Title

Early Life History of Prognichtys occidentalis and Caranx crysos Associated With Sargassus Habitat in the Northcentral Gulf of Mexico

Date of Award

Spring 2011

Degree Type

Masters Thesis

Degree Name

Master of Science (MS)

Department

Coastal Sciences, Gulf Coast Research Laboratory

Committee Chair

Bruce Comyns

Committee Chair Department

Coastal Sciences, Gulf Coast Research Laboratory

Committee Member 2

Harriet Perry

Committee Member 2 Department

Coastal Sciences, Gulf Coast Research Laboratory

Committee Member 3

Chet Rakocinski

Committee Member 3 Department

Coastal Sciences, Gulf Coast Research Laboratory

Committee Member 4

Eric Hoffmayer

Committee Member 4 Department

Coastal Sciences, Gulf Coast Research Laboratory

Abstract

Pelagic Sargassum and associated fronts provide an important combination of enhanced biological production and structural habitat in oceanic environments. Fronts are regions of convergence between two water masses and often provide enhanced prey densities for juvenile fishes. The present study examined the influence that this habitat has on the growth, feeding, and condition of larval and young juvenile blue runner Caranx crysos and bluntnose flyingfish Prognichthys occidentalis. Neuston tows were taken adjacent to fronts, and 1.6-3.2 km from each front in open water to serve as a reference. Sampling was conducted on each side of a front. Otolith increment analysis was performed, and analysis of covariance (ANCOVA) was used to determine the influence of habitat on growth rates. Stomach content analysis determined the influence of habitat on feeding success by means of ANCOVA. Diets were examined for each species and habitats using Morisita's and Shoener's Index. The influence of habitat on fish condition was determined by means of ANCOVA. Significant differences were found in the growth, feeding, and condition for these two species between habitats, although the directionality of the relationships was inconsistent. Variability in the results were likely caused by prey patchiness in the oceanic environment and suggests that Sargassum and associated fronts provide conditions for increased growth, feeding, and condition for many larval and young juvenile fishes.

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