By Nancy Richie
As the Gulf of Mexico water temperatures climb to 78 to 80 degrees Fahrenheit, the protected Loggerhead sea turtles (Caretta caretta) will soon return to the Marco Island beaches. Living year round in the open and near shore waters to feed and rest, the adult female sea turtles will begin nesting on our beaches between May and August. Sixty days after the nests are laid, the hatchlings will emerge and begin the trek to the Gulf of Mexico usually between July and October. So, the next six months – May 01 through October 31 – is a crucial time of year for this threatened marine sea turtle population on the Marco Island beaches.
Only adult female sea turtles emerge from the ocean, and only to dig their nests and to lay eggs. Male sea turtles spend their entire life in the ocean; resting along reefs or on the water surface in the sun. Taking approximately 15 years to reach maturity to reproduce, the female will mate with several males to ensure genetic diversity within the population. Once the water temperature reaches 80°, typically in early May in southwest Florida, she will leave the Gulf and crawl up the beach looking for a high and dry area of the sand, preferably at the dune line, to lay her eggs. Once a location is found, she will turn and face the Gulf and using her two hind flippers to dig an approximately 20 inch in depth nest chamber and lay between 90 to 120 eggs. When the eggs are deposited, she will bury them in the nest chamber, then turn and throw sand with her front flippers in an attempt to camouflage the nest site. (Her tracks to and from the Gulf and body imprint created by the turning and sand throwing, are the tell-tale signs for sea turtle monitors to track and mark newly made nests.) Then the female turtle will crawl back to the Gulf, never to return to her nest. An adult female sea turtle typically only lays eggs once every three years but in the nesting year can lay up to seven nests in one season.
The newly laid eggs take approximately sixty days to incubate in the nest chamber; longer if the sand is cooled by rain storms or sooner if the summer is dry and sand temperature is warm. The hatchling’s sex is determined by temperature variances in the nest chamber during incubation – a hatchling will be female if sand temperatures are warmer and male if sand temperatures are cooler. This temperature-dependent sex determination does skew the population numbers. If a nest is in the shade, cooler temperatures may produce more males and vice versa. (This is also a reason sea turtle species populations are a good indicator for global warming impacts. Studies have shown that it is a real possibility that as ocean temperatures rise, fewer to perhaps no males will be produced.) Once incubated and ready to hatch, it takes about three days for all the eggs in one nest to hatch. The 90 to 120 hatchlings will work together to explode (emerge) from the nest and make their way down the beach collectively to the Gulf of Mexico. The smell and sound of the ocean plus the reflective light from the moon and stars on the water’s surface guides the hatchlings to the Gulf.
Another issue on the beach is the area south of the Tigertail Lagoon to Residents’ Beach. This area is extremely wide thus creating a topography and drainage issue that creates standing water that stagnates, resulting in odor and health concerns and also creates poor conditions for successful sea turtle and shorebird nesting. Groundwater levels are monitored with gauges in this stretch of beach. If water levels are too high, nests are moved so success rates of hatching can occur. If eggs are left in saturated sand or water, they will “drown” and not survive. To improve the condition of the beach and have long term sustainability of the healthy condition, laser grading this area to a positive slope (10:1 ratio) to the Gulf of Mexico will improve water drainage and alleviate the standing water issue, thus remedying the odor and health concerns on this popular recreational beach and important sea turtle and shorebird habitat. Laser grading is done by tractor and grading equipment using a laser to program the exact slope necessary for a healthy beach. A grant application has been submitted by the City to the Collier County Coastal Advisory Committee for approval of Tourist Development Council funds to laser grade. Doing the project outside of sea turtle nesting season, a Florida Department of Environmental Protection (FDEP) field permit will be the necessary permit required.
