Coral reef health: then and now

By Don Stark, Chairman, Turks & Caicos Reef Fund

During the summer of 2001, we spent three months living on Providenciales and diving nearly every weekend. During nearly all those dives, we shot video of the dive sites. We have had the opportunity to dive most of those sites again in recent years, again with the video camera, so we thought it would be interesting to compare and contrast what we saw in 2001 with what we see in more current times. (Be sure to click on the links to view highlight videos of each site.)

This is not a rigorous scientific study, but an observational study with the goal of proposing some hypotheses about the health of the reefs around Providenciales, West Caicos and Pine Cay compared to their status ten or more years ago. We did not use formal transects to measure precise changes in coral coverage or any other strict scientific methods in the research done for this article. Our observations are simply that — observations of what appear to be the differences between selected dive sites in 2001 compared to dives on those same sites within the last two years.
We chose to focus this analysis on five distinct dive sites located around the islands of Providenciales, Pine Cay and West Caicos. These areas represent locations within the TCI that have faced various potential stresses to the marine environment. The sites around Providenciales, for example, are both located on the north side of the island, an area that potentially has been affected by a great deal of development since 2001 and also the potential adverse effects of Leeward Going Through dredging in the 2007–2008 time frame. The sites around West Caicos have faced little manmade stresses, other than the dredging of the marina there and the Molasses Reef development, which is mostly located far away from the dive sites in the marine park. The site off the coast of Pine Cay has also faced little manmade stress, other than potential impacts from Leeward Going Through dredging, but the prevailing currents probably minimized the impact from that activity. The only other potential manmade stresses in that area are the developments on Dellis Cay and around the Pine Cay area.
Since about 2006, all sites have also faced a new threat from an explosive growth in the population of lionfish, an invasive species with a voracious and non-discrimatory appetite for many fish and non-fish marine species.
The five dive sites upon which we have focused for this article are Boneyard (off shore from Thompson Cove area on Provo), Pinnacles (off shore from Grace Bay area on Provo), Football Field (off shore from Pine Cay), Driveway and Gully (both off the coast of West Caicos).

The Driveway
(West Caicos, 21º 39.540′ N, 072º 28.240′ W)
The Driveway is a site that is characterized by coral running along the top edge of the drop-off and down the side of the vertical wall. There is a large sand chute that gives the site its name.
In 2001, coral coverage on the top of the wall was about 20–30% of the surface area. There was little encrusting fan leaf algae (a brown algae) and large schools of blue chromis, masked gobies (very small schooling fish) and creole wrasses. Many parrotfish were also noted during the dive in 2001.
In April 2013, the coral coverage observed (http://www.youtube.com/watch?v=XFgk6hznIGc) was quite similar to that seen in the 2001 video. The fish species seen were also similar, although fewer parrotfish were noted. Since parrotfish are herbivores and responsible for keeping algae growth under control on the reefs, their smaller numbers may explain why we saw an increase in the encrusting fan leaf algae. Lionfish are common on this site, and this could account for the decrease in the parrotfish numbers (a large part of the lionfish diet), as well as decreases in other smaller, easy target fish, such as blue chromis and masked gobies.

The Gully
(West Caicos, 21º 40.617’ N, 072º 28.180’ W)
The Gully shares a topography similar to that of the Driveway. Coral covers the top of the wall, but only extends a short distance toward shore.
Coral coverage on the top of the wall is again about 20–30% of the surface area. In 2001, we observed lots of masked gobies, large schools of snapper and small cleaning gobies on many coral heads. Fish in general, including parrotfish, were abundant on the site. A large school of horse-eyed jacks were usually found here.
We revisited the site in April 2013 and observed similar changes as were observed on the Driveway dive site (http://www.youtube.com/watch?v=IAi4KuLQxr8). Fewer fish of all types were noted, including parrotfish, and an increase in the presence of encrusting fan leaf algae.

Football Field
(Pine Cay, 21º 54.384 N, 072º 06.870′ W)
Football Field is a large, rectangular-shaped sand patch surrounded on three sides by a rising wall of coral. The sand patch is at a depth of approximately 80 feet and the coral rises to within about 45 feet of the surface.
In 2001, the site featured many large growths of staghorn coral, a type of coral that is nearly extinct throughout the tropical waters of the Caribbean and Atlantic. Coral coverage was about 20–40% of the surface area and there were large schools of horse-eyed jacks and creole wrasses. Cleaning gobies (small fish that live on coral heads and sponges that remove parasites and dead flesh from other larger fish) were common and there was very little of the encrusting fan leaf algae.
In the summer of 2011 when we dove this site again (http://www.youtube.com/watch?v=bhbtjTW8FWQ), we noted that much of the staghorn coral was becoming covered with encrusting sponges, which get their start on dead or damaged sections of the coral and then spread at a rate of up to one cm per month, gradually killing off the healthy coral. There appeared to be less healthy staghorn coral, often considered an early indicator species of the health of a coral reef. Coral coverage, otherwise, appeared to be similar in the later time period compared to the earlier, but there appeared to be more of the encrusting fan leaf algae. Fish species appeared to be similar, but the numbers were fewer. No sign of the usual large school of horse-eyed jacks was observed in 2011.

