A preliminary survey of the invertebrate fauna of the Gunung Mulu World Heritage karst area, Sarawak, Malaysia Tim Moulds 1, Jay Anderson, Ross Anderson and Patrick Nykiel GHD 239 Adelaide Terrace Perth WA 6004 1 Email: [email protected] 1 Abstract microhabitat variability and availability within sampled caves, with greater The Gunung Mulu World Heritage Area invertebrate abundance related to bird and (Mulu) is situated in the north eastern bat guano deposits. This study represents corner of Sarawak, Malaysia on the Island of the first stage of invertebrate research at Borneo, adjacent to the South China Sea. Mulu, and future efforts will focus on The area was prescribed as a national park increasing the photo inventory to provide a in 1974 and is the largest national park in useful resource to the Mulu Park and 2 Sarawak covering an area of 528 km . The Sarawak Forestry staff to identify cave area contains significant karstic limestone, invertebrates in the field. Ultimately with some of the world’s largest caves by increasing the local knowledge of cave volume known from the area including invertebrate fauna will provide the best Deer Cave and the Clearwater System. protection for these important ecosystems. In 2012 a team of Australian speleologists Introduction undertook a preliminary survey of the invertebrate biodiversity of eight caves The Gunung Mulu World Heritage Area within Mulu. The caves were a mix of (Mulu) is situated in the north eastern tourist, adventure and wild caves within the corner of Sarawak , Malaysia on the Island park. Invertebrates were recorded from a of Borneo, adjacent to the South China Sea mixture of different microhabitats found (Figure 1). The area was prescribed as a within the caves and reference specimens national park in 1974 and is the largest from each cave were collected and national park in Sarawak covering an area of preserved for future study. 528 km 2. Mulu contains the second highest peak in Borneo, Gunung Mulu, a sandstone The aims of the study were to document the mountain situated to the east of the Melinau biodiversity of the caves; provide a photo Limestone that contains the extensive caves inventory of species recorded; compare the that are the subject of the current study. invertebrate diversity and abundance between different cave zones and Gunung Mulu World Heritage Area microhabitats; compare the invertebrate (GMWHA) contains significant karst and diversity and abundance between caves used associated subterranean fauna. Although for different tourism purposes. substantial research was undertaken on the bio-speleological values, this was more than The survey recorded over 19,000 specimens 30 years ago and much has changed in using a combination of collection and regard to our knowledge of such fauna observation of species that presently especially within tropical settings. represents 100 different morpho-species, from 28 orders and 9 classes. The number Dr G E Wilford was the first individual to of morpho-species is expected to increase visit the Mulu caves with the objective to with additional sampling and further explore the caves in the early 1960s. Wilford identification of the specimens already worked with the Geological Survey of the collected. Forty different species have been Borneo region and completed surveys of photo-inventoried thus far. Deer cave, parts of Wind cave and Terikan cave. He indicated in his book of the caves Preliminary analysis of data has shown no of Sabah and Sarawak that large and discernible differences in invertebrate spectacular caves are most likely to be diversity or abundance between tourist discovered in the Melinau area. caves and wild caves. Observed differences in invertebrate populations are related to ACKMA Cave and Karst Management in Australasia 20 Waitomo Caves, New Zealand, 2013 84 Prior to the 15 month scientific expedition 2. Provide a photo inventory of species by the Royal Geographical Society in 1977 - recorded. 78, the Mulu caves had first been reported 3. Compare the invertebrate diversity in 1858, however, little work had been done and abundance between different on the biospeleological values of the area. cave zones and microhabitats. Aims and Objectives of Preliminary 4. Compare the invertebrate diversity Survey and abundance between caves used The current preliminary survey aims to for different tourism purposes. provide a basis for future biological surveys 5. Provide management strategies to in Mulu by building upon the only other facilitate fauna survival and mitigate substantial biospeleological survey threats. undertaken in the area by Chapman (1982). The current preliminary survey aims to 6. Provide recommendations for future provide an initial overview of the works to compliment the