Biological indicators of river pollution must meet the following criteria:
1) Easily identifiable
2) Easy to be sampled, which means the operator does not need special assistance, as well as expensive equipment and can be done quantitatively.
3) Have a cosmopolitan distribution.
4) The abundance of a species can be used to analyze the diversity index.
5) Has the economic sense as a source of income (such as fish), or pests / intruder organism (eg algae)
6) Easy collecting / hoarding contaminants.
7) Easily cultivated in the laboratory.
8) Have a little diversity.
To consider in selecting biological indicators are each species has a specific response to pollution. Fish is hard to use as an indicator of the population. It’s easier to use other aquatic species that are not agile motion. Biological parameters commonly measured in observations of water quality for aquaculture is plankton, nekton, neuston, periphyton and benthos because each has distinct characteristics.
1) Plankton
Plankton is derived from the Greek ‘planktos’ which means to wander or roam. Then plankton defined as a collection of organisms (mostly microscopic), represented by almost all groups of plants and animals world, both as a primary producer, herbivore, carnivore, as well as transformers (such as fungi and bacteria). The way these organisms can live as a saprophyte or parasite.
This group lives passively floating in water, so it can be washed away. Although no one can move to certain organs and mechanisms, relatively weak movements. Margalef (1955) and Dussart (1965) in Subandiyo (1992) made a classification or classification of plankton based on differences in size, as shown in Table 11.
2) Benthos
Benthos is an organism that is attached to or resting on the base or living on the sediment bottom waters. Bentos can be divided into zoobentos (animals) and fitobentos (plants). Benthic animals live relatively sedentary, so that both are used as an indication of environmental quality, because it is always in contact with the waste that goes into their habitat. The animal groups can better reflect the changes in the environmental factors from time to time, because benthic animals continually exposed by the water quality is changing.
Among the benthic animals are relatively easy to identify and are sensitive to changes in the marine environment are the types included in groups of macroinvertebrates. This group is known as macrozoobenthos.
3) Nekton
Nekton is a group of organisms that live in the water column (water column), both in freshwater and sea. The word “nekton” awarded by Ernst Haeckel in 1890 were derived from the Greek word (Greek) which means swimming (the swimming pool) which includes (biofluidynamics, Biomechanics, functional morphology of fluid locomotion, locomotor physiology). His knowledge and his so-called Nektology called nektologis.
4) Neuston
Neuston is a term for organisms that float on the water (epineuston) or live just below the surface (hyponeuston). Neuston sometimes simply rely on the surface tension of water to maintain its position float on the water surface. Neustons consists of several species of fish that like to live on the surface of the water like a flying fish. Another example is the neuston, beetles, protozoa, bacteria and spiders.
Pictures. Neuston Insects Water