Jamaican Caving Notes

More notes for St Clair Cave: Nov 3, 2012, August 21-28, 2011, May 8, 2011, January 19-20, 2010, March 19, 2009, July 29, 2008, June 3, 2006, March 21, 2006, March 21, 2006.

St Clair Cave

Observations and Data
August 3, 2008
Prepared by R.S. Stewart - Jamaican Caves Organisation

St Clair Cave was visited on July 29-31 by R.S. Stewart, J. Pauel, and A. Haiduk, of the Jamaican Caves Organisation (JCO) in assistance to the National Environment and Planning Agency of Jamaica (NEPA). Temperature data was obtained in the Lemon Ridge Passage and in a section of the Inferno Passage. The bat emergence on the evening of July 29 was observed in the Lemon Ridge Passage and the area external of the Lemon Ridge Entrance. GPS georeferencing was carried out at the Lemon Ridge Entrance. The existing WGS84 position for the St Clair Entrance was confirmed. Rock samples were obtained from loose material on the floor of the Lemon Ridge Passage.

Position:

Temperatures and Humidity:

Lemon Ridge Passage: The temperature was 24 C +/- 1 for all stations examined.

Inferno Passage: Conditions prevented the team from obtaining data for the further section of the passage, but temperatures were judged to be generally 1-3 C higher than the measurements taken by Dr D. McFarlane in 2005, giving a range of 25-32 C from the start to the end of the passage. The increase in temperature is believed to be related to higher levels of bat guano and associated biological activity (BOD). This is addressed lower in the document.

Humidity was near 100% in the entire system.

Lemon Ridge Passage Flyway:

The investigations of January 2005 carried out by Dr D Mcfarlane, et al, did not include examination of the bat emergence in the Lemon Ridge Passage. Activities in this regard were limited to the main St Clair Entrance, and the junction of the Inferno Passage and Lemon Ridge Passage. It was assumed that because of the proximity of the main roost, in the Inferno Passage, to the St Clair Entrance, most of the bats would use the shortest route and exit/enter at St Clair. A serendipitous discovery on the evening of July 29 revealed that the Lemon Ridge Passage serves as an emergence route for approximately as many bats as the shorter route to the St Clair Entrance. Details follow:

It was the intention of the team on July 29 to push through to the Lemon Ridge Entrance, from St Clair, in order to obtain accurate GPS coordinates (there was no existing data and we didn’t know how to find it from the outside). Entry at St Clair was at 14:25 EST. Regular stops were made en route to observe bat traces (guano pellets, stained bell-holes, etc), troglobitic invertebrates, and geomorphology. The bottom of the mud-slope at Lemon Ridge was not reached until 17:00. The mud-slope ascends at 45 deg for 20m and was wet at the time. Much effort, which included two long slides to rocks below, resulted in one of the team, J. Pauel, reaching the top. It was deemed too dangerous for Stewart and Haiduk to follow, and too dangerous for Pauel to descend. A decision was made to have Pauel find his way out overland, while Stewart and Haiduk travelled back through the cave to the St Clair Entrance.

The return by Stewart and Haiduk through the cave began shortly before sunset. At first, during the swim in the Lemon Ridge canal and on the dry ground beyond, no bats were seen. Shortly after sunset, one or two bats at a time flew past, toward the Lemon Ridge Entrance. Soon after, numbers were in the dozens. During the ensuing minutes, the numbers increased to what we estimate to be in the tens of thousands, constantly flowing outward so thickly that we could not look forward, only at the floor. This continued for most of the journey back toward the Inferno junction, with numbers only easing off at the end, when much of the emergence was complete.

Pauel observed many bats in the bed of the Black River during the first part of his journey from the Lemon Ridge Entrance overland, apparently associated with the emergence that Stewart and Haiduk observed.

Deposits of individual grains of bat feces were noted throughout the entire Lemon Ridge Passage, but there were very few bats seen roosting (numbers in the tens, overall). This was confusing until the flight from the Inferno was observed, when it was realized that the guano is deposited while the bats are in flight. There is no substantial accumulation of guano due to the invasive roach, P. americana, present in most of the flyway, which consumes it.

The observations described above have great significance: It is clear that the Lemon Ridge Entrance is as important for the bat emergence as is the St Clair Entrance. The cave hosts many species of bats, and it may be that some species preferentially use the Lemon Ridge Entrance. There is good foraging potential in the Lemon Ridge Entrance area for insectivores (more so than at St Clair), and at least adequate foraging potential for frugivores. The internal route, through the passage, is safe from predators. Another factor may be that the shorter route simply becomes too crowded during the emergence if Lemon Ridge is not used. Whatever the reason for the Lemon Ridge emergence, it is clear that any conservation plans for St Clair Cave must include the eastern end of the system.

It should also be noted that Lemon Ridge is a better site for catch and release sampling, due to a more constricted entrance that offers better opportunities for setting a harp-trap.

