GIS Application for Mapping of Phytoplankton Using a Multi-channel Fluorescence Probe Derived Information

摘要

A submersible multi-channel fluorescence probe was recently introduced in Lake Kinneret, Israel, that enables the determination of phytoplankton density, in terms of chlorophyll a concentration, in real time, and provides information on the contribution of color-classes to the bulk of algal biomass. Using the GIS Arcinfo software package we also could derive information on the distribution of phytoplankton, and its components in different water layers and to relate that distribution to the thermal structure of the lake. The information on the vertical distribution adds a capability to cope with the constant uncertainty affiliated with remote-sensing of phytoplankton, which by its very nature is limited to the uppermost layers of the water column. We found that the vertical distribution of phytoplankton in the epilimnion was mostly fairly uniform, and can be reliably represented by a water layer where the phenomenon of fluorescence quenching is not detectable, i.e., at the depth of 4-6 m. When motile algae dominated the lake phytoplankton the layer of maximum chlorophyll concentration was used. The capability for phytoplankton mapping, almost synoptically, provides an expedient tool for acquisition of ground-truth information for the calibration and/or validation of information derived of remote- operated sensors, carried on-board aircraft or satellite