findings of invertebrate fauna in the cave systems near the current study. the Park Headquarters and predominately in 7. Preparation of recommendations for those used as tourist caves and adventure further cave biodiversity studies, caves. potentially focusing on sustainable The primary survey aims were to: cave management and adequate tourism development 1. Preliminary overview of the biodiversity and initial insights into The caves chosen were a mixture of tourist the cave ecosystems as a baseline caves, adventure use caves and wild caves and starting-point for future and included a range of habitats and use ecosystem studies of the cave levels. The caves examined are shown in systems. Table 1. ACKMA Cave and Karst Management in Australasia 20 Waitomo Caves, New Zealand, 2013 85 Figure 1 Map of all Mulu Cave systems (after www.mulucaves.org ) Cave Name Primary Use Limestone Section Visitation Deer Cave Tourism Deer/Green Section High Deer Water Cave Wild Deer/Green Section Low Green Cave Wild Deer/Green Section Low Stonehorse Cave Adventure Deer/Green Section Low Fruit Bat Cave Adventure Kenyalang/Fruit Bat Low Kenyalang Cave Adventure Kenyalang/Fruit Bat Low Lagang Cave Tourism/Adventure Gunung Api Moderate Racer Cave Adventure Gunung Api Moderate Clearwater Cave Tourism/Adventure Gunung Api Moderate Table 1 Cave usage and location within Mulu ACKMA Cave and Karst Management in Australasia 20 Waitomo Caves, New Zealand, 2013 86 Survey Timing and Participants severely alters or completely removes many circadian cycles affecting ecosystem th The survey was undertaken between the 29 function (Lamprecht and Weber, (1992), th April – 12 May 2012. The survey was Langecker, (2000)). Temperatures are undertaken by a specialist cave biologist, Dr usually constant, varying only slightly Timothy Moulds (Australia), and assisted by between seasons. Humidity is commonly a team of Australian speleologists who have high, providing an ideal habitat for many experience in cave interpretation, guiding invertebrate species susceptible to and speleology. An additional field visit was desiccation. The lack of photosynthetic undertaken by Dr Timothy Moulds and a plants changes the trophic structure of cave smaller speleological team from the Western ecosystems, with energy sources usually Australian Speleological Group (WASG) in being transported from the surface (Poulson th th December 2012 (12 – 17 December) to and Lavoie, (2000), Poulson, (2005)). Caves revisit some of the primary caves examined are defined as human-sized subterranean previously. The Australian biospeleological voids, although cave adapted animals are team were Dr Timothy Moulds, Jay known to occur in the smaller spaces Anderson, Ross Anderson, Patrick Nykiel, between large voids called micro- and meso Rob Susac, Barbara Zakrzewska, Dr caverns (Howarth, (2003)). Stephen Swabey, Toni Lowe, Sharon Thwaites, Ian Thwaites, Jane Pulford, Tony Caves are divided into several distinct Veness, Dr Bert De Waale, Gregoriy biological zones to aid interpretation (Figure Tsaplin, Christine Best, Andrew Thomas, 2). These correspond to the amount of and Sandi Cheema. available light and varying environmental conditions (Humphreys, (2000)). The Mulu park administration provided Entrance Zone is the area directly around the assistance to the project through the cave entrance; it is generally well lit, often provision of accommodation, staff for field supports photosynthetic plants, and work and guiding, and numerous other undergoes daily temperature and humidity forms. fluctuations. The Twilight Zone is just beyond Further field assistance was provided by the entrance zone and is often dominated by Mulu Park staff including, Bian Rumei, Syria lichen and algae that require low light Lenjau, Jeffry Simun, Brian Clark, Sue Clark, conditions. The temperature and humidity Jeremy Clark and Sarawak Forestry Staff led are still variable but fluctuations are by Anne Malissa King. dampened compared with epigean variation. Introduction to Subterranean Deeper into a cave, light is reduced to zero Biology and the Dark Zone is entered, which is subdivided into three zones, the transition, Caves form a very stable and generally deep cave and stale air zones. The Transition homogenous environment in which to Zone is perpetually dark, but still fluctuates conduct various ecological and evolutionary in temperature and humidity determined by experiments, such as on competition epigean conditions. The Deep Cave Zone is between species, resource partitioning, and almost constant in temperature and the processes of speciation (Poulson and humidity conditions. White, (1969)). The total absence of light ACKMA Cave and Karst Management in Australasia 20 Waitomo Caves, New Zealand, 2013 87 Figure 2 The