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RELATIONSHIPS BETWEEN TOTAL NITROGEN AND PLANKTONIC CHLOROPHYLL IN LONG ISLAND SOUND
Citation:
Dettmann, E H. AND L. B. Mason. RELATIONSHIPS BETWEEN TOTAL NITROGEN AND PLANKTONIC CHLOROPHYLL IN LONG ISLAND SOUND. Connecticut Sea Grant, Avery Point, CT, (2004).
Impact/Purpose:
To use data collected by the Connecticut Department of Environmental Protection's Long Island Sound Water Quality Monitoring Program to examine spatial and temporal trends in concentrations of total nitrogen and chlorophyll in the water column and in the relationship between these two variables
Description:
We used data collected by the Connecticut Department of Environmental Protection's Long Island Sound Water Quality Monitoring Program to examine spatial and temporal trends in concentrations of total nitrogen and chlorophyll in the water column and in the relationship between these two variables. Concentrations of both nitrogen and chlorophyll showed strong and similar spatial gradients in Long Island Sound, with peak concentrations in the western Sound, and much smaller concentrations near The Race, the seaward boundary of the eastern Sound. Concentrations of total nitrogen showed a net decline from 1995 to 2001. During this same period, summertime concentrations of chlorophyll showed much stronger trends, with concentrations declining substantially in 1997-1999, compared to previous summers, followed by a large increase in 2000 and 2001. These changes were reflected in the spatial relationship between chlorophyll and total nitrogen. The slope of this relationship declined substantially from 1995-1999, only to increase dramatically in 2000. The summers of 1997?1999 were preceded by winters with somewhat warmer water temperatures than the preceding and following two years. Other environmental variables examined (incident light intensity, river inflow, wind speed) did not show patterns that correlated with the observed chlorophyll to nitrogen relationship. Other investigators have reported reduced or missing winter-spring blooms in other estuaries during winters with warm water temperatures. In this study, the effect appears to persist into summer, even though summertime temperatures for years with low chlorophyll are not consistently higher than for years with high chlorophyll.