Aquatic Invertebrates

Collections begin by annual field sampling. ABMI field technicians sample an assortment of invertebrates from wetlands across the province via net sweeps at set points in a wetland. Habitat information such as water depth, temperature and chemistry, and vegetation type are consistently recorded and compiled from site to site and sample to sample. These samples are preserved and sent to the Processing Centre at the University of Alberta to be washed, subsampled, and analyzed.

1. Samples consist of invertebrates and numerous large pieces of vegetation. Vegetation such as submerged and emergent macrophytes, algae, and decomposing woody debris impede efficient subsampling and thus need to be removed. Samples are washed through an elutriation system that separates light-bodied invertebrates from dense vegetation pieces.

2. Washed samples are transferred to a Marchant box: a standardized Plexiglas box used to subsample the remaining organic material into manageable units. Invertebrates and small pieces of vegetative debris are distributed randomly across the Marchant box’s grid of 100 identical wells. Technicians use a random-number generator to select a corresponding unit that contains a small section of the sample. This unit is then closely examined for invertebrates present.

3. Invertebrates are removed and coarsely sorted into appropriate taxonomic groups. These groups are then examined by the aquatic invertebrate taxonomists who identify every invertebrate to the lowest taxonomic level possible. In some cases, an invertebrate can be identified to subspecies.

4. An average of 17,000 specimens are identified each year; these data are sent to the ABMI’s Information Centre to be analyzed. Identified specimens are stored in vials of 80% ethanol and are used in part in a voucher collection for future specimen referral. Currently, specimens are housed at the Royal Alberta Museum. 

• The Advance ID: Our aquatic invertebrate taxonomists renew their taxonomic certifications though the Society for Freshwater Science every five years. They always seek to improve their identification methods and refer to museum collections across Canada when needed.
• Some taxa present unique challenges for identification. For instance, tiny midge larvae (Family: Chironomidae) or freshwater worms (Family: Naididae) possess morphological features that are just too small to be seen by a dissecting microscope. These animals require an additional step of slide-mounting for accurate identification.