Sensitive records of climate change have been developed from a variety of indicators including, for example, paleotemperature reconstructions derived from chironomid fossils, and palaeosalinity records inferred from diatoms. Freshwater macroinvertebrates (invertebrates that can be see by naked eye; > 0.25 mm) are a very diverse group of small animals present in rivers, streams, lakes and wetlands. These animals include crustaceans, insects, molluscs, annelids and arachnids. They comprise a functionally and taxonomically diverse group that plays an important role in linking the food web in the aquatic ecosystem. They serve as a main source of food for the fishes and they depend on different types of algae and bacteria for the food. Most aquatic macro-invertebrates are small while some are quite large such as freshwater crayfish. They are very sensitive to different physical and chemical conditions and respond to it accordingly due to their limited mobility. For example, their community will change when a pollutant enters into the water or due to the change of water quality. Therefore, the water body which is rich with a macro-invertebrate community can be used to provide an estimate of water body health. Macro invertebrates termed "benthos" inhabit surfaces of vegetation, rocks and other aquatic sediments. They are widely distributed in the aquatic environment and present at a range of trophic levels. Most macroinvertebrates taxa are dependent on a range of abiotic factors and biotic factors and therefore community structure can be used to represent the local ecosystem. These factors may be the availability and quality of food, pH, temperature, salinity, land use pattern and water flow etc. These factors are interconnected and influence each other. For example, any change in the land use affects the riparian vegetation that may be increased or decreased which changes the inputs into the aquatic ecosystem, affecting the abundance and distribution of macroinvertebrate taxa. For all of these reasons, macroinvertabrates are considered as one of the best indicators of water quality. Taxonomic groups of macroinvertebrates vary in their tolerance to changes in the aquatic environment. Macroinvertebrateas are commonly and widely distributed in many types of water bodies and respond with a range of sensitivities to many kinds of stressors. They are commonly used for toxicity testing and ecological assessments in water bodies and many of them complete their life cycles in a single water body so they are exposed directly to physical, chemical, and biological stressors and they also integrate the long and short term changes.