Benthic macroinvertebrates (macros) are spineless bugs, visible to the naked eye. They are often the nymph and larvae forms of many familiar creatures buzzing and crawling around you every day. You may know them as adult dragonflies, mosquitoes, crane flies, stoneflies and many more. What you may not know, is that these critters can say a lot about the quality of the network of streams they live in, including your source of drinking water.
Unlike fish, macros aren’t as mobile and tend to live within the same area of a waterway for this phase of their lives, clinging onto stones, river banks, leaf packs and anything with an inviting surface. For a macro, it may be nice to call a section of a stream “home,” however with limited mobility; their habitat’s quality is at the mercy of external sources of contamination.
Natural waterways may often be forgotten as insignificant reservoirs of life, but ALL life depends on access to clean water – including humans. Most people in America have access to a kitchen faucet which provides fresh, drinkable water. Most people do not think about exactly how the water gets to that faucet, since clean water is a given to most people in developed countries.
It takes a major event such as the water crisis in Flint, Michigan or Hurricane Harvey, Irma, or Maria to get people to remember that there is a complicated treatment process to ensure clean water. You may remember that in 2014, the City of Flint, decided to use water from the Flint River, which unfortunately was too corrosive for many of the city’s lead-based water service lines, resulting in a lead contamination in the city’s water. More recently water treatment plants in storm affected areas were overwhelmed with flood water, pollutants and debris.
Rivers are a common source of drinking water to cities, including Philadelphia which uses the Schuylkill River. Water treatment plants will filter, disinfect and remove most contaminants. However, our waterways are becoming a more and more complicated pharmaceutical soup, making it impossible to remove everything.
By engaging public awareness through biological sampling of macros, it is possible to inexpensively evaluate a waterway’s quality. Not all macros tolerate pollution the same way and depending on the abundance, diversity, presence, and even absence, one can get an idea of how contaminated a particular section of a stream may be. A biological assessment won’t tell you the exact cause, but it will point an observer upstream in the right direction. Perhaps there is a sewerage discharge, industrial dumping, or major runoff from a busy commercial district.
Conducting your own biological sampling is a fun way to engage members of the community. There are many instructional resources online, and contacting your local environmental center is the best way to learn about safe sampling methods in your community. To learn more about sampling in the Philadelphia area, you can contact the TTF Watershed Partnership in Northeast Philadelphia, the Cobbs Creek Community Environmental Center in West Philadelphia or John Heinz National Wildlife Refuge in Southwest Philadelphia.