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Influence of organic carbon on estuarine benthic infauna of the US west coast
Citation:
FRAZIER, M. R., H. LEE, II, AND W. G. NELSON. Influence of organic carbon on estuarine benthic infauna of the US west coast. Presented at 40th Benthic Ecology Meeting, Mobile, AL, March 16 - 20, 2011.
Impact/Purpose:
Total organic carbon (TOC) is often used as an indicator of eutrophication in estuarine environments.
Description:
Total organic carbon (TOC) is often used as an indicator of eutrophication in estuarine environments. However, the determination of biologically relevant sediment TOC criteria to indicate estuarine condition is complicated by the relationship between TOC and grain size. Both variables independently influence species distributions, and thus estimates of species and community sensitivity to sediment TOC may be confounded. We examined how estuarine benthic infauna responded to sediment TOC after statistically controlling for sediment size using data from >1,400 benthic samples collected from Puget Sound, WA to Northern Mexico collected with a 0.1 m2 grab and 1-mm sieve. Sediment TOC ranged from 0 – 22%, with nearly 80% of the samples having 0-2% TOC. The probability of a species occurring in a sample was predicted from the percentage of fines (silt and clay) and sediment TOC using splinal logistic regression models. The distribution of common species was affected by percent fines; and, based on preliminary analyses, more than a quarter of these were affected by percent sediment TOC. In addition to determining potentially detrimental TOC thresholds, this approach identifies infaunal species that are sensitive or tolerant to eutrophication, which can be a key element for benthic indicator development.