Generally the presence of plankton in the water will be influenced by the type of waters (running and stagnant), quality of the chemistry and physics of water (eg, temperature, brightness, flow, pH, CO2 content is free, the content of nutrients), and their competitors and or predators of plankton. In the stagnant waters (eg, ponds, swamps, lake, lake), the presence of plankton will vary from time to time (temporal differences) and different in occupied space or the water column (spatial differences).
While in the flowing waters of the elements of time and space is relatively not significant, except if there are cases of river pollution by human activities. Based on the type of plankton can be divided into:
(1) Phytoplankton (plants) gets food from the diffusion of water and some are able to photosynthesize, acting as primary producers in the waters. Cyanophyta, Chlorophyta and Euglena is abundant phytoplankton species in freshwater, while dinoflagellate and pyrrophyta numerous in marine waters.
The role of phytoplankton in the water acts as:
(a) is used as a natural food animal aquaculture
(b) is used to determine the climate in different geological periods in determining palaeontologist (fossil) like cocolithopora and diatoms that have skin (skeleton) which is capable of acting identify natural areas of the sea.
(c) Specific features abundant species in an area used as an indicator of fertility terentu waters of the tropics and subtropics.
(d) Serving as a secondary indicator of pollution, as the detection of the presence of zooplankton which consume them.
(e) On a 100% marine phytoplankton are eaten by zooplankton, whereas only 10% marine phytoplankton are eaten by zooplankton
Figure 18. Plankton Phytoplankton
(2) Zooplankton (animal) is able to move horizontally and vertically but weak, dominated by crustacean and cladosera. Zooplankton can also be used as an indicator of pollution. Zooplankton are divided into 2 groups based on the phases of his life, namely:
(a) holoplankton, an organism whose entire life has properties planktonic phase (example: Diatoms, Dinoflagellates, Copepode)
(b) meroplankton, some of the organisms that are planktonic life phase before developing into nekton or benthos (eg larval sea cucumbers, starfish larvae, the larvae of marine worms)
Plankton in the water acts as:
(a) Caterers starters for all consumers: children zooplankton and fish
(b) Sources of dissolved oxygen (photosynthesis)
(c) The foundation of the food in the water cycle
(d) an indication of pollution of waters
Figure 18. Zooplankton Plankton