FORT MYERS, Fla. — (AP) — Hurricane Ian not only ravaged southwest Florida on land but was destructive underwater as well. It destroyed man-made reefs and brought along a red tide, the harmful algae blooms that kill fish and birds, according to marine researchers who returned last week from a six-day cruise organized by the Florida Institute of Oceanography.
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Researchers who used the cruise to study marine life in the Gulf of Mexico following the hurricane say it left in its wake a red tide and destroyed artificial reefs from as far away as 30 miles from the coast of southwest Florida.
Photos: Hurricane Ian's devastating impact on Florida MATLACHA, FLORIDA - SEPTEMBER 30: Whitney Hall (R) embraces a friend atop the remains of his home amidst wreckage left in the wake of Hurricane Ian on the island of Matlacha on September 30, 2022 in Matlacha, Florida. The hurricane brought high winds, storm surge and rain to the area causing severe damage. (Photo by Win McNamee/Getty Images) (Win McNamee/Getty Images)
Photos: Hurricane Ian's devastating impact on Florida MATLACHA, FLORIDA - SEPTEMBER 30: Pine Island residents Wolfgang Nester (R) and his son Sebastian walk amongst the wreckage lef in the wake of Hurricane Ian on the island of Matlacha on September 30, 2022 in Matlacha, Florida. The hurricane brought high winds, storm surge and rain to the area causing severe damage. (Photo by Win McNamee/Getty Images) (Win McNamee/Getty Images)
Photos: Hurricane Ian's devastating impact on Florida MATLACHA, FLORIDA - SEPTEMBER 30: A chair sits on a flooded roadway in the wake of Hurricane Ian on September 30, 2022 in Matlacha, Florida. The hurricane brought high winds, storm surge and rain to the area causing severe damage. (Photo by Win McNamee/Getty Images) (Win McNamee/Getty Images)
Photos: Hurricane Ian's devastating impact on Florida MATLACHA, FLORIDA - SEPTEMBER 30: Wreckage left in the wake of Hurricane Ian is shown on the island of Matlacha on September 30, 2022 in Matlacha, Florida. The hurricane brought high winds, storm surge and rain to the area causing severe damage. (Photo by Win McNamee/Getty Images) (Win McNamee/Getty Images)
Photos: Hurricane Ian's devastating impact on Florida A burned vehicle from an electrical fire following Hurricane Ian in Venice, Florida, US, on Friday, Sept. 30, 2022. Two million electricity customers in Florida remained without power Friday morning, according to the tracking site poweroutage.us. Photographer: Tristan Wheelock/Bloomberg via Getty Images (Bloomberg/Bloomberg via Getty Images)
Photos: Hurricane Ian's devastating impact on Florida MATLACHA, FLORIDA - SEPTEMBER 30: Whitney Hall waves to a friend from the remains of his home while waving the American flag amidst wreckage left in the wake of Hurricane Ian on the island of Matlacha on September 30, 2022 in Matlacha, Florida. The hurricane brought high winds, storm surge and rain to the area causing severe damage. (Photo by Win McNamee/Getty Images) (Win McNamee/Getty Images)
Photos: Hurricane Ian's devastating impact on Florida FORT MYERS, FLORIDA - SEPTEMBER 30: Sue Lepisto hugs her neighbor after they saw each other when they came to visit what was left of their homes after Hurricane Ian passed through on September 30, 2022 in Fort Myers, Florida. Their homes were flooded with about 6 feet of water. The hurricane brought high winds, storm surges and rain to the area causing severe damage. (Photo by Joe Raedle/Getty Images) (Joe Raedle/Getty Images)
Photos: Hurricane Ian's devastating impact on Florida FORT MYERS, FLORIDA - SEPTEMBER 30: Brian Siebert becomes emotional as he looks at what remains of his home after Hurricane Ian passed through the area on September 30, 2022 in Fort Myers, Florida. Mr. Siebert feels like he has lost everything in the apartment because there was about 6 feet of water that inundated it. The hurricane brought high winds, storm surges and rain to the area causing severe damage. (Photo by Joe Raedle/Getty Images) (Joe Raedle/Getty Images)
Photos: Hurricane Ian's devastating impact on Florida FORT MYERS, FLORIDA - SEPTEMBER 30: Frank Bruno speaks with members of the Texas A&M Task Force 1 Search and Rescue team as they look for anyone needing help after Hurricane Ian passed through the area on September 30, 2022 in Fort Myers, Florida. Mr. Bruno said he road the storm out in his home and told the search team members that he was okay. The hurricane brought high winds, storm surges and rain to the area causing severe damage. (Photo by Joe Raedle/Getty Images) (Joe Raedle/Getty Images)
