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DAMOS Contribution #116 Executive Summary |
Sediment-profile
and plan view photographs were collected at the Massachusetts Bay Disposal
Site (MBDS) for three separate objectives. The first objective was to assess
the recolonization status of the recently disposed dredged material. The
remaining two objectives were in response to results from the MBDS baseline
survey of 1993. The second objective was to determine the areal limits of
historical dredged material using acoustical data from the 1993 survey as a
reference. The final objective was to investigate the successional status and
general benthic conditions at the area around historical Station 12-3 that
has shown evidence of historical contamination. Results
from sampling at the active disposal buoy indicated that the disposal of
dredged material at MBDS is not impeding benthic recolonization. The results
were compared with reference area data and showed that the area near the
disposal buoy contained a relatively advanced benthic community, despite the
recent disposal of sediments. The
areal extent of both recent and historical dredged material that had been
defined using acoustical data in the 1993 baseline survey was confirmed with
the photographic data. Both the acoustic and the photographic data, however,
were not apt to detect highly reworked dredged material around the flanks of
the current and historical dredged material deposits at MBDS. Although
sediments at the 12-3 Grid did show signs of organic eutrophication (reduced
sediments with high sediment oxygen demand and locally thin apparent redox
potential discontinuity intervals), most of the stations still contained a
highly developed Stage III community. While any chemical contaminants that
may be present are not apparently toxic to the local benthic assemblage, the
potential for bioaccumulation in their tissues still persists. Because
Station 12-3 represents a small area (less than 400 m in diameter) there is
little risk of significant transfer of contaminants to benthic predators.
Station 12-3 may provide a field test bed for evaluation of the sensitivity
of REMOTS® technology in assessing the impact of sublethal contaminant levels
on the benthic community. |
Dated May 28, 1997