Date of Award

8-2023

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 Bologna

Committee Member

Ying Cui

Committee Member

Xiaona Li

Abstract

Gonionemus vertens, commonly known as the clinging jellyfish, is a small hydrozoan known for their conflicts with humans due to their neurotoxins that can lead to paralysis. Native to the Pacific Ocean, it has now invaded numerous ecosystems in the coastal waters of the Mediterranean Sea, Europe, and the United States. In the United States, it has flourishing populations from New Jersey to Maine. However, many questions remain as to how it arrived and spread, but equally important is what impact this species may have in the invaded communities they now reside. Research suggests that G. vertens actively feeds on zooplankton during the evening, but direct evidence is lacking. Field observations of G. vertens have demonstrated a variety of macrofauna in their gastrovascular pouch including fish and peracarid crustaceans. As these organisms are extremely abundant in the aquatic vegetation where they live, it is highly probable that they contribute to their diet. We collected specimens and potential food resources to conduct stable carbon (C) and nitrogen (N) isotope analyses from three locations (Rhode Island or RI, Connecticut or CT, and New Jersey or NJ). The NJ and CT populations had similar δ13C values of -19.16 ± 1.77‰ and -17.3 ± 0.3‰ respectively, while the average RI G. vertens δ13C value was significantly higher at -13.27 ± 0.28‰. However, with regards to δ15N values, NJ populations were significantly higher with an average δ15N value of 12.45 ± 1.3‰, compared to CT (10.25 ± 0.1‰) and RI (9.22 ± 0.48‰). Consequently, three trophic structures may be present among these three regions with NJ δ15N values being the highest suggesting that the G. vertens in NJ is feeding potentially one trophic level higher than the populations from RI and CT. With respect to δ13C data, RI populations (-13.28‰ δ13C) may be gaining greater energy resources from the vascular plant Zostera marina (-8.65‰ δ13C), while CT (-17.30‰ δ13C) and NJ (-19.16‰ δ13C) may have greater inputs from macroalgal (-16.35‰ δ13C) sources. Continued evaluation will help elucidate the trophic status of this invasive species and shed light on its actual diet. This includes, but is not limited to, collecting more samples to have a robust data set for fuller evaluation of their diet and trophic status. Collecting additional samples from the RI and CT G. vertens, prey items in all locations (e.g. phytoplankton), and primary producers would only strengthen the preliminary conclusions generated from this research.

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