell concentrations (less than 105 colony-forming unit per millilitre (CFU/mL)) when hydrocarbons are the attractants.     

Effects of the pharmaceuticals gemfibrozil and diclofenac on biomarker expression in the zebra mussel (Dreissena polymorpha) and their comparison with standardised toxicity tests

Pharmaceuticals, including the lipid regulator gemfibrozil and the non-steroidal anti-inflammatory drug diclofenac have been identified in waste water treatment plant effluents and receiving waters throughout the western world. The acute and chronic toxicity of these compounds was assessed for three freshwater species (Daphnia magna,Pseudokirchneriella subcapitata, Lemna minor) using standardised toxicity tests with toxicity found in the non-environmentally relevant mid mg L⁻¹ concentration range. For the acute endpoints (IC₅₀ and EC₅₀) gemfibrozil showed higher toxicity ranging from 29 to 59 mg L⁻¹ (diclofenac 47-67 mg L⁻¹), while diclofenac was more toxic for the chronic D. magna 21 d endpoints ranging from 10 to 56 mg L⁻¹ (gemfibrozil 32-100 mg L⁻¹). These results were compared with the expression of several biomarkers in the zebra mussel (Dreissena polymorpha) 24 and 96 h after exposure by injection to concentrations of 21 and 21,000 μg L⁻¹ corresponding to nominal concentrations of 1 and 1000 μg L⁻¹. Exposure to gemfibrozil and diclofenac at both concentrations significantly increased the level of lipid peroxidation, a biomarker of damage. At the elevated nominal concentration of 1000 μg L⁻¹ the biomarkers of defence glutathione transferase and metallothionein were significantly elevated for gemfibrozil and diclofenac respectively, as was DNA damage after 96 h exposure to gemfibrozil. No evidence of endocrine disruption was observed using the alkali-labile phosphate technique. Results from this suite of biomarkers indicate these compounds can cause significant stress at environmentally relevant concentrations acting primarily through oxidation pathways with significant destabilization of the lysosomal membrane and that biomarker expression is a more sensitive endpoint than standardised toxicity tests.     

Temporal and spatial changes in primary biomass as a diagnosis and prognosis in environmental impact (Rapel Reservoir,Central Chile)

Extensive mortality of silversides (Atherinidae), Odontesthes bonariensis, was recorded during July 1989 in the Rapel Reservoir. Temporal and spatial changes observed in biomass concentration (chlorophyll-a) through both ground and remote sensing samples (LANDSAT), allowed us to establish a potential environmental impact. Ground measurements established an input of sulfate (SO₄) in a eutrophic area. The mean concentration of biomass tended to decrease in this area in comparison with other mesotrophic areas. The local disfunction associated with the observed biomass changes has been used to develop a prediction in species composition and in biomass concentration.

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Resumen Durante la primera semana de Julio de 1989, se registró una muerte masiva de pejerreyes, Odontesthes bonariensis en el Embalse Rapel. En los procesos de monitoreo de la calidad de agua en el Embalse Rapel, se utilizó una representacion espacial primaria de las variables de estado elegidas. Las tendencias témporo-espaciales observadas en la concentración de biomasa fitoplanctónica (clorofila-a) permitieron establecer un impacto ambiental potencial por un agente exógeno al sistema. A partir de mediciones de terreno se estableció la presencia de sulfato (SO₄) en una zona de características eutróficas. Los efectos observados en esta zona, en comparación al resto del embalse, fueron una disminución en la concentración media de la biomasa. La disfunción local observada, permitió sustentar una prognosis asociada a la composición de especies fitoplanctónicas y la concentración de biomasa local.

     

Polycyclic aromatic hydrocarbons in sediments and mussels of Corral Bay, south central Chile

PAHs were measured in sediments and mussels (Mytilus chilensis) from Carboneros and Puerto Claro, located in Corral Bay, Valdivia. According to the ratio of phenanthrene/anthracene and fluoranthene/pyrene concentrations, these sites are medium polluted with PAHs originating mainly from pyrolytic sources. Fluoranthene was the major component measured in mussels (3.1-390 ng g(-1) dry weight) and sediments (6.9-74.1 ng g(-1) dry weight). In general, mussels were mainly exposed to the dissolved fraction of the lower molecular weight PAHs (tri- and tetra-aromatics) while the higher molecular ring systems (penta- and hexa-aromatics) were more bioavailable to sediments. Mussel PAHs content was relatively constant, with the exception of the 1999 summer season (March), when higher concentration values were found in both sites; however, PAHs residues in sediments showed a temporal variation.     

The effect of paraoxon on spermatogenesis in <Emphasis Type="Italic">Dugesia gonocephala</Emphasis> from the Chilean Altiplano: proliferation and apoptosis

Introduction and aims  

The Chilean Altiplano ecosystem is conserved free from contaminants and pollutants because of the absence of major local human activities such as agriculture or other industries. We studied the effects of paraoxon on proliferation and apoptosis of testicular cells during active spermatogenesis in Dugesia gonocephala collected from a pristine river (Guacollo) in the Altiplano region nearby Visviri town, Chile.     

Effects of Spatial and Temporal Data Aggregation on the Performance of the Multi‐Radar Multi‐Sensor System

The objectives of this study were to (1) evaluate the performance of the Multi‐Radar Multi‐Sensor (MRMS) system in capturing precipitation compared to gauge data, and (2) assess the effects of spatial (1–50 km) and temporal (15–120 min) data aggregation scales on the performance of the MRMS system. Point‐to‐grid comparisons were conducted between 215 rain gauges and the MRMS system. The MRMS system at 1 km spatial and 15 min temporal resolutions captured precipitation reasonably well with average R², root mean square error (RMSE), and percent bias (PBIAS) values of 0.65, 0.5 mm, and 11.9 mm; whereas Threat Score, probability of detection, and false alarm ratio were 0.57, 0.92, and 0.40, respectively. Decreasing temporal resolution from 15 min to two hours resulted in an increase in R² and a decrease in RMSE, whereas PBIAS was not affected. Reducing spatial resolution from 1 to 50 km resulted in increases in R² and PBIAS, whereas RMSE was decreased. Increasing spatial aggregation scale from 1 to 50 km resulted in an R² increase of only 0.08. Similarly, improvement in R² was only modest (0.17) compared to an eightfold reduction in temporal resolution (from 15 min to two hours). While aggregating data at coarser temporal resolutions resolved some of the under/overestimation issues of the MRMS system, it was apparent even at coarser spatial and temporal resolutions the MRMS system inherently overestimated smaller precipitation events while underestimated bigger events.     

Locomotion versus spawning: escape responses during and after spawning in the scallop Argopecten purpuratus

The energetic cost of spawning and the endogenous factors that modulate spawning could modify escape response performance, leading to a conflict between the requirements of two fundamental components of fitness: reproduction and survival. We examined whether spawning changed force production during escape responses by the functionally hermaphroditic scallop, Argopecten purpuratus, and whether the response of smooth (tonic) and striated (phasic) muscles differed. Force production during escape responses by mature scallops was compared before induction of spawning, during spawning and after completion of spawning. Maximum tonic force and the area under the force curve (total force recorded) were diminished during gamete release, whereas phasic force production (maximum and mean force) increased after spawning was completed. The number and frequency of phasic contractions did not change during the spawning process, suggesting that spawning did not limit fuel availability for phasic contractions. The decrease in tonic force during spawning and the increased phasic force production after spawning may reflect changes in monoamine levels during gamete release. Whereas the spawning process modified force production during escape responses, the changes would, if anything, enhance escape performance during an initial encounter between a scallop and a predatory sea star.