Aquatic organisms are extremely sensitive to their environment. Crawling along the bottom of waterbodies across the globe. They serve as mobile water quality detectors. Although some aquatic macroinvertebrates such as midges, dobsonflies, some beetles, and worms can thrive in heavy silt, high nutrient, high temperature, and extreme pH waters. Other taxa of aquatic macro invertebrates serve as pollution indicators, and are known as pollution sensitive taxa. These pollution sensitive taxa include stoneflies, and some genera of mayflies. Moving up in the food chain, axolotls and other amphibians are often noted as common indicators of water quality due to the sensitivity of their skin to the environment. Additionally, amphibians populations have been on a drastic decline over time, a trend which has been linked time and time again to pollution among other factors. However, this sensitivity may not be as high as previously predicted based on studies conducted by Jacob Kerby et al., in 2010.
Kerby and his co-authors analyzed 28,000 pollution studies and generated the trend graphs pictured below. Together the data showed that sensitivity is based largely on the type of pollution, but also showed amphibians to be middle ground or poor indicator in many cases. It is possible that together these organisms could be used to generate a comprehensive biological report of Water quality. However, it appears that especially in the case of amphibians, that habitat destruction has the greatest effect on the survival these organisms (Chanson et al., 2008), so without parameters to quantify the habitat change parameters, this may be an incredibly difficult task. Despite the effect humans have had on habitat destruction, biologists use a variety of parameters, both physical such as sedimentation, chemicals, and temperature as well as biological parameters such as fish population surveys, and the use of macro invertebrate surveys, and algal analysis to determine changes over time. However, these sampling events represent random time point analyses which usually occur once a year, and are often influenced by recent weather events. Therefore, the field is moving towards ways to determine changes overtime and although collecting a net full of bugs requires much less maintenance than scrubbing out a silted up stream sensor, the future of impairment and stream health decisions may be moving towards reliance on data-intensive monitoring campaigns.
Chanson, J. et al. (2008). The State of the World’s Amphibians. In: Stuart et al. (Eds.) Threatened Amphibians of the World, pp. 33-52. Barcelona/Gland/Arlington: Lynx Edicions/IUCN/Conservation International.
Kerby, J. et al. (2010). An examination of amphibian sensitivity to environmental contaminants: are amphibians poor canaries? Ecology Letters, 13(1), 60-67. doi:10.1111/j.1461-0248.2009.01399.x