Scientists still don’t know how they do it, but every year sea turtles around the globe are driven by innate instinct to embark on incredible migrations to mate and lay their eggs, often travelling thousands of miles back to the beaches where they were born. Enduring hunger, exhaustion, and the constant threat of predation, they are driven by an ancient imperative to ensure the survival of their species, pressing on to complete the circle of life that has persisted for millions of years.
Sea turtles are both historically and culturally significant to the Cayman Islands but global and regional overfishing by sailors and settlers in the 16th to 18th centuries brought populations of various sea turtle species to near extinction.
Department of Environment Marine Research Officer and Sea Turtle Programme Manager, Jane Hardwick (PhD Tropical Ecology) summarised the foundation of sea turtle research in Cayman. “Nesting females produce anywhere from two to eight nests per season, so nest counts do not give an exact population size of nesting turtles, but do allow for population trends to be monitored, and so far things are going in the right direction. With around 80 – 120 eggs per nest and a vague hatchling survival rate estimate of one in one thousand making it to adulthood, the recorded steady increase in nest numbers shows the impacts of long-term conservation efforts and is a welcome data point.”
Cayman’s nesting season starts with loggerhead turtles arriving in April, and green sea turtles later in June. However, as the planet continues to log record-breaking temperatures and humans continue to cause habitat loss, turtles may struggle to adapt to a changing world. “Sea turtles are losing nesting habitat to coastal development, and face future threats from warming climates and sea level rise.” Dr. Hardwick explained.
Nesting obstacles
Cayman’s beaches are internationally renowned for white sands and crystal-clear waters, however, residents and long-time visitors to Grand Cayman will have witnessed the steady decline in beach habitat. While this undoubtedly presents challenges to property owners and tourism, unfortunately this also means sea turtles are attempting to nest in areas which have buildings, seawalls, swimming pools, and beach furniture in the way. Nesting females are also rescued each year from falling into pools that are built directly in the sand, or getting trapped under decks or construction materials and other man-made obstacles.
Even worse, there are areas of nesting beach where there is simply no longer any sand left due to the construction of hard structures which have caused erosion. Exacerbating the problem is artificial lighting from landscaping, walkways, buildings and street lights which mimics the moonlight hatchling turtles instinctively follow to find their way to the sea.
Thousands of hatchling turtles are at risk of “misorientation” which occurs when artificial lighting attracts them away from the sea as they emerge from their nests.
DoE Senior Environmental Management Officer, Jerrica Campbell (MSc Sustainable Development) is focused on assessing and monitoring the impacts of development on the natural environment.
“Sea turtles are born with the energy stores needed to crawl to the sea and swim out past the reef, away from predators,” she explained. “But sea turtle hatchlings attracted to artificial lighting end up going the wrong way and unless rescued and released, they tire out and die. In the 2023 nesting season 34 nests were found to have had misorientations. In some of these nests up to 100 hatchlings never made it to the sea. In others, some were rescued and released, but by this point, their energy levels are much lower than they need to be to face their first days out at sea.”
Warming planet
One area DoE turtle scientists are focusing on, using grant funding awarded in 2023 from the UK’s Darwin Plus initiative and in collaboration with University of Exeter, is the impact warming and rising seas, increased storm activity and warmer air temperatures are having, and will have, on Cayman’s nesting turtle population. Dr Hardwick outlined the objectives of the new research. “The three year study will assess whether climate is causing a shift in the nesting seasons for loggerhead and green turtles, as it is believed sea turtles may adapt to warming temperatures by altering the start of their nesting seasons to earlier or later in the year.
Temperature during the nesting season is particularly important for sea turtles as the gender of the hatchlings is determined by the temperature at which the eggs are incubated in the sand. Ongoing research around the world is showing that warming temperatures are causing a disproportionate number of female hatchlings, creating an imbalance for mating in future decades and even risk of extinction past a certain point,” she said. While determining the sex of sea turtle hatchlings is not possible by looking at them, it is possible to infer sex ratios by using highly accurate unobtrusive miniature thermometers which are placed into the freshly laid nest and retrieved after hatching has occurred. “This nest temperature data allows predictions of the sex ratios of the hatchlings to be made. Temperatures over a certain point also impact the number of eggs that are successfully able to hatch, so monitoring this now is vital for understanding what could change in the future.” The study will use past, present and predicted future land and sea temperatures, storm surge and sea level rise data for future policy and decision making to help ensure the protection of sea turtle populations both locally and internationally in the face of climate change.
Turtle Friendly Lighting (TFL)
Despite increasing threats from climate change and habitat loss, perhaps the greatest threat to nesting sea turtles is artificial lighting from coastal development. “While a dark beach is the best for turtles, the good news is that light pollution is manageable with the right lighting,” explained Jerrica.
“Turtle friendly lighting (pictured) is a proven solution which safely and effectively lights beachside properties without endangering sea turtles. It has been in use for many years in several jurisdictions in the United States, including Florida’s coastal communities. These products have had great success in both increasing nesting activity and lowering misorientations and have already undergone decades of testing, continually reinforcing that human activity can successfully integrate with nature.”
Turtle friendly lighting is a term used to describe a suite of lighting options designed to fully and continuously meet the lighting needs of beachfront residents and guests without adversely impacting turtles. The aim of TFL is to ensure that the sandy beach and sea are not directly, indirectly, or cumulatively illuminated. When you are standing on the beach, you should not be able to see the bulb or glowing lens of a light fixture.
The 3 key principles of turtle friendly lighting include:
- Keep it Low – Use low-level lighting when possible. Mount fixtures as low to the ground as possible and direct light downwards and away from the sea and sandy beach to prevent sky glow. Use the lowest amount of light (lumens and wattage output) needed for the purpose of the lighting, such as human safety and functionality.
- Keep it Long – use long wavelength light sources (such as amber) in the appropriate lighting wavelength of 560 nanometres (nm) and above. It is important to remember that not all bulbs that appear amber to the human eye are turtle friendly, so the wavelength is crucial. Sea turtles are less sensitive to long-wavelength lights, but they are not blind to them. If the beach is illuminated, even by long-wavelength turtle friendly lights, sea turtles may still become misoriented, especially on a dark night with little to no visible moon.
- Keep it shielded – Lights should be fully shielded, meaning they are designed to direct all light downward. This prevents light from spilling upwards into the sky or horizontally onto the beach. Fully shield the light so bulbs and/or glowing lenses are not visible from the beach.
It’s important to make sure both placement and the correct type of lighting are used, so please contact the DoE for advice on your lighting design and product.
Please contact the Environmental Management Unit directly at emu.doe@gov.ky to inquire about Turtle Friendly Lighting options for your project.
Culture of sustainability
Small island nations, coastal communities, and indeed the Cayman Islands are at a crossroads as the effects of warmer temperatures, warmer and rising seas, stronger storm activity, and longer periods of drought create increasingly unpredictable weather. As global human activity continues to expand absent of regard for the natural world it is inevitable that biodiversity and the ecosystems which connect all life on Earth will begin to perish. However, if each of us were to choose instead to harness sustainability in the choices we make today, perhaps we can begin to shift the paradigm away from complacency and towards one that acknowledges, maybe even cherishes, the impossible journeys happening all around us. Reducing our carbon footprint, maintaining native vegetation, designing our properties with TFL and set back from the sea, and making time to appreciate the wonder of our planet, we can choose how to share our spaces with the incredible species around us with every decision we make.
Though we all will have to make some sacrifices it is possible for us to live and work together with nature. If we truly want to find a way, we can, and we will.
For more information, contact the DoE:
T 949-8469
E doe@gov.ky
W doe.ky/tfl