Skip to main content
In partnership with the NYS Housing Trust Fund Corporation, Housing Action Council and select municipalities, Habitat for Humanity will coordinate the construction of accessory apartments on the properties of low- to moderate-income residents of Bedford, Dobbs Ferry, Hastings-on-Hudson, Irvington, Cortlandt, Croton-on-Hudson and Yorktown. 

For additional information please visit Plus One ADU - Habitat NYC and Westchester

Water Critters

Critters without a backbone that live in the water and are large enough to be seen with the naked eye are called macroinvertebrates. These small critters are vital to an aquatic system. They make up the bottom of the food chain, serving as food for fish, birds and other larger animals. Examples of some common ones that can be found in streams in Westchester County are:

Young dragonfly
Young Mayfly
Crawfish

Young Dragonfly

Young Mayfly

Crawfish

Some species are more sensitive to pollution than others. For example the young mayfly (pictured above) is only found in streams with excellent water quality, because mayflies cannot survive in polluted water. On the other hand, species like aquatic worms and leeches are often found living in somewhat polluted stream sections. These species are called pollution tolerant. Determining what species of macroinvertebrates are present in a stream is an important tool in determining water quality in lakes and streams.

In fact, it can be argued that macroinvertebrate composition is a better indicator of the health of streams than chemical testing. Since water flows downstream, chemical tests can only identify pollutants in the water during that brief period of time when testing, it is just a snapshot.

On the other hand, macroinvertebrates are around much longer than most chemicals because they are unable to travel great distances. If the stream stretch they live in becomes polluted they cannot get to cleaner water because their small size makes it impossible to swim very far. Pollution sensitive macroinvertebrates will die if the contaminant remains in the water or is extremely harsh. In such a case, a macroinvertebrate sample will contain only pollution tolerant species, while a chemical test may show no sign of the pollution. Macroinvertebrates are an important tool to monitor water quality.

The report "Assessment Using Benthic Macroinvertebrates" is a collaborative study completed among 6 states along the Mid-Atlantic seaboard. In this study, a consistent approach was developed for collecting and interpreting macroinvertebrate data for low gradient nontidal coastal streams. 

The following resources will help you identify the aquatic critters you found.