SEASONAL OCCURRENCE AND ABUNDANCE OF BRACHYURAN LARVAE IN A COASTAL EMBAYMENT OF CENTRAL CALIFORNIA

Abstract

ABSTRACT Little information is available on the larval ecology of brachyuran crabs on the western coast of North America. Horizontal plankton tows were conducted biweekly over a 14-month period at 4 stations in Elkhorn Slough, California, and at 1 station 1 km offshore and adjacent to the slough. The brachyuran larvae of 5 families represented by 12 taxa were identified to the lowest possible taxon. Larvae of Pinnixa franciscana, Hemigrapsus oregonensis, Cancer gracilis, Pinnixaweymouthi, and Pachygrapsus crassipes occurred most frequently. Larvae were most abundant at all sites in early spring and late winter. One exception was the larvae of P. crassipes which had a peak abundance in late summer and early fall. Larvae of P. franciscana and P. weymouthi generally remained within Elkhorn Slough, whereas larvae of H. oregonensis and P. crassipes appeared to be transported offshore. The numerous first stage zoeae of P. Fanciscana. H. oregonensis, and P. crassipes collected in the upper Elkhorn Slough suggest that adult females use this habitat as a spawning ground.