Distribution of plankton, particles, and hydrographic features across Georges Bank described using the Video Plankton Recorder

It is well known that plankton abundance is highly variable over a broad range of scales. Conventional sampling with nets, pumps, and bottles is discrete and covers only a small portion of the total variance spectrum. Development of the Video Plankton Recorder (VPR) has enabled us to quantify the abundance of seston and plankton, including delicate taxa, over a range of scales from centimeters to hundreds of kilometers. During the 1994–1995 GLOBEC Georges Bank field years, three VPR surveys were conducted across the bank from the Slope Water in the south to the Gulf of Maine in the north, a distance of ∼200 km. The surveys, conducted in June 1994, January 1995, and March 1995, intersected at least four distinct water types (Slope Water, stratified bank water, well-mixed bank water, Gulf of Maine water) and crossed several frontal boundaries (shelf break front, tidal front, Gulf of Maine front). The Video Plankton Recorder was equipped with temperature, conductivity, fluorescence, and transmissivity probes in addition to two video cameras, permitting comparison of the plankton and particle distributions with the physical fields. Only data collected using the low-magnification camera are considered here. A combination of analytical methods including temperature–salinity–plankton plots and statistical analyses (spatial variance spectra, principle component analysis, and correlation analysis) revealed that the distribution of taxa and particles were associated with particular water mass types but that smaller-scale variability in plankton abundance did not appear to be tightly coupled to or correlated with hydrography. The distributions and seasonal progression in abundance of Calanus finmarchicus, the most abundant plankton taxon, revealed a deep dwelling population in the Slope Water and shallower populations on the bank and in the Gulf of Maine in January with abundance becoming increasingly greater on the bank in March and June. The data indicate that physical advection of water mass types and intrinsic plankton was important to the establishment of Calanus populations on Georges Bank.