Plum Island Ecosystems LTER. aquatic metagenome

The Plum Island Sound estuary, located on the Gulf of Maine in northeastern Massachusetts is part of the Plum Island Ecosystems (PIE) Long Term Ecological Research site. The estuary is 25 km long with a mean depth of 2 m at low tide. Tidal range averages 2.6 m, salinity ranges from 0 to 32 psu, and temperature varies seasonally from -1.0 to 28C. The upper half of the estuary is a tidal river flowing through extensive salt marshes, and the lower half is a broad, shallow sound. Three watersheds drain into the estuary: Parker (155 km2), Rowley (26 km2), and Ipswich (404 km2). The Parker River, which flows over a dam and into the head of the estuary, supplies most of the freshwater that is retained in the estuary and exerts the greatest control on salinity distribution and water residence time. Seasonal freshwater discharge in combination with tidal forcing determines the salinity gradient and residence time of water masses, which affect the establishment of planktonic communities in the estuary. Springtime high discharge in the Parker River creates short residence times and displaces the salinity gradient downstream to the lower estuary. During the spring, offshore diatom blooms are tidally driven into the sound and lower portions of the estuary. During summer and fall, periods of low discharge, the majority of the salinity gradient is in the upper and middle portions of the estuary. Summer and fall oligohaline phytoplankton blooms are often prevalent in the upper Parker River when residence times are longer. General research questions for the PIE local MIRADA data sets are: What is the diversity and relative abundance of Bacteria, Archaea and Eukarya along salinity gradients? What is the diversity and relative abundance of Bacteria, Archaea and Eukarya during seasonal periods of short and long water residence times? What is the diversity and relative abundance of Bacteria, Archaea and Eukarya during seasonal changes in phytoplankton blooms?