Larval transport of brachyuran crab in Kachemak Bay, Alaska

Abstract

"This study's primary goal was to understand the oceanographic effects on larval crab transport and distribution between an estuarine inner and more oceanic outer bay in the subarctic estuary of Kachemak Bay, Alaska. Plankton tows and hydrographic measurements (temperature and salinity) were taken along the boundary between the two bay parts from March - October on spring and neap tides. Summer water flow and in Kachemak Bay is predominantly freshwater-driven and density patterns vary inter-annually with the amount of freshwater supplied to the inner bay. Larvae of seven crab species occurred in a seasonal sequence and the crab larval assemblage was closely correlated to temperature in the upper 20 m. The influence of tidal forcing on larval transport was not clear even though most species exhibited peak abundances at spring tides. Larval distribution patterns across the inner/outer boundary indicated that Oregonia gracilis larvae may be transported into inner Kachemak Bay; however, late larval stages of the two commercially relevant species, Chionoecetes bairdi and Cancer magister, were never observed and may be exported from the inner estuary. These observations provide an important baseline for further studies to understand Kachemak Bay's role as a source or sink for larval crab"--Leaf iii