Cave habitats
Endangerment and Protection
The speleological objects and their fauna are endangered in different ways. They are largely endangered as a result of changes in hydrological regimes. These changes occur mainly due to the construction of hydropower plants to obtain energy, which primarily affects the aquatic fauna, but also the terrestrial subterranean fauna. The construction of hydropower plants and their operation require the provision of minimum environmentally acceptable flow in order to preserve the underground and aboveground fauna of the region.
Croatian caves and pits are very commonly used like waste disposals and septic tanks, which endanger and destroy the object and its fauna in different ways. The organic waste has a very strong adverse effect on shallow aquifiers, the septic tank fluid contains a variety of different types of microorganisms that distort the biological balance and are also very harmful to the human health. In addition to organic pollution, the waste also causes inorganic pollution in the form of hazardous chemicals such as mercury compounds from batteries, etc. The karst areas have a rather poor self-filtering capacity and the majority of pollutants that reach the undergound come out with water. Different forms of destruction of speleological objects, such as vandalism, mechanical damages caused by different factors: stone quarry activities, road construction works, tunnel digging, power industry projects, spring water intake and concrete laying, etc. irreversibly alter or cause disappearance of subterranean animal habitats, but also of important archaeological and palaeontological finding sites. These activities should be conducted in such a way that destruction and their adverse effects be reduced to the minimum.
The modern industrial agricultural production with its progressive and frequently uncontrolled use of artificial fertilisers and a variety of treatments for soil quality improvement and pesticides are increasingly threatening the underground and its fauna. The process of industrialization and transport development very often result in pollution from heavy metals, but also oil derivatives as a result of road accidents. The subterranean fauna and fish that hide in the underground are very commonly endangered by allochtoon fish ranching, mostly by the Californian trout, but also by many other fishes and spreading of invasive species. Indigenous fauna is endangered by fish mainly in two ways, by predators and competitors in habitats.
Many subterranean animals are endangered by excessive and illegal collection of animals, primarily beetles. Beetles are mostly collected with a large number of baited traps. The collectors are frequently foreigners who do not collect the material for scientific purposes, but for collections and illegal markets.
Today bats are increasingly endangered by the human factor. In the past they would commonly get killed by intentional killing, whereas today they mostly suffer due to human alterations to their hunting habitats and destruction of their roosts. The traditional roosts are also destroyed when the caves, which have hundred year old bat colonies, are used for tourist purposes. For some species it is not even necessary to destroy their roosts, but is enough to disturb them while they are there, e.g. during critical times when they breed or hibernate, as they tend to leave their roosts if they feel it is not safe. Hence, this is an increasingly frequent occurrence due to exploitation of caves for tourist purposes. Unfortunately, it is not often the case that wealth of bats is taken into consideration while adapting caves for touristic purposes. For some more sensitive species the placing of a door with horizontal iron bars at the cave entrance is enough to make them abandon the cave as their roost.
Inadequate adaptations and exploitation of caves for tourist purposes have multiple adverse effects on the fauna. It results in endangerment of many winter, breeding and migrating bat colonies, which are forced to look for new, often inadequate roosts. Cave adaptations commonly show three basic mistakes: inadequate building interventions, excessive number of visitors above the acceptable capacity and inadequate lighting, which results in modifications of microclimate factors. The fauna hence retreats into less accessible parts of the cave that are sometimes inconvenient for some taxa. The development of flora, as a result of inadequate lighting, brings about the destruction of speleothems, which is an important geomorphological cave factor.
The subterranean fauna and bat fauna is legally protected by the Nature Protection Act of 2005 and the Ordinance on Protected and Strictly Protected Wild Taxa, and cannot be killed or disturbed at any cost and neither can their habitats be endangered or destroyed.
Bibliography:
Bedek, J., Bilandžija, H., Hamidović, D., Cvitanović, H., Dražina, T., Jalžić, B., Jalžić, V., Kovač konrad, P., Lukić, M., Miculinić, K., Ozimec, R. & Pavlek, M., 2009: Svijet ispod svijeta (World under World), Zagreb, p. 1-79.
