Capt. Rick Grassett recalls the anguish when he saw a floating school of dead adult redfish during a red-tide bloom in Sarasota Bay five years ago. That was when a persistent red-tide bloom and 2,000-mile dead zone lingered off Southwest Florida.
Now, red tide is back on the satellite radar, and it has gotten the attention of beachgoers, changed the way some charter guides fish and has marine biologists studying Karenia brevis, the bacteria that causes red tide.
“It affects everything from fish down to oyster bays,” said Grassett.
Although Grassett sticks to mobile, light-tackle fishing, other charter captains are shifting their focus and moving farther from the red-tide bloom offshore, hoping the bloom doesn’t get worse.
Dr. Bruce Neill, president of the Sanibel chapter of START and a marine biologist, described the bloom, which formed off Lee County, as a cloud in the Gulf of Mexico that stretches northward into Sarasota County. The bloom is worse in some patches.
“We have measured in some places up to 7 million cells per liter (of K. brevis),” Neill said of the bloom off Lee County.
A million cells per liter is considered high.
This week, levels of K. brevis decreased throughout Sarasota County because the bloom was pushed offshore by several days of persistent northeasterly and northerly winds, said Tom Higginbotham, environmental health administrator with the Sarasota County Health Department.
The bloom remains offshore, and changing weather conditions could shift its direction, Higginbotham cautioned.
What concerns Neill, and other biologists, is the increased likelihood in the future of extended red-tide blooms worsened by nitrogen-rich runoff.
“We have had small blooms for hundreds of years,” Neill said. “What we don’t want is long, extended red-tide blooms. Those blooms that live for long periods of time are really what we believe are the result of having all these nutrients in our rivers. Those blooms are hardest on our local fish and manatee and dolphin populations.”
Cause and effect
Because agricultural fertilizer has likely contributed to the current bloom, Neill said, the region’s reliance of fertilizers to keep lawns and golf courses green is also a fuel for the growth of the bloom that local health officials say could worsen.
The basin area between Lake Okeechobee and the Gulf of Mexico is a giant drainage area for rainwater that eventually flows into the Gulf. Rainwater carries nitrogen and phosphorous used in fertilizers, which then acts as food for single-cell plankton that speeds the spread of K. brevis.
Water polluted with the elevated levels of nitrogen and phosphorous does not directly cause red tide, but through a chain of events it allows the red tide-causing bacteria to flourish. Neill said that there is a link between polluted runoff and the intensity of blooms lingering offshore.
Just weeks after water was released from a swollen Lake Okeechobee, the recent red-tide bloom formed off Southwest Florida’s coast. The runoff from Lake Okeechobee and heavy rains emptied into the Gulf at the Caloosahatchee River in Lee County.
“Where all that water came out is where the red tide started,” said Capt. Wayne Genthner, a longtime charter captain who guides trips throughout the Sarasota area.
Anytime there are extra nutrients that wash off the land and go into the Gulf of Mexico and the bay, “that is throwing gas on the fire,” Genthner said.
In addition to agricultural runoff, another culprit comes from closer to home — in the form of fertilizers used on lawns.
“A lot of nutrient rich water coming into the Gulf is coming from Lee, Sarasota and Charlotte countries, downstream of Lake Okeechobee. We don’t have to blame Lake Okeechobee,” said Neill, a biologist a the Sanibel Sea School.
Although local municipalities have enacted fertilizer ordinances and a ban on fertilizer use throughout the rainy summer months in Sarasota County, enforcing those laws can be difficult.
“It’s really hard to enforce because you have to catch them in the act,” said Laura Ammeson, environmental specialist with the county. There have been some written and verbal warnings, but only two citations have been issued — each for $100 — during the ban in Sarasota County.
The County Commission began discussions about adding restrictions to fertilizer use into the county code in 2007, during the last major red-tide bloom. The following year, commissioners adopted what was considered one of the strictest fertilizer regulations in the state at the time.
A combination of 20 code-enforcement officers and natural-resources staff patrol assigned zones and issue fines for using fertilizer from June 1 to Oct. 1, when more rain can lead to more runoff.
“Maybe these regulations work,” said Genthner.
In addition to the ordinance, Sarasota County partners with nearby counties and environmental organizations in “Be Floridian,” an educational campaign to get residents to “protect our fun” and skip fertilizer in the summer.
Howard Wells, an avid boater and former executive director of The Snook Foundation, said sometimes local residents are their own enemies when it comes to protecting the environment.
Wells, also a golfer, said that he realizes that even the golf courses he loves to play on may contribute to the red-tide blooms.
One small thing, however, Wells thinks can help is if residents use xeriscaping or low-irrigation landscaping.
“I have 146 feet of waterfront (property) and it’s xeriscaped,” Wells said. “It was built in 2003, and I haven’t used a bit of fertilizer (since).”
Impact on fishing
Genthner said he fielded a few calls last week from prospective clients.
“I’m starting to get a few people calling, people from London or Amsterdam who are booking a trip for a week,” Genthner said. “They ask how everything is going. They’re not asking directly about red tide. Just seeking information.”
The good news — in addition to lower K. brevis levels this week — is that so far mostly only small pinfish and baitfish have died. One 14-inch snook was discovered dead in southern Sarasota County last week.
Larger fish species such as snook, trout and grouper, can usually detect red tide and move away from it, Genthner said.
When fish sense the toxin, the ones that escape tend to bunch near the outer edge of the bloom.
“The fishing can actually be better right next to patches of red tide,” Grassett said.
Larger blooms, however, make it more difficult for those species to escape to toxin-free waters.
The toxins in a red-tide bloom move up the food chain. Many species of sealife, including sea turtles, are severely impacted by brevetoxin exposure, as shown in an April 2012 report in the journal “Harmful Algae.”
Genthner said he will shift his focus to light-tackle fishing in the bay, farther from the red-tide bloom offshore.
Grassett continues to monitor red-tide results released by Mote Marine Laboratory.