Fall 2006 Update: Spring Conditions on the Northeast Shelf Ecosystem
The spring indices for sea surface temperature and zooplankton biomass on the Northeast Shelf exhibit definite trends suggesting decadal and multi-decadal changes in these parameters. The time trend of SST during the spring season follows a pattern similar to the annual trend in SST for the entire shelf system; both indicate surface waters have cooled during the past few years on the order of 1-2°C (See Annual Conditions of the Northeast Shelf Ecosystem). Inter-annual variability in spring levels of chlorophyll has been large, making it difficult to discern a shelf-wide trend. Spring zooplankton biomass is apparently increasing. The lowest biomasses were observed in the early 1980's, and some of the highest biomasses have been observed in recent years. The level of increase in on the order of 30% over the time series minima observed in the early 1980's.