The Low Salinity Event - a Unifying Theme for Synthesis?

Mountain, David

html ppt

Abstract

The five years of the Georges Bank GLOBEC program were characterized by relatively low salinities - compared to comparable measurements from the1970's through the early 1990's. The cause of this low salinity event was a greater inflow of water from the Scotian Shelf, as documented in current meter measurements by Peter Smith. The temporal pattern of the salinity variation was reflected in many of the biological observations ­ with lower salinity associated with higher chlorophyll, higher copepod abundance, higher larval growth rates and lower larval mortality rates. A process-based understanding of the possible dynamic connections between these series should be an important focus of the synthesis phase of our program. The low salinity event appears related to large-scale variability in the Northwest Atlantic, including movement of the north wall of the Gulf Stream and transport of the Labrador Current. Isotope measurements suggest the low salinity is of high latitude origin. An important and intriguing question is whether the salinity variation on Georges Bank, and the biological variability that appears associated with it, are associated with the changes that have recently been documented occurring in the Arctic Ocean. Do the changes on Georges Bank represent the downstream, ecological effects of climate-scale changes in the Arctic and the North Atlantic Basin?