ABSTRACT
Research in caves is important, not only for instrinsic academic reasons, but
also for establishing management baselines, and for providing input into
interpretative programs.
Cave biota depend on outside foodsupply. Management of cave ecosystems
must therefore include protection of surface habitats. Cave ecosystems require an
uninterrupted and unmodified transport of organic matter through air, water and
visiting fauna. Movements of facultative cave animals which are important food
suppliers, especially at natural entrances, should be free of disturbance.
An interdisciplinary approach is essential for studying caves and their biota,
and for devising any suitable conservation methods for management of natural
resources, which are unrenewable and unretrievable.
Subterranean and surface phenomena are interconnected, the cave dwelling
bats and swiftlets acting as intermediate fauna, linking the cave
microecosystems with the outside world.
Management of caves for conservation should be based on maintaining
ecological equilibria, proper technical design, permit systems, and where
necessary, on access restrictions
INTRODUCTION
SPELEOLOGY, derived from SPELAEON, meaning CAVE and LOGOS,
SCIENCE, is the science of caves and their environment. Their physical,
biological and ecological aspects have been studied in depth only in the past few
decades. Speleology comprises many discrete fields of sciences, but avoids
pigeonholing, that may hamper an interdisciplinary approach.
According to the definition of the International Union of Speleology, a cave is
a subterranean void which can be entered by man. This definition implicates, that
Speleology is a science, limiting itself only to underground spaces accessable to
investigators. This is very misleading, since caves enterable by man are only part
of a much more complicated system which exists in a matrix - in this case
limestone – consisting of innumerable cracks, fissures and crevices, forming a
labyrinth of interconnected spaces, capable of accommodating some forms of
life.
THE CAVE ENVIRONMENT
Exploring caves needs special skills, equipment and preserverance to
overcome a multitude of physical obstacles, in often hazardous surroundings, in
complete darkness - their foremost and distinctive property. Extremely limited
food supply as energy source is a constraint to cave biota. On the other hand,
nearly constant temperature (approximating the average annual surface
temperature) and the unchanging humidity plus relatively few predators in the
deep, completely dark cave passages, makes this unique environment suitable for
specially adapted organisms to develop and subsist. Cave dwelling species,
adapted to a total dark environment and sparse energy sources, possess different
rates of growth, external features, behaviour, life spans, circadian and rhythmic
seasonal (circannual) activities and foodchains.
Caves therefore proves a unique natural laboratory for the study of evolution.
In few places on this planet is an environment available for study, that is so
uncomplicated and frequently so free from contamination as that of caves.
INTERACTION WITH SURFACE CONDITIONS
Research methods of interdisciplinary sciences in Speleology have awaken the
importance of ecological interactions in the past 15 years. Hence concepts
developed in Speleology have been successful in devicing guidelines for
environmental protection. For example, the concept of monitoring small changes
in an uncomplicated microenvironment, such as a cave, may be useful in
sounding a warning against potentially harmful broader changes at the surface,
that might be masked by human intervention.
Caves inhabitated by bats, swiftlets and other fauna, which forage above
ground, form a dynamic link with the surface. Fecal droppings and urine,
differing in quality and quantity, cause specific communities to develop in the
organic residue. These are in a state of dynamic equilibrium. A decline in
numbers of these surface active fauna, due to disturbance of their above-ground
environment, will have a direct impact on the cave fauna and flora, requiring
adaptation to new dynamic equilibria or causing complete disruption, depending
on the severity of disturbance..
Water, air, silt, vegetation and animal remains, guano are the means of
interplay between the dark cave interior with the outside world. Without energy
transfer from the outside to the inside of caves, only a limited number of highly
specialized cave fauna and flora can exist, maintaining a nearly closed ecological
system in a darkest zones of caves. The energy required for metabolism is then
derived from minerals in the wall rock and sediment of cave floors. The basic
food cycle in such a cave condition, would depend on chemoautotrophic
bacteria, serving as nutrient material for cave dwelling animals with no input
from outside the cave.
Scientists frequently encounter the close connection between outside
phenomena and the interior of caves, so that it is now a coined term, to explain
this as the surface-subsurface or subterranean intimate and dynamic interplay.
The study of underground phenomena may even contribute to space biology,
physiology and psychology. It might be possible, for instance, to recycle the
human waste products that would accumulate on a long space voyage, as a
source of new nutrients. Study of the food cycles in caves may give clues to
possible ways of recycling waste products.
The study of caves may provide a deeper insight into nature. Monitoring the
delicate microenvironment in caves may develop conservation methods of the
living world.
CAVE ECOLOGY
Till 1979, a space, deep below ground, in solid bedrock, is considered the
most sheltered environment, free from human disturbance. But a 1980, short
scientific paper, published in France, challenges this view of cave life. Juberthie,
Delay and Bullion working in the underground laboratory of the C.N.R.S.,
reported “cave limited” fauna in cracks of rocks and screes situated just below
the soil. They call this environment the “Superficial Underground Compartment”
(S.U.C.). This is not only found in karst, but also in shales and sandstone. So the
few, thinly scattered animals in the depths of caves are actually the advance
guard or frontier pushers of a much less deep-ranging underground community.
