Why Pigeon Point sand is so white

  Anjani Ganase, Trinbagonian marine biologist, continues her exploration of marine Tobago. In this issue, she considers the sand on the beaches. This feature was first published in Tobago Newsday on Thursday September 1, 2016.
Follow Anjani Ganase on twitter: @AnjGanase

For me there is nothing more comforting than digging my toes into soft warm sand, taking in the soothing sounds of gentle waves breaking and an unobstructed view of the ocean. The beach for me is a place of relaxation and serenity. For others, the beach is a place for adventure and exploration: a big swell signals great surfing, strong winds call for kites and even sailing. At the beach, nearby reefs or rocky outcrops can be explored by snorkelers and divers. The beach is always an ideal spontaneous location for a lime, gathering of families to socialise, play sports or be lazy together. Going to the beach must be the single favourite pastime for islanders. 

Sandy Point beach with coral rubble, © Ganase photo

The winds and waves are the natural sculptors of our perfect beach. A beach is an extremely dynamic environment constantly evolving from the forces of air and water. Here in Tobago our most popular beaches for sun bathing and leisure swimming - Store Bay, Englishman’s Bay, Castara - are all found along the part of the island facing northwest. They sit within naturally curved bays that provide shelter. The gentle winds and the eddying currents within the bay allow fine sand to be deposited and accumulated rather than being washed away. On the other hand, beaches that are exposed to stronger seasonal winds and water, such as those beaches found on the Atlantic side of the island, may be more suitable for surfing or exploring among rocks. Strong waves push the sand shoreward and in these higher wave environments, the smaller grains of sand tend to be taken offshore in the back wash as they remain suspended in the water column, so what is left on the beaches are coarser sand, pebbles and rocks. The wind adds to this effect; after the sand is deposited on the beach by the waves, the wind determines how far the finer grains may be blown inland – creating sand dunes behind the beach or a very dusty porch.

The sand that makes up the beach also speaks of the natural environment. Here in Tobago most of the sand is terrigenous in nature, meaning that it comes from eroded rock from land; this gives most beaches a tanned look. However, if you look carefully, you may find some exceptions – the dark green sand of Hope Beach, the black sand of Grafton and the dark grey sand of Black Rock. These sands were collected and used by Peter Mannette, who used ocean views as inspiration and beach sand as the tools in creating scenic sand designs. 

Sand designs by Peter Mannette. Photo by Ryan Mannette, ©Revolution Photography.

The one exception is the white sandy beach of Pigeon Point, which is unlike any other beach in Tobago. This sand comes from the sea. The white sand is provided mostly from the skeletons of a marine calcifying algae, known as Halimeda that grows within the Buccoo Reef. Water movement and wave action break down these skeletons to produce the fine sand particulates that make up this beach. Another surprising contributor of white sand comes from parrotfish which graze on the reef’s carbonate structure. Although they are scraping the reef surfaces for turf algae, in the process they wear away calcium carbonate, which is then deposited on to the reef as it passes through their digestive system. Some of the most beautiful white sand beaches in the world are the product of parrotfish poop.

Other beaches on some neighbouring Caribbean islands have become famous for their beach sand. Farther along the Venezuelan coast the islands of Aruba, Bonaire and Curacao have hallmark white sand beaches owing to being surrounded by coral reefs. Some of their beaches however, are laden with large coral rubbles making lying on the sand more of a massage therapy session. Bahamas and Bermuda are famous for their pink sand beaches, which comes from pink shells of teeny tiny creatures known as foramnifera that live in the water column.

So why do we flock to the beach every weekend or vacation? Beaches are a natural source of stress relief, exercise, exfoliation and a great opportunity to soak up some vitamin D. Floating has been thought to relieve anxiety and is being tested for treatment of post traumatic stress disorder (PTSD). Soft sand running is a solid workout, while swimming also gives full body exercise without added stress on your joints. Finally, sunlight is associated with the release of serotonin a neurotransmitter associated with wakefulness and good moods, so it is hard to be sad on a sunny beach.

Knowing your beaches means that you know what beach is safe for liming, swimming or exploring underwater. Knowing your beaches also means being aware of other creatures that you share this beach with and respecting their habitat. Avoid driving cars on the beaches: they crush the little crustaceans and other animals that live in the sand, not to mention the turtle nests. Also take back everything you brought with you. Knowing your beach means observing changes in its health by observing its ecosystem, looking at what washes up onshore, as well as the colour and clarity of the water. The presence of muddy beaches and waters may be the result of heavy rain fall but excessive amounts may come from indiscriminate land clearing and erosion nearby. On more and more beaches people dig their toes into the sand and stub them on rubbish or plastic pieces. Knowing the health of your beach is especially important when the beach is also a popular drawing card for tourism. Knowing your beach means understanding that the beach is the crucial link between the nearby land and sea habitats. Changes along the coastline influence environments downcurrent: shoreline structures such as ports and jetties greatly alter coastal water movement, and their placement must be done with careful consideration for the beaches farther down the coast that rely on the sand deposits coming from up the coastline.

Caring for the beach is the least we can do in return for all the enjoyment and fun we get from going there. Next time you plan a trip to the beach, I encourage you visit a new beach, since no two beaches are alike. Each location will provide its special and unique enjoyable experience. 

Reference: Julia Layton "Can the sun make me happy?" 21 May 2009, HowStuffWorks.com -http://science.howstuffworks.com/life/inside-the-mind/emotions/sun-happiness.htm>

C.T. Perry, C.T., Kench, P.S., O’Leary, M.J., Morgan, K.M., Januchowski-Hartle, F. (2015) Linking reef ecology to island building: Parrotfish identified as major producers of island-building sediment in the Maldives, Geology (Boulder)43, 503-506.

Goreau, T. F. (1967), Observations and recommendations concerning the preservation of the reef and its lagoon in relation to urbanisation of the neighbouring coastal islands.


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