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Relationships Between Chemical Exposure and Parasites in Flatfishes from Santa Monica Bay, Southern California
Numerous studies have shown that fish parasite communities change in response to pollution levels and could serve as effect bioindicators of ecosystem health. My study sought bioindicators of chemical pollution in parasitological data, i.e., species richness and overall abundance, and the prevalence and intensity of individual endohelminths in particular host fishes. The hosts I studied were Citharichthys stigmaeus (speckled sanddab), Citharichthys sordidus (Pacific sanddab), and Parophrys vetulus (English sole). Of these three species, 250 flatfish were collected from 13 trawl stations in the Santa Monica Bay and Los Angeles-Long Beach Harbor areas, both areas known to be affected by anthropogenic pollution. Flatfish were necropsied for macroparasites. Also recorded were host measures (sizes of fish and of livers, age, and gender). Sediment profiles of PCBs, DDT, and select heavy metals for spots near my sample locations were used from Hyperion's 2008 sediment pollutant data. I characterized pollutant risk at each station using Sediment Quality Values (SQVs), and I generated hazard quotients (HQ) scaled to Threshold Effects Levels (TEL) and Probable Effects Levels (PEL). My results indicate that endohelminth community parameters such as species richness and abundance may indicate sediment pollutant loads of DDT and of heavy metals. In addition, the endoparasites Lacistorynchus dollfusi, Scolex pleuronectis, Anisakis simplex, and Cucullanus annulatus may serve as effect bioindicators of pollution.