Photos: Hurricane Ian's devastating impact on Florida FORT MYERS, FLORIDA - SEPTEMBER 30: Deb McGinty walks with outstretched arms near her apartment as she said she was, "Thanking God that I'm alive" after Hurricane Ian passed through on September 30, 2022 in Fort Myers, Florida. Mrs. McGinty said she rode the storm out in her home and feels lucky to be alive. The hurricane brought high winds, storm surges and rain to the area causing severe damage. (Photo by Joe Raedle/Getty Images) (Joe Raedle/Getty Images)
Photos: Hurricane Ian's devastating impact on Florida FORT MYERS, FLORIDA - SEPTEMBER 30: Lucy Montoya hugs niece Judy Sanchez after seeing her for the first time since Hurricane Ian passed through the area on September 30, 2022 in Fort Myers, Florida. Mrs. Montoya said she road the storm out in the apartment and had to flee through a window because of flood waters in the middle of the storm to a second floor apartment. The hurricane brought high winds, storm surges and rain to the area causing severe damage. (Photo by Joe Raedle/Getty Images) (Joe Raedle/Getty Images)
Photos: Hurricane Ian's devastating impact on Florida FORT MYERS, FLORIDA - SEPTEMBER 30: Val Stuart talks on a cell phone as she sits on the bed she setup on the floor after the apartment she was staying in was flooded when Hurricane Ian passed through the area on September 30, 2022 in Fort Myers, Florida. Mrs. Stuart who evacuated from Sanibel before the storm ended up staying in the apartment and had to flee in the middle of the storm through a window because of flood waters to a second floor apartment. The hurricane brought high winds, storm surges and rain to the area causing severe damage. (Photo by Joe Raedle/Getty Images) (Joe Raedle/Getty Images)
Photos: Hurricane Ian's devastating impact on Florida FORT MYERS, FLORIDA - SEPTEMBER 30: Jordan Reidy carries his dog, Ivory, back to their second-floor apartment after fleeing when Hurricane Ian passed through the area on September 30, 2022 in Fort Myers, Florida. Mr. Reidy and his mother plan to stay at the home because they feel like they have no where else to go. The hurricane brought high winds, storm surges and rain to the area causing severe damage. (Photo by Joe Raedle/Getty Images) (Joe Raedle/Getty Images)
Photos: Hurricane Ian's devastating impact on Florida FORT MYERS, FLORIDA - SEPTEMBER 30: Omar Sanchez walks through flood waters to his apartment after Hurricane Ian passed through the area on September 30, 2022 in Fort Myers, Florida. Mr. Sanchez said he had to flee from his first floor apartment to the second floor because flood waters inundated it. The hurricane brought high winds, storm surges and rain to the area causing severe damage. (Photo by Joe Raedle/Getty Images) (Joe Raedle/Getty Images)
Photos: Hurricane Ian's devastating impact on Florida FORT MYERS, FLORIDA - SEPTEMBER 30: A member of the Texas A&M Task Force 1 Search and Rescue team looks for anyone needing help after Hurricane Ian passed through the area on September 30, 2022 in Fort Myers, Florida. The hurricane brought high winds, storm surges and rain to the area causing severe damage. (Photo by Joe Raedle/Getty Images) (Joe Raedle/Getty Images)
Photos: Hurricane Ian's devastating impact on Florida A woman walks down the stairs from her house as a creek overflows from flooding following Hurricane Ian on September 30, 2022 in Kissimmee, Florida. - Forecasters expect Hurricane Ian to cause life-threatening storm surges in the Carolinas on Friday after unleashing devastation in Florida, where it left a yet unknown number of dead in its wake. After weakening across Florida, Ian regained its Category 1 status in the Atlantic Ocean and was headed toward the Carolinas, the US National Hurricane Center said Friday. (Photo by Bryan R. Smith / AFP) (Photo by BRYAN R. SMITH/AFP via Getty Images) (BRYAN R. SMITH/AFP via Getty Images)
