Very few crustacea were present, although occasionally a number of 

 amphipods, Capvetla sp. , were found on small clumps of algae {Viva) or 

 hydroids {Aglaophenia) . 



Larval settling in the harbor was observed at the control station and 

 the dredged station. At the control station, undisturbed by dredging, no 

 great number of larvae settled and persisted, either because they selected 

 not to settle or they settled and were eaten by the existing residents, 

 Notomastus tenuis, a large deposit- feeding worm. In contrast, a newly 

 exposed surface at the dredging station was recolonized by several species 

 in large numbers (the tube worm, Capitella, the polychaete, Armandia, and 

 the plumed worm, Phoronopsis) . Presumably, competition for space resulted 

 in phoronid dominance. By April 1973, the dredged area supported a popula- 

 tion of adult P. virid-is. At that time, there was another large recruit- 

 ment of phoronids and no significant, detectable settlement of polychaetes, 

 although Armandia was present in the water and a persistent patch of 

 P. viridis was established at the dredged station. What was once an 

 active-burrowing, deposit-feeding assemblage was replaced by sedentary, 

 suspension-feeding tube worms. The patchy distribution of animal assem- 

 blages in the slough and harbor probably increases the number of alternate 

 sequences and end products of recolonization. In a stable, homogeneous 

 benthic community such as the offshore 20-meter control station, the 

 probability of reestablishing both trophic and taxonomic structure after 

 disturbance is considerably higher. 



The number of species decreased over 60 percent from July to September 



1971, immediately following dredging. The biomass was small in September 

 because the individuals were small and apparently newly settled. After 

 September the number of species increased to a maximum in June 1972, when 

 there were twice as many species as before dredging. By September 1972, 

 the number of species remained relatively stable, but was above pre- 

 dredging values. There was a decrease in the number of species in January 



1972, and an increase in April 1973. This was probably the result of 

 winter mortality and spring recruitment, respectively. 



The control area was sampled in April 1973 and the fauna was similar 

 to that at the dredge station before dredging (Figs. 12 and 13). The 

 variation in species per core was small at all stations. There was a 

 significant difference between the values in July 1972 and the species per 

 core after recolonization (April 1973). 



The rate of recolonization (Fig. 13) and also the rate of recovery at 

 the disposal station (Fig. 14) were similar to that determined in other 

 investigations (Reish, 1963; Odum 1969; Simberloff and Wilson 1969, 1970). 



Species diversity, H" and evenness, J, did not follow the same 

 trend as the number of species (Fig. 13). Species diversity and evenness 

 before dredging and at the control station in April 1973 were similar, 

 but differed from the dredged station after recolonization (Fig. 13). 

 Diversity increased directly after dredging, although the density and 

 number of species decreased (Figs. 12 and 13). This was primarily due to 



52 



