MESO-ZOOPLANKTON FOOD-WEBS IN INTERMITTENT UPWELLING SYSTEMS: AN OVERLOOKED LINK IN A PRODUCTIVE OCEAN

Eastern boundary currents are among the most productive marine ecosystems on the planet and support a significant proportion of global fisheries, yet there are unanswered questions about the role of non-crustacean zooplankton in transferring production through upwelling food webs. Organic material in the coastal ocean moves through often complex marine food webs. While much effort has focused on quantifying the movement of carbon from nutrients to phytoplankton, zooplankton, and detritus, and from zooplankton to upper trophic levels, the trophodynamics associated with the middle link through the mesozooplankton (0.2-20 mm) are not well understood. Within this group are the early stages of marine fishes and small gelatinous zooplankton, which comprise a substantial portion of the plankton but whose interactions are poorly documented. This gap in our knowledge is due, in part, to the difficulty of sampling these taxa using traditional sampling gear, especially as gelatinous taxa are often damaged during net retrieval.

The northern California Current (NCC) is a dynamic, highly productive major eastern boundary current that exhibits strong physical and ecosystem variability spatially and on seasonal, interannual, and decadal time scales. Strong latitudinal gradients in the seasonality and timing of upwelling within the NCC make it a highly suitable setting for testing hypotheses regarding potential contributions of different trophic pathways to ecosystem productivity and the roles of diverse meso-zooplankton in mediating these transfers. Shifts in major currents, including upwelling strength, together with temperature-induced latitudinal shifts in species ranges that are already occurring and predicted to continue will have major effects on interactions among species, and consequently, food webs. Understanding these interactions and predicting future changes is highly relevant to science, society, and economies.

Beginning in February 2018, we will be sampling the winter and summer seasons in the NCC off central Oregon where upwelling is intermittent and off northern California where upwelling is more continuous. We will be using the high resolution In Situ Ichthyoplankton Imaging System (ISIIS) to obtain an accurate description of meso-zooplankton communities: their abundances, and horizontal and vertical spatial distributions, over contrasting upwelling/downwelling system dynamics. This novel system is able to image zooplankton over a range of sizes as they occur naturally in the wild. Continuous images are fed through a processing and classification pipeline that uses computer algorithms to segment and classify individual plankton. In parallel, we will collect depth-discrete mesozooplankton samples to quantify seasonal diets for larval fishes and gelatinous zooplankton and prey-specific growth rates of larval fishes. Stable isotope analysis of mesozooplankton predators and prey will reveal the relative role of new vs. regenerated production in sustaining food webs in the NCC.

During the project, in addition to training undergraduate and graduate students and post-doctoral scholars, we aim to engage a diversity of audiences. We will use ISIIS imagery from this project to build the Global Plankton Imagery Library, an open-access repository for plankton imagery. We will also continue our work with Plankton Portal, a public website we developed in partnership with the Citizen Science Alliance’s Zooniverse, that invites citizen scientists to participate in classifying plankton images. We will collaborate with Oregon Sea Grant to include Plankton Portal kiosks in a new public exhibit at the OSU Hatfield Marine Science Center Visitor Center, which annually hosts 150,000 visitors of all ages. Importantly, this activity will not only educate K-gray, but will serve as a new research platform for Free-Choice Learning researchers to understand citizen science recruitment strategies, intrinsic and extrinsic motivations for citizen scientists, characteristics of “uber-users”, and how those users can be supported and encouraged into advanced collaborator roles. Through a new Artist-At-Sea program, we will be collaborating with the Sitka Center for Art and Ecology to invite an artist to join our research cruises and create artistic products that give a unique voice to the project findings and processes. This artwork will be displayed at the HMSC Visitor Center and UO Charleston Marine Life Center and a scaled traveling show will tour Oregon metropolitan areas and underserved communities.