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.

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).

In 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. Asignificant difference in ChE activity was determined in muscle of fish captured from Laguna Madre de Dios compared to fish from Canal Batán. 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.

The effect of thermal stress on protein composition in dogwhelks (Nucella lapillus) under normoxic and hyperoxic conditions.

In this laboratory study, dogwhelks (Nucella lapillus) were collected from the intertidal zone and exposed to 16 degrees C (ambient), 26.5 degrees C and 30 degrees C under normal and hyperoxic conditions respectively. It was shown that there was no thermally induced mortality at 26.5 degrees C, but that the mortality rate was 40-50% in 30 degrees C. This mortality rate was reduced to 10% if extra oxygen was provided, indicating that oxygen supply was setting the limit for whole organism thermal tolerance. Tissue samples were then analysed for protein features using two-dimensional gel electrophoresis, and both up and down regulation of proteins were visualised by silver staining and crosswise comparisons of gels from control vs. treated animals. The results clearly show that the protein profiles from dogwhelks exposed to increased water temperatures differ from those of the control, but that increased oxygen availability alleviates these differences thus increasing the similarity between heat-shocked and control animal protein pattern. This implies a more stable protein metabolism and might explain the increased survival of heat-shocked individuals when extra oxygen is supplied.

Effects of the multiple stressors copper and reduced salinity on the metabolism of the hermatypic coral Porites lutea.

This study investigates the physiological responses in the hermatypic coral Porites lutea when exposed to a combination of reduced salinity (from ambient 30 psu to 20 psu) and two concentrations of copper (CuS04), 10 microg 1(-1) and 30 microg 1(-1). Corals were exposed for 14 h and changes in metabolism in terms of primary production rate per chlorophyll a and respiration per surface area (cm2) were used as measures of stress. The results showed no significant changes in respiration rate in any of the treatments compared with controls, or between treatments. The primary production rate, however, displayed a more complex pattern. Corals exposed to reduced salinity, 30 microg 1(-1) copper, and the combination of the two stressors significantly reduced the production rate, whereas corals exposed to 10 microg 1(-1) only, remained unaffected. However, adding 10 microg 1(-1) copper to reduced salinity did not affect the production rate thus indicating an antagonistic effect.

Experiences from long-term research cooperation between Costa Rican, Nicaraguan, and Swedish institutions.

This paper summarizes experiences from long-term ongoing cooperation between Swedish research institutions and institutions at the National Universities in Nicaragua and Costa Rica. 24 researchers and teachers from the Central American institutions and ten Swedish research students have been trained. In addition to three full doctoral and three licentiate (two-year PhD program) theses, the two programs have so far published 15 articles in English-language, international, refereed journals and about three times as many abstracts for conferences in more than ten countries. A "sandwich" model for training is recommended, where the southern researchers come to the wealthier partner for collaborative analyses and write-ups of the publications, while spending 50-75% of their time in their home countries for data collection. Such collaboration should be planned for a time span of at least eight years and include substantial numbers of researchers and students. Means to minimize the risk of brain drain are suggested. The collaboration has been important for the globalization of the research cultures at the participating institutions and has trained international experts.

Protein expression signatures identified in Mytilus edulis exposed to PCBs, copper and salinity stress.

Applied to environmental toxicology, proteome analysis may be used to isolate chemical-specific protein expression signatures (PES). In this project specific PES were isolated in mussels, Mytilus edulis, from the Baltic Sea subjected in the laboratory to treatment with copper (70 ppb), Aroclor 1248 (1 ppb), and to lowered salinity. Four mussels in each treatment group were acclimated in the laboratory for 24 h before beginning the 7-day exposure. Whole body tissue was homogenized and separated using two-dimensional gel electrophoresis. The protein gels were scanned to TIFF files and compared using MELANIE II 2D gel analysis software (BioRad). Protein expression signatures including proteins induced and repressed by exposure were isolated for each treatment group. The specificity of PES due to environmental changes shows promise in bioindication, toxicity testing and in helping identify possible toxicity mechanisms.