Seasonal and historical mesozooplankton dynamics in Delaware Bay: an application and optimization of the ZooScan optical imaging tool
Date
2016
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
University of Delaware
Abstract
The mesozooplankton community in Delaware Bay is an important part of the pelagic ecosystem, connecting primary production to higher trophic levels while also representing larval forms of commercially important species such as blue crabs and eastern oysters. While Delaware Bay’s physico-chemical characteristics and primary production are well-described, its mesozooplankton community remains relatively understudied, particularly in comparison to Chesapeake Bay. To understand future changes to this estuarine system and compare it to other estuaries in the region (e.g., Chesapeake Bay), we need an updated characterization of Delaware Bay’s mesozooplankton community and its relationship to key environmental variables that have changed over time, or likely will change into the future. To this end, I describe here a year-long, seasonal time series to characterize and quantify Delaware Bay zooplankton using a new optical instrument ZooScan, and compare my results to the historical data presented in Cronin et al. (1962). Results found seasonal changes in community composition and species dominance. Historical comparisons show a remarkable similarity in the abundance of the dominant zooplankter Acartia tonsa found by Cronin et al. (1962) and the present study. These results have implications for demonstrating how mesozooplankton respond to systemic changes. I also present a new method of determining biovolume in highly turbid areas where standard displacement volumes are skewed by non-zooplankter material such as detritus. Finally, I present a validation and application of a citizen-based zooplankton collection method for use by volunteer monitoring groups.