Its discovery has profound implication for conservation of cave life.
To have an insight in the energy transfer, a study of the cave ecosystem and
foodsupply is mandatory. Cave communities of specialized organisms living in
total darkness, towards which they have adapted themselves, passes energy and
useful chemicals in a fairly organized way. The length of foodchains is limited
by the energy input of the system.
Cave communities depend mainly on the detritus from surface ecosystems.
Organic material is also obtained from fecal matter of animals that periodically
look for food outside the cave, such as bats, cave rats, birds and crickets. In each
case, bacterial decomposers rely on a flow of organic material from sunlit areas,
from plant remains in cave streams, organic substances in cave silt, even from
suspended organic matter in drip water. Thus the primary energy sources
exploited by cave organisms are surface derived organic material utilized by
heterotrophic bacteria, or minerals, broken down by autotrophic bacteria, the
former being quantitatively the more important factor. Decomposer bacteria in
turn are eaten by protozoans, which are utilized by aquatic cave dwelling
flatworms, isopods, amphipods, which in turn are preyed upon by larger aquatic
fauna.
Life in caves actually works on the same principles as in the highly complex
outside world, but with fewer variables in the ecologic equations. Caves
therefore provide ecologists with relatively simplified, easily studied “model
ecosystems”.
The importance of cave streams carrying bits of vegetation, has been
emphasized by most American biospeleologists. Organically rich mud are
dumped onto the stram banks in caves during floods. Streams are particularly
important in cave systems, developed in massive horizontally bedded limestone.
Many such caves are found in Indonesia. But when vertical joints and steeply
inclining bedding planes are present as found in many continental Europe and
English karst regions, and also in the massive highland karst of Irian Jaya, the
food supply is usually carried into the caves by water trickling down fissures
from the soil above. This is without doubt the source of food for fauna living in
the S.U.C. It will vary in energy richness and chemical composition with the
type of the soil-cover from which it comes. This in turn, partly owes its character
to the surface vegetation and to human activities above the caves. In some areas
of Hawaii, whole cave communities have been wiped out in recent times by
forest clearance and crop cultivation.
The routes along which energy travels in most ecosystems have been refined
over many thousands of years of evolutionary selection. Separate food chains
often meet and cross to form a network of routes along which energy flows
through the community. Complex foodwebs allow continuous uninterrupted flow
of energy through the ecosystem, so that if the population of one particular
organism declines dangerously, its predators can switch to another food source,
rather than starve.
Every now and then, an established ecosystem may be disupted by major
pertubations such as climatic change, forest fires, human disturbance that cause it
to be thrown out of balance. If this happens, the main casualties will generally
be the highly specialized species, being slower to respond to a forced change in
role than less specialized species, which have more variation in their gene pools
and can therefore adapt faster to changed circumstances.
DISCUSSION
Tropical cave biology is still in its infancy. The British New Guinea
Speleological Expedition of 1975 was among the first European expeditions to
study tropical biospeleology. Until recently, European and American cave
biologists believed, that only a very few creatures were adapted to tropical cave
life, and that cave evolved “troglomorphic” animals are only present in
significant numbers in caves of temperate latitudes. But deep in Selinum Tem,
the largest cave found in Papua New Guinea, cave biologists found a community
of animals which consisted almost entirely of troglomorphic species, living in
small flood-prone passages just above the phreatic level, where slowly-draining
flood waters deposit a harvest of food and where constant temperature and
humidity prevail.
Subsequent visits to the caves of Mulu (Sarawak, 1982) have revealed
different, but equally specialized cave evolved communities in deep cave
habitats. Meanwhile Howarth (1973) begun to uncover yet another specialized
cave-evolved community in Hawaii’s lava tubes..
In most cave passages of large diameter, which contain big populations of
bats or swiftlets and lots of guano, there are few, if any, “troglomorphic” species.
It is often only in the remote flood-prone passages, where most of the
biospeleological interest lies! Chapman (1985) predicts with confidence, that
many tropical karst areas, like the Gunung Sewu karst in Central and East Java,
contains rich and complex troglomorphic faunas, rivaling those of New Guinea,
Hawaii and Sarawak.
The earliest description of cave animals from Indonesia was given by
Jacobson E. (Febr., March, 1911) who visited several caves in the Gunung Sewu
area, describing his experiences in collectiong animal life from subterrranean
water, obtaining among others some species of fish, crabs and prawns (1912;
513-516). The cave crabs were later examined by Ihle (1912; 177-182) and
consist of the previously known Parathelpus convexa (de Man, 1879) a common
epigean species and a new species, described by Ihle: Sesarmoides jacobsoni
(Ihle, 1912), collected at Ngingrong and Jomblang caves.The “small white
crabs” reported by Waltham et al (1983; 90) frm underground water of Gunung
Sewu could very well belong to this species. The prawns collected by Jacobson
(1912) at Ngingrong cave consists of Macrobrachium lar (Fabricius, 1798) and
Macrobrachium pilimanus (De Man, 1879).
