Four weeks after Suffolk County announced a toxic blue-green algal bloom was discovered in Georgica Pond, another was confirmed on Sept. 5 in Sagg Pond in Sagaponack Village. In the weeks leading up to these blooms, others had also been confirmed in Southampton Village and in Manorville.
Algal blooms have been around since the 1950s but have increasingly become a concern for local scientists, who have observed sharp increases in algae presence. The number of affected bodies of water on the East End is only increasing, according to Christopher Gobler, a scientist who directs the New York State Center for Clean Water Technology at Stony Brook University.
His own research into freshwater harmful algal blooms (HABs) began in 2003.
“To my knowledge, there was no record of freshwater HABs prior to that,” Dr. Gobler said in an email to The Star last month. “My experience in marine HABs dates to 1992 . . . and there have been surprises since that time. Many new HABs have appeared; some have disappeared. Some have gotten more intense. Some [have] vanished.”
These harmful algal blooms are caused by excess nutrients, primarily nitrogen and phosphorus, entering the water. Together with climate change and coastal erosion, experts say these harmful blooms pose serious ecological and economic issues for the East End.
There are several types of harmful algal blooms. A brown tide is a marine microalgal bloom caused by a species called Aureococcus anophagefferens, which turns the water a light brown color and kills scallops and other shellfish. Dr. Gobler said one was first discovered on the East End in 1985.
A red tide is usually caused by a type of phytoplankton called Dinoflagellates, turning the water red. These tides are not always harmful, but they can be lethal to fish and shellfish and potentially pose significant health problems.
Rust tides are more recent, caused by the organism Cochlodinium polykrikoides. Discovered in 2004, rust tides are lethal to fish, shellfish, phytoplankton, zooplankton, scallops, clams, and oysters.
Cyanobacteria, otherwise known as blue-green algae, are found both in marine and freshwater environments. The Suffolk County Health Department addresses this type on its website, saying: “They are usually present in low numbers, but under favorable conditions of sunlight, temperature, and nutrient concentrations, [they] can form massive blooms that discolor the water and often result in 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.”
Experts say there are many factors that lead to these blooms. Broken or outdated septic tanks are one. Another, storm runoff, can carry pollutants into ponds and lakes. Excess fertilizer usage on lawns, gardens, and golf courses can also lead to nutrient runoff into waterways.
Algae consume oxygen during respiration, and when they die they decompose, further reducing oxygen levels. This results in the phenomenon known as “dead zones,” areas where no oxygen remains and no aquatic life can survive. Blue-green algae can sicken or kill fish, shellfish, and even larger animals such as birds or marine animals. Dense blooms can block sunlight and hinder the growth of aquatic vegetation, which disrupts underwater ecosystems.
Humans have contracted illnesses due to toxic bacteria in freshwater and saltwater bodies. Many fish have died, and in 2012, the death of a dog was attributed to contact with blue-green algae in Georgica Pond, according to Dr. Gobler.
He estimates that at least 20 bodies of water between Southampton and Montauk, not including estuaries, are contaminated with harmful algal blooms.
“With warming water and continued excessive nutrient (nitrogen and phosphorus) loading, they certainly will not improve” on their own, he said.
A significant reduction in nitrogen content and in freshwater phosphorus content will be needed to safely move forward and protect the waters of Long Island, he added.
Julian Koray was a participant in The East Hampton Star Summer Academy.
