Feeding dynamics of the invasive copepod Pseudodiaptomus inopinus in two northeast Pacific estuaries, and potential competition with its invasive congener, P. forbesi
Abstract
Northeast Pacific estuaries have been invaded by at least nine Asian copepod species, including the calanoid copepod Pseudodiaptomus inopinus. First observed in the Columbia River Estuary (CRE) in the early 1990s, it has become rare or absent in this system. It is now the dominant zooplankton taxon in at least eleven other Northeast Pacific estuaries, yet little is known about P. inopinus feeding dynamics. The disappearance of P. inopinus from the CRE coincided with the introduction of a congener species, P. forbesi. This study aimed to: 1) determine the feeding dynamics of P. inopinus in two estuaries where it is dominant, and 2) compare results with feeding rates previously measured for P. forbesi in the CRE, to explore the potential for resource competition. We conducted incubation experiments with samples collected from the Chehalis River estuary (Washington, USA) and the Yaquina River estuary (Oregon, USA) during autumn of 2019 and 2020, during P. inopinus peak abundance. Preliminary results show that P. inopinus feeds preferentially on ciliates (Chehalis) and diatoms (Yaquina), whereas P. forbesi feeds non-preferentially (CRE). Based on the feeding behaviors of these species, and the prey assemblage in the CRE, we conclude that P. inopinus prefers prey taxa not readily available and was ill-suited to the CRE, whereas P. forbesi was likely better able to thrive on the prey available. From this, we now have a clearer picture of the trophic impacts of these planktonic species on their invaded ecosystems, as well as the potential for competition between the two.
About the Presenter
Jade Jacobs
Jade Jacobs is a Master’s student in the School of the Environment at WSU Vancouver. Her research is in the Aquatic Ecology Lab and is under the direction of Dr. Gretchen Rollwagen-Bollens. He thesis project is focused on the feeding dynamics of an invasive zooplankton in two estuaries of the Pacific Northwest and has included shipboard field sampling as well as laboratory experiment.