There are a number of physical, chemical and biological factors that influence the composition and abundance of zooplankton communities. Factors recognised mostly are temperature, pH, and availability of food, in natural environment these act simultaneously causing it to interact to different degrees modifying the zooplankton structure in many ways.
Temperature controls the reproductive rate, population size and metabolism of the species (Edmondson, 1965). In tropical regions, precipitation and wind are significant physical factors affecting zooplankton structure (Matsumara-Tundinsi & Noguiera, 1996). Predation by fish may affect its structure as well in accordance with the fish feeding mode: selective feeders, differential capture of organisms, tendency to eliminate large species which are replaced by less vulnerable forms (Brooks & Dodson, 1965). The diversity of species may be less sometimes but the abundance of a single species may be superior over other groups, and the abundance of zooplanktons has a relation to hydrography, physico-chemical factors and availability of phytoplankton. Temparature and pH are both positively connected to species diversity while conductivity and salinity are negatively related. Quality and quantity of food, interference competition, predation and ecological conditions influence plankton communites which will lead in favoring species over others that is why reservoirs mostly found in Brazil is dominated by Rotifers,
Based from a study conducted by (Lirio & Labana, ) Copepods became dominant in Laguna de Bay which can be compared to the data gathered by (Sampaio et al, 2002) wherein Rotifers normally outweigh tropical waters. Species diversity is lower during summer months and higher during winter months which will result that the richness of some copepods have an accurate evidence (Duggan et al, 2001) that the changes in water temperature would really play a significant role.