In the 2010 nesting season, there were 46 nests on Marco Island beaches with 39 of these hatching producing approximately 2995 hatchlings. With only one out of one thousand hatchlings making it to maturity, every hatchling counts to sustain this species’ population. Artificial lights confuse sea turtles and interfere with their natural instincts. Too often this results in discouraging the females from nesting – she emerges from the Gulf ready to lay her eggs, but is confused or disorientated which results in her crawling back to the Gulf without nesting or dropping her eggs as she leaves - a “false crawl”. Last season, our beach had 90 “false crawls”. Artificial lights also can cause the death of hatchlings due to disorientation – they will travel inland toward the brighter, artificial lights, using the energy they need to swim into the Gulf of Mexico. Last season there were 3 instances of disorientation which caused 236 hatchling mortalities.
Overall, lighting compliance was good last year on the Marco Island beaches! The beachfront properties’ efforts to shade and turn off lighting visible from the beach was important, especially with last summer’s BP oil spill impacts in the Gulf waters. Many Loggerhead sea turtles died due to the oil spill. The spill continues to have negative impacts to the Loggerhead and other species of sea turtles which make all conservation efforts more important for the dwindling population of nesting Loggerhead sea turtles in the Marco Island and surrounding waters.
The beachfront properties once again will be asked to take this special opportunity and the responsibility to ensure protection of these imperiled marine animals, both adults and hatchlings, in our own backyard by shading and turning off lights visible to the beach each night by 9 PM from May 01 to October 31. General “urban glow” – the collective light from a populated area, was the cause of the three disorientations. As our communities, Isles of Capri, Naples and beyond develop, the light that goes along with this development causes the night sky to be lit up, especially on cloudy nights, drawing the newly hatched sea turtles toward the land not the Gulf. So, not only beachfront properties need to be cognizant of lights at night. If you don’t need a light on, please turn it off – save electricity, money and a sea turtle.
Sea turtles and people can easily coexist if actions to preserve and share the common habitat – Marco Island’s beautiful beach! In the effort to support the Collier County Sea Turtle Monitoring Program and to help prevent disorientation from occurring and protect the sea turtles, the City of Marco Island does monitor and ensure compliance with the following ordinances: Ordinance 01-35 (Sea Turtle Protection), Ordinance 99-7 (Lighting Regulations), and Ordinance 98-12 (Beach Ordinance). General lighting requirements for sea turtle nesting and hatching season are the following:
Any lights visible to the beach after 9 PM should be turned off, shielded, or otherwise modified between the dates of May 01 through October 31.
Outside lights that can not be turned off for safety reasons can be temporarily shielded with foil, hoods or painted with black heat resistant oven paint on the beach-facing side.
Low wattage yellow lights (preferably low pressure sodium vapor lights) are less attractive to sea turtles and good replacements for white lights.
Closed blinds and curtains can shield bright interior lights that normally shine onto the beach.
Outside wall and ceiling balcony lights should be off by 9 PM.
To ensure compliance, property managers, beach vendors, and/or residents, please step out on the beach at 9 PM, view the building or vendor area to determine what lights need shading or turned off. If you can see the direct light or your shadow on the beach, the light is too bright!
The sea turtles need a beach free of any barriers that would prevent nesting. Beach furniture, toys, tents, any other equipment and all garbage should be removed from the beach EVERY night.
If you witness a turtle crawling out of the ocean or digging a nest, remain quiet and at a distance and never stop a turtle that is returning to the water. Movements and noises can easily frighten a female sea turtle and prevent nesting.
No flashlights, flash photography or cell phone lights should be used on the beach and lights should never be pointed at sea turtles or light a nest.
To report dead or injured sea turtles or disoriented hatchlings, please immediately call Florida Fish & Wildlife Conservation Commission (FWC) at 1-888-404-3922 (FWCC) and the Marco Island Sea Turtle Monitor, Mary Nelson: Mobile # 239-289-9736.
If you need additional information or have any questions and/or comments, please contact the City of Marco Island at 239-389-5003 (office), 239-825-0579 (mobile) or nrichie@cityofmar
coisland.com. Nancy Richie is a long time Island resident and Marine Biologist.