Observations on the Utility of Phytoplankton Parameters in Ocean Disposal Assessments

Field monitoring of effects on phytoplankton from brine discharges over an 18-month period at the Department of Energy Strategic Petroleum Reserve West Hackberry (Louisiana) site has provided some insight as to our ability to discern impact on phytoplankton through field studies. Seven sampling sites were monitored at multiple depths with three replicate samples for biomass (chlorophyll and cell counts) and composition during eleven sampling periods. The observed variation in the parameters measured provided a data base from which statistical conclusions were drawn concerning the suitability of the parameters to impact detection, adequacy of sampling design (both temporally and the spatial distribution of sampling sites), the optimization of sampling sites and replicates, the sampling designs required to detect statistically significant changes in phytoplankton parameters, and the relevance of some parameters to the question of impact detection and assessment.