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Date Permissions Signed


Date of Award

Winter 2021

Document Type

Masters Thesis

Department or Program Affiliation


Degree Name

Master of Science (MS)



First Advisor

Strom, Suzanne L., 1959-

Second Advisor

Sobocinski, Kathryn L.

Third Advisor

Arellano, Shawn M.


Long term monitoring in the Northern Gulf of Alaska (NGA) has shown that the high productivity of the region is closely coupled to lower trophic level food web dynamics. From previous observations of the NGA, we know that many nano- and dinoflagellates that compose this food web are mixotrophic, and therefore capable of both phagotrophy and phototrophy in a single cell. This behavior is believed to stabilize food webs by providing multiple pathways to energy and nutrients and may play an important role in the NGA, where environmental conditions are harsh and highly variable. To better understand the role of mixotrophic phytoflagellates in this region and how environmental factors drive mixotrophic behavior, field experiments and environmental sampling were conducted in summer and fall of 2019.

For the dinoflagellate, nanoflagellate, and cryptophyte communities there was a relationship between ingestion and environmental factors, with responses being specific to each taxonomic group. For the nanoflagellate community, a positive correlation between Synechococcus concentration and ingestion and a negative correlation between phosphate concentration and ingestion were observed. Alternatively, the dinoflagellate and cryptophyte communities responded to ambient light, where a negative correlation between ingestion and irradiance was observed. These differing responses indicate that phytoflagellates in the NGA are utilizing mixotrophy for both energy and nutrient acquisition and that differences are taxonomically specific. This initial study of small-celled mixotrophy highlights the prevalence and importance of this strategy in the NGA and indicates it may be a key contributor to overall ecosystem resilience and productivity.




mixotrophy, dinoflagellate, nanoflagellate, cryptophyte, alaska, LTER


Western Washington University

OCLC Number


Subjects – Names (LCNAF)

Long-Term Ecological Research Program

Subject – LCSH

Phytoflagellates--Ecology--Alaska; Multitrophic interactions (Ecology)--Alaska

Geographic Coverage

Alaska, Gulf of (Alaska)




masters theses




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