In situ measurements of the functional response of benthic suspension feeders exposed to cadmium and anti-fouling paint

In situ measurements of the functional response (feeding, respiration and excretion) of Mytilus edulis and Ciona intestinalis showed that the effects of 2.5 µg 1-1 tributyl tin and 100 µg 1-1 cadmium on an assemblage of the two species was lower than what could be predicted from the response of the two species separately. This is explained by biological interactions between the species and by the fact that the two species may react in different ways to the same disturbance. Thus, results from single species tests seem inadequate for making predictions of pollution effects in marine environments, and tests should instead be carried out at the community or ecosystem level

Geographic and seasonal patterns and limits on the adaptive response to temperature of European Mytilus spp. and Macoma balthica populations

Seasonal variations in seawater temperature require extensive metabolic acclimatization in cold-blooded organisms inhabiting the coastal waters of Europe. Given the energetic costs of acclimatization, differences in adaptive capacity to climatic conditions are to be expected among distinct populations of species that are distributed over a wide geographic range. We studied seasonal variations in the metabolic adjustments of two very common bivalve taxa at European scale. To this end we sampled 16 populations of Mytilus spp. and 10 Macoma balthica populations distributed from 39° to 69°N. The results from this large-scale comprehensive comparison demonstrated seasonal cycles in metabolic rates which were maximized during winter and springtime, and often reduced in the summer and autumn. Studying the sensitivity of metabolic rates to thermal variations, we found that a broad range of Q10 values occurred under relatively cold conditions. As habitat temperatures increased the range of Q10 narrowed, reaching a bottleneck in southern marginal populations during summer. For Mytilus spp., genetic-group-specific clines and limits on Q10 values were observed at temperatures corresponding to the maximum climatic conditions these geographic populations presently experience. Such specific limitations indicate differential thermal adaptation among these divergent groups. They may explain currently observed migrations in mussel distributions and invasions. Our results provide a practical framework for the thermal ecophysiology of bivalves, the assessment of environmental changes due to climate change and its impact on (and consequences for) aquaculture

Assessing the ecological impact of banana farms on water quality using aquatic macroinvertebrate community composition

In Costa Rica, considerable effort goes to conservation and protection of biodiversity, while at the same time agricultural pesticide use is among the highest in the world. Several protected areas, some being wetlands or marine reserves, are situated downstream large-scale banana farms, with an average of 57 pesticide applications per year. The banana industry is increasingly aware of the need to reduce their negative environmental impact, but few ecological field studies have been made to evaluate the efficiency of proposed mitigation strategies. This study compared the composition of benthic macroinvertebrate communities up- and downstream effluent water from banana farms in order to assess whether benthic invertebrate community structure can be used to detect environmental impact of banana farming, and thereby usable to assess improvements in management practises. Aquatic invertebrate samples were collected at 13 sites, using kick-net sampling, both up- and downstream banana farms in fast flowing streams in the Caribbean zone of Costa Rica. In total, 2888 invertebrate specimens were collected, belonging to 15 orders and 48 families or taxa. The change in community composition was analysed using multivariate statistics. Additionally, a biodiversity index and the Biological Monitoring Working Party (BMWP) score system was applied along with a number of community composition descriptors. Multivariate analyses indicated that surface waters immediately up- and downstream large-scale banana farms have different macroinvertebrate community compositions with the most evident differences being higher dominance by a single taxa and a much higher total abundance, mostly of that same taxon. Assessment of macroinvertebrate community composition thus appears to be a viable approach to detect negative impact from chemical-intensive agriculture and could become an effective means to monitor the efficacy of changes/proposed improvements in farming practises in Costa Rica and similar systems

Use of cholinesterase activity as a biomarker of pesticide exposure used on Costa Rican banana plantations in the native tropical fish Astyanax aeneus (Günther, 1860)

