Patterns of larval distribution and settlement in a river-dominated estuary

UNCW Author/Contributor (non-UNCW co-authors, if there are any, appear on document)
Russell W. Barbour (Creator)
The University of North Carolina Wilmington (UNCW )
Web Site:
Robert Roer

Abstract: Several species of crabs utilize the estuary as adults, with larval development occurring in the plankton either within the estuary or offshore. Habitat selectivity necessitates postlarval movement within the estuary in order for suitable settlement sites to be reached. Postlarval dispersal and settlement are critical factors in determining adult abundances. Data on such dispersal and settlement are particularly sparse for the more poorly studied small, riverdominated systems prevalent along the southeastern coast of the United States. Night plankton tows were taken during flood tides to examine issues of postlarval distribution and transport to upper portions of the Cape Fear River Estuary (NC, USA) for several brachyuran species commonly found in the estuary. The blue crab Callinectes sapidus was used as a model organism to compare planktonic availability, settlement (utilizing passive larval collectors) and juvenile abundances over a broad estuarine gradient. Sampling occurred in five-day periods around both the new and full moons from July to mid-October 2001 to target peak recruitment. The four groups of megalopae present in sufficient numbers for statistical analysis: 1) Uca spp., 2) xanthids, 3) Sesarma cinereum, and 4) Callinectes spp. all demonstrated a high degree of spatial and within-period variability. When the abundance of Callinectes megalopae in plankton tows was low, settlement occurred primarily at sites closer to the mouth of the estuary, however, in mid-September when abundances in the plankton rose, the settlement pattern shifted to the upper portion of the estuary. Patterns of early juvenile abundances appeared to reflect late period settlement of Callinectes megalopae in the upper regions of the estuary. Callinectes megalopae appear to follow a mixed model settlement pattern that varies seasonally and this may have consequences for megalopal survival.

Additional Information

A Thesis Submitted to the University of North Carolina at Wilmington in Partial Fulfillment Of the Requirements for the Degree of Master of Science
Language: English
Date: 2009
Crabs--Geographical distribution--North Carolina--Cape Fear River Estuary, Crabs--Larvae--North Carolina--Cape Fear River Estuary
Crabs -- Larvae -- North Carolina -- Cape Fear River Estuary
Crabs -- Geographical distribution -- North Carolina -- Cape Fear River Estuary

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