ASSESSING GELATINOUS ZOOPLANKTON TROPHIC FLEXIBILITY IN A COASTAL UPWELLING SYSTEM USING STABLE ISOTOPES

Gelatinous zooplankton are abundant and diverse members of marine communities, yet their role in food webs has often been overlooked. Though gelatinous organisms all have large watery bodies compared to carbon content, they have a variety of taxonomic identities, life histories, and feeding strategies. These varied characteristics suggest that gelatinous zooplankton taxa may occupy distinct roles in the food web and may respond in different ways to changes in environmental conditions, nuances which are not yet accounted for in current conceptions of marine food webs and food web models. Using nitrogen and carbon stable isotope analysis, we examined seasonal and spatial shifts in the trophic niche of 33 taxa of gelatinous and semi-gelatinous zooplankton and fish larvae in the Northern California Current (NCC). The NCC experiences strong seasonal upwelling which allows for comparisons across temperature and productivity gradients. Taxa varied in carbon and nitrogen stable isotope ratios and in C:N ratios, suggesting unique trophic roles. Additionally, comparisons across seasons and space revealed that gelatinous zooplankton taxa may respond uniquely to changes in environmental parameters including temperature and primary production. This study highlights the complexity of gelatinous zooplankton trophic dynamics in an eastern boundary current. It suggests that variations between taxa are essential for accurate modelling of gelatinous zooplankton food webs especially when considering human-induced changes in temperature and nutrient levels.

Presentation Preference: Oral

Primary Presenter: Elizabeth Wallace, University of Oregon (ewal@uoregon.edu)

Authors:

Elizabeth Wallace, University of Oregon  (ewal@uoregon.edu)

Kelly Sutherland, University of Oregon  (ksuth@uoregon.edu)