The Gunung Sewu Cave Survey in 1982, a joint British-Indonesian
undertaking, sponsored by the British Royal Geographical Society, collected a
few subterranean prawns, repeated in 1983 by Willis et al. These material were
placed at the disposal of Holthuis and proved to be a new species:
Macrobrachium poeti, which are kept in collection of the Rijksmuseum van
Natuurlijk Historie Leiden (RMNH Crust. D no. 35796 and D no. 35794). They
are found in Luweng Jurangjero, about 100 m inside the entrance from the main
stream, from a static canal, and from a percolation-fed pool with mud floor.
Visits to caves at Tuban (Ngerong cave) by Buadi (1981), Segaranten
(Cidolok caves) by Buadi and Supriatna (1981), Cigudeg (Sipahang cave) by
Suyanto (1982), several caves at Nusakambangan isle and Gombong (Ratu and
Lawa caves, Petruk cave) by Suyanto (1983) and some caves at Gombong and
Gunung Sewu by Notowinarno (1985) obtained many biospeleological
specimen, some of which are still waiting for determination, but none of them
are thought to be troglobionts.
The trend is for more and more species to be collected from tropical caves for
identification, by fewer and fewer specialists capable of doing so. The prawns
found by the English team in Gunung Sewu, for instance, had to be sent to
Holland for identification. How many specimens lie idle on Indonesian shelves,
waiting for specialists to identify them is anybody’s guess.
What is needed are detailed, systematic studies of whole cave faunas and
their relationship to the cave environment, not merely collection of a few cave-
evolved animals. A dead specimen is useless, unless it is accompanied by
detailed description of its surroundings, where and preferably how it lived; its
behaviour, food, population and habitat characteristics. It is indeed impossible to
record too much information.
Bat guano maintains specialized cave ecosystems, known as guano
ecosystems, which differs from one cave to the other, owing to the specialized
cave organisms being specifically adapted to different composition and granule
size of bat dung . It is therefore essential to study the biochemistry of guano.
Dung of insectivorous bats consists predominantly of indigestible insect chitine,
which breaks down relatively slowly, and is therefore not an ideal substrate for
huge amounts of decomposers
Where frugivorous bats contribute to form soft fruity dung, with plenty of
carbohydrates, the guano becomes a very rich source of food, maintaining
extensive fauna of decomposers, scavengers and their associated predators.
Guano of frugivorous bats is mainly decomposed by fungi;that of insectivorous
bat guano is primarily attacked by bacteria.
The relative proportion of the two types determines the relative abundance
of fungi and bacterial decomposers and their respective micropredators. In the
great Niah Cave in Northern Borneo, where 1 million bats live with 4 million
swiftlets (collocalia), the dung and corpses support an extraordinary range of
life in which counts of 1 million arthropodes per 1 m2 of dung are encountered,
consisting of collembolas, mites, millipedes, pseudoscorpions, beetles,
cockroaches, isopods.
In fermenting bat guano, at the Ngerong river cave, we have counted about
100 very large cockroaches per square meter (Tuban cave expedition, 1981).
The data of cave fauna on given dates form “bench marks” for comparative
studies to determine changes in variety and quantity of these animals, caused by
detrimental factors to the ecosystem, like deforestation, forest fires, quarrying.
But as mentioned before, the highly specialized fauna, found in the deepest parts
of the cave, in complete darkness, without temperature fluctuations, are the most
sensitive to such changes.
Individual species survive in an ecosystem only as long as they have a place
in their community. Damage to the ecosystem is repaired in an adjustment in the
numbers of individual species, leading to a new level of dynamic equilibrium,
where an efficient flow of energy through system is again reached. Human
activities on the surface environment may already have deeply affected the
S.U.C. community, even causing the local extinction of some cave animals and
collembola species.
It is useless and uneconomic to protect individualrare species, if they are
deprived of theirecological niche. This is what “popular” conservation efforts
have often done – keeping spectacular animals in captivity, while their habitat is
destroyed. Increasing public awareness and action to protect the whole ecosystem
is fundamental to prevent species of flora and fauna becoming endangered or
wiped out. Coneservation of bats, swiftlets and other imsect eating birds and rare
cave dwelling animals mean conservation of their habitat. This permits complete
cave guano ecosystem conservation.
The diversity of our natural environment should be preserved for future
generations to enjoy. It is a pity, that cave communities are low on the priority
list of most conservation programmes! Their man importance is as easily
understood “modal ecosystems”, whose study can lead to a greater knowledge to
manage our natural environment.