GIS:

On July 31, the team returned overland to the Lemon Ridge Entrance using observations made by Pauel on July 29. GPS positions were obtained with accuracy of <15m. The positions were used with the existing St Clair coordinates to georeference the mapping survey done by McGrath of the Geological Survey Dept (GSD) in 1954, which was in turn used to generate shape files in JAD2001 (attached). Due to the limited number of calibration points, those being the St Clair and Lemon Ridge entrances, which are almost due east-west, the shape files are most accurate in the east-west direction, and less so north-south. However, they are sufficiently accurate to indicate broad areas where the external flora and fauna should be protected to prevent climate change in the underlying system.

The following files have been forwarded with this document:

st_clair_entrances.shp [Shape file of the two entrances in JAD2001]

st_clair_lemon_ridge.shp [The main passage, St Clair Entrance to Lemon Ridge Entrance, in JAD2001]

st_clair_inferno.shp [The Inferno, Inferno Plus, and start of the Acheron R, in JAD2001]

Bat Foraging Areas:

The required foraging area for the bat colonies at St Clair Cave extends well beyond the area near the two entrances. The St Clair Entrance end has much farming in the vicinity and an associated limit to the flora and fauna necessary to support the bats that roost in the Inferno Passage. The land external to the Lemon Ridge end of the cave is less developed, and appears to offer greater foraging opportunities, with this possibly a factor in the observed flight through the Lemon Ridge Passage. Land conservation to ensure continuing success should include a large set-aside at the eastern end of the system, as well as at the western end.

Geology:

Silica sand deposits are regular throughout the Lemon Ridge Passage, as well as non-calcareous stream pebbles. The input is undetermined, but is obviously well upstream of the limestone rock in which the cave is developed. Several samples were taken from loose material on the floor of the cave in an attempt to determine hydrological connectivity.

Geomorphology:

The geomorphology of St Clair Caves is variable, consisting of bedding-plane passages, possibly yellow limestone, in the west end of the Lemon Ridge Passage, and rifting in the Inferno and eastern Lemon Ridge Passage, with short sections of phreatic tubes in the latter, developed in massively-bedded white limestone. Echinolith is present in constricted areas of the Lemon Ridge Passage, developed as protruding shelves on the walls, which indicates that during the history of the cave there were strong flows of water in a vadose zone. There is currently no regular flow through the Lemon Ridge Passage, with water present only as pools formed by surface water percolation and direct rain input at the Lemon Ridge Entrance. Stream development now takes place in the lower section of the cave, the Acheron River.

Biological Oxygen Demand in the Inferno, Inferno Plus, and Acheron River:

JCO visits to the Inferno, Inferno Plus, and Acheron River have found poor air to a varying degree in all sections west of the Inferno–Lemon Ridge Passage junction. There are two mechanisms involved:

Inferno Passage: This is the main bat roost for St Clair Cave. The floor is pooled water in places, and simply wet in the rest. The guano deposited by the hundreds of thousands of bats present accumulates in the water and results in high bacterial activity and an associated high BOD. The O2 is reduced, the CO2 is raised, and H2S is present. The quality of the air varies, and we suspect it depends on “flushing events”. During times of high rains, such as Oct 2007, the guano is washed out and diluted, resulting in breathable air. At such times, it is possible to push beyond the Inferno to the Inferno Plus, which leads to the Acheron River, this section last accessed in November 2007. When there have been no recent flushing events, the air is so poor in the Inferno that one cannot proceed, as during our most recent visit.

Inferno Plus and Acheron River: The Acheron River, discovered by the JCO in March 2006, is at a lower level than the rest of the system and appears to flow year-round, with input from Worthy Park. The source includes sinkholes being used by the local sugar refinery to dump waste water. There is an associated high BOD that causes very poor air, which can reach lethal levels at times (the passage is only of moderate size, and has very little airflow to the rest of the system, so the gasses created by the BOD are highly concentrated). The quality of the air is directly related to the input from Worthy Park: When waste water is not being dumped, the BOD is low. When it is being dumped, especially in large amounts (so great that you can smell it in Riverhead Cave, well upstream),  the Acheron can become a death-trap (n.b. - the conditions can change very quickly). The Inferno Plus periodically suffers from poor air pushed out from the Acheron, which in turn pushes bats back into the Inferno passage causing a greater concentration in this section.

Suggestions:

Catch and release sampling of bats, to be representative, should take place at both the St Clair and Lemon Ridge entrances.

Conservation of flora and fauna should take place at both entrances, as well as over the Lemon Ridge and Inferno passages, with priority on Lemon Ridge.

Regular monitoring of the system is recommended, with visits occurring at least every six months. Spot inspections of the Inferno within one month of heavy rains or tropical storms may be of use in confirming the existence of the suspected flushing events.

St Clair Cave - McGrath Survey, 1954, plus JCO Survey of the Inferno Plus, 2006

St Clair Cave - McGrath, JCO Surveys Plotted on 1:50,000 Metric Topo