2 Paleontology I - Taphonomy and Global Change

Sunday, 31 October 2010
8:00 AM - 12:00 PM
Hall F

USE OF HISTORICAL AND BASELINE SPECIMENS TO TRACK RESPONSES OF MOLLUSCAN PRIMARY CONSUMERS TO THE EFFECTS OF THE 2010 DEEPWATER HORIZON HYDROCARBON SPILL

Paper number: 2-6
Program: Technical Sessions
Time: 9:15 AM – 9:30 AM

Authors

Abstract

Documenting direct and indirect effects of environmental stressors on benthic marine communities requires incorporation of baseline and historical data. For instance, hydrocarbons from the 2010 Gulf of Mexico Deepwater Horizon well explosion is impacting coastal areas long affected by natural hydrocarbon seeps, petroleum exploration and development, and other anthropogenic effects. In Louisiana, exploration in coastal areas that began in the 1920s, expanded greatly with the development of the first mobile drilling barge in 1933. In total nearly 50,000 wells are reported to have been drilled in the Gulf of Mexico region. Given this historical context, we are assessing pathways and rates at which hydrocarbons from the 2010 spill are incorporated into northern Gulf of Mexico coastal food webs using sclerochronological techniques to unlock the high-resolution records preserved within molluscan shells. We are using specimens collected from the early 20th century through August 2010.

We are examining changes in live history traits (growth rate, recruitment, mortality, reproduction) of a variety of primary consumer species, including the commercially important oyster Crassostrea virginica. The species range from epifaunal, sessile, filter feeders; to infaunal, mobile, deposit feeders; to epifaunal, mobile, omnivorous grazers. In this way, multiple pathways into coastal food webs are monitored. Because environmental perturbations are recorded on multiple scales by the accretionary growth of mollusk shells, we are monitoring the incorporation of crude oil components into shells, e.g., the trace metals V and Ni, and simultaneously measuring changes in growth rate, survivorship, and post-spill larval recruitment. Life-history parameters are calculated from ontogenetic δ13C and δ18O profiles of the mollusks' shells. In this way, we will track secondary impacts (not related to fouling by direct contact) of hydrocarbons through trophic levels of the coastal ecosystem.