Effect Of Low PH On The Survival And Management Of Freshwater Aquatic Life

pH is an important factor to sustainable aquatic life because it effects the ability of such organisms to regulate and carry out vital life-sustaining processes, including the exchange of respiratory gases and salts within the water they occur. If the pH range exceeds the physiologically tolerated pH level of the aquatic organisms, then this can lead to mortality and diminished growth rate. There is no definite pH range in which all aquatic organisms can survive unharmed. The tolerance value ranges according to different species, as well as prior pH acclimatization, water temperature, dissolved oxygen concentration, and the concentrations and ratios of various cations and anions. In this investigation, only temperature of the water will be used alongside pH levels and number of dragonflies present at each site. According to Alabaster and Lloyd (1980), the pH range that is not directly dangerous to fresh water fish is 5.0 - 9.0. However, there are exceptions, with a pH value of 6.5 - 9 being satisfactory. Healthy waterbodies with productive aquatic organisms and macroinvertebrates usually have a pH of 6.5 - 8.5 units. There are only a few amounts of organisms which can survive outside the usual pH range, including algae which can survive at a pH of 2 units. Mosquito larvae and caddis fly larvae (Trichoptera) were found to exist in a stream with a pH of 2.4 units. An extreme decrease in pH levels of a water body, approximately below 5, will cause a decrease in the food supply for larger organisms and return disrupt food chains and the ecosystem. According to this article, studies have also shown that pH levels of between 9 and 10 can result in partial mortality of bluegill sunfish (Lepomis macrochirus), rainbow trout (Oncorhynchus mykiss), brown trout (Salmo trutta), salmon, and perch. The pH values of lakes and streams can change according to the time of day in response to photosynthetic activity. A review of the effects of rapid pH changes on benthic macroinvertebrates revealed evidence indicating that macroinvertebrates rapidly exposed to pH changes of one unit or more, when pH is maintained within the 6.5 to 8.5 range, would not experience mortality, or other long-term adverse effects. This information is reliable and credible because it was written by a specialist in the field of water and power resources. However, it could be biased as it was only written by one author.

Mature larvae and nymphs of 9 different types of species of aquatic insects (dragonflies, stoneflies, caddisflies, and mayfly) were observed and tested in a laboratory under the conditions of different pH values, ranging from 1 - 7. 10 specimens of each species was used. The investigation continued over a period of 30 days with 50% of the organisms dying between a pH range of 2.45 - 5.38 and 50% of the organisms began to emerge between a pH rang of 4 - 5.9. All of the 9 species, which were under observation and were tested on, were more sensitive to pH during their emergence stage. All the tests were conducted in a stainless steel tank (60.5 cm long, 23.0 cm wide and 10.0 cm deep). The functions of these steel tanks were to act as artificial streams in order to maintain various water flows. Five dipping birds were used, as well as an electrically operated solenoid valve to start or stop the water flow into the top row of water cells. There were two tanks which acted as control tests. Temperature of the water in each tank was also controlled and kept constant at approximately 18°C. This ensures that any changes are due to the pH and that the results are accurate.

Water from Lake Superior was used during the duration of the experiment. The water was dechlorinated using carbon filters, before the investigation commenced. The chemical make-up of the water was determined by means of standard methods and showed that it had a pH of 7.58 - 7.81. In order to ensure that healthy organisms were chosen from the collected material, they were placed in tanks with a temperature of 11-14°C and a pH level of approximately 7.8 for one week prior to the investigation. Each organism was fed twice a week during the investigation to ensure they are healthy and able to survive under normal conditions. As pH of the water decreased, the percentage of aquatic organisms which emerged successfully also decreased. According to this study, 50% of Opldofomphus rupinsulensis (dragonfly) died at a pH of 4.30 withing 30 days and 50% of them emerged at a pH of 5.2. Also, 50% of Boyerla vinosa (dragonfly) died at a pH of 4.42 within 30 days and 50% of them emerged at a pH of 5.2 therefore, a pH level of lower than approximately 4.5 will cause the dragonflies to not be suitable to the water and die. This experiment is reliable when it comes to the method because control variables were used and because it comes from the United States Department of the Interior, Federal Water Pollution Control Administration.