Photos: Hurricane Ian's devastating impact on Florida Osceloa County Sheriffs use a fanboat to rescue residents from flooding following Hurricane Ian on September 30, 2022 in Kissimmee, Florida. - Forecasters expect Hurricane Ian to cause life-threatening storm surges in the Carolinas on Friday after unleashing devastation in Florida, where it left a yet unknown number of dead in its wake. After weakening across Florida, Ian regained its Category 1 status in the Atlantic Ocean and was headed toward the Carolinas, the US National Hurricane Center said Friday. (Photo by Bryan R. Smith / AFP) (Photo by BRYAN R. SMITH/AFP via Getty Images) (BRYAN R. SMITH/AFP via Getty Images)
Photos: Hurricane Ian's devastating impact on Florida Osceloa County Sheriffs use a fanboat to rescue a 93 year-old resident from flooding following Hurricane Ian on September 30, 2022 in Kissimmee, Florida. - Forecasters expect Hurricane Ian to cause life-threatening storm surges in the Carolinas on Friday after unleashing devastation in Florida, where it left a yet unknown number of dead in its wake. After weakening across Florida, Ian regained its Category 1 status in the Atlantic Ocean and was headed toward the Carolinas, the US National Hurricane Center said Friday. (Photo by Bryan R. Smith / AFP) (Photo by BRYAN R. SMITH/AFP via Getty Images) (BRYAN R. SMITH/AFP via Getty Images)
Photos: Hurricane Ian's devastating impact on Florida Osceloa County Sheriffs use a fanboat to rescue residents from flooding following Hurricane Ian on September 30, 2022 in Kissimmee, Florida. - Forecasters expect Hurricane Ian to cause life-threatening storm surges in the Carolinas on Friday after unleashing devastation in Florida, where it left a yet unknown number of dead in its wake. After weakening across Florida, Ian regained its Category 1 status in the Atlantic Ocean and was headed toward the Carolinas, the US National Hurricane Center said Friday. (Photo by Bryan R. Smith / AFP) (Photo by BRYAN R. SMITH/AFP via Getty Images) (BRYAN R. SMITH/AFP via Getty Images)
Photos: Hurricane Ian's devastating impact on Florida A man stops in front of his house as a creek overflows from flooding following Hurricane Ian on September 30, 2022 in Kissimmee, Florida. - Forecasters expect Hurricane Ian to cause life-threatening storm surges in the Carolinas on Friday after unleashing devastation in Florida, where it left a yet unknown number of dead in its wake. After weakening across Florida, Ian regained its Category 1 status in the Atlantic Ocean and was headed toward the Carolinas, the US National Hurricane Center said Friday. (Photo by Bryan R. Smith / AFP) (Photo by BRYAN R. SMITH/AFP via Getty Images) (BRYAN R. SMITH/AFP via Getty Images)
Photos: Hurricane Ian's devastating impact on Florida Osceloa County Sheriffs speaks to a resident as a creek rises from flooding following Hurricane Ian on September 30, 2022 in Kissimmee, Florida. - Forecasters expect Hurricane Ian to cause life-threatening storm surges in the Carolinas on Friday after unleashing devastation in Florida, where it left a yet unknown number of dead in its wake. After weakening across Florida, Ian regained its Category 1 status in the Atlantic Ocean and was headed toward the Carolinas, the US National Hurricane Center said Friday. (Photo by Bryan R. Smith / AFP) (Photo by BRYAN R. SMITH/AFP via Getty Images) (BRYAN R. SMITH/AFP via Getty Images)
Photos: Hurricane Ian's devastating impact on Florida PORT CHARLOTTE, FLORIDA - SEPTEMBER 30: In this aerial view, vehicles line up to purchase gasoline in the wake of Hurricane Ian on September 30, 2022 in Port Charlotte, Florida. The hurricane brought high winds, storm surges and rain to the area causing severe damage. (Photo by Win McNamee/Getty Images) (Win McNamee/Getty Images)
Photos: Hurricane Ian's devastating impact on Florida PORT CHARLOTTE, FLORIDA - SEPTEMBER 30: In this aerial view, vehicles drive through standing water left in the wake of Hurricane Ian on September 30, 2022 in Port Charlotte, Florida. The hurricane brought high winds, storm surges, and rain to the area causing severe damage. (Photo by Win McNamee/Getty Images) (Win McNamee/Getty Images)
Photos: Hurricane Ian's devastating impact on Florida A fallen sign following Hurricane Ian in Venice, Florida, US, on Thursday, Sept. 29, 2022. Ian, now a hurricane again, is threatening to carve a new path of destruction through South Carolina Friday when it roars ashore north of Charleston. Photographer: Tristan Wheelock/Bloomberg via Getty Images (Bloomberg/Bloomberg via Getty Images)
