Date of Award

8-2024

Document Type

Thesis

Degree Name

Master of Science (MS)

College/School

College of Science and Mathematics

Department/Program

Biology

Thesis Sponsor/Dissertation Chair/Project Chair

Paul A. X. Bologna

Committee Member

Matthew Schuler

Committee Member

Lisa Hazard

Abstract

Eutrophication is a phenomenon caused by changes in nutrient loading that results in harmful algal blooms, an overgrowth of macroalgae, altered aquatic benthic invertebrate communities, and loss of ecosystem functions. Barnegat Bay, NJ is a highly eutrophic system that has experienced a substantial loss of seagrass beds with subsequent expansion of drift macroalgae. Although considered poor quality, these algal beds represent valuable habitat for many benthic invertebrates. This research assesses the value of macroalgae as a habitat for macrofauna in regions where macroalgae are the dominant “vegetation.” Benthic drift algal samples were collected during June and August 2023 to reflect changes at the beginning and end of the summer due to peak levels of eutrophication. Macrofauna were identified to determine whether types of algae impacted the abundance or richness of organisms. Algal samples were dominated by Ulva lactuca and Agardhiella subulata. 4 groups of amphipods (Aoridae, Corophiidae, Ampithoidae, and Gammarus) and the isopod Erichsonella sp. dominated samples, regardless of algal species. Sea anemones and the tunicate, Molgula manhattensis, were abundant sessile organisms present. Few decapods were present, but juvenile blue crabs and grass shrimp were collected. In general, the drift macroalgae in this eutrophic coastal bay provides valuable habitat for many crustaceans in comparison to previously dominant seagrasses, Zostera marina and Ruppia maritima. Zostera marina and R. maritima provided resources for a wider diversity and abundance of species throughout the season, while algae progressively lost the ability to sustain animal abundance. As such, algal mats provide some value as habitat for invertebrates, but are reduced in value compared to formerly dominant seagrass beds.

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