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Bio-indicators such as diatoms from algae considered to be key factors in ecological studies as an assessment of freshwater ecology. Algae are very sensitive to environmental changes and reflect the spatiotemporal changes on exists or biomass of diatoms in waters. Diatoms have been used not just for the assessment of water quality, but also can be used as an organic pollution indicator in the freshwater ecosystems, such as algal water bloom. The reason for using diatoms as bio-indicators was for several characteristics such as rapid growth, and represent high biomass in the freshwater ecosystem. Also, diatoms have high biodiversity among the other aquatic biota and energy flow and cycling. Compared with the other aquatic biota, diatoms reflect ecological disturbance due to high sensitivity to light, temperature, water flow, pH, and oxygen content. Additionally, diatoms are used as an assessment of eutrophication, organic pollution and climate change.

The current study included testing the toxicity of Mesurol pesticide and its effects on the freshwater snail Viviparous bengalensis. Snails’ mortality is recorded at each 24 hours with a replacement of solution toxicity in order to avoid volatilization. Value of LC50 is obtained and is (0.55) mg/l, during the period of 96 hours. No mortality is noticed in the control treatment for the duration of the experiment, and the toxicity of Mesurol pesticide is very toxic and deadly impact on the snails.

The first case of bacterial infection was recorded in 1862, while it was first isolated in 1882 from the scientist Gessard, who was called Bacillus pyocyaneus. The most common infections caused by bacteria are the first bacteremia in patients with serious burns, chronic lung injuries in patients with cystic fibrosis, and acute ulcerative keratitis in people who use contact lenses. The gastrointestinal tract is an important gateway for entry into the blood infection caused by bacteria, and the bacteria cause endocarditis, where the bacteria infects the heart valves from the direct invasion of the bloodstream, as it causes meningitis and brain abscesses, and it can invade the central organ The inner and nasal sinuses can also be accessed from a site far from the injury, such as the urinary tract. Other pathogenic infections caused by bacteria are pulmonary injuries, as bacteria are the most common disease associated with lung injuries. They are caused by bacteria Hospitalized lung with a mortality rate greater than 70%. Bacteria are a common cause and acquired by hospitals for urinary tract infections due to their ability to adhere to urinary epithelial cells in the bladder, as they cause cystitis and urinary tract infections. The percentage of deaths caused by bacteria can reach 50% due to many factors, including weak body defenses and bacteria resistance to anti-life as well as the production of bacteria, enzymes and external toxins.