IRETIn Costa Rica, thousands of tones of agricultural pesticides have been used for decades and their use is continuously increasing due to intensive and expanding production of coffee, pineapple, rice, ornamental plants and bananas. The objective of this study was to evaluate whether choline esterase (ChE) activity could be used as a biomarker of exposure to pesticides in the Costa Rican native fish Astyanax aeneus (characidae). Three methods used in order to evaluate the ChE biomarker were as follows: Laboratory studies where A. aeneus was exposed to organophosphate pesticide (ethoprophos); In situ 48 hr exposure assessment using caging experiments with fish exposed upstream and downstream of banana plantations and ChE activity estimation of in fish captured directly at sites with different degrees of pesticide exposure. Results from the laboratory studies showed that ChE activity in both brain and muscle tissue was significantly lower in fish exposed to ethoprophos than in controls. Fish from the caging experiments showed no difference in ChE activity neither in brain nor in muscle tissue between the four tested sites and was attributed to the short duration of the exposure. A significant difference in ChE activity was determined in muscle of fish captured from Laguna Madre de Dios compared to fish from Canal Batan. Although our laboratory results revealed that ChE activity in A. aeneus was highly responsive to ethoprophos, results from field experiments were less conclusive and showed that the captured fish showed large variability in ChE activity and that more research is needed before ChE activity can be used as reliable biomarker of pesticide exposure.En Costa Rica, se han utilizado miles de toneladas de pesticidas agrícolas durante décadas y su uso aumenta continuamente debido a la producción intensiva y en expansión de café, piña, arroz, plantas ornamentales y banano. El objetivo de este estudio fue evaluar si la actividad de la esterasa de colina (ChE) podría utilizarse como biomarcador de exposición a plaguicidas en el pez nativo costarricense Astyanax aeneus (characidae). Los tres métodos utilizados para evaluar el biomarcador ChE fueron los siguientes: estudios de laboratorio en los que A. aeneus estuvo expuesta a plaguicidas organofosforados (etoprofos); Evaluación de exposición in situ de 48 horas mediante experimentos de enjaulamiento con peces expuestos río arriba y río abajo de plantaciones de banano y estimación de la actividad de ChE en peces capturados directamente en sitios con diferentes grados de exposición a plaguicidas. Los resultados de los estudios de laboratorio mostraron que la actividad de ChE tanto en el cerebro como en el tejido muscular fue significativamente menor en los peces expuestos al etoprofos que en los controles. Los peces de los experimentos en jaulas no mostraron diferencias en la actividad de ChE ni en el cerebro ni en el tejido muscular entre los cuatro sitios evaluados y se atribuyó a la corta duración de la exposición. Se determinó una diferencia significativa en la actividad de ChE en el músculo de los peces capturados en la Laguna Madre de Dios en comparación con los peces del Canal Batán. Aunque los resultados de nuestro laboratorio revelaron que la actividad de ChE en A. aeneus era muy sensible al etoprofos, los resultados de los experimentos de campo fueron menos concluyentes y mostraron que los peces capturados mostraron una gran variabilidad en la actividad de ChE y que se necesita más investigación antes de que la actividad de ChE pueda usarse como biomarcador confiable de exposición a plaguicidas.Na Costa Rica, milhares de toneladas de pesticidas agrícolas têm sido usados ​​há décadas e seu uso está aumentando continuamente devido à produção intensiva e em expansão de café, abacaxi, arroz, plantas ornamentais e bananas. O objetivo deste estudo foi avaliar se a atividade da colina esterase (ChE) poderia ser usada como biomarcador de exposição a pesticidas no peixe nativo da Costa Rica Astyanax aeneus (characidae). Os três métodos utilizados para avaliar o biomarcador ChE foram os seguintes: Estudos laboratoriais onde A. aeneus foi exposto a pesticida organofosforado (etoprofós); Avaliação da exposição in situ de 48 horas usando experimentos de enjaulamento com peixes expostos a montante e a jusante das plantações de banana e estimativa da atividade de ChE em peixes capturados diretamente em locais com diferentes graus de exposição a pesticidas. Os resultados dos estudos de laboratório mostraram que a atividade ChE no cérebro e no tecido muscular foi significativamente menor nos peixes expostos ao etoprofós do que nos controles. Os peixes dos experimentos de enjaulamento não mostraram diferença na atividade ChE nem no cérebro nem no tecido muscular entre os quatro locais testados e foi atribuído à curta duração da exposição. Uma diferença significativa na atividade de ChE foi determinada no músculo dos peixes capturados na Laguna Madre de Dios em comparação com os peixes do Canal Batan. Embora os resultados do nosso laboratório tenham revelado que a atividade ChE em A. aeneus foi altamente responsiva ao etoprofós, os resultados dos experimentos de campo foram menos conclusivos e mostraram que os peixes capturados mostraram grande variabilidade na atividade ChE e que mais pesquisas são necessárias antes que a atividade ChE possa ser usada. biomarcador confiável de exposição a pesticidas.Department of Systems Ecology, SwedenUniversidad Nacional, Costa RicaInstituto Regional de Estudios en Sustancias Tóxica

Additive effects of the herbicide glyphosate and elevated temperature on the branched coral Acropora formosa in Nha Trang, Vietnam

The combined effects of the herbicide glyphosate and elevated temperature were studied on the tropical staghorn coral Acropora formosa, in Nha Trang bay, Vietnam. The corals were collected from two different reefs, one close to a polluted fish farm and one in a marine-protected area (MPA). In the laboratory, branches of the corals were exposed to the herbicide glyphosate at ambient (28 °C) and at 3 °C elevated water temperatures (31 °C). Effects of herbicide and elevated temperature were studied on coral bleaching using photography and digital image analysis (new colorimetric method developed here based on grayscale), chlorophyll a analysis, and symbiotic dinoflagellate (Symbiodinium, referred to as zooxanthellae) counts. All corals from the MPA started to bleach in the laboratory before they were exposed to the treatments, indicating that they were very sensitive, as opposed to the corals collected from the more polluted site, which were more tolerant and showed no bleaching response to temperature increase or herbicide alone. However, the combined exposure to the stressors resulted in significant loss of color, proportional to loss in chlorophyll a and zooxanthellae. The difference in sensitivity of the corals collected from the polluted site versus the MPA site could be explained by different symbiont types: the resilient type C3u and the stress-sensitive types C21 and C23, respectively. The additive effect of elevated temperatures and herbicides adds further weight to the notion that the bleaching of coral reefs is accelerated in the presence of multiple stressors. These results suggest that the corals in Nha Trang bay have adapted to the ongoing pollution to become more tolerant to anthropogenic stressors, and that multiple stressors hamper this resilience. The loss of color and decrease of chlorophyll a suggest that bleaching is related to concentration of chloro-pigments. The colorimetric method could be further fine-tuned and used as a precise, non-intrusive tool for monitoring coral bleaching in situ.</p