Photos of the Long Island Sound

Research & Monitoring


The Long Island Sound Study has launched a new version of the Environmental Indicators section. The data below may be out of date. Please visit and bookmark the new section here to see the most recent data.

Status and Trends: LISS Environmental Indicators



Osprey are one of the largest birds of prey in North America, and found throughout the world. Their population was seriously affected by pesticides such as DDT in the 1950s and 1960s. Populations recovered due to the ban on DDT and management efforts to increase available habitat. Populations have recovered to the point where state conservationists have stopped tracking their numbers. View Indicator

No Discharge Area

Areas designated as "no discharge zones" prohibit the release of sewage from any vessels. Sewage can damage habitats and be a major source of pathogens to the coastal environment. This map shows the areas in Long Island Sound designated as No Discharge Zones. View Indicator

Lead Concentrations in Sediment by Basin

This map shows the concentration of the heavy metal lead within the seafloor sediments throughout Long Island Sound. View Indicator

Heavy Metals in Sediment

Sediment cores were sampled near Norwalk Harbor to determine the historic trends of toxic contamination in the seafloor sediment of the Sound. The cores give a record of metal contamination from the pre-colonial period to the post-industrial era. View Indicator

Sediment Delta 13C

δ13C is an isotope of carbon used as a proxy for hypoxia in this indicator, enabling the creation of a 1000-year historical record of bottom water conditions in Long Island Sound. View Indicator

Sediment Organic Carbon Concentration Chart

Sediment Organic Carbon Concentration

Measurements of organic carbon concentration in sediment cores can be used to reconstruct a historical record of organic carbon in Long Island Sound. View Indicator

Increases in Population and Sewage

Clostridium perfringens, a bacterial spore found in sediments, is an indicator of sewage inputs and can be used to create a historical record of the magnitude of sewage input to the Sound. View Indicator

Sediment Delta 15N

Delta 15N is a nitrogen isotope whose relative abundance in benthic sediment is used to determine the contribution of wastewater and sewage to total nitrogen. View Indicator

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