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Marine Environmental Monitoring Program Memo

To: John Sowles
From Lee Doggett
Date April 28, 1998
Subject: Visit to General Alum 4/16/98

An area on the western part of the site was qualitatively surveyed. The area had a sand flat in the lower two thirds of the intertidal zone and a gravel beach in the upper third of the intertidal zone.

The rest of the area was a mixed substrate of boulders, cobbles, mud and sand.

The gravel beach area had no obvious fauna present except for large numbers of amphipods (probably Orchestia platensis) in the wrack in the high intertidal zone. Oligochaetes and nematodes are likely to be the dominant fauna in the gravel beach. These animals are generally too small to be observed in a qualitative survey.

The predominant species found in the upper part of the sand flat area were Nemertean worms and Capitellid polychaetes (Heteromashrs filiformis). Also collected were two Baltic clams (Macoma balthica one Gammarid amphipod, and three polycheates (Nereis succinea Scoloplos ?robustus and Polydora sp.). Animals collected in the lower part of the flat included the bloodworm (Glycera dibranchiata) and Capitellid (Heteromastms filiformis). Nemertean worms were also present. One green crab (Carcinus maemus) and numerous periwinkles (Littorina littorea were observed.

The patches of Nemertean worms and Capitellid polychaetes, and to a lesser extent, the presence of the polychaetes, Nereis succinea (same genus as the sandworm), and Polydora may indicate that there could be some type of environmental stress at this site. The apparent diversity and abundance of animals seemed low; however, that could be related to the sediment type and/or the time of year. Potential stresses to animals living in the sediments at this site could include clam digging, environmental conditions of the previous winter, run-off of sediments and stormwater from the upland site or some other unknown factors. There were obvious signs of previous clam digging. The Searsport shellfish warden said that the clamflat was dug the previous fall. April is somewhat early in the season to assess the full community of animals that may inhabit the flat in the summer. Also, there is evidence that sediments and associated materials have run off the upland site.

In addition market-size clams were dug in various areas by the Searsport Shellfish warden. Mussels were abundant in the area towards the eastern end of the site.