Friday, April 28, 2017

Sharing the beaches with sea turtles


Marine scientist and Technical Advisor to Save Our Sea turtles (SOS) Tobago, Dr Michelle Cazabon-Mannette, discusses how we manage events and activities mindful of other creatures with whom we share the coasts and beaches of Tobago. This feature was published in the Tobago Newsday on April 28, 2017.

Our beaches are a natural asset whose value we can’t deny. Who doesn’t enjoy a beach lime? Locals and tourists alike flock to our beaches every chance they get, for recreation and relaxation. Beachfront properties are in high demand and drive real estate prices up. Like most small islands, we experience generally high levels of coastal development, with the majority of residential, industrial and tourism activities located within our coastal zone. The coastal zone, however, is fragile and contains biodiverse ecosystems such as coral reefs, seagrass beds and mangrove swamps, which provide a range of services upon which we all rely. In addition to the pressure placed on the coast by society’s demand, the effects of global climate change, including sea level rise and increasing frequency and intensity of storms, adds to the continuous pressure on the coast. Careful management of the coastal zone is therefore necessary.


  Multiple sources of artificial light along a beachfront. Photo credit: Ryan P. Mannette
Beaches in the tropics are considered critical habitat for sea turtles. Although sea turtles spend 99% of their life at sea, they rely on warm sandy beaches for incubating their eggs to ensure successful reproduction and continuation of their species. Almost any sandy beach can serve as a suitable nesting site for sea turtles, so long as the beach is wide enough and steep enough to allow a nesting turtle to get beyond the high tide mark to lay her eggs where they will be out of reach of the sea.
Coastal development is therefore a direct threat to sea turtles, since development can reduce the availability of suitable nesting habitat through the placement of permanent structures, removal of native vegetation and improper drainage which can all wreak havoc on the natural coastline by altering natural patterns of sand movement (loss and build-up of sand). Furthermore, coastal development can lead to additional threats to sea turtles through other activities that are often associated with development. One major threat associated with development is artificial lighting, which interferes with sea turtles’ natural navigating ability, and can even result in mortality of nesting or hatching turtles and reduce reproductive success.

Sea turtle nesting happens almost exclusively under cover of darkness. When navigating on beaches at night, nesting females and hatchlings emerging from their nest, rely on natural light cues to orient themselves to the sea. On a natural beach, the brightest horizon is the sea, when compared with the dark vegetation at the back of the beach, since available light from the moon and stars is reflected off the sea surface. Artificial lights on beaches may deter turtles from nesting or result in the misdirection of nesting females and hatchlings. Misdirection manifests as both misorientation, where turtles move in the wrong direction (towards the artificial light instead of towards the ocean), and disorientation, where turtles are unable to orient in a constant direction. Hatchlings are generally more sensitive to artificial light than nesting females, and are also more vulnerable due to their small size. Turtles that are misdirected as a result of artificial lights may expend a lot of extra energy wandering around the beach, or may encounter roads, drains, walls, predators etc. Many hatchlings and some nesting females will die as a result of dehydration, falling prey to crabs, dogs, birds etc, becoming trapped or sustaining fatal injuries from falls, impalement or in some cases they are run over by cars. Some individuals will eventually make it to the sea, but only after expending so much energy that their chances of survival are much reduced. This is a major threat to sea turtles in some areas with intensively developed coastlines, such as the west coast of Barbados which was featured in BBC One’s Planet Earth II episode “Cities”.  In Tobago, we see the effect of artificial light on sea turtles at those beaches with hotels such as Turtle Beach, Grafton and Magdalena Grand.

A general rule of thumb is if a light source is visible to a person on the beach, then it is likely to be a problem for sea turtles. As discussed in last week’s column, the most effective conservation measures are those which directly address identified threats. Artificial lights can be effectively managed by taking a combination of steps such as turning off unnecessary lights, reducing number of lights and intensity/wattage, shielding and directing lights away from the beach and using long-wavelength light sources (yellow/red) instead of blue/white. Natural vegetation can be an excellent means of shielding light from the beach. Many counties and cities along Florida’s coast have adopted lighting regulations which provide guidance for artificial light management. The intention is to protect sea turtles during the nesting season by restricting the amount of light permitted through windows and doors. Locally, we have no such regulations to enforce artificial light management, but SOS Tobago continues to work directly with stakeholders such as hotels and businesses to reduce the effect of beachfront lighting on sea turtles and their nesting beaches. Most recently, SOS has conducted a lighting assessment for Rex Resorts Turtle Beach Hotel, and will work with the hotel management towards implementing the report recommendations.

Other activities at beaches can lead to disturbance of sea turtle nesting/hatching, such as events with large numbers of patrons, placement of any structures on the beach, and associated lights, noise, litter etc. The Tobago Beach Jazz to be held on April 29 and 30  (2017) at Rex Turtle Beach, raised concerns from The Division of Infrastructure, Quarries and the Environment (DIQE) of the Tobago House of Assembly, SOS Tobago, members of the public and the Environmental Management Authority (EMA), regarding the impact on sea turtles at this important nesting beach, where leatherbacks lay approximately 200-400 nests annually, accounting for about 70% of leatherback nesting activity in Courland Bay. The event organizers and hotel management consulted with SOS Tobago and agreed to a number of measures for management of the event in such a way as to avoid and reduce impacts to the nesting beach. The EMA also stepped in to ensure that stakeholders were consulted and appropriate measures are in place.

Dover Beach, Barbados at night. Photo credit: Carla Daniel
It should be noted that the event will be held at Turtle Beach Hotel, not on the beach itself and scheduled to be finished promptly at 8pm on the 29th April and 6pm on the 30th April. There will be a number of steps taken to address crowd control including signage, public announcements, and patrols by SOS, Department of Forestry and the Environmental Police. Lighting and sound will be directed away from the beach and plastic recycling collection will be instituted. DIQE have indicated that the consultative approach and actions outlined for the event would serve as an example for all other beach-related events for which issues of protecting sensitive species arise. This is a positive step towards improved management of our important sea turtle habitat, and SOS looks forward to this being implemented for future events.

We can continue to share our beaches with sea turtles, once we give careful consideration to the needs of sea turtles and make appropriate decisions about what activities should be allowed and what measures are needed to ensure the continued successful nesting and hatching of sea turtles.
Dr Michelle Cazabon-Mannette continues to advocate for conservation of sea turtle ecosystems. You can view some of her work in Tobago at this link: https://www.youtube.com/watch?v=6Xq7Bi_N76w








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