Diablo Canyon power plant site ecological study Annual Report July 1, 1976 - June 30, 1977 and Quarterly Report no. 16 April 1, 1977 - June 30, 1977

摘要

More stations were surveyed during this report periodudthan during any previous period. A total of 818 mandaysudwas spent surveying 18 permanent and 67 randomudsubtidal stations, 19 permanent and 50 random intertidaludstations, and 64 sportfish catch-per-unit-of-effortudstations, as well as conducting corollary laboratoryudwork.udIn the subtidal areas, Laminaria dentigera and Pterygophoraudcalifornica, both important subsurface kelpudspecies, increased in their combined total numbers fromudthe 1976 survey. However, Nereocystis luetkeana, theudbull kelp, declined substantially in all study areas.udPopulation trends of many of the dominant subtidaludmacro-invertebrates have varied depending on the speciesudand on the type of method utilized. Regression analysesudhave been performed on selected species for numbersudversus depth. Red algal abundance and diversity appearudto have increased in both subtidal study areas.udOf the three observation areas, sea otters were observedudleast frequently in Diablo Cove. However, there continuesudto be fresh evidence of otter foraging withinudDiablo Cove.udSeveral seasons' data for intertidal algae and invertebrates have been summarized for one study area. While the algae biomass shows a fairly clear seasonality ofudabundance, the trends in numbers of the six invertebrateudspecies considered are not as well defined.udBecause of high variability in the data, the sportfishudcatch-per-unit-of-effort and hook-and-line study wasudcancelled in December.udPopulations of intertidal red and black abalones,udHaliotis rufescens and H. cracherodii, respectively,udappear to have remained fairly stable during theud1976-77 period.udTwo other ancillary studies were also terminated duringudthis period: interviews of commercial abalone andudurchin fishermen, and observations of foam in Diablo Cove. (107pp.)