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Project Information

Title: Subtidal Monitoring: Eelgrass Communities

Project Year and Number: 1996: 96106

Other Fiscal Years and Numbers for this Project: 1995: 95106, 1993: 93047-A, 1993: 93047-2, 1993: 93047-1, 1993: 93047, 1992: ST02-A, 1991: ST02

Principal Investigator (PI): Stephen Jewett, University of Alaska Fairbanks

Assisting Personnel: Tom Dean

Research Location: Prince William Sound

Restoration Category: Monitoring

Injured Resources Addressed: Subtidal Organisms

Abstract: This study has focused on the injury to, and recovery of, shallow (< 20 m) subtidal eelgrass communities in western Prince William Sound following the Exxon Valdez oil spill (EVOS). Effects were assessed in 1990, 1991, and 1993 primarily by examining differences in population parameters (e.g., abundance, biomass) of dominant taxa within the subtidal eelgrass habitat. A final resampling of this habitat is planned for the summer of 1995.

In 1990, we noted significant differences between oiled and control sites with respect to a number of taxa. Among the differences noted were greater densities of eelgrass flowers and shoots, amphipods, trochid snails, Telmessus crabs, and Dermasterias sea stars at the control sites. Other taxa, including small epifaunal mussels, (Musculus) and spirorbid worms, a variety of infaunal polychaetes, and juvenile cod, were more abundant at oiled sites.

The infaunal benthic community within the deeper portion (3 to 20 m) of the eelgrass habitat appeared especially affected by the EVOS, as there was a decline in diversity as well as reductions in a number of dominant taxa. On the other hand, the benthic community in shallower portions of the habitat, within the eelgrass bed, showed a general enhancement of both diversity and abundance of several dominant taxa. The notable exception was for amphipods, which declined in all habitats.

By 1991 there was strong evidence of recovery of eelgrass by as evidenced by fewer differences in community parameters and dominant taxa than observed in 1990. Although some recovery was still evident by 1993, e.g., large epifaunal crabs (Telmessus) and sea stars (Dermasterias), many infaunal and small epifaunal taxa were more prevalent in oiled eelgrass sites, resembling 1990.

Polycyclic aromatic hydrocarbon (PAH) concentrations in sediments were generally higher at oiled than control sites and in the deeper portions of the habitat. The highest concentrations observed were greater than 1000 ng g-1 at several eelgrass sites in 1990. PAH concentrations declined to less than100 ng g-1 by 1993, but were still somewhat higher at oiled sites.

Many of the observed effects appeared related to the effects of oil. The reduction in the abundance of amphipods was presumably due to the acute toxicity of oil. However, most other declines in population density were probably related to either the sublethal effects of oil or to indirect effects such as increased predation. Increased abundance of most taxa at oiled sites appeared related, either directly or indirectly, to organic enrichment from either oil or from bioremediation.


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Proposal: PDF Not Available

Funding Recommendations: View

Funding Detail For: 1996

Quarterly Project Tasks For: 1996

Annual Report: 1996: Not Available

Final Report: See Project 1033

Publications from this Project: None Available

More information may be available for this project under other years:

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Project Number Proposal Annual Reports Final Report Data
1995: 95106 Not Available 1995: Not Available
View No datasets
1993: 93047-A Not Available 1993: Not Applicable
Not Available - For Current Status Please Contact Us No datasets
1993: 93047-2 Not Available 1993: Not Applicable
View No datasets
1993: 93047-1 Not Available 1993: Not Applicable
View No datasets
1993: 93047 Not Available 1993: Not Applicable
View No datasets
1992: ST02-A View (PDF) 1992: Not Applicable
See Project 93047 No datasets
1991: ST02 Not Available 1991: Not Applicable
Not Available - For Current Status Please Contact Us No datasets