Analyzing Spatial Variations of Zooplankton Community Size Structures on the Northeast US Shelf

Fisheries and other marine resources from the Northeast US Shelf (NES) are dependent on zooplankton as they provide vital trophic connections in the food webs that drive ecosystem production. In recent decades, observations gathered from the NES ecosystem demonstrate notable changes in the temporal and spatial distribution of organisms, ranging from plankton to predators, as well as changes to the physical environment, corresponding to similar patterns in other large marine ecosystems. To further understand planktonic food webs and their response to anthropogenic changes, we developed a protocol aimed to use ZooScan to analyze community size structure variations of spatially and temporally varying zooplankton samples collected as part of the Northeast US Shelf Long-Term Ecological Research (NES-LTER). Cross-shelf NES-LTER zooplankton samples, from July 2018, were imaged using ZooScan. Vignettes were produced by ZooScan and processed for size measurements using Zooprocess. Median log(area) of zooplankton communities were similar for the stations analyzed (9.609 ± 0.221 µm², n = 7). Total abundance of organisms per m³ peaked at the most inshore station analyzed and was lowest at the two furthest offshore stations analyzed. Continued utilization of ZooScan in NES-LTER, and the development of software for automatic zooplankton identification, may deepen the understanding of changing planktonic food webs on ecosystem function and production of the NES.