Island hopping ... and hoping
Anjani Ganase, Trinbagonian marine biologist, continues her exploration of marine Tobago. In this issue, she considers three islands with coral reef ecosystems: Tobago, Curaçao and Heron Island. This feature was first published in the Tobago Newsday on Thursday, September 8, 2016.
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Between 2009 and 2012, I worked and lived on three islands doing research in marine ecology. Each island had very different marine, terrestrial and social landscapes. Working on these islands taught me the importance of understanding all three aspects in order to implement environmental management and protection. Let’s have a look at these different islands with coral reef ecosystems, and peek into what makes each so special.
In the summer of 2009, after graduating with a first degree in marine biology, my first job was in Tobago diving and collecting information on the juvenile turtles that lived on Tobago coral reefs. This was my first time observing coral reefs as a scientist albeit a novice in the field. Our dive sites were mostly along the Caribbean side of the island, with some surveys on the Atlantic side at Speyside. Among these sites there was considerable variation in the reef formations, community composition and overall reef health. The southeast reefs fringed some of our most popular beaches; and although these were well-developed reefs, home to a diverse fish and critter community, they also appeared to have suffered from heavy sedimentation. On the other hand, in the north east of Tobago, Atlantic currents swirled among the reefs off Speyside; which were visited frequently by schools of pelagic fish and sharks passing between the Caribbean Sea and the Atlantic Ocean on the currents.
Tobago’s coral reef ecosystem is different from other Caribbean reefs. Less than 300 km away from the Orinoco outflow, and with a mountainous main ridge and heavy rains, Tobago experiences large fresh water pulses carrying nutrients and sediment that influence the water quality and clarity of coastal waters. I remember the rapid changes in visibility from clear water to dark green water when diving on consecutive days. River runoff is not necessarily bad for coral reefs, as they do provide some nutrients to the reef communities and as a long-term natural influence, reef communities have evolved to be more sediment and nutrient tolerant. It is also likely the reason why Tobago reefs have a very high abundance and diversity of marine sponges that play a major role in the cycling of nutrients on coral reefs. However, declining water quality upstream results in excessive amount of nutrients and particulates that negatively affect the corals. Tobago as a tourist destination is also very special. It is still relatively unspoilt by large hotels, high rises and high traffic. If there is an appearance of “under-development”, it is this unhurried relaxed way of life that makes it so attractive.
In March 2011, after my first Dutch winter in Amsterdam and six months of gruelling courses for my master’s degree, I got the chance to live and do research in Curaçao. It was also the first time I dived on another Caribbean island. Curaçao lies just off the Venezuelan coastline about 800 km northwest of Trinidad. However, the geography and geology of Curaçao are very different from Tobago, with very different coral reefs. This flat, dusty island may be slightly larger the Tobago but is certainly not taller. Curaçao is composed of limestone built up by coral reefs growing over basalt rock: there’s no mountain range to trap rains and little soil build up. However, this is one reason why the waters around Curaçao are clear. Curaçao is also located much farther away from the Orinoco river mouth. These transparent warm waters are the ideal environment for coral reefs. The calm currents along the island’s lee also made diving a walk in the park. On days off, we would cruise around the island with dive gear in the car. It was easy to jump into the water and explore any reef that skirted the beach. These calm conditions and relatively healthy reefs made Curaçao the best place to study healthier Caribbean coral reef ecology. However, these reefs are not without their own threats. Overfishing of reef fish is a major problem. Coastal development, in particular waterfront hotels, poses a major risk to the fringing reefs as a result of beach in-filling. Curaçao also has a huge oil processing plant and coastal areas have been exposed to damaging oil spills in the past.
|Heron Island at sunset. Photo by Anjani Ganase|
While working in Curaçao, I got the opportunity to carry out my second master’s research project on an even smaller island, Heron Island in the southern Great Barrier Reef of Australia. The Great Barrier Reef is considered a natural wonder of the world, running north-south along the east coast of Australia. It has an area equivalent to the size of Italy and can be seen from outer space. However, Heron Island is anything but big. In February 2012, I made my way to the research station of Heron Island, a two-hour boat ride from the mainland. Unlike Tobago and Curaçao, this island has no permanent residents, with an eco resort on one part of the island and the research station on the other. It is little more than a sand cay held together by stands of trees and colonies of nesting birds. You can swim around the island in less than an hour.
I was on a non-Caribbean reef for the first time. There is no overlap in coral species between the Caribbean and Pacific regions; these ecosystems are very distinct. Caribbean reefs have just over 100 species of coral, while the Great Barrier Reef supports over four times the coral species. It was the first time I saw Nemo in the wild, the famous clown fish in his natural world. Heron Island sits along the Tropic of Capricorn so the reef is more temperate, and subject to significant seasonal water temperature variations instead of the wet and dry seasons of the southern Caribbean. Winter on Heron Island brought crisp clear waters and whales migrating to warmer waters. Sometimes we would hear them underwater. Heron Island is also a protected marine park, a sanctuary for reef sharks, rays, turtles and fish life and pristine corals undamaged by anchors or construction. Nevertheless, Heron Island’s corals are not immune to the activities of the mainland or even climate change.
ALL ISLANDS ARE CONNECTED
Although the marine ecosystem of each island is unique, the threats are the same: human development and climate change. At the same time, the management for the protection of each must be unique and driven by the activities of local communities. Reef management and protection must come from the appreciation and need of the local communities who are the ones to suffer most from their loss or benefit most from their conservation. The challenge for us all at this moment in the 21st century: as a species is to stop contributing to climate change; and individually and in communities, to help preserve these unique ecosystems, on land or in the ocean, be they rainforests, savannahs or coral reefs.