PARASITES IN THEIR ROLE AS BIOINDICATORS WATER QUALITY

The parasite that has been widely known is a harmful organism where the life phase is very dependent on the host as a place to live, the presence of parasites causes disruption of physiological activity, organ damage to the death of the host. No exception to parasites in Tilapia where these fish are easily found in Tukad Badung Waters, moreover at several locations such as the Fishing Park which is always crowded and other points along the Tukad Badung River. Based on the location of living parasites on its host, there is an ectoparasite that is attached to the outside while the endoparasites attach to the internal organs of the fish's body. But in addition to its detrimental nature, fish parasites also have the potential as useful biological indicators in efforts to biomonitoring the health of river’s ecosystems. The requirements that must be fulfilled as bioindicators must include criteria that are sensitive to environmental stressors and have a fast response to environmental changes, are easily measured, abundant or are easily found in waters.

               One of the influence of the excistence of parasites its self is because of  environmental conditions of the waters that support parasitic life. Like the river waters in the middle of big cities like Tukad Badung where along the river flows are densely populated settlements with a variety of community activities which certainly allows a lot of pollutant input that can have an impact on the decline in river water quality. Various kinds of environmental stressors present in the waters allow fish parasites to also respond quickly to these environmental changes. Under conditions of poor water quality, several types of ectoparasites in fish tend to be abundant. However, if the stressor of the aquatic environment gets higher, ectoparasites will no longer be able to tolerate the condition, which in the end is rarely found or not even found. While there are also parasites that can still survive because it is still protected by the organs in the body of the fish, including endoparasites.

               Therefore some further studies are needed regarding the inventory, composition and diversity of parasites both on Tilapia and other types of fish that inhabit aquatic habitats, such as the Tukad Badung River. Changes in species composition, parasitic diversity can be a clue to changes in the aquatic environment. At several points in the river waters, there are differences in composition and diversity of parasites, both ectoparasites and endoparasites based on the environmental conditions of the waters. This can be used as preliminary information related to early warning of declining water quality. Thus the other side of the parasite which is not only known as a harmful organism, but has a role as a biological marker that can provide information related to changes in water quality which can later be used as biomonitoring in order to create a sustainable ecosystem balance for public welfare.