Amchitka Bioenvironemtnal Program, Research Program on Marine Biology, Amchitka Island, Alaska: Annual Progress Report July, 1972, through September, 1973 and Summary Report 1967 through 1973.
This report presents FBI's Amahitka research activities of FY 1973 and highlights of the entire program on the marine ecology of Amchitka since its inception in July, 1967. The primary mission of the program was to assess and evaluate both the short and long termed effects of the Milrow (October 2, 1969) and the Cannikin (November 6, 1971) underground nuclear tests on the marine environment and biota. While most of the program efforts were devoted to evaluating test effects, much work was in fundamental research, such as taxonomic work, to obtain baseline information so as to assess and intelligently interpret the changes observed after the tests.
The FY 1973 work covered largely the evaluation of the effects of Cannikin 1-year postevent and the effects of Milrow 3-year postevent. Cannikin caused the permanent uplifting of intertidal benches along 6.1 km (alongshore distance) of Bering Sea coastline which disrupted intertidal invertebrate and algal communities. Although these communities were destroyed in localised areas, this disruption is considered short-termed because invertebrate and algal communities still remaining in the tidal influence will eventually be reestablished. Offshore studies revealed that rock sole catches which declined soon after Cannikin increased and are now not significantly different from pre-Cannikin values. Nearshore studies showed that rook greenling catches which declined immediately postevent have also recovered to pre-Cannikin values.
Milrow was estimated to have uplifted and disrupted the adjacent intertidal region less than 4 ha. Milrow caused a portion of the intertidal bench to be partially uplifted and also caused a rockfall from an adjacent cliff at Duck Cove. Algal recolonization in this area has progressed with the replacement of the former Hedophyllum community by Fucus and Alaria. The area of siltation on the intertidal bench below the rockfall at Square Bay has been reduced and is now almost completely covered by algae.
Experimentally disturbed intertidal algal communities which experienced no change in tidal level recovered within 1 to 2 years after disturbance. Since most of the intertidal invertebrate communities depend on algal communities, they are expected to recover in 3 to S years. Observations on test-disturbed intertidal benches showed that recolonization of invertebrate and algal communities is progressing, but the communities are still neither stable nor complete. These communities are not expected to stabilize for at least 2 more years.
Recovery of fish populations in localized offshore and nearshore waters to pre-Canniliin levels has occurred because of immigration from adjacent areas. Fish 'habitat disruption was localized and was not great enough to reduce significantly the carrying capacity of disrupted areas.
In summary, it appears that long-term biological damage by Cannikin or Milrow to the marine communities studied is negligible. Although permanent physical changes occurred in localized portions of intertidal benches, adjacent cliffs, and possibly to some sub tidal formations, only 6,1 km of approximately 190 km of total island coastline was permanently uplifted and disturbed by Cannikin.
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Prepared for Battelle, Columbus Laboratories under Atomic Energy Commission Prime, contact no, (26-1)-171