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 Bologna

Committee Member

Matt Schuler

Committee Member

Lisa Hazard

Abstract

Researching invasive species is vital to the health of ecosystems. Any invasion can place an ecosystem at risk of deterioration through increased competition with native species, food web changes, and community dynamic alterations. Clinging jellyfish (Gonionemus vertens) have recently emerged as a nuisance invader in New Jersey. They pose an additional threat to humans because they possess both paralysis venoms, which cause muscle seizures and intense pain, and neurotoxins that can cause neuropsychiatric symptoms. Jellyfish possess a complex life history involving sexually reproducing medusae and a cryptic asexual polyp stage. Medusae blooms occur during May and June, but locating their polyps in the field, which generates these medusae, has been elusive. In native ranges, G. vertens is known to live among eelgrass and it is proposed that the polyps live within these seagrass beds, but in NJ, the massive blooms occur in regions devoid of eelgrass. During the summer of 2023, I took a novel approach by collecting, preserving, and staining large volumes of drift macroalgae to assist with locating the polyps. From these samples, 1,630 polyps were identified on the algae Ulva lactuca and Agardhiella subulata. Peaks in polyp abundance occurred in May and June, reflecting medusae bloom conditions but were absent in July. During August, polyps reappeared, likely as a result of larval recruitment and asexual reproduction but could also reflect surviving polyps. The greatest abundance of polyps occurred on U. lactuca, despite its lower biomass among samples, suggesting it is the primary polyp habitat in the absence of eelgrass. Ulva lactuca reflected just 32% of the total algal biomass, however 69% of the total polyps were attached to this species. In August, this relationship was amplified as U. lactuca was only 3.50% algal biomass for all samples and had an average of 50.66 polyps per gram of biomass. The alternate substrate, A. subulata averaged just 1.36 polyps per gram of biomass in August, yet consisted of 96.5% of the total algal biomass for the month. The higher attachment rate found on U. lactuca suggests a preferred habitat for the polyps, providing critical information on understanding the distribution and potential spread of this toxic invader.

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