Site selection for aquaculture: plankton and benthos

The organisms in the aquatic environment can be devided into three large groups - the plankton, nekton and benthos. In the benthos are included sessile, creeping or burrowing organisms found in the bottom of water bodies. The nekton is composed of swimming animals such as the fish and in the plankton is included all of the floating or drifting organisms. The term plankton was proposed by Victor Hesner in 1887 to designate that “heterogeneous assemblage of organisms which float and move at the wi ll of the waves and other water movements”. Much of the available information on plankton and benthos existing refer to those in natural water bodies, often large lakes and seas, which are described well in text books of limnology and marine biology - oceanography. These are also certainly of aquaculture importance in special cases, especially coastal aquaculture (“Pen and cage culture”) and also in extensive aquaculture, beginning with “stocking of open waters”, both natural and man-made. O ur interest here is to increase the richness of the water bodies by water quality assessment (physical and chemical feature of water, we already referred to in chapter 8 and 9 and also biological productivity, referred to in chapter 10), to judge their suitability for aquaculture. While biological productivity of a water body can be obtained by measurement of primary productivity, a good index of biological productivity is the measure of abundance of plankton and benthos.