On a sticky July afternoon, as the sun shone and temperatures soared above 80 degrees, several dozen people gathered on the banks of a murky pond in Manhattan’s Morningside Park to talk about a slimy green problem.
Built in 1989, the pond is a highlight of the leafy park, which runs 13 blocks through Harlem and Morningside Heights. But in recent years it has turned a sickly green hue as algae has overtaken the surface. And on this Saturday, scientists from Columbia University and the city’s Parks Department began a new research effort at the site into the spread of harmful algal blooms worldwide.
For the university, the project marks a new chapter in the complicated and sometimes tense relationship with the surrounding community over this part of the park. The pond itself was built on the site of a proposed Columbia gymnasium, which was abandoned after students and Harlem residents objected and the issue sparked the bitter Columbia student protests of 1968.
The small size of the pond and the amount of water taken up by algae make it a perfect case study, said Joaquim Goes, the project’s lead researcher and a biology professor at Columbia’s Lamont-Doherty Earth Observatory. Dr. Goes has spent years studying toxic algal blooms around the world, even tracking a bloom that grows “three times the size of Texas” each year off the coast of Oman, in the Arabian Peninsula.
The city approached the university about the algae problem a month and a half ago, says Dr Goes. By taking samples from the pond and trying different remedies, his team hopes to find the best way to curb the spread of harmful algae and create an “early warning system” for future blooms, he said.
“If we can control it from the source, we can prevent it from spreading,” he said.
Most algae are harmless to humans and animals, but some, called cyanobacteria or blue-green algae, can be toxic.
Harmful algal blooms thrive when there are excess nutrients — such as phosphorus or nitrogen — in a waterway, along with plenty of sunlight and calm water. The flowers, which usually appear in summer, have steadily spread across the city’s freshwater ponds and lakes. The problem is exacerbated by climate change, which could cause flowers to be “more common, in more bodies of water and more intense,” according to the Environmental Protection Agency.
The city has been monitoring the blooms since 2016, said Rebecca Swadek, director of wetlands management for the Parks Department. “They’re certainly scattered all over the city,” she said.
In 2020, the Parks Department issued a press release detailing safety tips for avoiding the poisonous blooms, primarily advising park visitors and their pets to stay out of the water and rinse off immediately if they come into contact with algae. Exposure can cause eye or throat irritation, difficulty breathing and dizziness, according to the department.
The New York State Department of Environmental Conservation maintains an online map of places where harmful algal blooms have been confirmed throughout the state. The state has also provided $371 million in grants to reduce pollution that contributes to the bloom, along with $14 million for research and monitoring projects.
When students and residents near the park began protesting Columbia’s construction of the gym in the late 1960s, the main criticism of the building’s design was that while students could enter it on the west side of the park, public access would have been through a basement-level entrance on the east side, and only to part of the building. Later the university built the gymnasium elsewhere. In 1989, the crater left by the abandoned project was converted into an ornamental pond and waterfall.
Standing by the pond on Saturday, Columbia University’s new president, Minouche Shafik, praised the university and the surrounding community for now working together to improve the park “instead of fighting over a neighborhood property.”
While scientists and officials work to control the algae, some residents have another goal: to get the waterfall flowing again. It was rehabilitated in 2018 but is not currently working.
Part of the Columbia University project includes engineering school work to repair broken water pumps and restore the waterfall (which has not been affected by the algae).
“I would say that the pond and waterfall are, in people’s minds, the most impressive feature of the park,” said Brad W. Taylor, an architect and president of the Friends of Morningside Park volunteer organization, who drafted a petition in June to push for the waterfall to be restored.
“That’s often the first thing they mention,” he said.
