Caribbean. Two Years Post Irma: Marine Life Begins to Recover
Two years after hurricanes Irma and Maria ripped through the islands, optimistic nature lovers are quick to point out signs of recovery – sea grape trees are once more putting out fruit; at least one species of humming birds is frequenting bird feeders; and snorkelers can find spots where schools of fish thrive and sea fans wave in the currents.
Biologists, however, are much more reticent about celebrating nature’s recovery. Although plants and creatures – especially those species native to the islands – have evolved to withstand the devastation of major hurricanes, scientists say recovery is a matter of decades, not of years.
Although divers and snorkelers still find places where marine life is thriving, especially in deeper waters, there’s no doubt that hurricanes Irma and Maria destroyed vast areas of coral reefs throughout the territory.
How much recovery can be expected, or even hoped for, are still open questions.
“Coral grows so exceptionally slowly that we measure recovery in terms of decades,” said Jeff Miller, a fisheries biologist who’s worked for the National Park Service for more than 20 years.
It’s not like on land, where the trees can go from brown to green in a matter of days, Miller said.
“Corals are animals, not trees. Many corals grow a millimeter – the width of a dime – in a year. A half inch of growth is fantastic.”
Some of the species of branching corals, notably elkhorn and staghorn, can grow inches within a year if conditions remain ideal, and Miller has seen signs of new growth among these species.
“We look at elkhorn where branches have been broken off. These are like amputations. We’ve seen new tissue growing over the stump where the segment broke off,” he said.
“Pillar corals took a tremendous hit. You can see them lying on the bottom, but sometimes, you can see new nubs – one-quarter to one-half inches tall, growing up towards the sun from the fallen coral,” he said.
Scientists are also noticing the growth of some coral species that Miller characterizes as “fast growing” and “opportunistic.” These include plate corals and mustard hill corals.
“They’re rapid response corals which take advantage of open space. We’re watching that succession. Recovery, if it’s going to happen, is a multi-decade process,” he repeated.
The key word is “if,” he said.
“We’re at the warmest time of the year, September. We’re at the bleaching threshold,” Miller said.
“Bleaching” occurs when tropical waters warm beyond what corals can tolerate. In general, healthy coral reefs thrive in water temperatures ranging from about 73 degrees to about 83 degrees.
When water temperatures rise beyond 84 degrees, symbiotic algae (which live within coral colonies and provide energy) are expelled from coral polyps, leaving the coral weak and more vulnerable to diseases. The corals may change color, become pale, and eventually turn white or “bleached.”
Late summer is a stressful time for coral, especially with the onset of storms like Hurricane Dorian, which was a Category 1 storm when it rumbled across St. Thomas and St. John before moving on to devastate the Bahamas. However, if coral reefs can survive the damage from wave action, they can benefit from the cooler water brought in by a storm that mitigates bleaching.
Miller and his team will know more when they survey their monitoring sites later in September, but he’s not wildly optimistic.
“The normal stresses – sedimentation, nutrient runoff, unsustainable fishing practices – are the same, if not increased, on a system severely damaged by Irma and Maria. Now we’re throwing in the most virulent coral disease we’ve seen yet.”
Miller is referring to stony coral tissue loss disease, a disease new to the territory that appeared over the winter in an area south of St. Thomas.
The reefs on St. Thomas affected by this disease look the same as reefs that died during a prolonged, severe bleaching event from 2005-2006.
“It’s extremely difficult to tell if you’re seeing the new coral disease or something else,” Miller said. “It’s like trying to diagnose if a person’s high fever and body aches are the result of the flu, dengue fever, or chikungunya.”
For now, the area affected by the disease appears to be limited.
“We’ve not officially seen stony coral tissue loss disease on St. John or St. Croix, but the reefs of the territory are continuing to be shaped by coral diseases of all kinds,” he said. “We just don’t know how to prevent them.”
Stony coral tissue loss disease is particularly damaging to coral reefs because it affects the large, reef-building corals, such as brain corals, branching corals, and star corals.
The health of the coral reefs determines the amount and types of fish that flourish.
“When reef structure dies, it’s like their apartment buildings are destroyed. The fish become homeless and have to go elsewhere,” said Miller.
Although people have anecdotally reported seeing more fish and more diversity of species since ‘Irmaria’, Miller declined to comment about the fish populations in the territory because he has not seen the data yet.
As president of the Caribbean Oceanic Restoration & Education Foundation (CORE) and the owner of a dive business (SNUBA,) Frank Cummings observes marine life almost daily. “I’m not a scientist,” he’s quick to say, but he does see signs of recovery.
Sea fans, which are soft corals, are making a very good comeback, he said.
Cummings had heard estimates that fish stocks are down 25 to 35 percent, but he said he finds plenty to look at on dives. Some species are even more prevalent.
“I’m seeing grouper on almost every dive,” he said. “They were very sparse from the 1990’s until the last five years or so. This is a sign that catch regulations have absolutely had an effect.”
CORE has been the lead Virgin Islands organization combating the spread of invasive lionfish, which have been known to eat more than 70 species of fish and invertebrates. In some locations, lionfish have reduced their fish prey populations by as much as 90 percent.
The war on lionfish is never-ending, Cummings has said, and tropical storms may add to it. He’s recently seen an increase in very small juvenile lionfish at two sites on St. John.