Everyone appreciate that cave are habitats for bats and other insectivorous
birds. Plant dispersal by bats, specializing e.g. in pollinating Mangrove trees or
the act of chiropterochory, is of great importance in tropical forests. Nectivorous
bats also play important roles in cross-pollination of these fruit plants. Many
genera of trees and shrubs, depend wholly or mainly upon these bats, which form
an important links in the complex interrelationships of a tropical forest.
Conflict of interest in karst areas, as shown through agricultural activities,
quarrying of limestone, chalk production and cement factories in Indonesia,
should be solved by a multidisciplinary, intergovernmental and environmental
approach.
Preservation of these unrenewable and unretrievable habitats and ecosystems
should beaccorded its full importance. Underground water resources in limestone
are also very important. Their replenishment depends on the management of
rainwater catchments areas, including pattern of silvicultute.
RECOMMENDATION
The Indonesian Federation of Speleological Activities, as member of the
International Union of Speleology, recommends to the Indonesian Government
trough a Panel Discussion (Karanganyar-1984), Seminar (Semarang-1984), First
National Symposium of Karst and Caves (Jakarta-1985), Second National
Symposium of Karst and Caves (Jakarta-1996), Informal Meeting on karst
silviculture (Yogyakarta-1985), and a Workshop on the Utilization of Caves
(Bandung-1986), that :
1. Data on karst and caves in Indonesia be collected, filed uniformly,
computerized and reported to Scientifical Institutes, Departments
(Ministries) and other Governmental Agencies, for further evaluation of
their use and where possible, to promote their conservation.
2. The Indonesian public at large should be educated to arouse their awareness
of the Cultural, Physical, Biological and Ecological values of caves and their
environments.
3. Plans to exploit karst areas for commercial reasons, must be assessed on a
multidisciplinary and ecological bases.
4. Management of biological resource in caves should be based on ecological
principles. Biota of caves, fissure and cracksystems, should be evaluated and
monitored. Availability of food resources (biotops) should be regularly
monitored using cave collembolae, pseudoscorpions and cave crickets at
fixed locations as indices of abundance. Bat population densities can be
assessed at intervals, counting these animals during their flight out of the
caves by means of serial photographs. Diversity of cave animals, guano
quality and quantity should also be monitored. Should a cave contain
outstanding biospeleological resources (such as great numbers of bats and
swiftlets, presence of blind troglobiontic cave fishes and other cave
troglomorphs), it should be reported to the Directorate General of Nature
Conservation, The Indonesian Scientific Institute, The Ministry of
Population and Environment, The Ministry of Interior and The Local
Government. Such a cave should be closed to unauthorized individuals and
preferably gated. (A number of papers concerning cave gating can be read
from the proceedings of the yearly symposia on cave management in the
United States. The spaces between the bars should accommodate bats and
swiftlets to fly through and the structure should not impede with air flow.
Access should be limited by requiring special permits or recommendations
from above mentioned authorities).
5. Should a cave, already frequented by tourists, contain these outstanding
features in certain cave passages, these locations should also be closed to
public. It is therefore essential that a full assessment of cave biota, including
their food chain(s) and their (micro) ecosystems should precede any attempt
to open caves for tourism and appropriate restrictions devised.
6. Some caves should be recognized as underground laboratories for the study
of various aspects of biology, ecology, hydrology, sedimentology.
paleontology and archaeology.
Only by strictly adhering to these principles can we expect that caves, their
environment and their biota, and associated surface ecosystem can be protected,
so that we and future generations in Indonesia get all the benefit from these
unique and outstandingly important natural resources.
REFERENCES
1. Buadi and Supritana (1981) Catatan tentang kelelawar yang ditemukan
di dalam gua-gua di Cidolok, B.G.I. 2 (1) : 9 – 10.
2. Buadi (1981) Biologi Gua Ngerong Laporan Ekspedisi ke Gua Ngerong
: 21-24
3. Chapman P. (Nov. 1983) Cave Life part 9, Caves and Caving,
10 (22) : 21 – 25.
4. - (Sept. 1985) Cave Biology on Tropical Expeditions, Caves
and Caving, 12 (13) : 24 – 25.
9
5. Christiansen K. and Bullion M., An Evolutionary and Ecological
Analysis of the Terrestrial Arthropods of Caves in the
Central Pyrenes, NSS Bulletin,40 : 103 – 117.
6. Ford T. D. and Cullingford C.H.D. (1976) The Science of Speleology, ,
Academic Press : 362, 365, 397 – 407.
7. Holthuis L. B. (1984) Freshwater Prawns (Crustacea, Decapoda,
Natantia) from Subterranean Waters of the Gunung Sewu
Area, Central Java, Indonesia, ZOOL. MED. Leiden 58
(19) : 141 – 148 ISSN 0024-0672.
8. Howarth F. G. (1981), Non-Relictual Terrestrial Troglobites in the
Tropical Hawaiian Caves. Proceedings 8thInt. Congress
of Speleology (1) : 593.
