Posted 12-01-1997
On Tues. Dec. 4, I will fly to Bermuda to present testimony before a Department of Planning hearing concerning approval for construction a $60 million resort directly above Church Cave, one of the largest and most significant caves on the island. This cave is home to nine critically endangered cave species that will be adversely affected by the development and may become extinct as a result. I am requesting you to e-mail me your comments on this proposed development which I will present at the hearings. The following is an account of the current situation.
Dr. Thomas M. Iliffe
Associate Professor of Marine Biology
Texas A&M University at Galveston.
As a rather small oceanic island, no place in Bermuda is far from the sea. Due to its karst limestone topography, more than 150 caves are known from the island. Many of these inland caves extend down to sea level, such that they contain tidal, brackish water pools in their interior. Extending from these cave pools, networks of submerged passages have been explored by divers and found to contain a rich and diverse community of marine cave-limited species. More than 60 endemic species have been identified from Bermuda caves including two new orders, one new family and 14 new genera. Due to their limiting distribution, the fragile nature of the cave habitat, and serious water pollution threats, 25 of these species have been listed with The World Conservation Union (IUCN) as critically endangered. Two of the most significant caves in Bermuda, Church and Bitumen Caves, are situated beneath Ship's Hill on the grounds of the Marriott Castle Harbour Resort. A $60 million housing development proposed for this site includes plans to build 37 luxury townhouses directly on top of Church Cave and a retail center located immediately above Bitumen Cave. The original plan called for partially treated wastewater from the new development to be used for irrigating golf courses surrounding the caves. The Karst Waters Institute recently named these caves to the list of Top Ten Endangered Karst Ecosystems in the world.
The Castle Harbour Development was given planning permission in July 1995 under discretionary powers granted to the Minister of the Environment, thus bypassing normal development restrictions. This bill overrode the Bermuda Plan 1992 that states: "protection of caves shall take precedence over all other planning considerations." As a result of protests raised by a local conservation group, Save Open Spaces (SOS), Bermuda Properties, owners of the Castle Harbour Resort, were required to prepare an environmental impact statement costing $100,000. In December 1996, an independent UK body, the Institute of Environmental Assessment, reviewed the Bermuda Properties report and labeled it "unsatisfactory." Major areas of concern were lack of details about the proposed sewage plant and scientific justification for the report's conclusions. Bermuda Properties Ltd. hired international consultants Arthur D. Little for an additional $100,000 to revise the report. The Arthur D. Little report, submitted in July 1997, concluded that the proposed development would improve the environmental water quality within the cave. This assumption is based on the admission the present hotel is already contaminating the cave water with cesspit seepage and only if the proposed development is approved would they be able to correct the situation.
Church Cave, previously known as Paynter's Vale Cave, contains the largest underground lake in Bermuda with an area of 1500 m2 and maximum depth of 22.5 m. During H.M.S. Challenger's visit to Bermuda in 1873, Wyville Thomson observed that in his opinion: "Paynter's Vale cave is the prettiest of the whole. The opening is not very large. It is an arch over a great mass of debris forming a steep slope into the cave, as if part of the roof of the vault had suddenly fallen in. At the foot of the bank of debris, one can barely see in the dim light the deep, clear water lying perfectly still and reflecting the roof and margin like a mirror. We clambered down the slope, and as the eye became more accustomed to the obscurity, the lake stretched farther back. There was a crazy little punt moored to the shore, and, after lighting candles, Captain Nares rowed the Governor back into the darkness, the candles throwing a dim light for a time - while the voices became more hollow and distant - upon the surface of the water and the vault of stalactite, and finally passing back as mere specks into the silence."
