Date of Award
Honors College Thesis
Biological Sciences BS
Michael J. Andres, Ph.D.
Coastal Sciences, Gulf Coast Research Laboratory
Palaemonidae is an ecologically important and abundant family of shrimp that link the benthos to many estuarine food webs. Palaemon pugio and Palaemon vulgaris regularly co-occur along estuarine edge habitats despite previous studies suggesting different preferred sediment types and salinity regimes. The objective was to determine if competition is occurring between the congeners by comparing their relative abundance and assessing isotope niche space along an estuarine gradient. I seasonally sampled various edge habitats at four sites throughout Biloxi Bay, MS, using fyke nets fished over a tidal cycle from November 2020 to November 2021. Collected organisms were identified to the species level, enumerated, relative abundance estimated using catch per unit effort (CPUE), and up to 20 individuals were measured for total length and weighed. Stable carbon and nitrogen isotope values (δ13C and δ15N) of the subsampled shrimp from each sampling event were analyzed. Palaemon pugio was the more abundant congener based on relative abundance estimates, and P. pugio CPUE varied based on abiotic factors (salinity, season, estuary position). During the study period, Biloxi Bay experienced a prolonged, high freshwater discharge event that likely influenced the lower CPUE of P. vulgaris based on presumed physiological stress from this event. Stable isotope analyses suggest P. pugio and P. vulgaris are partitioning resources and occupying different niche spaces throughout the estuarine gradient. Palaemon vulgaris occupied a higher trophic position regardless of abundance, estuarine position, or if P. pugio co-occured. Palaemon pugio trophic position was influenced by P. vulgaris trophic position, P. vulgaris CPUE categories, and salinity regime. These observations were attributed to exploitative competition between congeners, affecting ecological niche spaces and trophic positions.
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Lynch, Baylor K., "Analysis of Ecological Tradeoffs Between Congeneric Shrimp in Coastal Mississippi Waters" (2022). Honors Theses. 878.