9. Juberthie C. and Delay B. (1981), Ecological and Biological Implication
of the Existense of a “Superficial Underground
Compartment” Proceedings 8thInt. Congress of
Speleology : 203 – 205.
10. Ko R. K. T. (1981) Ekspedisi ke Gua Ngerong (Laporan)
11. - (1984) Kehidupan Binatang Dalam gua –Lecture
Notes.Finspac Basic and Advanced Courses..
12. Moore W. G. (1978) Speleology, the Stufy of Caves, Zephyrus Press :
6 – 8, 73 – 78, 84 – 85, 111.
13. Pack S. B. (1981) The Geological and Environmental Setting of Cave
Faunal Evolution. Proceedings, 8th Int. Congress of
Speleology: 501.
14. Petty P. E. (1976) Subsurface Management as a Component of General
Land Management. National Csve Mangement
Symposium: 30-33
15. Poulson T. L. and White W. B. (1969) The Cave Environment. Science,
165 : 971 – 981.
16. Poulson T. L. (1975), Management of Biological Resources in Caves.
National Cave Management Symposium,: 46 – 50.
17. Stitt R. R. (1976) Human Impact on Caves. National Cave
Management: Symposium, 36 – 50.
18. Supriatna J. (1981) Biospeleologi Gua Selatan Cidolok. BGI (3) 1:14.
19. Suyanto A. (1982), Catatan Binatang yang ditemukan di dalam Gua Si
Menteng BGI (4) : 5 – 7.
20. - (1983), Biospeleologi Gua-Gua di Kabupaten Cilacap dan
Kebumen.Laporan Survai ke Nusakambangan dan Gua
Petruk:: 27 – 40.
21. Tuttle M. D. (1976) Gating as a Means of Protecting Cave Dwelling
Bats. National Cave Management Symposium: 77 – 82.
22. Waltham et al (1983) The Caves of Gunung Sewu, Java – Cave Science
10 (2) : 55 – 96.
23. Yalden D. W. (1975), The Lives of Bat. A Demeter Press Book : 66 –
68, 71.
SPELEOLOGY, derived from SPELAEON, meaning CAVE and LOGOS,
SCIENCE, is the science of caves and their environment. Their physical,
biological and ecological aspects have been studied in depth only in the past few
decades. Speleology comprises many discrete fields of sciences, but avoids
pigeonholing, that may hamper an interdisciplinary approach.
According to the definition of the International Union of Speleology, a cave is
a subterranean void which can be entered by man. This definition implicates, that
Speleology is a science, limiting itself only to underground spaces accessable to
investigators. This is very misleading, since caves enterable by man are only part
of a much more complicated system which exists in a matrix - in this case
limestone – consisting of innumerable cracks, fissures and crevices, forming a
labyrinth of interconnected spaces, capable of accommodating some forms of
life.
THE CAVE ENVIRONMENT
Exploring caves needs special skills, equipment and preserverance to
overcome a multitude of physical obstacles, in often hazardous surroundings, in
complete darkness - their foremost and distinctive property. Extremely limited
food supply as energy source is a constraint to cave biota. On the other hand,
nearly constant temperature (approximating the average annual surface
temperature) and the unchanging humidity plus relatively few predators in the
deep, completely dark cave passages, makes this unique environment suitable for
specially adapted organisms to develop and subsist. Cave dwelling species,
adapted to a total dark environment and sparse energy sources, possess different
rates of growth, external features, behaviour, life spans, circadian and rhythmic
seasonal (circannual) activities and foodchains.
Caves therefore proves a unique natural laboratory for the study of evolution.
In few places on this planet is an environment available for study, that is so
uncomplicated and frequently so free from contamination as that of caves.
INTERACTION WITH SURFACE CONDITIONS
Research methods of interdisciplinary sciences in Speleology have awaken the
importance of ecological interactions in the past 15 years. Hence concepts
developed in Speleology have been successful in devicing guidelines for
environmental protection. For example, the concept of monitoring small changes
in an uncomplicated microenvironment, such as a cave, may be useful in
sounding a warning against potentially harmful broader changes at the surface,
that might be masked by human intervention.
Caves inhabitated by bats, swiftlets and other fauna, which forage above
ground, form a dynamic link with the surface. Fecal droppings and urine,
differing in quality and quantity, cause specific communities to develop in the
organic residue. These are in a state of dynamic equilibrium. A decline in
numbers of these surface active fauna, due to disturbance of their above-ground
environment, will have a direct impact on the cave fauna and flora, requiring
adaptation to new dynamic equilibria or causing complete disruption, depending
on the severity of disturbance..
Water, air, silt, vegetation and animal remains, guano are the means of
interplay between the dark cave interior with the outside world. Without energy
transfer from the outside to the inside of caves, only a limited number of highly
specialized cave fauna and flora can exist, maintaining a nearly closed ecological
system in a darkest zones of caves. The energy required for metabolism is then
derived from minerals in the wall rock and sediment of cave floors. The basic
food cycle in such a cave condition, would depend on chemoautotrophic
bacteria, serving as nutrient material for cave dwelling animals with no input
from outside the cave.
