Benthic macroinvertebrates are a one of the basic biological elements to be monitored under the Water Framework Directive, for the ecological status classification of inland surface waters.
The advantage in using benthic macroinvertebrates lies in the abundance that they are found in natural systems under any conditions with a high species diversity covering an extensive range of response to pressures and a low mobility that characterises their aquatic life cycle. They are able to provide a “historic” representation of pollution of aquatic ecosystems, and are therefore sampled seasonally (in contrast to physicochemical elements), decreasing the cost of constant monitoring. The use of benthic macroinvertebrates to assess ecological status has a long scientific tradition and is useful in showing evidence of environmental degradation caused by anthropogenic impact, such as organic and chemical pollution, hydromorphology, etc.
Two (2) different methods are being used for IMBRIW benthic macroinvertebrates field operations, according to the requirements of scientific research programs:
1) The STAR-AQEM method (www.eu-star.at):
a semi -quantitative method, widely used across Europe through the implementation of various European programs. It provides evidence of the overall stream condition, including hydrogeomorphology, riparian zone condition, anthropogenic pressures and land uses. The STAR-AQEM methodology was designed for use in WFD monitoring programs. Sampling site selection is the first step of the process; and should be based on the representativeness of the physical and ecological characteristics of the entire stream, or at least of the study area.
The STAR-AQEM methodology is based on the multi- habitat approach (Barbour et.al, 1999). It is designed to enable distribution of the sampling units according to the estimated microhabitat (habitats that cover at least 5% of the sampling site) distribution of a sampling site. Twenty (20) sampling units are collected from microhabitats categories, found in the STAR-AQEM protocol. Sampling units are the samples collected with a hand net from an area of exact size as the frame of the net (covering 1.25 m2 of the riverbed), using stationary method. Sampling starts from downstream, moving upstream, over an area of 50 to 100m (for streams and rivers respectively
2) The three-minute kick-sampling (ISO 7828, 1985) method:
the most widespread, semi -quantitative and simple method for macroinvertebrate sample collection. It lies on identification of different habitat types; each habitat type is the scanned within a 3 minute period. The potential habitats are identified using a list of habitats (Chatzinikolaou et al., 2006). The handnet is placed downstream of the sampler that agitates the river bottom for 3 minutes, causing benthic macroinvertebrates to flow into the handnet.
In case of rocks and boulders the sample is collected manually by inverting the obstacles. A sampling protocol is filled out with site location/date/sampler information, physicochemical and hydromorphological parameters at the time of the sampling survey. After collecting 2-3 sampling units, the sample is rinsed out 2-3 times into a basin, using clear running stream water. Then it is transferred in clear sampling containers and is sealed after adding 95% ethanol as a preservative agent. The samples are transferred into the lab for systematic taxonomical classification and identification