How Does Red Tide Affect The Endangered and Threatened Sea Turtles?

How Does Red Tide Affect The Endangered and Threatened Sea Turtles?

 

For the last 110 million years the sea turtle has been part of this planet’s longest surviving species. They were here before the dinosaurs. However in recent decades they have been nearly wiped off the face of our planet by mankind, population growth, fishing and development. 

For the last 13 years I have been part of an area volunteer group that tries to helps save the endangered and threatened sea turtle population. In our local area, Sarasota and Charlotte counties, two organizations lead the conservation efforts. Mote Marine of Sarasota monitors sea turtle nesting activity from Longboat Key to Caspersen Beach in Venice. The second organization is called the Coastal Wildlife Club. I belong to the Coastal Wildlife Club. I volunteer two to three mornings a week from late April through October to monitor sea turtle nesting activity along the beaches from Caspersen to Stump Pass.
 
As you can imagine this year has been a particularly hard year for the sea turtles and volunteers due to the heavy and unrelenting red tide. It is not just the overwhelming presence of red tide and the irritation that it causes to your respiratory system. It is thousands upon thousands of dead, stinking and rotting fish, the maggots, the fleas and the sad loss of other sea life. Many dolphins, manatees and even a whale shark or among the ocean species that have lost their lives to Red Tide this summer. Plus hundreds of sea turtles have been stranded and near-death, on local beaches. A few hundred sea turtles have died from red tide. The red tide blossom stretches about 150 miles and it is may be anywhere from 10 to 20 miles wide. Of course daily the concentrations along the beach can change and the tide can shift North and South.
 
For a newborn hatchling the odds for survival are incredibly small to begin with. Scientists, marine biologists and sea turtle researchers estimate that only one out of a thousand hatchlings make it to adulthood and therefore capable of reproduction. With the current Red Tide outbreak the obvious question is; how is the red tide affecting the baby turtles?
 
The answer according to the experts, is counter-intuitive to what you might think. 
All statewide sea turtle conservation and monitoring activities are directed and licensed by the Florida Fish and Wildlife Conservation Commission (FWC).

In a  recent email  Simona A. Ceriana, Ph.D, a research scientist from the Marine Turtle Program at FWC, has given us a recent summary about the effects of Red Tide on sea turtle hatchlings.
 
“… many of you may wonder whether hatchlings are being impacted by the current Red Tide event. FWC has never documented any apparent adverse effects of red tide on hatchling sea turtles. They are probably not affected because they quickly move offshore, then live at the surface of oceanic areas for at least several years. They likely do not spend much time in any areas with high concentrations of Karenia brevis (red tide) they encounter because they are constantly moving or being moved. Additionally, the primary route of lethal exposure to brevetoxin for sea turtles is through ingestion of food containing brevetoxin. Hatchling sea turtles subsist on internalized yoke for at least a week or so before they begin feeding. By the time they begin feeding, they are well away from nearshore areas where red tide blooms often persist. Hatchlings could be exposed to brevetoxin in aerosols and may experience some irritation to the respiratory tract but, at present, we do not have any indication that this causes mortality or noticeably effects behavior (i. e., no reported  unusual number of live or dead wash backs). We will continue to monitor the situation and provide guidance as needed.”
 
Well that is welcome news at least for the baby turtles, but what about the adults especially those of reproductive age? 
Loggerhead sea turtles which make up about 99% of the nests in our area, generally nest multiple times in a single nesting season. Then, most skip a year or more before their next nesting season. Many sea turtles migrate huge distances from their foraging areas to the nesting beaches. Mature females will return to the beach that they were born to lay their eggs.

In another recent email to our volunteer group in mid August, Allen Foley, the stranding coordinator with FWC gave us the following information about live stranded and dead washed up sea turtles.
” Indications are that nesting females either do not forage during the inter-nesting interval and during their reproductive migrations or forage very little. At least when they are reproductively active. Females and males are probably not at much risk of accumulating a worrisome amount of brevetoxin since ingestion of brevetoxin in food is how they get lethal exposure. As far as we know none of the current strandings attributed to Red Tide were nesting females but there are adult loggerheads among the strandings.”
“… both adult male and female loggerheads are killed by Red Tides but we haven’t discovered a gravid female among those dead. It is more difficult to determine if an adult male is reproductively active so we may have missed some. Yes, we don’t think the reproductive active males likely forage much during these times either. Males would be reproductively active from around March through the end of June. Many appear to be active every year but some appear to be active only every other year.”
So far this year (mid August), we’ve attributed 266 stranded turtles to red tide. In 2006, we attributed 345 stranded sea turtles to red tide. In 2005, we attributed 223 stranded sea turtles to red tide. In 2003 we attributed 230 stranded sea turtles to red tide.
So the current event isn’t the largest yet for stranded sea turtles and it isn’t too different, yet, from several other recent major red tide events. The current event is a major one for sea turtles but it has a way to go before to equal what we saw in 2006 but it still has  quite a way to go to equal what we saw in 2005 and 2006 combined.” (since the 2005-2006 was a single, two year long event)
 
So for now according to the experts, the current red tide event that we are experiencing every day, has not drastically harmed the sea turtles compared to previous red tide events.  However, if this current red tide event stretches into next year, similar to the red tide of it in 2005 to 2006, the nesting sea turtle nesting activity could be significantly diminished and negatively affected. Hopefully though with all the media attention and our polarized political environment more research, more funds and more science will help us understand red tide and discover ways to effectively deal with it.
 
If you would like to see an amazing sea turtle educational video from the BBC, click the link below. The program focuses on the nesting activity on a beach area in Costa Rica.

The link will start about halfway into the program, about 47 minutes. It shows the world maybe for the first time ever the inside of a turtle nest while in it’s incubation period and eventual hatching. It is truly informative and surprising. The entire program is fascinating if you want to watch the whole program.

Thanks.

Dan Heschmeyer

https://www.youtube.com/watch?v=-mKvuGi8RTA&index=15&t=2873s&list=PLoVPHYX4QFnxF2paSl93MPagDNKK3vcGI

2018-08-30T00:30:13+00:00 August 30th, 2018|Community|0 Comments

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