Monitoring Bloom Dynamics of a Common Coastal Bioluminescent Ctenophore

Abstract

The long-term objective is to develop predictive models of bioluminescence potential in the coastal zone environment. OBJECTIVES In the coastal zone, watershed runoff and discharge of submarine groundwater can profoundly impact growth conditions of bioluminescent plankton on very short space and time scales. Bioluminescent blooms include dinoflagellate red tides, which are occurring more frequently, lasting longer and extending further off shore due to excessive nutrient loading from land-based runoff. Bioluminescent blooms of the carnivorous ctenophore Mnemiopsis leidyi that may be either seasonal or event driven can also develop on remarkably short time scales (Kremer, 1994) and also appear to be on the increase (Sullivan et al., 2001). The Ocean Research & Conservation Association's (ORCA) objective is to improve understanding of the conditions leading to bioluminescent blooms in coastal waters such that forecasting is possible. Achieving this requires more frequent, automated sampling of greater spatial density, a reduction in dependence upon hand sampling, and automating all aspects of the data collection and analysis processes. APPROACH Increasing the frequency of field sampling and removing the bias introduced by fair-weather sampling requires automation. Achieving greater spatial density of measurements in a sustainable manner requires reducing the cost of sensor systems through component-level integration. New technologies, such as ORCA's bathyphotometer to measure bioluminescence, are necessary to automate biological sample collection and processing. When hand sampling is still necessary, the processing should make use of automated methods for processing. ORCA's approach to monitoring bloom dynamics is to supplement the ORCA Kilroy network with low-cost, autonomous bathyphotometers, using the intensity of bioluminescence as an estimator of abundance and the flash kinetics to assist in distinguishing organisms.