As red grouper and porkfish fish ignored them Saturday, a team of divers did a little stratified random transect work 53 feet down in the clear, warm water of the Gulf of Mexico.
In other words, the divers collected algae on a limestone ledge 14.8 miles southwest of Redfish Pass.
It was all part of a two-year, $700,000 study to answer questions about massive algal blooms that occasionally pile up on Lee County's beaches.
Paying for the project are Lee County, the Lee County Tourist Development Council, the West Coast Inland Navigation District and the city of Sanibel.
"This is important because we have a $2 billion tourism industry that depends on good water quality and healthy beaches," Sanibel environmental planner James Evans said. "When you have 4 or 5 feet of algae on the beach, it covers up foraging habitat for birds and discourages tourists from coming to use our beaches.
"What the study will do is give us management strategies to make sure these algal blooms don't happen in the future or, if they do, how to mitigate them."
The project is a joint effort that includes Florida Gulf Coast University, the Sanibel-Captiva Conservation Foundation, Fort Myers hydrogeologist Greg Rawl and Larry Brand of the University of Miami's Rosenstiel School of Marine and Atmospheric Sciences.
Among the project's goals are:
- Determining the source of nutrients that fuel local algal blooms.
- Developing computer models to help reduce nutrients in the water.
- Determining whether nutrients from rotting algae fuel new blooms.
"The question is should we clean algae off our beaches?" Evans said. "Typically we don't remove detritus from the beach because it's a natural component of the ecosystem. But if we leave algae, are we contributing to the problem by recycling the nutrients."
Part of the project involves collection of algae from three of Lee County's artificial reefs (GH Reef, Edison Reef and Sherman's Reef) and three natural ledges.
Diving Saturday from Capt. Guy Gudvangen's 32-foot Wellcraft the Master Plaster, FGCU research associate David Ceilley along with Susie Hassett, Kay Owen, Jennifer Brown and Marc Brennan of the Volunteer Scientific Research Team (recreational divers trained to gather scientific data) collected algae at a site informally known as Ledge 53 because it's in 53 feet of water.
To do the work, they laid out a 30-meter tape measure and dropped a 1-square-meter quadrat - a four-sided frame - at intervals along the tape; then they plucked the algae from inside the quadrat and bagged it for analysis at FGCU.
"One component of the study is to look at the artificial reefs," Ceilley said. "There is concern that algae accumulate on the reefs, so we said, 'Let's evaluate what's going on on the reefs on a seasonal basis: Are there certain times of year that algae accumulate?' We don't know yet."
Another issue is whether algae that start on artificial reefs break off and wash onshore, Ceilley said.
"Are the nuisance algae species that are washing onto the seagrass beds and beaches the same as we're seeing offshore?" he said. "My gut feeling is that the reefs are so insignificantly small that they don't provide enough algae to make a difference, so we added ledges to the study as well."
So far, project divers have documented a wide variety of red, brown and green alga species on artificial reefs and natural ledges.
"We're finding a surprising amount of diversity, and no single species appears dominant," Ceilley said. "We're finding a diversity that we don't see on the beaches."
The study is also looking at the role of sea urchins in the control of algae - algae are an important food source for sea urchins.
"Where we're seeing a lot more sea urchin, we're seeing a lot less algae," Hassett said. "The urchins are like a herd of sheep mowing the lawn."