“Lionfish lay eggs which float with the currents. There’s a good possibility they came from the south with Dorian,” he said.
Nicole Angeli, acting director of the Division of Fish and Wildlife, part of the territory’s Department of Planning and Natural Resources, is also concerned about the state of coral reefs.
“The problem today is storms are more frequent and stronger, so when a storm hits the populations [of fish, coral, and other marine species] never return to their pre-storm level.
Angeli said the Coastal Zone Management Division of DPNR recently was awarded a disaster assistance grant. The focus is “getting human-caused disturbances out, so our reefs can recover.”
Several months after Irmaria, the territory coordinated with the Coast Guard to remove many of the vessels that sank or wound up in mangroves that are critical nurseries for marine species, but “There were limits to what the Coast Guard could do because of their mandate after the storm,” Angeli said.
The territorial government is also doing its part to better prepare for a storm. DPNR recently received a grant to clarify its “workflow processes,” laying out exactly who within the agency is responsible for each specific task when a storm hits.
DPNR is working with the National Oceanic and Atmospheric Administration to implement a marine debris task force.
“Human health is always our priority when a storm approaches,” Angeli said. “Prepare yourself and your family, and be a good steward, so your debris is not going to be flying all around.”
The amount of debris remaining below water caught the attention of Mike Anderson on a visit to St. John in August. A retired park ranger, Anderson lived in the Virgin Islands in the 1980’s and more recently.
“We encountered quite a bit of metal roofing in Haulover Bay. It is a concern because it will wreak havoc as it moves around the bottom. At some point it would be beneficial to have volunteers try to remove as much debris as they can,” he said.
One area that was particularly affected by debris is Hurricane Hole – a series of sheltered bays on the east end of St. John where boaters have gone for decades to escape the wrath of storms. The National Park Service, working with the Friends of the Virgin Islands National Park, maintains a chain secured to the bottom that boats can tie onto during hurricanes.
Unfortunately, Hurricane Irma turned out to be the storm that disproved the safety of the location.
“Hurricanes are part of life cycles in the Caribbean,” said Caroline Rogers, a marine ecologist with the U.S. Geological Survey. “However, the combination of Hurricanes Irma and Maria in September 2017 was unprecedented in terms of destructive forces which smashed the U.S. Virgin Islands. Irma, a Category 5 storm with sustained winds of 185 mph and gusts over 220 mph, was followed less than two weeks later by Hurricane Maria, a Category 4 storm in St. John and a Category 5 in St. Croix and Puerto Rico.”
Only a handful of more than a hundred boats that had moored in Hurricane Hole stayed afloat after the storms. The National Park Service – working with U.S. Navy contractors – removed more than 40 boats that were still tangled in the mangroves or sunken at the bottom almost a year after the hurricane. The lingering effects of the contaminants from so many wrecked vessels is unknown.
The destruction was particularly heartbreaking because Hurricane Hole was a unique and rich habitat for marine life.
Rogers said scientists had identified at least 30 species of coral, 80 species of fish, and 60 species of sponges prior to the storm. Other organisms that lived in Hurricane Hole included soft corals, anemones, jellyfish, crabs, shrimp, lobsters, tunicates, bryozoans, octopuses, conchs, starfish and algae.
One explanation for the extraordinary diversity of Hurricane Hole was that the shade provided by the mangrove trees protected the corals from bleaching events. A group of students from Santa Fe College in Florida has made several trips to map the diverse species that flourished there.
When Rogers snorkeled the mangroves several months after the storms, she found the annihilation of this habitat shocking. Some of the corals were pulverized. Some were buried.
“Five months after the storms, there were few signs of life – a video of the area looks like a black and white film,” she said.
Now, two years after the storms, there are some signs of recovery. Some corals that were buried or overturned are growing up towards the light. The team from Santa Fe College returned in May 2019 to document the recovery, but the data hasn’t been analyzed yet.
Rogers agrees that recovery, which is not guaranteed, may take decades, especially with the loss of the red mangrove trees. Their leaves, which provided shade for corals, were torn off by the winds, and the prop roots which sheltered so many juvenile fish were damaged by the waves. Given their value to this habitat, “It might be worthwhile to try to replant mangroves at Hurricane Hole to jumpstart the recovery,” Rogers said.
Rogers is also concerned about the recent influx of rafts of sargassum seaweed that have affected the Virgin Islands and the entire Caribbean.
Aside from being an unpleasant nuisance, sargassum can destroy shallow reefs. As it builds up along shorelines for weeks at a time, it can abrade the coral and block vital sunlight, Rogers said.
In spite of all the elements working against the survival of marine life since the hurricane season of 2017, environmental activists have made one change that could have a huge positive effect over time. They have worked with lawmakers to implement a set of regulations banning chemical sunscreens which have proved to be harmful to marine life.
Although Hawaii and Key West have implemented similar laws, the ban passed by the Virgin Islands Legislature in June is “the best” according to Frank Cummings of CORE. The speed of its enactment was part of the legislation’s success.
“It didn’t get a lot of the opposition from the corporations that manufacture sunscreens as some other places did,” he said.
The first part of the law – prohibiting stores from re-ordering chemical sunscreens to restock their shelves – goes into effect September 30. Locals and visitors are prohibited from possessing banned sunscreens after Jan. 1. “I’m hoping to see healthier reefs and more fish,” said Cummings.