Scientists frequently encounter the close connection between outside
phenomena and the interior of caves, so that it is now a coined term, to explain
this as the surface-subsurface or subterranean intimate and dynamic interplay.
The study of underground phenomena may even contribute to space biology,
physiology and psychology. It might be possible, for instance, to recycle the
human waste products that would accumulate on a long space voyage, as a
source of new nutrients. Study of the food cycles in caves may give clues to
possible ways of recycling waste products.
The study of caves may provide a deeper insight into nature. Monitoring the
delicate microenvironment in caves may develop conservation methods of the
living world.
CAVE ECOLOGY
Till 1979, a space, deep below ground, in solid bedrock, is considered the
most sheltered environment, free from human disturbance. But a 1980, short
scientific paper, published in France, challenges this view of cave life. Juberthie,
Delay and Bullion working in the underground laboratory of the C.N.R.S.,
reported “cave limited” fauna in cracks of rocks and screes situated just below
the soil. They call this environment the “Superficial Underground Compartment”
(S.U.C.). This is not only found in karst, but also in shales and sandstone. So the
few, thinly scattered animals in the depths of caves are actually the advance
guard or frontier pushers of a much less deep-ranging underground community.
Its discovery has profound implication for conservation of cave life.
To have an insight in the energy transfer, a study of the cave ecosystem and
foodsupply is mandatory. Cave communities of specialized organisms living in
total darkness, towards which they have adapted themselves, passes energy and
useful chemicals in a fairly organized way. The length of foodchains is limited
by the energy input of the system.
Cave communities depend mainly on the detritus from surface ecosystems.
Organic material is also obtained from fecal matter of animals that periodically
look for food outside the cave, such as bats, cave rats, birds and crickets. In each
case, bacterial decomposers rely on a flow of organic material from sunlit areas,
from plant remains in cave streams, organic substances in cave silt, even from
suspended organic matter in drip water. Thus the primary energy sources
exploited by cave organisms are surface derived organic material utilized by
heterotrophic bacteria, or minerals, broken down by autotrophic bacteria, the
former being quantitatively the more important factor. Decomposer bacteria in
turn are eaten by protozoans, which are utilized by aquatic cave dwelling
flatworms, isopods, amphipods, which in turn are preyed upon by larger aquatic
fauna.
Life in caves actually works on the same principles as in the highly complex
outside world, but with fewer variables in the ecologic equations. Caves
therefore provide ecologists with relatively simplified, easily studied “model
ecosystems”.
The importance of cave streams carrying bits of vegetation, has been
emphasized by most American biospeleologists. Organically rich mud are
dumped onto the stram banks in caves during floods. Streams are particularly
important in cave systems, developed in massive horizontally bedded limestone.
Many such caves are found in Indonesia. But when vertical joints and steeply
inclining bedding planes are present as found in many continental Europe and
English karst regions, and also in the massive highland karst of Irian Jaya, the
food supply is usually carried into the caves by water trickling down fissures
from the soil above. This is without doubt the source of food for fauna living in
the S.U.C. It will vary in energy richness and chemical composition with the
type of the soil-cover from which it comes. This in turn, partly owes its character
to the surface vegetation and to human activities above the caves. In some areas
of Hawaii, whole cave communities have been wiped out in recent times by
forest clearance and crop cultivation.
The routes along which energy travels in most ecosystems have been refined
over many thousands of years of evolutionary selection. Separate food chains
often meet and cross to form a network of routes along which energy flows
through the community. Complex foodwebs allow continuous uninterrupted flow
of energy through the ecosystem, so that if the population of one particular
organism declines dangerously, its predators can switch to another food source,
rather than starve.
Every now and then, an established ecosystem may be disupted by major
pertubations such as climatic change, forest fires, human disturbance that cause it
to be thrown out of balance. If this happens, the main casualties will generally
be the highly specialized species, being slower to respond to a forced change in
role than less specialized species, which have more variation in their gene pools
and can therefore adapt faster to changed circumstances.
DISCUSSION
Tropical cave biology is still in its infancy. The British New Guinea
Speleological Expedition of 1975 was among the first European expeditions to
study tropical biospeleology. Until recently, European and American cave
biologists believed, that only a very few creatures were adapted to tropical cave
life, and that cave evolved “troglomorphic” animals are only present in
significant numbers in caves of temperate latitudes. But deep in Selinum Tem,
the largest cave found in Papua New Guinea, cave biologists found a community
of animals which consisted almost entirely of troglomorphic species, living in
small flood-prone passages just above the phreatic level, where slowly-draining
flood waters deposit a harvest of food and where constant temperature and
humidity prevail.
Subsequent visits to the caves of Mulu (Sarawak, 1982) have revealed
different, but equally specialized cave evolved communities in deep cave
habitats. Meanwhile Howarth (1973) begun to uncover yet another specialized
cave-evolved community in Hawaii’s lava tubes..
