An algal bloom is the excessive growth and accumulation of one or more species of microscopic single-celled plants called phytoplankton. Phytoplankton are generally beneficial, as they form the basis of the food chain and provide the main source of energy that sustains aquatic life. When unusual conditions exist however, such as when excess nutrients are present (termed eutrophication), a particular phytoplankton species may gain a competitive advantage over others and grow uncontrollably into a nuisance algal bloom. Some blooms involve species that produce potent toxins or have other harmful ecosystem impacts, and may pose health hazards for both humans and other animals. These are referred to by the scientific community as "Harmful Algal Blooms" or HABs.
In recent decades, HABs have increased in frequency and duration around the world, and represent a significant threat to fisheries and public health. An ongoing Suffolk County capital project administered by the SCDHS Office of Ecology, Public Health Related Harmful Algal Blooms (CP-8224), was initiated to determine and monitor the extent to which HABs exist in Suffolk County waters and to assess their potential impact on public health. To meet these goals, the program has provided operational and financial support for numerous scientific research projects in addition to in-house monitoring efforts. A second capital project that is no longer operational, Study for the Occurrence of Brown Tide in Suffolk County Marine Waters (CP-8228), provided critical support to researchers studying the infamous brown tide blooms of the 80’s and 90’s.
HABs that have been documented to occur in Suffolk County waters include the following:
- The brown tide is a marine microalgal bloom caused by a species called Aureococcus anophagefferens
, that turns waters a light brown color and has been responsible for the decline in eelgrass beds in various locations, as well as the mortality of shellfish, particularly bay scallops. The bloom has appeared in Long Island's Peconic and South Shore estuaries as well as in Narragansett Bay (Rhode Island), Barnegat Bay (New Jersey), Delaware's inland bays, Maryland's coastal bays, and in South Africa. The brown tide was first detected in Suffolk County waters in June of 1985, and has recurred in a number of locations, although unpredictably and in varying degrees of intensity.
In recent years brown tide blooms have been most prevalent in waters extending from eastern Moriches Bay through Quantuck Bay and western Shinnecock Bay, as well as throughout Great South Bay, but have generally been absent in the Peconic Estuary.
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– Red tides are generally caused by a class of phytoplankton called Dinoflagellates, which, under bloom conditions, can discolor effected waters red. Not all red tides are harmful, although those that produce biotoxins can be lethal to fish and shellfish and potentially pose serious public health threats.
The red tide caused by the organism Alexandrium
, is associated with an illness known as Paralytic Shellfish Poisoning (PSP) that results from the ingestion of shellfish contaminated with a potent toxin that these algae produce. When concentrated by consuming shellfish, this biotoxin (called saxitoxin) can result in levels that are lethal to humans. Symptoms of PSP will depend on the amount of toxin ingested, and can progress from tingling of the lips and tongue, to numbness of the face, neck and limbs, loss of muscular control, followed by difficulty breathing.
Previous investigations conducted by the Office of Ecology (1986-1989 and 2000-2001) found Alexandrium
(and measureable levels of saxitoxin) in various Suffolk County embayments, although no cases of paralytic shellfish poisoning were documented. More recent monitoring conducted by the NYSDEC has noted almost annual blooms in the Huntington-Northport Bay complex (2006, 2008-2012), resulting in precautionary shellfish bed closures. In 2012, PSP was also detected in Shinnecock Bay, Mattituck Inlet and Sag Harbor Cove.
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– The rust tide is a relatively new (to Suffolk County) “red tide” caused by the organism Cochlodinium polykrikoides
. Since 2004, this HAB has recurred throughout the Peconic Estuary, including in Flanders Bay, Great Peconic Bay, West Neck Bay, and Coecles Harbor, as well as in eastern Shinnecock Bay. In 2011, the organism was also observed in Great South Bay.
During the widespread blooms of 2008 and 2009, fishermen reported the mass mortality of fish held in pound nets both in the Peconic Estuary and in Shinnecock Bay. During 2009, a mass mortality of scallops that occurred in Little Peconic Bay and Noyack Bay was likewise attributed to a bloom of Cochlodinium polykrikoides
Studies conducted by Dr. Chris Gobler of the School of Martine and Atmospheric Sciences of Stony Brook University, and funded by Suffolk County Capital Project 8224 (Harmful Algal Blooms
), have demonstrated that this organism can have a serious impact on marine resources, as it is capable of killing other phytoplankton, zooplankton and fish, as well as juvenile and larval shellfish including bay scallops, hard clams and oysters, in a matter of hours to days.
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– An illness known as Diarrhetic Shellfish Poisoning (DSP) is caused by the ingestion of shellfish that have been feeding on blooms of Dinophysis acuminata
, a Dinoflagellate organism that produces the biotoxin Okadaic acid. In 2011, a Dinophysis
bloom in Northport Harbor caused the first documented DSP event in Suffolk County. Recently, blooms have been documented in Meetinghouse Creek in the western Peconic Estuary.
- Cyanobacteria, also known as blue-green algae, are microscopic organisms found in both marine and fresh water environments. They are usually present in low numbers, but under favorable conditions of sunlight, temperature, and nutrient concentrations, can form massive blooms that discolor the water and often result in a scums and floating mats on the water’s surface. Some species of cyanobacteria produce toxins that can cause health problems in humans and animals if exposed to large enough quantities.
Past studies have documented cyanobacteria blooms in a number of freshwater systems in Suffolk County, including some that contain public bathing beaches. A twenty lake survey conducted in 2004 by Stony Brook University, and funded by Suffolk County Capital Project 8224 (Harmful Algal Blooms
) found that all of the lakes studied contained potentially toxic cyanobacteria and detectable levels of the toxin microcystin. Fifteen of the lakes showed toxin levels exceeding World Health Organization (WHO) levels permissible for drinking water, with five lakes having levels that posed a moderate–to-high risk to human health for recreation. One of the latter five sites is a very popular bathing beach on Lake Ronkonkoma.
Follow-up studies have found have found nearly annual blooms in some lakes (Lake Agawam and Mill Pond in Southampton), with periodic blooms occurring in other systems, some of which include bathing beaches (Lake Ronkonkoma, Deep Pond - Schiff Scout Camp, and Great Pond – Peconic Dunes Camp). The blooms in Lake Ronkonkoma in 2009 and 2013 were of a magnitude that warranted immediate closure of the lake’s bathing beaches.
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- Pfiesteria piscicida
is a toxic dinoflagellate that has been implicated in recent years in causing fish kills in brackish coastal waters from North Carolina to Delaware. The organism has a complex life cycle that includes numerous different morphological forms, some of which produce toxins. Sampling conducted from 1998-2004 documented the presence of Pfiesteria
in a number of Suffolk County embayments. Although the organism was found to be widespread, the colder waters characteristic of Long Island are not thought to be optimal for bloom formation and thus toxin production. With the onset of climate change however, this may need to be re-evaluated.
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