On a sticky July afternoon, as the sun beat down and the temperature climbed into the high 80s, several dozen people gathered on the banks of a murky pond in Manhattan’s Morningside Park to talk about a slimy green problem.
The pond, built in 1989, is a highlight of the leafy park that runs for 13 blocks through Harlem and Morningside Heights. But in recent years, it has turned an unhealthy shade of green as algae has overgrown its surface. And this Saturday, scientists from Columbia University and the city’s Parks began a new research effort at the site of the spread of harmful algal blooms worldwide.
For the university, the project represents a new chapter in its complicated and sometimes tense relationship with the surrounding community over this section of the park. The pond itself was built on the site of a proposed Columbia gymnasium, which was abandoned after students and Residents of Harlem protested and the issue triggered the bitter Columbia student protests of 1968.
The pond’s small size, and the amount of its water that has been taken over by algae, makes it a perfect case study, said Joaquim Goes, the project’s principal investigator and a biology professor at Columbia’s Lamont-Doherty Earth Observatory. For years, Dr. Goes has studied toxic algal blooms around the world, even monitoring a bloom that grows to “three times the size of Texas” every 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, Dr. Goes said. By taking samples from the pond and testing different remedies, his team hopes to figure out the best way to mitigate 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 stop it from spreading,” he said.
Most algae are harmless to humans and animals, but some called cyanobacteria or blue-green algaecan be toxic.
Harmful algae blooms when there are excess nutrients – such as phosphorus or nitrogen – in a waterway, along with plenty of sunlight and calm water. The flowers that usually appears in summer, spread steadily throughout the city’s freshwater ponds and lakes. The problem is exacerbated by climate change, which can cause blooms to “occur more often, in more bodies of water and be more intense,” according to the Environmental Protection Agency.
The city has been monitoring the bloom since 2016, said Rebecca Swadek, the Parks’ director of wetlands management. “They are definitely spreading throughout the city,” she said.
In 2020, the Parks Department released news with safety tips to avoid the toxic blooms, mainly advising parkers and their pets to stay out of the water and wash off immediately if they have come into contact with algae. Exposure can cause eye or throat irritation, breathing difficulties and dizziness, according to the department.
The New York State Department of Environmental Conservation maintains an online map of locations where harmful algal blooms have been confirmed throughout the state. The state has also issued $371 million in grants to reduce pollution that contributes to the blooms, 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 60s, a major criticism was of the design of the building: While students could enter it on the west side of the park, the public would have had access through a basement-level entrance on the east side, and only to part of the building. The university later built the gymnasium elsewhere. In 1989, the crater left behind by the abandoned project was converted into an ornamental pond and waterfall.
The new president of Columbia University, Minouche Shafik, standing near the pond on Saturday, praised the university and surrounding community for working together now to improve the park “instead of fighting over a neighborhood asset.”
As scientists and officials work to control the algae, some residents have another goal: to get the waterfall flowing again. It was rehabilitated in 2018but currently not working.
Part of the Columbia University project will include work from the engineering school to repair broken water pumps and restore the waterfall (which was not affected by the algae).
“I would say that the pond and the waterfall are, in people’s minds, the most impressive feature of the park,” said Brad W. Taylor, architect and president of the volunteer organization. Friends of Morningside Parkwho created a petition in June to push forward restoration of the waterfall.
“That’s often the first thing they mention,” he said.