Prorocentrum bloom on the Rhode River 
Prorocentrum minimum bloom on the Rhode River

Estuarine Water Quality

Water quality refers to measurements of physical, chemical and biological properties of water that affect a wide range of ecological processes within the estuary. Variations in concentrations of chemical constituents (for example, nutrient concentrations) and the magnitude of physical parameters (such as temperature) are affected both by natural processes and by human activity within the surrounding watershed and airshed. Distinguishing chronic, anthropogenic, trends from natural seasonal and interannual variations requires long term observations of the system, as well as experimental studies to understand the underlying mechanisms that determine water quality conditions in the estuary.

Measurements of water quality in the Rhode River are among the longest running observations at SERC. Concentrations of nutrients, suspended sediments, and phytoplankton pigments have been measured along a transect from beyond the mouth of the Rhode to the shallows of Muddy Creek at weekly to bi-weekly intervals since the mid-1980's. Analysis of the phytoplankton chlorophyll data have revealed a trend in the eutrophication (overproduction of phytoplankton algae by nutrient enrichment) of the system that peaked in the late 1980's, and has shown signs of improvement through the decade of the 1990's. Research to determine the underlying causes of the observed trends is still in progress.

Automated instruments are maintained at the SERC dock on the Rhode River to measure water level, temperature, salinity, dissolved oxygen, and pH. Various instruments have been operated since the 1970's. Currently, the data are downloaded by computer at approximately weekly intervals, and examined graphically for data quality. The data supply scientists with a nearly continuous record of conditions that affect the suitability of the water as habitat for estuarine organisms, and provide a record of extreme events such as major storms that impinge on the system.

For more information, contact Dr. Charles Gallegos.