Photos: Hurricane Ian's devastating impact on Florida ORLANDO, FLORIDA, UNITED STATES - SEPTEMBER 29: Members of the Florida National Guard look for stranded residents in a flooded neighborhood in the aftermath of Hurricane Ian on September 29, 2022 in Orlando, Florida. The storm has caused widespread power outages and flash flooding in Central Florida as it crossed through the state after making landfall in the Fort Myers area as a Category 4 hurricane. (Photo by Paul Hennessy/Anadolu Agency via Getty Images) (Anadolu Agency/Anadolu Agency via Getty Images)
Photos: Hurricane Ian's devastating impact on Florida FORT MYERS, FLORIDA - SEPTEMBER 30: A wall of a condo was torn off as hurricane Ian passed through on September 30, 2022 in Fort Myers, Florida. The hurricane brought high winds, storm surge and rain to the area causing severe damage. (Photo by Joe Raedle/Getty Images) (Joe Raedle/Getty Images)
Photos: Hurricane Ian's devastating impact on Florida FORT MYERS, FLORIDA - SEPTEMBER 30: Ron Waselenchuk inspects his sailboat which was pushed ashore by hurricane Ian on September 30, 2022 in Fort Myers, Florida. The hurricane brought high winds, storm surge and rain to the area causing severe damage. (Photo by Joe Raedle/Getty Images) (Joe Raedle/Getty Images)
Photos: Hurricane Ian's devastating impact on Florida Damage to a McDonald's restaurant following Hurricane Ian in Venice, Florida, US, on Thursday, Sept. 29, 2022. Ian, now a hurricane again, is threatening to carve a new path of destruction through South Carolina Friday when it roars ashore north of Charleston. Photographer: Tristan Wheelock/Bloomberg via Getty Images (Bloomberg/Bloomberg via Getty Images)
Photos: Hurricane Ian's devastating impact on Florida ORLANDO, FLORIDA, UNITED STATES - SEPTEMBER 29: Street signs are seen in the water in a flooded street in the aftermath of Hurricane Ian on September 29, 2022 in Orlando, Florida. The storm has caused widespread power outages and flash flooding in Central Florida as it crossed through the state after making landfall in the Fort Myers area as a Category 4 hurricane. (Photo by Paul Hennessy/Anadolu Agency via Getty Images) (Anadolu Agency/Anadolu Agency via Getty Images)
Floridians begin assessing catastrophic Hurricane Ian damage In this aerial view, boats sit grounded in a woodland area and along the side of the road after being pushed by rising water from Hurricane Ian near Fort Myers Beach on September 29, 2022, in San Carlos Island, Florida. (Win McNamee/Getty Images)
Floridians begin assessing catastrophic Hurricane Ian damage In this aerial view, the Sanibel Causeway bridge collapsed in places after Hurricane Ian passed through the area on September 29, 2022, in Sanibel, Florida. (Joe Raedle/Getty Images)
Floridians begin assessing catastrophic Hurricane Ian damage In this aerial view, a neighborhood remains flooded near downtown after Hurricane Ian on September 29, 2022, in Orlando, Florida. (Gerardo Mora/Getty Images)
Floridians begin assessing catastrophic Hurricane Ian damage Boats sit atop one another in a marina near Fort Myers Beach on September 29, 2022, in San Carlos Island, Florida. (Win McNamee/Getty Images)
Floridians begin assessing catastrophic Hurricane Ian damage A man documents storm damage with his phone after Hurricane Ian on September 29, 2022, in Bonita Springs, Florida. (Sean Rayford/Getty Images)
Floridians begin assessing catastrophic Hurricane Ian damage Vehicles float in the water after Hurricane Ian on September 29, 2022, in Bonita Springs, Florida. (Sean Rayford/Getty Images)
Floridians begin assessing catastrophic Hurricane Ian damage Doc's Beach House after Hurricane Ian on September 29, 2022, in Bonita Springs, Florida. (Sean Rayford/Getty Images)
Floridians begin assessing catastrophic Hurricane Ian damage Seth Jones, left, sorts through storm damaged video games as Jason Crosser looks on at Crossers storm damaged business, 8-Bit Hall of Fame, after Hurricane Ian on September 29, 2022, in Bonita Springs, Florida. (Sean Rayford/Getty Images)
Floridians begin assessing catastrophic Hurricane Ian damage In this aerial view, a home burns after Hurricane Ian passed through the area on September 29, 2022, in Sanibel, Florida. (Joe Raedle/Getty Images)
Floridians begin assessing catastrophic Hurricane Ian damage A man looks out to the Gulf of Mexico after Hurricane Ian on September 29, 2022, in Naples, Florida. (Sean Rayford/Getty Images)
