What Tobago could learn from Curaçao

Dr Anjani Ganase looks at two similar Caribbean islands, two hours apart, with very different island ecosystems; and shares what we should learn from Curaçao.

On a map, Curaçao is positioned as the mirror opposite to Tobago. Both share a vague resemblance to a cigar. Tobago is named for Tobacco. The origin of the name of Curaçao is unknown but thought to be given by the Arawaks who lived on the island. While Curaçao is 61 km long and 7 km wide, the island follows a north west to south east alignment, Tobago is shorter and fatter – 41 km long and 12 km wide – with a north east to south west alignment. It is the islands’ locations, geological histories and ecologies that make Curaçao and Tobago so distinctive with regard to their considerable natural wonders and biodiversity.

On the shoulder of South America Curaçao lies 70 km from the Venezuelan coast (north east of Trinidad) but sits off the South American continental shelf. Around Curaçao, the ocean is more than 1200 metres deep. Curaçao is therefore completely flushed by the turquoise water of the open Caribbean Sea. Tobago is farther from Venezuela, about 118 km away, and lies on the South American shelf in relatively shallow waters.

Most of Tobago is surrounded by waters less than 100 metres deep, making it geologically more connected to Venezuela. Tobago is influenced by the Caribbean Sea on the west and the Atlantic Ocean on the east. Furthermore, Tobago’s closer proximity to the Orinoco Delta enjoys the seasonal influx of nutrient-rich fresh water during the rainy season, which has a strong influence on the marine communities around Tobago. In the southern Caribbean, both islands are certainly strangers to hurricanes with some of the lowest exposures, especially compared to the northern Caribbean islands such as Bahamas, that are hit every year. The last and most devastating hurricane to hit Tobago was Flora in 1963, while Curaçao has never had a direct hit from a hurricane.

Curaçao, a flat coral island, was built up from over 145 million years of reef growth on top of volcanic rock. The island was formed from a series of tectonic shifts, reef growth and sea level shifts resulting in a low-rise coral island. The highest point of the island is Christoffel mountain just 300 metres above sea-level and overlooking most of western Curacao. Tobago, on the other hand, was a part of mainland South America and geologically the Tobago Main Ridge is the tail end of the Andes with the highest elevation at Pigeon Peak, 550 metres. Tobago had become an island largely because of sea level rise separating it from Venezuela during the last melting of the ice caps about 10,000 years ago. The unique environmental conditions, the location and geology of the two islands make a world of difference when it comes to the richness of biodiversity and ecology above and below the ocean.

Shaped by the sea

Because Curaçao emerged from the sea, everything living on Curacao migrated from the mainland and evolved over time. This means that Curacao has much lower diversity on land compared to Tobago which retained its biodiversity after its separation from South America. There are a few endemic species in Curaçao such as the white-tailed deer, three-scaled ground snake and the brown-throated parakeet. Curaçao’s landscape is semi-arid environment. The flora comprise stands dominated by thorny acacia. Giraffes from the African savannah might fit right into terrain of Curaçao nibbling on the acacia leaves. Other common sights in Curaçao include the northern crested caracara birds that frequent the roads for road kill, and iguanas that often become road kill. Curaçao is home to the endangered.

Lignum vitae or "wood of life” used in traditional medicine and very durable. Tobago, in contrast, is the classic wet tropical South American rainforest with much higher biodiversity through connectivity with the South American mainland. Tobago does have a few endemic species of its own, such as the Tobago false coral snake and the Bloody Bay poison frog.

Curaçao has no rivers; rain collects in the porous rock and drains quickly to the ocean. No rivers mean no riverbeds or riverbed ecosystems, instead salt water inlet bays provide extremely salty environment for residing flamingoes but is also where salt was harvested. Tobago’s nature is dependent on the waterways; the groundwater permits the growth of an array of fruit trees and agriculture, which was Tobago’s mainstay until the 1960s.

Curaçao is as magical below as Tobago is above the water. Such clear tropical water allows us to view some of the most beautiful reefs in the Caribbean. The reef structure with considerable coral diversity and growth supports a wealth of marine life. There are very few locations in the Caribbean left that continue to have reef communities still reflective of reefs of the 1950s and 60s. This is certainly not observed in Tobago. Curacao’s shallow reefs exposed to waves are full of branching elkhorn, fire corals and beds of finger coral, and as you go deeper there are boulder star and mountain star corals with brain corals, sea plumes and sea fans in between. Tobago’s reefs have seen considerable coral loss and, while many boulder and mountainous corals remain, many reefs have become overgrown by sea plumes and sea fans.

In the water as on the land

For both islands, it is true that the land above directly influences the marine life below. I’ve spent many years in Curaçao learning about coral reefs. Curaçao, like Tobago, is prone to run off and pollution that penetrates the porous limestone of coral rock. What I have observed is the importance of management and protection of connected ecosystems above and below the water which sustain healthy and resilient coral reefs and forests. Coral reefs around Tobago are threatened by lack of wastewater management exacerbated by large coastal development projects such as housing, hotels, shopping centres, and cruise ship infrastructure. This pattern that favours land-based development allowing destruction of the reefs has been commonplace throughout the Caribbean.

Curaçao has a research and management authority responsible for the health of marine and land based national parks. Visitors pay about US$15 to enter the parks, and park rangers are present to enforce rules and also to share the knowledge about the park’s rich ecology and natural history. Sections of the parks are protected from the highest point to the coastal and marine zones covering the full scope of ridge to reef. This is something that is yet to be fully appreciated in Tobago. We are fortunate in the preservation of the Main Ridge since 1768, but still to make the connection of healthy ridge and healthy reefs. Conservation of ridge to reef ecosystems can generate profits for the sustainability and management of the nature (on land and in the ocean) that attracts visitors and their income to the country.