Development of a Moored in Situ Fluorometer for Phytoplankton Studies

Abstract

Marine ecology is a complex science because of the many interactions between physics, chemistry and biology that occur simultaneously. In addition, these physical, chemical and biological processes are quite variable in time and space as a result of secondary processes, and produce an almost unlimited combination of possibilities for ocean variability. At present, one of the most critical areas in biological oceanography is to observe and understand the variability of biological parameters through the range of time scales of minutes to years. Special instrumentation is needed which will enhance our ability to collect many data points over a relatively long period of time. In bothboth the technological sense and biological importance, a phytoplankton biomass indicator, chlorophyll, is widely considered to be the “best” initial in situ Eulerian measurement. Hence an in situ fluorometer to estimate chlorophyll a concentration was developed at the Division of Oceanographic Sciences at Brookhaven National Laboratory to be moored in the ocean at depths up to 300 m for as long as three months. During a given three month data gathering experiment, with data being collected at rates up to 75 times each day, approximately 7000 data points could be available to show the range and scales of variability of chlorophyll at a fixed point in the ocean.