Salinity In The Daphnia

Effects of salinity on the survival of the Daphnia

Introduction The Daphniidae daphnia is a freshwater crustacean from the branchiopod class that is common to most ponds, lakes, pools, streams and springs around the world. The water flea, as it is sometimes referred to, is very small in size growing to a length of less than ¼ inch, it has a flat back, a rounded belly, black round eyes and a pair of antennae (Kindersley, 2006). The Daphnia have leaf-like appendages used in respiration, filter feeding and locomotion (Miller, 2010). Unfortunately, due to the size of these crustaceans they are often easy prey for bigger organisms in their ecosystem. Daphnia are often found in the bottom layers of the water column during the day and the upper layer at night to avoid visually feeding fish (Dawidowicz, 1992).
Estuaries are partially enclosed coastal bodies of water that have an opening to the ocean (Columbia University Press, 2011). This opening causes freshwater from inland and saltwater from the ocean to mix, determining the populations and numbers of these daphnids in different areas of the estuary. Estuaries represent one of the most ecologically important habitats on earth because they serve as sanctuaries for a variety of vulnerable organisms. However, human impacts on these estuaries are having a negative effect on the life of organisms that have made these their home. One example is that the withdrawal of freshwater is increasing the levels of salinity into the estuaries making it uninhabitable for daphnia among other organisms (Columbia University Press,