Aquatic Macroinvertebrates

  The term macroinvertebrate does not respond to a taxonomical concept but to an artificial delimitation of part of the groups of invertebrate animals. In running waters, we generally consider as macroinvertebrates those organisms large enough to be able to be caught with a mesh size of 250 μm, and thus observed at first sight. In fact most of them are larger than 1 mm in size. Despite the general definition given above, some animal groups that could fit in it are never considered as macroinvertebrates (i.e. Protozoa and Tardigrada), while other groups (i.e. Nematoda, Nematomorpha, Cladocera, Copepoda, etc.) are not taken into account by methodologies based on macroinvertebrates. Mostly (around 80%) belong to arthropods, mainly insects and especially their larval stage are the most abundant.
     Aquatic macroinvertebrates are inhabitants (at least during part of their life cycle) of the benthos aquatic systems (sediments, trunks, rocks, litter, macrophytes, etc.). They are ubiquitous and abundant organisms, and therefore could be affected by environmental perturbation in different types of aquatic ecosystems.
The elevate number of species provides a big number of responses to different perturbations, both physical and chemical (organic pollution, eutrophization, acidification, habitat alteration, hydrological regulation, canalizations, etc.). Similarly, their sedentary nature allows spatial analyses of the perturbations, and their long life cycle compared with other groups, allows identifying temporal changes on such perturbations (Helawell 1986; Newman et al. 1992; Rosenberg y Resh 1993; Hering et al. 2004; Alba-Tercedor, 1996, 2006; De Pauw et al. 2006).