Response of the Common Mummichog (Fundulus heteroclitus) to Water Quality Changes in Long Island Sound Tributaries

Abstract

Long Island Sound is a complex watershed which lies between Connecticut and New York. Surrounded by high concentrations of industrial and residential properties, Long Island Sound is extremely susceptible to water quality changes. The complexity of the watershed makes it difficult to accurately measure real time impacts to water quality and the subsequent impacts to aquatic species. One method of assessing water quality is the monitoring of indicator species. In particular, the fish species mummichog may be viable for monitoring water quality parameters. The common mummichog is an abundant species within Long Island Sound that possesses several qualities which may make them suitable as an indicator species. This project aimed to identify which water quality parameters, if any, for which the mummichog would be suitable for use as an indicator species. To investigate this, water quality parameters and mummichog population density were monitored at two separate sites. Of the parameters monitored as part of this project, it was found that salinity levels exhibit a non-linear correlation to the presence and density of mummichogs. Specifically, mummichogs were present at all observed salinity levels above 1.003 specific gravity. However, the maximum number of mummichogs was observed at a specific gravity of 1.019. Above this salinity, the number of mummichogs collected began to decrease. The Long Island Sound Study reports that the average salinity of the Long Island Sound is 1.026 specific gravity. The influx of freshwater into the watershed likely plays a vital role in diffusing salinity to levels within the estuaries that are tolerable by the mummichog. Further research is needed to better quantify the mummichog’s response to changing salinity levels and the potential water quality impacts due to anthropogenic sources.