In most cave passages of large diameter, which contain big populations of
bats or swiftlets and lots of guano, there are few, if any, “troglomorphic” species.
It is often only in the remote flood-prone passages, where most of the
biospeleological interest lies! Chapman (1985) predicts with confidence, that
many tropical karst areas, like the Gunung Sewu karst in Central and East Java,
contains rich and complex troglomorphic faunas, rivaling those of New Guinea,
Hawaii and Sarawak.
The earliest description of cave animals from Indonesia was given by
Jacobson E. (Febr., March, 1911) who visited several caves in the Gunung Sewu
area, describing his experiences in collectiong animal life from subterrranean
water, obtaining among others some species of fish, crabs and prawns (1912;
513-516). The cave crabs were later examined by Ihle (1912; 177-182) and
consist of the previously known Parathelpus convexa (de Man, 1879) a common
epigean species and a new species, described by Ihle: Sesarmoides jacobsoni
(Ihle, 1912), collected at Ngingrong and Jomblang caves.The “small white
crabs” reported by Waltham et al (1983; 90) frm underground water of Gunung
Sewu could very well belong to this species. The prawns collected by Jacobson
(1912) at Ngingrong cave consists of Macrobrachium lar (Fabricius, 1798) and
Macrobrachium pilimanus (De Man, 1879).
The Gunung Sewu Cave Survey in 1982, a joint British-Indonesian
undertaking, sponsored by the British Royal Geographical Society, collected a
few subterranean prawns, repeated in 1983 by Willis et al. These material were
placed at the disposal of Holthuis and proved to be a new species:
Macrobrachium poeti, which are kept in collection of the Rijksmuseum van
Natuurlijk Historie Leiden (RMNH Crust. D no. 35796 and D no. 35794). They
are found in Luweng Jurangjero, about 100 m inside the entrance from the main
stream, from a static canal, and from a percolation-fed pool with mud floor.
Visits to caves at Tuban (Ngerong cave) by Buadi (1981), Segaranten
(Cidolok caves) by Buadi and Supriatna (1981), Cigudeg (Sipahang cave) by
Suyanto (1982), several caves at Nusakambangan isle and Gombong (Ratu and
Lawa caves, Petruk cave) by Suyanto (1983) and some caves at Gombong and
Gunung Sewu by Notowinarno (1985) obtained many biospeleological
specimen, some of which are still waiting for determination, but none of them
are thought to be troglobionts.
The trend is for more and more species to be collected from tropical caves for
identification, by fewer and fewer specialists capable of doing so. The prawns
found by the English team in Gunung Sewu, for instance, had to be sent to
Holland for identification. How many specimens lie idle on Indonesian shelves,
waiting for specialists to identify them is anybody’s guess.
What is needed are detailed, systematic studies of whole cave faunas and
their relationship to the cave environment, not merely collection of a few cave-
evolved animals. A dead specimen is useless, unless it is accompanied by
detailed description of its surroundings, where and preferably how it lived; its
behaviour, food, population and habitat characteristics. It is indeed impossible to
record too much information.
Bat guano maintains specialized cave ecosystems, known as guano
ecosystems, which differs from one cave to the other, owing to the specialized
cave organisms being specifically adapted to different composition and granule
size of bat dung . It is therefore essential to study the biochemistry of guano.
Dung of insectivorous bats consists predominantly of indigestible insect chitine,
which breaks down relatively slowly, and is therefore not an ideal substrate for
huge amounts of decomposers
Where frugivorous bats contribute to form soft fruity dung, with plenty of
carbohydrates, the guano becomes a very rich source of food, maintaining
extensive fauna of decomposers, scavengers and their associated predators.
Guano of frugivorous bats is mainly decomposed by fungi;that of insectivorous
bat guano is primarily attacked by bacteria.
The relative proportion of the two types determines the relative abundance
of fungi and bacterial decomposers and their respective micropredators. In the
great Niah Cave in Northern Borneo, where 1 million bats live with 4 million
swiftlets (collocalia), the dung and corpses support an extraordinary range of
life in which counts of 1 million arthropodes per 1 m2 of dung are encountered,
consisting of collembolas, mites, millipedes, pseudoscorpions, beetles,
cockroaches, isopods.
In fermenting bat guano, at the Ngerong river cave, we have counted about
100 very large cockroaches per square meter (Tuban cave expedition, 1981).
The data of cave fauna on given dates form “bench marks” for comparative
studies to determine changes in variety and quantity of these animals, caused by
detrimental factors to the ecosystem, like deforestation, forest fires, quarrying.
But as mentioned before, the highly specialized fauna, found in the deepest parts
of the cave, in complete darkness, without temperature fluctuations, are the most
sensitive to such changes.
Individual species survive in an ecosystem only as long as they have a place
in their community. Damage to the ecosystem is repaired in an adjustment in the
numbers of individual species, leading to a new level of dynamic equilibrium,
where an efficient flow of energy through system is again reached. Human
activities on the surface environment may already have deeply affected the
S.U.C. community, even causing the local extinction of some cave animals and
collembola species.
