Date of Award

5-2014

Degree Type

Masters Thesis

Degree Name

Master of Science (MS)

Department

Coastal Sciences, Gulf Coast Research Laboratory

Committee Chair

Chet F. Rakocinski

Committee Chair Department

Coastal Sciences, Gulf Coast Research Laboratory

Committee Member 2

Sara E. LeCray

Committee Member 2 Department

Coastal Sciences, Gulf Coast Research Laboratory

Committee Member 3

Wei Wu

Committee Member 3 Department

Coastal Sciences, Gulf Coast Research Laboratory

Abstract

The field of zooplankton biology contributes to more accurate stock assessments as well as to a greater understanding of the marine food web. However, adequate information for the invertebrate component of zooplankton is lacking compared to the ichthyoplankton component. In this thesis, identification of Portunidae (Crustacea: Decapoda) megalopae collected during the fall of 2003 from a NOAA SEAMAP cruise revealed 7 species and 11 morphs with 90% of the total density comprised of Callinectes sapidus, Achelous gibbesii, Callinectes similis, Achelous spinicarpus, and Achelous sp.I. Keys and detailed descriptions are provided along with photographs and morphological drawings for each morph to use for future identification. Spatially explicit maps and non-metric multi-dimensional scaling (NMDS) depicted geographic distributions and community structure during the study period. Mapping of NMDS coordinates illustrated distribution patterns for four community types of portunid megalopae as mainly distinguished by the differences in relative abundances of the most dominate morphs. This showed Callinectes species were predominantly located in the western GOM while Achelous species dominated the eastern GOM. Spatial representation of station locations and assemblages at station locations was illustrated through the maps generated by Geographic Information System (GIS) software. Examination of environmental data associated with the plankton samples was accomplished via visual inspection of spatial maps to identify any clear spatial coherence and/or linkages relative to the density or presence of portunid crab larvae. Time of day of sampling and currents, including the Loop Current, had the most visible effect on larval densities and distributions.

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