An edition of: WaterAtlas.orgPresented By: Sarasota County, USF Water Institute

Water-Related News

In red tide blooms, peril for stone crabs

Mote research finds the algal blooms can make juveniles and young adults more vulnerable to predators, or even kill them

SARASOTA — Red tide toxins can threaten and possibly kill stone crabs, according to preliminary research conducted by scientists from Mote Marine Laboratory in conjunction with the Florida Fish and Wildlife Conservation Commission’s Fish and Wildlife Research Institute.

The tests were conducted on adult stone crabs with claws too small to harvest.

The study was inspired by stone crab fishermen at a state advisory panel meeting who wanted to know why their traps were relatively empty during six months of red tide.

Phil Gravinese, a postdoctoral research fellow at Mote Marine, noted that the fishermen also reported catching crabs that looked lethargic. Gravinese was first author on the research, which was published in the scientific journal “Marine Environmental Research.”

At the least, stone crabs affected by the toxic red tide algae become more vulnerable to predators, while prolonged exposure to higher levels of the kill them outright.

Gravinese noted that other research suggests that sublegal and juvenile stone crabs can’t travel far enough to escape a red tide bloom that may be several miles long, 40 feet deep and last several months.

Adult crabs are more mobile and one mark-and-recapture study conducted by other scientists found that adult crabs may be able to travel quickly enough to escape the effects of a bloom.

Gravinese characterized this study as a first step of a more lengthy research process. “The primary goal was to basically see if there is something there worth investigating,” he said.