It is useless and uneconomic to protect individualrare species, if they are
deprived of theirecological niche. This is what “popular” conservation efforts
have often done – keeping spectacular animals in captivity, while their habitat is
destroyed. Increasing public awareness and action to protect the whole ecosystem
is fundamental to prevent species of flora and fauna becoming endangered or
wiped out. Coneservation of bats, swiftlets and other imsect eating birds and rare
cave dwelling animals mean conservation of their habitat. This permits complete
cave guano ecosystem conservation.
The diversity of our natural environment should be preserved for future
generations to enjoy. It is a pity, that cave communities are low on the priority
list of most conservation programmes! Their man importance is as easily
understood “modal ecosystems”, whose study can lead to a greater knowledge to
manage our natural environment.
Everyone appreciate that cave are habitats for bats and other insectivorous
birds. Plant dispersal by bats, specializing e.g. in pollinating Mangrove trees or
the act of chiropterochory, is of great importance in tropical forests. Nectivorous
bats also play important roles in cross-pollination of these fruit plants. Many
genera of trees and shrubs, depend wholly or mainly upon these bats, which form
an important links in the complex interrelationships of a tropical forest.
Conflict of interest in karst areas, as shown through agricultural activities,
quarrying of limestone, chalk production and cement factories in Indonesia,
should be solved by a multidisciplinary, intergovernmental and environmental
approach.
Preservation of these unrenewable and unretrievable habitats and ecosystems
should beaccorded its full importance. Underground water resources in limestone
are also very important. Their replenishment depends on the management of
rainwater catchments areas, including pattern of silvicultute.
RECOMMENDATION
The Indonesian Federation of Speleological Activities, as member of the
International Union of Speleology, recommends to the Indonesian Government
trough a Panel Discussion (Karanganyar-1984), Seminar (Semarang-1984), First
National Symposium of Karst and Caves (Jakarta-1985), Second National
Symposium of Karst and Caves (Jakarta-1996), Informal Meeting on karst
silviculture (Yogyakarta-1985), and a Workshop on the Utilization of Caves
(Bandung-1986), that :
1. Data on karst and caves in Indonesia be collected, filed uniformly,
computerized and reported to Scientifical Institutes, Departments
(Ministries) and other Governmental Agencies, for further evaluation of
their use and where possible, to promote their conservation.
2. The Indonesian public at large should be educated to arouse their awareness
of the Cultural, Physical, Biological and Ecological values of caves and their
environments.
3. Plans to exploit karst areas for commercial reasons, must be assessed on a
multidisciplinary and ecological bases.
4. Management of biological resource in caves should be based on ecological
principles. Biota of caves, fissure and cracksystems, should be evaluated and
monitored. Availability of food resources (biotops) should be regularly
monitored using cave collembolae, pseudoscorpions and cave crickets at
fixed locations as indices of abundance. Bat population densities can be
assessed at intervals, counting these animals during their flight out of the
caves by means of serial photographs. Diversity of cave animals, guano
quality and quantity should also be monitored. Should a cave contain
outstanding biospeleological resources (such as great numbers of bats and
swiftlets, presence of blind troglobiontic cave fishes and other cave
troglomorphs), it should be reported to the Directorate General of Nature
Conservation, The Indonesian Scientific Institute, The Ministry of
Population and Environment, The Ministry of Interior and The Local
Government. Such a cave should be closed to unauthorized individuals and
preferably gated. (A number of papers concerning cave gating can be read
from the proceedings of the yearly symposia on cave management in the
United States. The spaces between the bars should accommodate bats and
swiftlets to fly through and the structure should not impede with air flow.
Access should be limited by requiring special permits or recommendations
from above mentioned authorities).
5. Should a cave, already frequented by tourists, contain these outstanding
features in certain cave passages, these locations should also be closed to
public. It is therefore essential that a full assessment of cave biota, including
their food chain(s) and their (micro) ecosystems should precede any attempt
to open caves for tourism and appropriate restrictions devised.
6. Some caves should be recognized as underground laboratories for the study
of various aspects of biology, ecology, hydrology, sedimentology.
paleontology and archaeology.
Only by strictly adhering to these principles can we expect that caves, their
environment and their biota, and associated surface ecosystem can be protected,
so that we and future generations in Indonesia get all the benefit from these
unique and outstandingly important natural resources.
REFERENCES
1. Buadi and Supritana (1981) Catatan tentang kelelawar yang ditemukan
di dalam gua-gua di Cidolok, B.G.I. 2 (1) : 9 – 10.
2. Buadi (1981) Biologi Gua Ngerong Laporan Ekspedisi ke Gua Ngerong
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3. Chapman P. (Nov. 1983) Cave Life part 9, Caves and Caving,
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9
5. Christiansen K. and Bullion M., An Evolutionary and Ecological
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