Below the sparkling, turquoise waters of Florida Bay are plants that don't always get the credit they deserve. South Florida's seagrasses filter water, absorb carbon dioxide, house small marine life and feed manatees — a primary source of food that has, giving them the endearing name of "sea cow."
"Without the seagrasses, the fish wouldn't be there, the shrimp wouldn't be there. All the other groups of animals and plants that are dependent on these foundation communities," said Florida Atlantic University coastal marine ecologist and climate change professor Marguerite Koch.
But as important as seagrass is for Florida and its ecosystem, it has some serious threats including climate change, pollution, development, dredging and boating.
READ MORE: Seagrass growth in Tampa Bay is at its highest level since 2016
Climate change is one of the biggest problems. Heat waves exacerbate seagrass decline by impacting water quality and the oxygen the plants depend on, said Koch, who has been studying seagrasses in the tropics for two decades.
During the day the plants produce oxygen through photosynthesis, but then at night, they have to get oxygen from the water. The warmer the water, the less oxygen there is in it, Koch said.
When temperatures are high, water also evaporates faster and waters — particularly in shallow coastal areas like Florida Bay and Biscayne Bay — can get too salty, Koch said. Salt water holds less oxygen than fresh water. Sea life in affected areas can suffocate as they fight for oxygen, which explains why seagrass dieoffs and fish kills often go hand-in-hand.
"As things are dying they start consuming more oxygen. It's a cascading impact," Koch said.
It can be a problem especially in shallow and sheltered areas like Florida Bay where there isn't a lot of tidal action and water sits for long periods of time, Koch said.
Then there are other problems, like climate change increasing hurricane's intensity, Koch said. When hurricanes go through shallow sea grass areas they pick up nutrients in the sentiment that get re-suspended into the water column and could cause an algae bloom that blocks light from filtering through the water. Warmer water temperatures can also stimulate algae.
"If you have low light, you don't get the photosynthesis, you don't get the oxygen into the to the roots, and you can get die off," Koch said.
The heat and nutrients can make the sea grass more prone to disease, according to the Fish and Wildlife Conservancy.
The last major die-off in the Florida Bay was after a drought period resulting in high salinity in 2015. The one before that was in the 1980 when 100,000 acres were lost. It took more than 20 years to recover from.
Steve Davis, the Everglades Foundation's chief science officer, said restoration of the natural water flow through the Glades could help build seagrass resilience for Florida Bay. Stormwater and plumping projects in the Everglades and a plan to retain water in a giant planned reservoir are ways to push more water south and lower the salinity, he said. Many previous restoration projects, including adding bridges along Tamiami Trail, are all designed to improve the flow south.
"We know more fresh water coming off the Everglades to the bay is for its benefit," Davis said.
This climate report is funded by MSC Cruises USA and the Lynn and Louis Wolfson II Family Foundation in partnership with Journalism Funding Partners. The Miami Herald retains editorial control of all content.
This story was originally published by the Miami Herald and shared in partnership with the Florida Climate Reporting Network, a multi-newsroom initiative founded by the Miami Herald, the Sun-Sentinel, The Palm Beach Post, the Orlando Sentinel, WLRN Public Media and the Tampa Bay Times.
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