Date of Award

Summer 8-2024

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science (MS)

Department

Oceanography

Advisor

Lee Karp-Boss

Second Committee Member

Emmanuel Boss

Third Committee Member

Fabien Lombard

Additional Committee Members

Jeff Runge

Abstract

The tropical and subtropical Pacific are oligotrophic ecosystems with low overall biomass and productivity. However, the presence of islands results in local nutrients enhancement in that in turn promotes phytoplankton growth, a phenomenon known as the island mass effect (IME). The cascading effects of the IME on higher trophic levels, particularly zooplankton, have not been as thoroughly investigated. I examined the impacts of islands on micro- and mesozooplankton assemblages across 12 islands in the tropical and subtropical Pacific Ocean by analyzing changes in abundance, biovolume (as a proxy for biomass), size, and composition using the Tara Pacific FlowCam and ZooScan dataset. Communities were analyzed in the context of 3 oceanographic provinces: the South Pacific Subtropical Gyre, the Western Pacific Warm Pool, and the Fiji-Tonga-Samoa Complex. Results show that changes in zooplankton communities in response to the IME varies between taxa and provinces. There were more significant impacts of the IME on zooplankton assemblages in the Western Pacific Warm Pool than in the South Pacific Subtropical Gyre, with ciliates showing a significant increase in biovolume and cell size and metazoan zooplankton (copepods, nauplii, and other crustaceans) showing significant increases in abundance and biovolume. These findings suggest that the tropical and subtropical Pacific is a much more dynamic environment than previously believed with islands being important in community dynamics and succession within this region.

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Oceanography Commons

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