Construction and Testing of a Plankton Imaging and Identification System in Gliders and Drifters for Use in Low-cost Plankton Observing Systems

Cabell Davis, Woods Hole Oceanographic Institution

Abstract

Understanding plankton distributions and abundance is fundamental to understanding marine ecosystems. Recruitment success in marine fish populations is linked to the timing of spawning in relation to spring phytoplankton blooms. Zooplankton serve as the critical link between primary producers and higher trophic levels including exploited fish and protected marine mammals. Marine snow represents the downward flux of matter that feeds the benthos. A fundamental limitation to our understanding of plankton and marine snow dynamics is sparseness of data. Traditional sample collection and processing methods are arduous, destructive to ubiquitous fragile forms, and grossly undersample submesoscale patches, where the bulk of productivity and predator-prey interactions occur. The time consuming nature (and coupled expense) limits the amount of data that can be generated to inform assessments. Temporal and spatial resolution of plankton surveys is coarse and limits the ability to initialize and validate coupled-plankton-hydrodynamic models. These models are an important component of the developing ecosystem-based fisheries management.

New optical imaging systems provide real-time high-resolution data on plankton size and taxonomic composition, but this capability has not been incorporated into autonomous Lagrangian platforms (e.g., gliders, drifters). Such integrated platforms, with on-board plankton classification and satellite telemetry, coupled interactively to a shore-based 3D hydrodynamics- plankton model would provide a novel and cost effective modeling-observing system. These systems could be used to better understand fish, shellfish, and marine mammal distribution and productivity.

We propose to build a modular, low power, compact plankton imager with on-board processing and incorporate it into a glider for long-term (months) ocean observations of plankton taxonomic and size composition together with environmental variables. We will use low-power image acquisition and processing hardware that will allow automatic in situ object detection and identification and satellite telemetry of processed plankton data together with CTD and navigation data. We will test the new system in coastal and open ocean areas including Georges Bank and the NE shelf as part of NEFSC surveys. The resulting system will allow for long-term high-resolution autonomous measurement of micro-meso-plankton and marine snow abundance and composition on an economical platform.