PS 77-186
Ecological effects of heavy metal leaching in the Bahamian lobster fishery
Lobster condos are rapidly becoming the predominant fishing method for Bahamian lobster. Condos are comprised of corrugated sheet metal nailed to 2x6s, open on one or both ends and weighed down by cement blocks. Condos create artificial habitats for lobster and encourage congregations of a large number of individuals for the lobster fishery. Despite the predominance of condo use in The Bahamas, little work has been done looking at ecological impacts of condo habitats. Of primary importance is the possibility that the materials comprising the condos – chemically-treated wood and paint applied to sheet metal – leach hazardous chemicals into the marine system over time. Bioaccumulation of metals in tissues has served as a proxy for metal inputs into disturbed systems in previous marine studies. In order to provide a baseline for metal contamination, we conducted heavy metal isotopic analysis of wood from condos, primary production (seagrass and macro algae), and lobster tissue to determine if concentrations of leached heavy metals are found in higher concentrations by condos. Metal leaching into nearby systems highlights that condos may be having direct (higher harvest) and indirect (metal toxicity) effects on lobster populations.
Results/Conclusions
Isotopic analysis of twenty-six different heavy metals demonstrated that concentrations vary drastically based on location and material throughout the system. Heavy metal concentrations in wood were two to three orders of magnitude higher when compared to most tissue types. Macroalgae, which grows directly on the wood, has significantly higher metal values as well. There is a significant difference (p<0.05) in Arsenic, Chromium, and Magnesium concentrations between the two islands surveyed, which we believe reflects differences in the predominant fishing style of fishermen accessing the waters surrounding each island. Despite variation across metals, the consistent variation between islands could serve as a proxy for fishing effort with condos. Understanding sources and sinks of these heavy metals has direct ecotoxicological implications for the health and sustainability of the Bahamian Lobster fishery.