"After landing the Governor on the opposite side, Captain Nares returned for me, and we rowed round the weird little lake. It was certainly very curious and beautiful; evidently a huge cavity out of which the calcareous sand had been washed or dissolved, and whose walls, still to a certain extent permeable, had been hardened and petrified by the constant percolation of water charged with carbonate of lime. From the roof innumerable stalactites, perfectly white, often several yards long and coming down to the delicacy of knitting-needles, hung in clusters; and wherever there was any continuous crack in the roof or wall, a graceful, soft-looking curtain of white stalactite fell, and often ended, much to our surprise, deep in the water. Stalagmites also rose up in pinnacles and fringes through the water, which was so exquisitely still and clear that it was something difficult to tell where the solid marble tracery ended and its reflected image began. In this cave, which is a considerable distance from the sea, there is a slight change of level with the tide, sufficient to keep the water perfectly pure."
Bitumen Cave lies just to the north of Church Cave. The entrance consists of a collapse sinkhole floored with broken glass and other debris. At the base of the sink, a small, very unstable opening over glass and metal debris descends into a large chamber with a sloping floor. This chamber contains hundreds of rusted and crumbling metal drums still containing bitumen residue. The barrels presumably date from the early days of the hotel. At the south end of the main chamber, a vertical 8 m deep pit reaches a tidal salt water pool that extends down to a depth of 25.5 m making this the deepest underwater cave in Bermuda.
The saltwater lakes in Church and Bitumen caves contain at least eleven species of endemic, cave-limited invertebrates, nine of which are on the IUCN Red List as critically endangered. The fauna includes five species of copepods, two isopods and one each of ostracod, amphipod, shrimp and polychaete. Many of these species are extremely primitive forms representing ancient lineages that have survived in the refuge provided by the caves.
Bermuda cave pools characteristically contain a thin, brackish layer overlying waters approaching typical open ocean salinities. Water temperatures are lowest at the surface and increase gradually with increasing depth. Seasonal variations, although most pronounced in the surface waters, are minor in comparison with those in open water. Depleted dissolved oxygen levels are found in the deeper waters of all cave systems. In the lightless cave environment, the absence of photosynthetic oxygen production characteristically results in depleted dissolved oxygen levels. Even low levels of organic pollution from run-off, dumping or sewage can, in such circumstances, produce anoxic conditions that may result in the extinction of entire species of cave animals. It has been calculated that a doubling of the present annual input of only 40 kg of oxidizable organic matter would produce anoxic conditions in Church Cave. Pools in Admiral's Cave, located directly beneath the Grotto Bay Hotel staff quarters, were found to be severely polluted, probably due to seepage of sewage or run-off into the cave. Thus, a development substantially smaller than that proposed at Ship's Hill has grossly polluted an underlying cave.
Considering the geological, ecological and biological significance of the caves, along with their susceptibility to damage or pollution, any development whatsoever on the Ship's Hill site would very likely lead to destruction of the cave habitat and extinction of the rare, endemic species therein. There is a high potential for collapse, especially in Bitumen Cave, because the limestone overlying the cave is particularly soft and crumbly and since all known caves in Ship's Hill were formed by collapse into larger underlying voids in the highly cavernous limestone. The entrance area of Bitumen is particularly unstable and significant collapse was noted in this section of the cave between 1981 and 1991. Bermuda cave waters have a long turnover rate with open waters and can thus accumulate pollutants. Organic matter, even in small amounts, can produce bacterial blooms that consume the limited dissolved oxygen in the cave water column. Such organic pollution results in depletion of dissolved oxygen, production of highly toxic hydrogen sulfide, precipitation of metal sulfides, extreme reduction of water clarity, and the extermination of all higher life forms. Bermuda Planning laws clearly and explicitly prohibit any developments having an adverse impact on caves. Unfortunately, the vast amounts of money behind the Castle Harbour Development apparently have clouded the minds of government officials and created a strong political momentum that will be difficult to stop.
Dr. Thomas M. Iliffe
Associate Professor
Dept. of Marine Biology
Texas A&M University at Galveston
Galveston, TX 77553-1675
(409) 740-4454 - office
(409) 740-5001 - fax
iliffet@tamug.tamu.edu - e-mail