Contaminants and Stable Isotopes: Tools to Unravel the Effects of Anthropogenic Stressors on Aquatic Food Webs.

Anthropogenic stressors can have a wide range of effects on aquatic ecosystems. While at times these effects can be very apparent, there are often subtle effects that are less obvious, and the mechanisms behind these shifts in aquatic food webs can be difficult to determine using standard observational methods, such as measures of abundance, or stomach content analysis. In order to better understand the effects of stressors on food web dynamics, including energy flow, feeding habits, and trophic cascades, analytical methods may be used to infer the mechanisms and processes responsible for the food web changes. Stable carbon, nitrogen, oxygen, and/or sulfur isotope analysis may be used to describe trophic status, feeding habits, and patterns of primary productivity. These processes may be further informed by using persistent contaminants as tracers, since they tend to bioaccumulate in varying amounts depending on trophic position and feeding habit. Examination of which habitats and life history traits are associated with higher contaminant levels can provide important information of the mechanisms of accumulation in aquatic food webs. By combining these isotopic and contaminant analytical methods, it is possible to unravel how stressors may be affecting ecosystems of concern across the globe, and provide information for managing these ecosystems.  The objectives for this symposium are to disseminate the most current theory, methodology, and findings regarding stable isotope and contaminant-based ecological research in aquatic food webs.  The accumulation and magnification of contaminant concentrations in biological organisms is a human health concern, but the mechanisms responsible for high levels of contaminants in top predators, like fish, are often not well-understood.  New analytical techniques and novel applications of food web theory using stable isotopes and contaminants have the potential to be powerful tools in understanding complex trophic dynamics in aquatic ecosystems.

Ariana Chiapella and Angela Strecker
Ariana Chiapella and Angela Strecker
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