The seasonal settlement of wood-borers in Los Angeles-Long Beach harbors

Four species of wood-borers were found during this study; Teredo (Teredops) diegensis, Bankia (Bankiella) setacea, Limnoria (Limnoria) tripunctata, and Limnoria (Limnoria) quadripunctata. Marine borers were widely distributed through the harbor. The only station lacking borers was Station C, a station showing an average annual dissolved oxygen concentration less than 1.0 ppm. The distribution of L. quadripunctata was restricted to stations in the outer harbor and because this species was generally more abundant on bottom rather than surface tests blocks, it is believed that this species is restricted to the cooler temperatures of the outer harbor and of deeper water. The settlement of teredine larvae was adversely affected by dissolved, O2 concentrations between 1.0 and 0.5 ppm. Increase in the seasonal settlement of Limnoria in the harbor was associated with sea-water temperatures above the annual mean for the station studied. The settlement and migration of borers could be expected to occur during all seasons of the year with maximum intensity during the summer and warmer months of the year unless the dissolved 02 content were to fall below 1.0 ppm. The data suggest maximal settlement of Teredo larvae during the warm months of the year and maximum settlement of Bankia larvae during cold months of the year. Mean annual dissolved O2 concentration between 0.12 and 2.9 ppm. were associated with reduced Limnoria settlement. The isopod Limnoria appears to be more sensitive to dissolved O2 depletion than in Teredo or its larvae.