Larval Brachyuran Crab Timing and Distribution in Relation to Water Properties and Flow in a High-Latitude Estuary
2014
Murphy, Megan | Iken, Katrin
Crab larval dispersal and, thus, adult population size can be influenced by oceanographic conditions, especially in highly dynamic and variable environments such as high-latitude estuaries. This study's primary goal was to understand larval timing, abundance, and distribution in relation to oceanographic effects between the more estuarine inner and more oceanic outer part of the subarctic estuary of Kachemak Bay (south-central Alaska, USA). Temperature and salinity measurements and plankton tows were taken along the boundary between the two bay parts from 31 March to 28 October 2008 on spring and neap tides. Summer water flow and stratification in Kachemak Bay were chiefly buoyancy driven, and predominant flow patterns were not affected by the large tidal range in the region. Larvae of seven brachyuran species were found over the sampling period, with seasonally different peak abundances. Larval spatial distribution patterns, presence of most larval stages for each species, and their seasonal timing and persistence within the water column suggest that most species are locally transported within or close to Kachemak Bay. The larval assemblage was correlated with seasonal changes in water temperature, and peak abundances of some species coincided with spring tides and/or frontal systems between the in- and outflow regions of the bay. The strong influence of freshwater on the local circulation pattern in the summer indicates that larval transport will likely be strongly affected by future changes in glacial melt and precipitation.
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