The biodiversity of Krem Mawkhyrdop of Meghalaya, India, on the verge of extinction

Abstract

THE adjoining geophysical architecture and climatic conditions always act as proximate factors that regulate the internal environmental conditions of any cave. Nevertheless, the cave (hypogean) ecosystem remains more or less stable compared to its ambient epigean environmental niche. Perpetual darkness, high humidity, almost constant temperature, low airflow and higher CO2 concentrations altogether make the subterranean ecosystem a unique niche. The biota of the caves stays tuned with its ecological regime for successful survival. The biodiversity of the karst ecosystem is highly restrictive, i.e. species existing in a particular cave system may be restricted to that ecosystem only and perhaps completely absent in other adjacent caves. Any natural/unnatural disturbances that can alter/modify the originality of the cave ecosystem could become a major deciding factor to destroy/alter its complete biodiversity. Natural geological disasters (i.e. collapse, wall dislocations, etc.), climatic abnormalities (long period of droughts, inundations) and mostly human encroachments (mining/quarrying, tourism, waste disposal, and rapid ways of agriculture) are some of the factors that are responsible for the same. Krem (=cave) Mawkhyrdop is situated in the village Mawmluh, Meghalaya (25.30°N, 91.70°E), India. It is popularly known as the Mawmluh cave. This area enjoys the highest rainfall in the world. In fact, the monsoon sweeping the Bay of Bengal results in an average of 10– 12 m rainfall per year. The combination of huge limestone deposits of this area with high rainfall has led to extensive cave development in Meghalaya. The Mawkhyrdop cave was for the first time lighted in the 18th century along with a small cave Mawsmai in the same region, at a distance of about 10 km. In 1859, Oldham 1 reported the existence of these caves. The Mawkhyrdop cave is formed of pure limestone (Cherra limestone) with both sides covered by sandstone beds (with some coal at the bottom). Thus the sandstone at the base of the Mawkhyrdop cave is a limiting factor for its vertical development. Frequently calcirudite, a coarse (gravel-sized) limestone can be viewed on the walls. These clasts (broken fragments) are suspected to be rock fossils or pieces of coral, shells or fragments of limestone, with the interstices filled with calcite, sand or mud with the whole bonded by calcareous cement. The cross-section of the cave passages resembles the shape of an inverted funnel. This feature is quite peculiar with Krem Mawkhyrdop (and a couple of other caves in Meghalaya), as it is a typical product of interstratal karst