W5 PM Toxicity of Complex Mixtures
Wednesday, 16 November 2005: 1:50 PM - 5:30 PM in 321-323

(MER-1117-838618) PAH-induced impacts on the bioenergetics and PCB bioaccumulation in Fundulus heteroclitus.

Merten, A¹, Beard, E², Baker, J², ¹ NOAA Office of Response and Restoration, Seattle, WA, USA² University of Maryland, Chesapeake Biological Lab, Solomons, MD, USA

ABSTRACT- Long-term residual contamination from oil spills and other sources of polycyclic aromatic hydrocarbons (PAHs) may exert sublethal narcosis on fish by reducing standard metabolic rate (SMR), and subsequently affecting bioaccumulation. We conducted a 120 day study (2x4x3 factorial, random block design) to quantify the impacts of long-term exposure to dissolved and dietary narcotics on Fundulus heteroclitus. The study evaluated bioenergetic parameters (growth, fraction of lipid, and standard metabolic rate) and PCB bioaccumulation to correlate chronic exposure to dietary PAHs with changes in bioenergetics and bioaccumulation. Fish were exposed to two levels of MS-222 (0 and 50 mg/L), and four levels of food treatments (1: control food, 2: 10% contaminated food:90% control food, 3: 50% contaminated food:50% control food, and 4: 100% contaminated control food). Contaminated food consisted of caging clams at a creosote-contaminated site for 30 days to accumulate bioavailable PAHs (3000 ng/g -PAH). Background concentrations of -PCBs were used to assess treatment-induced changes in accumulation. On days 0, 35, 62, 90, and 120, we measured individual fish growth parameters, SMRs, and PCB accumulation. SMR responded in a non-linear manner to the exposure treatments. The 10% PAH-contaminated food depressed SMR. Above the 10% PAH-contaminated food concentrations (> 835 ng/g), SMR increased masking sublethal narcosis by other modes of PAH toxicity. PAH-contaminated food significantly increased PCB accumulation between the control food treatments and the 10% contaminated food treatment (p = 0.0307). On day 120, PCB accumulation increased as the PAH concentration in the food increases (p = 0.038). To further examine the interactions between fish bioenergetics and contaminant bioaccumulation dynamics at individual and population levels, we developed a bioenergetics model for Fundulus. The model examined how sublethal changes in individual energetic potentially impact population parameters and compares change in total population biomass from altering energetics to changing mortality probabilities.

Key words: narcosis, PAHs, PCB accumulation, bioenergetics