Region 1: EPA New England
Macro Invertebrate Equipment
General Description
The macro invertebrate equipment described below is utilized in assessing the biological integrity of stream ecosystems. Macro invertebrates are collected and identified to help determine what type of aquatic life the stream ecosystems are sustaining.
Several different types of collection methods are utilized in collecting macro invertebrates; kicks, jabs, and sweeps. The different types of stream habitats are sampled in proportion to their representative surface area of the total sampling reach. For example, if fifty percent of the stream reach was comprised of riffles, then fifty percent of the samples would be collected from these areas. Sampling begins at the downstream end of a reach and continues upstream until all samples have been collected.
Equipment
The following is a list of equipment needed to perform the collection of macro invertebrates:
- A large kick-net (500 µm)
- A one-fifth meter square quadrat
- A holding bucket with an opening mesh at the bottom (500 µm)
- A large sample container to hold the macro invertebrates and transport to lab
- Data sheets and writing utensils
Significance to Biological Integrity of Stream Ecosystem
A
combination of 20 jabs, kicks, or sweeps are taken over the entire
length of the reach. A jab consists of forcefully thrusting the
kick-net into a productive habitat for one minute in duration. A
kick is a stationary sampling accomplished by positioning the kick-net
and disturbing the substrate for a minute in duration upstream of
the net. A sweep consists of sweeping or “bumping” the
net along the stream bottom in a silty substrate area for a duration
of a minute.
The three different methods, jabs, kicks and sweeps, are used to collect a sampling of the macro invertebrates in a stream ecosystem depending on the types of macro habitats that are present. The abundance and types of macro invertebrates collected are indicative of what level of water quality and physical impairments occur within a stream. Certain species of invertebrates can only survive in fast flowing, cold, and well oxygenated waters. Other types thrive in poor quality waters. When sampling results don’t reveal what would be typically expected for the stream type samples, biologists can look closer at possible sources in the watershed causing impairments to the system.