The Buccoo Reef Crisis: Facts and Fiction
*Aldo Leopold (1887-1948) one of the pioneers of wildlife conservation in the USA, described "system" health before the word "ecosystem" was coined, but his definition and wisdom still apply: "Health refers to the capacity for self-renewal" and "conservation is the effort to understand and promote the capacity for self-renewal." As scientists, it is our role to understand the conditions necessary for self-renewal; and the role of managers/ stewards is to use science to create conditions that promote self-renewal.
To the statement that "Buccoo is predominantly dead", I would argue that Buccoo is far from dead, but it is in trouble if things continue as they are.
"Coral reef death" is a misnomer. Coral reefs are ecosystems, and unlike living organisms cannot die. They can cease to support optimal conditions for coral growth resulting in reduced coral cover (we want reefs with high coral cover), and in some instances can shift to an alternate or undesirable state. There is no doubt in the minds of most, that coral reefs are valuable to Tobago: a source of food, livelihood, recreation, biodiversity, shoreline protection and national identity. But subtle shifts are happening, resulting in less coral cover, facilitating less desirable alternate states such as soft coral dominated hard bottoms (called gorgonian plains) or macroalgal dominated plains. It is this algae dominated state that is often referred to as a dead reef.
An ecosystem responds to biological, chemical, geological, and physical conditions along a continuum; it changes. An organism also responds as it is exposed to different conditions, but exposure to too much or too little outside the range of adaptation (e.g., higher seawater temperatures, toxicants, substrate collapse, loss of food resources) can lead to its death, and it will no longer exist. There are parts of Buccoo where the combination of dead corals and algae dominance, have lead some to say that the reef is "predominantly dead”: in fact, it continues to exist, just not in the same stable state we recognized. This is an issue challenging reefs throughout the Caribbean.
Scientific semantics aside (but these distinctions are important if the message is to mean anything), Buccoo is far from dead. Data from as far back as the 1980s show that coral cover in the Buccoo Reef (coral cover is used as an indicator of reef condition and the effectiveness of management), is on a downward trajectory, due to impacts associated with growing populations, development of tourism markets, non-compatible activities within the coastal zone and ocean warming.
The data show that Buccoo Reef complex is relatively one of the most resilient reef systems in southwest Tobago, where self-renewal is demonstrated in spite of impacts from multiple mass coral bleaching events, disease outbreaks, frequent physical damages and a regime of declining poor water quality. Strong grazing by herbivores such as parrotfish help regulate algal growth (an indicator of poor reef condition); and ample substrate for coral recruitment and good recruitment all help to improve the resilience of the ecosystem. Additionally, the connectivity of the reefs to the nearby seagrass and mangrove areas helps to maintain the life cycle of the organisms present. The Buccoo Reef Marine Park (a no fishing zone) has encouraged the proliferation of a rich diversity of fish and other invertebrates, especially when compared to what exists outside the park.
Here we use “resilience” to mean the capacity of an ecosystem to absorb recurrent disturbances or shocks and adapt to change while retaining essentially the same function and structure (Holling 1973). Ultimately, major changes in how we interact with the marine environment are needed if we are to continue to benefit from coral reef ecosystems as we do today. There are a number of ecosystem indicators (~60) to measure reef condition as it changes with time and space, but practically 10-15 are used; some of the major indicators being biodiversity, herbivory, recruitment and productivity.
THE BUCCOO REEF THAT WE SEE
Most of us view the Buccoo Reef through the lens of a glass bottom boat tour. These tours are conducted along the areas referred to as the reef flat (the landward side of the reef). These areas are dominated by monospecific (one species) stands of corals with relatively low coral diversity. Fish diversity is rich, dominated by several species of small bodied fish (usually juvenile life stages and adults of smaller fish) including parrot fish, grunts and snappers, as well as elusive apex predators such as sharks and groupers, and other charismatic species such as turtles, rays and octopi. These heavily trafficked areas are highly disturbed (due to years of physical damage from storm surges and human disturbances and sedimentation), and support fewer fish. It’s easy to perceive these areas as impoverished. But they are not dead.
There is a wide continuum of ecosystem conditions that exist in Buccoo, from rich underwater aquariums to impoverished zombie-like reefs. The question is which end of the continuum would we like future generations to enjoy.
|Backreefs at Buccoo are thriving. Photo courtesy Jahson Alemu|
Certainly, the Buccoo Reef Complex is a shadow of what it used to be, as evidenced by over 30 years of scientific research, and by the oral history of the area, related through stories shared by local fishermen, divers, some of the first glass bottom boat operators and general recreationists (all before my time). Unfortunately, the uptake of science into management has been slow and an ecosystem approach to management remains elusive. Diving in Buccoo, you can see the relics of what it used to be. Large fallen treelike corals (Elkhorn corals) which once dominated Buccoo, now lie broken and dead on the seafloor, providing the bedrock on which the current Buccoo Reef has developed: an altered state, but still acceptable. A new regime of conditions (a combination of conditions necessary for reef growth and stressors limiting growth) has re-shaped our current reef ecosystems. It is very likely if these stressors continue to intensify and synergise, there will be another change in Buccoo Reef to an alternate state, one which provides fewer goods and services.
The Buccoo Reef is a dynamic system. It is constantly changing. It will not remain a treasured part of Tobago’s heritage without appropriate management. The Buccoo Reef Marine Park is an effort to protect the legacy of an iconic part of Tobago’s identity, but, like our Australian counterparts at the Great Barrier Reef, much of the effort to protect and conserve the Buccoo Reef, must deal with managing activities outside the park.
Leopold, Aldo. "A Sand County Almanac. 1949." New York: Ballantine (1970).
Holling, Crawford S. "Resilience and stability of ecological systems." Annual review of ecology and systematics 4, no. 1 (1973): 1-23.