Date of Award

Summer 7-1-2022

Degree Type

Masters Thesis

Degree Name

Master of Science (MS)

School

Ocean Science and Engineering

Committee Chair

Zachary Darnell

Committee Chair School

Ocean Science and Engineering

Committee Member 2

Kelly Darnell

Committee Member 2 School

Ocean Science and Engineering

Committee Member 3

Frank Hernandez

Committee Member 3 School

Ocean Science and Engineering

Abstract

Seagrasses are important submerged coastal habitats that support nearshore communities. Ruppia maritima (widgeon grass) is a widespread species whose leaves branch extensively when reproductive. The goal of this study was to understand use of reproductive and non-reproductive R. maritima by fishes, recognizing the morphological change undergone by the plant when flowering. During the peak reproductive season in August and September 2021, R. maritima meadows at the Chandeleur Islands, LA were sampled to describe the spatial distribution and morphology of reproductive plants and investigate habitat use by fish assemblages. We assessed spatial trends in R. maritima presence and occurrence of reproduction and evaluated differences in shoot morphology using the metrics of longest leaf length, surface area, number of branches, and root to shoot ratios. We calculated density, Shannon diversity, and species richness to describe fish assemblages in reproductive and non-reproductive meadows. Additionally, general additive models were used to predict drivers of fish assemblage metrics. Results indicate that R. maritima was distributed along the entire length of North Chandeleur Island, but reproductive plants were located in the central, protected portion of the island. Reproductive plants were more morphologically complex than non-reproductive plants, but this did not drive fish assemblages. Rather, fish abundance was related to R. maritima biomass. This study provides information on patterns and drivers of habitat use by fish in R. maritima-dominated ecosystems that can be used to inform management and restoration.

Available for download on Monday, January 01, 2024

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