Floridians begin assessing catastrophic Hurricane Ian damage A woman walks her bike past boats blocking a road after Hurricane Ian on September 29, 2022, in Bonita Springs, Florida. (Sean Rayford/Getty Images)
Floridians begin assessing catastrophic Hurricane Ian damage In this aerial view, cars sit in floodwater near downtown after Hurricane Ian on September 29, 2022, in Orlando, Florida. (Gerardo Mora/Getty Images)
Floridians begin assessing catastrophic Hurricane Ian damage In this aerial view, the Sanibel Causeway bridge collapsed in places after Hurricane Ian passed through the area on September 29, 2022, in Sanibel, Florida. (Joe Raedle/Getty Images)
Floridians begin assessing catastrophic Hurricane Ian damage A storm damaged building after Hurricane Ian on September 29, 2022, in Bonita Springs, Florida. (Sean Rayford/Getty Images)
Floridians begin assessing catastrophic Hurricane Ian damage Meagan Hoeschler recovers a family surf board on the beach after Hurricane Ian on September 29, 2022, in Naples, Florida. (Sean Rayford/Getty Images)
Floridians begin assessing catastrophic Hurricane Ian damage Storm debris fills a street after Hurricane Ian on September 29, 2022, in Bonita Springs, Florida. (Sean Rayford/Getty Images)
Floridians begin assessing catastrophic Hurricane Ian damage A car sits in floodwater after Hurricane Ian on September 29, 2022, in Orlando, Florida. (Gerardo Mora/Getty Images)
Floridians begin assessing catastrophic Hurricane Ian damage Storm damaged vehicles after Hurricane Ian on September 29, 2022, in Bonita Springs, Florida. (Sean Rayford/Getty Images)
Floridians begin assessing catastrophic Hurricane Ian damage People walk along a sidewalk blocked by boats after Hurricane Ian on September 29, 2022, in Bonita Springs, Florida. (Sean Rayford/Getty Images)
Floridians begin assessing catastrophic Hurricane Ian damage In an aerial view, damaged buildings are seen as Hurricane Ian passed through the area on September 29, 2022, in Fort Myers Beach, Florida. (Joe Raedle/Getty Images)
Floridians begin assessing catastrophic Hurricane Ian damage In this aerial view, boats sit atop one another in a marina near Fort Myers Beach on September 29, 2022, in San Carlos Island, Florida. (Win McNamee/Getty Images)
“The one-time vibrant reefs are now underwater disaster sites themselves,” said Calli Johnson, safety dive officer for the research cruise. “Where there used to be a complete ecosystem, there are now only fish that were able to return after swimming away.”
Watch: FEMA hiring locals to help with Hurricane Ian recovery
Before the Category 4 storm made landfall a month ago, southwest Florida had a reputation for being one of the best saltwater fishing destinations in the U.S.
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Saltwater and freshwater fishing in Florida has an economic impact of around $13.8 billion, according to the Florida Fish and Wildlife Conservation Commission.
“Time will tell how this affects our greater economy, because changes in the fishing industry and tourism will come from changes in our underwater world,” Johnson said.
Read: Over $1 billion in federal funding put towards Hurricane Ian recovery
The marine researchers on the cruise found high counts of the naturally-occurring algae that cause red tide offshore Punta Gorda, Boca Grande and southwest of Sanibel Island. It will be several weeks before researchers can analyze water samples that were collected to determine the threat to sea life off the Florida coast.
The red tide outbreak also is threatening manatees off Sarasota and Charlotte counties that rely on seagrass for food, according to the Ocean Conservancy.
Read: Hurricane Ian’s damage to Florida agriculture as high as $1.8 billion
“Florida is at a crossroads, with a record number of manatees dying,” said J.P. Brooker, director of Florida conservation for the Ocean Conservancy. “We must keep this issue at the forefront, so leaders statewide will invest in solutions to improve water quality—protecting natural habitats to save our beloved manatees.”
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Through mid-October, there have been 719 manatee deaths recorded by Florida wildlife officials. There were 982 manatee deaths last year.
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