Third Annual Long Island Natural History Conference




































The effects of excessive nitrogen loading on Long Island’s coastal ecosystems

Christopher J. Gobler, Ph.D., Professor, Stony Brook University, School of Marine and Atmospheric Sciences

The nitrogenous waste from more than one million Suffolk residences is leaching out of septic tanks and cesspools and into the groundwater beneath our feet. This unplanned experiment is proceeding quickly, as the recently released Suffolk County Comprehensive Water Resources Management Plan reported rapid and large changes (40 and 200% increase) in the levels of nitrogen in Suffolk County’s groundwater between 1987 and 2005, with measurements in 2013 showing the same rate of change and models indicated these levels will continue to rise for several decades.

Nitrogen rich groundwater seeps from land into our bays, harbors, and estuaries where it is exacting an unwanted toll. Excessive nitrogen loading has contributed to the loss of up to 80% of Long Island’s coastal salt marshes since the 1970s. Excessive nitrogen seepage is also stimulating the growth of multiple strains of harmful and toxic algae such as brown tides, red tides, green tides, rust tides, which were unknown to Long Island three decades ago, but recur annually today. These algae are having a cascading negative impact on our coastal ecosystems and in some cases can be a human health threat. Eelgrass meadows are critical benthic habitats that sustain our most important shellfish and finfish but are highly sensitive to nitrogen and shading by algae.

As nitrogen levels in groundwater have increased, 90% of Long Island’s eelgrass has vanished and Suffolk County has recently predicted these grasses will be extinct on Long Island in two decades if current nitrogen loading trends continue. Algal blooms stimulated by excessive nitrogen loading can also starve coastal waters of oxygen and make them more acidic, two conditions that are also detrimental to fish and shellfish.

For all of these reasons, Long Island fisheries have been on the ropes. In the 1970s, the bay scallop fishery on eastern Long Island and the hard clam fishery on the south shore were the two largest fisheries for these mollusks on the US east coast. Since that time, landings of hard clams and bay scallops on Long Island have diminished more than 90% due to a combination of the woes brought about by excessive wastewater nitrogen outlined above: Algal blooms, seagrass loss, low oxygen, and lower pH. In the end, these trends could directly affect every Long Islander as billions of dollars of our economy are wrapped up in fisheries and tourism and home values have been shown to trend with coastal water quality.

Christopher J. Gobler ( is a professor within the School of Marine and Atmospheric Sciences (SoMAS) at Stony Brook University. He received his M.S. and Ph.D. from Stony Brook University in 1995 and 1999, respectively.

Chris Gobler’s research examines the functioning of aquatic ecosystems and how that functioning can be effected by man or can affect man. He investigates harmful algal blooms (HABs) caused by multiple classes of phytoplankton in diverse ecosystems (e.g. estuaries, lakes, coastal ocean) using a variety of approaches (field, laboratory, experimental, molecular.) Another research focus within his group is climate change effects on coastal ecosystems including investigations of how future and current coastal ocean acidification effects the survival and performance of early life stage bivalves and fish. A final area of interest is how anthropogenic activities such as eutrophication and the over-harvesting of fisheries alter the natural biogeochemical and/or ecological functioning of coastal ecosystems.

Dr. Gobler has received more than $10M in funding for his research via grants from government agencies and private foundations, with core research support from NOAA, NSF, US EPA, the State of New York, and from the New Tamarind, Simons, Dolan, and Laurie Landeau Foundations. He has published more than 125 papers in international, peer-reviewed journals and has mentored more than 30 graduate students at Stony Brook University. He has provided testimonies and briefings to the US House of Representatives and US Senate on multiple water-related topics. He is a two-term (2008-2014; term limit) elected member of the National Harmful Algal Bloom Committee (NHC) commissioned by US Congress. Gobler is on the editorial board of the scientific journals PLOS One, Frontiers in Aquatic Microbiology, Perspectives in Phycology, and Harmful Algae. Gobler has received numerous awards for his research and the usefulness of his science in shaping policy including the Bay Guardian Award (WaterKeeper Alliance), the Environmental Equinox Award (Citizen’s Campaign for the Environment), the Dennis Puleston Award for Environmental Achievement (Pine Barrens Society) and the Trustee’s Award for Scholarly Achievement (Long Island University).