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Plankton Stress Responses From Pah Exposure And Nutrient Enrichment, Morten Hjorth, Valery E. Forbes, Ingela Dahllöf
Plankton Stress Responses From Pah Exposure And Nutrient Enrichment, Morten Hjorth, Valery E. Forbes, Ingela Dahllöf
Valery Forbes Publications
The hypothesis that the nature and force of PAH stress responses from plankton systems are coupled to the nutrient status of that system was tested in a mesocosm experiment. Four treatments were applied consisting of control (Cn), pyrene exposed (Py). nutrient spiked (Nu), and nutrient spiked and pyrene exposed (NuPy) groups in replicate bags (n = 3) representing plankton communities including bacteria, phytoplankton and zooplankton. Regardless of nutrient status, all the Py mesocosms were affected directly with decreases in chlorophyll α concentrations to 20 % of control values on Day 1. Primary production was also significantly lower (< 50 %) than Cn communities in both Py and NuPy communities after the first pyrene exposure. Indirect effects were observed as increased bacterial activity due to nutrient release from algal death, thereby channelling growth to another trophic level. With time the plankton system became top-down controlled, dominated by zooplankton, which was also the trophic group experiencing the longest lasting effect on structure. The occurrence of late effects in the zooplankton communities were seen in all treatments, but the magnitude of the effects was dependent on the nutrient status, most probably because of a larger trophic transfer of the contaminant. To improve our understanding of contaminant effects on food webs in natural communities, it is imperative that interactions between trophic levels in relation to abiotic factors are investigated.
Inducible Metabolism Of Fluoranthene By The Opportunistic Polychaete Capitella Sp. I, Valery E. Forbes, Thomas L. Forbes, Marianne Holmer
Inducible Metabolism Of Fluoranthene By The Opportunistic Polychaete Capitella Sp. I, Valery E. Forbes, Thomas L. Forbes, Marianne Holmer
Valery Forbes Publications
The polychaete Capitella sp. I has been described as an enrichment opportunist and is one of very few species able to thrive in highly organic sediments heavily contaminated with polycyclic aromatic hydrocarbons (PAH) and other organic pollutants. We examined 3 plausible explanations for the success of Capitella sp. 1: (1) worms prevent uptake of PAH across body surfaces, (2) worms take up PAH but metabolize them effectively to excretable forms, and (3) worms utilize PAH as a carbon source. We examined the uptake and depuration of sediment-associated fluoranthene by Capitella sp. 1 and measured the metabolic loss of ingested 3-[ …