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Date of Award

Fall 2024

Document Type

Masters Thesis

Department or Program Affiliation

Biology-Marine and Estuarine Science

Degree Name

Master of Science (MS)

Department

Biology

First Advisor

Strom, Suzanne L., 1959-

Second Advisor

Arellano, Shawn M.

Third Advisor

Olson, M. Brady (Michael Brady)

Abstract

Rhizaria are a diverse supergroup of large marine protists that are often overlooked due to their lower abundances and wide size range relative to other plankton, and fragility. Despite their global distribution, the fundamentals of Rhizaria ecology are poorly understood due to an insufficient number of datasets and differing methodologies. Here we present the first characterization of Rhizaria ecology in the northern Gulf of Alaska (NGA), a variable yet productive subarctic ecosystem with important fisheries that is experiencing long-term warming. This knowledge will provide a more complete picture of protist community composition and trophodynamics in the NGA; shifts to which may impact food web resiliency. These amoeboid organisms produce biomineralized skeletons and use sticky pseudopodia to capture prey; structures that allow Rhizaria to drive biogeochemical cycling and carbon export. Some mixotrophic taxa also maintain symbiotic algae. Seawater samples were collected from CTD-secured Niskin bottles at stations within the NGA Long-Term Ecological Research study area during summer 2023. We report some of the highest Rhizaria abundances (25 cells L-1) from any ocean environment to date and thus suggest a restructuring of the current biogeographical paradigm, where abundances near the poles are similar to the equatorial region. Acantharia was the most ubiquitous subgroup. Distinct depth niches were also revealed; Foraminifera dominated surface waters, Radiolaria exhibited a cosmopolitan distribution, and Cercozoa were the deepest living. We highlight Rhizaria as key players in NGA food web dynamics as evidenced by their wide distributions, diversity, and unique nutrition strategies.

Type

Text

Keywords

Rhizaria, Radiolaria, Foraminifera, Cercozoa, northern Gulf of Alaska, ecology, abundance, biogeography, diversity, trophodynamics

Publisher

Western Washington University

OCLC Number

1463949391

Subject – LCSH

Radiolaria--Ecology--Alaska--Alaska, Gulf of;Foraminifera--Ecology--Alaska--Alaska, Gulf of;Marine protozoa--Alaska--Alaska, Gulf of;Marine ecology--Alaska--Alaska, Gulf of;Food chains (Ecology)--Alaska--Alaska, Gulf of

Geographic Coverage

Alaska, Gulf of (Alaska)

Format

application/pdf

Genre/Form

masters theses

Language

English

Rights

Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author’s written permission.

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