Pinnacles
(Grace Bay, 21º 48.840′ N, 072º 11.210′ W)
Pinnacles is a typical Grace Bay area dive site. It has numerous sand chutes through which the tidal waters entering and exiting Grace Bay flow. The top of the drop- off is about 25–30 feet and the wall drops down vertically to about 110 feet before leveling out onto a large sand plain.
In 2001, coral coverage on the top of the wall was about 20% of the surface area and very little encrusting fan leaf algae was observed. This site had large growths of black coral on the deepest part of the wall and many large sea fans, sea plumes and gorgonians both on the wall and at the top of the wall.
When we visited this site again in the summer of 2011 (http://www.youtube.com/watch?v=_8tAnJVf-OU), we noticed that coral coverage on the top of the wall had decreased to about 10–15% of the surface area and there were few soft corals (sea plumes, fans and gorgonians). Two types of algae were also seen in many more places — the encrusting fan leaf algae and red fuzzball algae. On the bright side, new growths of staghorn coral were seen which were not observed in 2001. Since staghorn is thought to be an early indicator species of the health of a coral reef, this suggests that whatever has caused damage and degradation of the Grace Bay reef system between 2001 and 2011 may not be ongoing and the reef may be regaining its health.

Boneyard (Thompson Cove,
21º 48.368′ N, 072º 12.109′ W)
The underwater topography of the north side of Provo changes as one moves toward the west. The shallow reef top and vertical wall dropping to about 110 feet morphs into a much deeper reef top (about 50 feet) and a sloping wall that drops down to about 180 feet before leveling off onto a sandy plain.
In 2001, this site was the home for large numbers of small fish, such as blue chromis, blennies and gobies. Large schools of grunts and snapper were observed, as were numerous parrotfish and wrasse adults and juveniles. Coral coverage on the wall was about 20% of the surface area and encrusting fan leaf algae was common, but not overwhelming the reef (covering 10–20% of surface area). Soft corals were also abundant and healthy.
When we visited the site in the summer of 2011 (http://www.youtube.com/watch?v=Eq5HVR0MFCU), we observed less coral coverage (less than 20% of the surface area), potentially fewer soft corals and a definite decrease in the numbers and variety of fish, especially smaller fishes, such as blennies, cleaner gobies, wrasses and juvenile parrotfish. In addition, no grunts or snappers were observed, where in the past, large schools were seen on this site. Encrusting fan leaf algae now covers 30–40% of the surface area at the top of the reef and red fuzzball algae was also present. There were also potential signs of coral disease — one brain coral exhibited potential signs of dark spot disease.

Conclusions
While the percentage of coral coverage does not appear to have changed dramatically in the past 10–12 years on the reefs frequently visited by Provo-based dive operators, the number of fish on the reefs appears to have declined. Also, smaller fish, such as blennies, wrasses and gobies seem to be fewer in number and species variety. These species could be especially vulnerable to predation by the invasive lionfish that first appeared in these waters approximately seven years ago. Loss of these smaller fish and other marine animals can have a long-term adverse impact on the health of a reef system, as they are common cleaner fish that help maintain the health of other fish species. The decline in fish numbers could be attributable to general over-fishing that has been noted by declining commercial fisher catches over the past few years.
In areas where there has been substantial development activity since 2001 — Grace Bay and Thompson Cove areas — algae growth seems to have increased in surface area coverage. There are a number of factors that could be causing this effect. One potential cause could be a declining parrotfish population as a consequence of overfishing or the lionfish invasion (parrotfish juveniles are a common prey of lionfish) or both. Parrotfish are one of the primary fish species that help control algae growth on coral reefs. Another explanation is that increased development has led to increased nutrients in the waters off Provo’s north coast. The increased nutrients could be generated by overuse or poorly controlled use of fertilizers on landscaping, waste runoff from poorly designed septic systems or both. A third potential contributing factor is increased stress on these reefs caused by either natural events (climate change) or human-caused events (e.g. dredging in Leeward Going Through area in 2007–8).
As the coral reefs around the Turks & Caicos Islands are the lifeblood of the economy of these islands, proper monitoring of the health of the reef systems throughout the TCI is critical to early identification of potential problems and their causes. Without proper monitoring of TCI’s reefs, we could quickly lose the asset that attracts most visitors — clear, blue waters and a healthy marine environment. The TCIG Department of Environment and Maritime Affairs is proposing to establish a monitoring program and we strongly encourage this program to be put into place as quickly as possible.