Use of optical imaging datasets to assess biogeochemical contributions of the mesozooplankton

Abstract

Abstract The increasing use of image-based observing systems in marine ecosystems allows for more quantitative analysis of the ecological zonation of zooplankton. Developing methods that take advantage of these systems can provide an increasingly nuanced understanding of how morphometric characteristics (especially size) are related to distribution, abundance and ecosystem function via a wider application of allometric calculations of biogeochemical fluxes. Using MOCNESS sampling of zooplankton near the Bermuda Atlantic Time Series and a ZooSCAN/EcoTaxa pipeline, we apply a new taxonomically resolved biomass to biovolume dataset and a suite of R scripts that provide information about the relationships between zooplankter size, taxonomy, distribution, depth of migration, magnitude of migration and biogeochemical contributions (e.g. respiratory O2 consumption). The analysis pipeline provides a framework for quantitatively comparing and testing hypotheses about the distribution, migration patterns and biogeochemical impacts of mesozooplankton. Specifically, our code helps to visualize a size-based structure in the extent of vertical migration and allow for a quantification of the relative importance of non-migratory versus migratory organisms of various size classes. It additionally allows us to quantify the error associated with various methods of calculating active flux, with size-based analysis being the most important methodological choice, and taxonomic identification being the least.