Study says Everglades water harming Keys corals, but not everyone agrees
Diseased coral is seen in October at Alligator Reef (off Islamorada) in the Florida Keys National Marine Sanctuary. A new study has reignited a decades-old dispute over pollution and the Everglades.
The Florida Everglades can be a contentious place. Politicians, conservationists and farmers never seem to agree on much.
Debate among scientists tends to be collegial. But a new study on coral and the Florida Keys that gained national headlines last week has reignited a decades-old dispute over pollution and the Everglades.
The study, published in the journal Marine Biology by Florida Atlantic University marine biologist Brian LaPointe, concludes that water from the southern Everglades is harming reefs near Looe Key. LaPointe said water sampling he conducted over 30 years showed that big pulses of water from the Everglades’ Shark River preceded the Keys’ mass bleaching events over the years. He says the remote river is polluted with nitrogen from farms and urban development, which can harm corals.
“There is, you know, multiple lines of evidence showing that run-off from the Everglades is a contributing factor to algal blooms and nitrogen enrichment,” LaPointe said.
But at least 16 scientists who work in the Everglades are raising questions. They say more widespread monitoring doesn’t appear to support the findings of excess nitrogen. They’re taking a closer look and plan to submit a formal rebuttal.
“That would be very surprising,” said aquatic biologist Evelyn Gaiser, who leads a team of Everglades scientists as part of a longterm research project at Florida International University established by the National Science Foundation in 1980 and involving 29 institutions. None were asked to peer-review the article, she said.
“We have an incredible wealth of data that we can evaluate to help understand those trends and dynamics,” she said. So far, they show nitrogen only spiking during natural events like tropical storms, cold freezes and hurricanes.
The South Florida Water Management District said in an email that its monitoring also failed to detect dangerous levels of nitrogen in Florida Bay outside severe storms.
Spokesman Randy Smith said the agency was also reviewing the findings.
The editor of the journal article, Sandra Shumway, a Universitiy of Connecticut marine biologist who specializes in shellfish, said by email she was traveling and unavailable for an interview.
Part of the complexity is understanding the dynamic between nitrogen and phosphorus, the two chemicals at play in the ecosystem. Seagrass thrives on a ratio of high nitrogen and low phosphorus. Reefs, which are disappearing at an alarming rate and now in the midst of an unprecedented disease outbreak, are the opposite.
If LaPointe is correct, the consequences could be major. Everglades restoration is based largely on the premise that flood protection has cut off the southern Everglades from the water that naturally flowed out of Lake Okeechobee, down the river of grass and out marshes into the vast seagrass meadows in Florida Bay. The meadows help maintain the kind of ginclear water that reefs need to thrive by stabilizing the muddy bottom. They also provide food and habitat for the rich mix of marine life that lives on reefs.
Over the years, too little water has made Florida Bay’s seagrass vulnerable to drought. In droughts in 1987 and again in 2015, the bay became too salty and triggered major die-offs. More than 60 square-miles of seagrass died by 2016. The 1980s die-off set the stage for catastrophic algae blooms that caused the bay to crash.
The state of Florida has spent millions, including $880 million for filtering marshes, to clean water and get it back into the the southern Everglades. But it focuses on phosphorus, the chemical in fertilizer coming off sugar fields and in water out of Lake Okeechobee. Too much phosphorus can cause cattails and other plants to grow in the sparse marshes and interrupt the flow of water and over-stimulate seagrasses. The state does not focus on removing nitrogen.
In 1999, Everglades scientists published findings blaming the drought for the Evelyn Gaiser,
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Scientists also say the data he relies on for this study measured Everglades nitrogen at the north end, near Tamiami Trail, not the mouth of the river.
LaPointe looked at nitrogen levels in water he sampled over 30 years at Looe Key, about 25 miles east of Key West. He also looked at chlorophyll-a to see what affect the nitrogen was having on water and at nitrogen levels in seaweed.
Leaky septic tanks and deadend canals have long been blamed for driving up nitrogen levels in water around the Keys. Monroe County has spent about $1 billion to convert the string of islands to a central sewer line. The county had planned to spend about another $700 million to clean up canals before Irma hit.
LaPointe said while it’s clear that local sources provide some nitrogen, his research found it’s likely carried from the Everglades as well. He said water sampling from 2010 and 2011 showed elevated levels of nitrogen at Shark River.
biologist
Gaiser said scientsts would normally confer with one another if data suggest unexpected findings.
“The way that many of us would react to that is to reach out to colleagues and build as robust of an analysis as possible to figure out what’s going on,” she said. “You have a result that isn’t what most scientists would anticipate, then you would want to dig in more deeply and see if there might be some other explanation.”
The team is now reviewing LaPointe’s study. Their rebuttal will undergo the same peer-review as LaPointe’s paper.
Jenny Staletovich writes for WLRN Public Media.
This story was produced in partnership with the Florida Climate Reporting Network, a multinewsroom initiative founded by the Miami Herald, the South Florida Sun Sentinel, The Palm Beach Post, the Orlando Sentinel, WLRN Public Media and the Tampa Bay Times.