INVESTIGATORS: Irvine, Gail V.; Mann, Daniel H.; Short, Jeffrey W.
PROJECT DESCRIPTION:
As a result of the 1989 Exxon Valdez oil spill,
extensive shorelines and intertidal biological communities were contaminated.
Concern for the longer-term effects of such oiling became focused in 1991 on
mussel beds, which showed the highest levels of contamination at that point, and
persistent contamination of national park coastlines. Mussel (Mytilus trossulus)
beds were of concern both because of their structural importance intertidally
and their importance as prey for numerous consumers, including other species
that had not recovered since the spill. Residual oiling of national park
coastlines represented continuing injury to the wilderness characteristics of
these special-value lands. Studies on both projects were begun in 1992. The
objectives of the oiled mussel bed study were to: 1) determine the geographical
extent of continued contamination of mussel beds outside of Prince William Sound
(PWS) (NOAA was studying effects inside PWS), 2) determine the degree of
contamination of both mussels and underlying sediments, and the rate of recovery
to baseline hydrocarbon levels, and 3) confirm the contamination source was
Exxon Valdez oil (EVO). Objectives of the shoreline contamination study were to
determine: 1) in which geomorphic situations oil persisted, 2) the rate of
degradation of the oil, and 3) what mechanisms contributed to persistence and
state of weathering of the oil.
APPLICATION OF RESEARCH: The results of this research will increase our understanding of the long-term and ecological effects of spills in sub-arctic waters, and may affect revision of environmental sensitivity indices, and future response (protection and clean-up)actions following spills.
PROGRESS: 2/4/2000
During FY1999, both mussel beds on the Kenai Peninsula and oiled shorelines of
Kenai Fjords and Katmai National Parks were resampled. Mussel and sediment
samples are being analyzed for the relative abundance of polynuclear aromatic
hydrocarbons and a weathering coefficient will be determined. The apparent
oiling of mussel beds has declined at most sites since these particular beds
were last sampled four years ago. Hydrocarbon analyses of oil from the
boulder-armored shorelines indicate that the oil mousse that persists as
subsurface oil has changed little in chemical composition since the last
sampling 5 years ago. In fact, this oil is essentially equivalent to 11-day old
Exxon Valdez oil, even though it traveled up to 500 km from the spill origin
over periods of up to 30 days. The persistence and lack of weathering of oil on
such high energy beaches was quite unexpected prior to this study. Further
hydrocarbon analyses of mussels and associated sediments are awaited.