It is one of the most commonly measured water quality variables in aquaculture, and probably the most misunderstood water quality variable in aquaculture. The pH levels in water have a propensity to change rapidly, but this is a natural phenomenon
Phytoplanktonic organisms, or microalgae, are very abundant in aquaculture ponds and have critical roles in these ecosystems, significantly influencing overall pond ecology and water quality. Proper management of phytoplankton populations is essential for successful aquaculture pond production.
Light penetrating water is scattered and absorbed exponentially as it passes downward. The presence of dissolved organic matter and suspended solids further impedes light penetration, and different types of solids absorb different wavelengths.
The silicon plants take up in silicic acid from water strengthens cell walls. Among the phytoplankton, diatoms particularly need silicon.
Animal manures, grasses and other organic matter have been widely used as fertilizers in aquaculture ponds. The fertilizers decompose and release nutrients that promote the growth of phytoplankton and enhance the base of the food web.
The simplest tool for assessing phytoplankton abundance in aquaculture ponds is the Secchi disk. An electronic turbidimeter can be used to measure the amount of light scattered by a water sample.
Aquaculture ponds typically have ideal conditions for the growth of various species of phytoplankton. Green algae are considered most desirable in freshwater ponds.
Iron supplementation of pond fertilizers can improve their effectiveness in promoting phytoplankton growth. Ferrous iron in bottom sediment precipitates hydrogen sulfide gas produced by microbial activity.
Phosphorus from uneaten feed and feces of culture animals can cause excessive phytoplankton growth and associated degradation of water quality.