By Ty Colvin, PhD candidate at McGill University ; On behalf of the Quebec Student Subunit of the American Fisheries Society

This past summer the Quebec Student Subunit of the American Fisheries Society (AFS Quebec) held an aquatic biodiversity bioblitz on iNaturalist with support from the Quebec Centre for Biodiversity Science Champions Grant. We set out to “Blitz the Gap”, a Canada-wide BioBlitz initiative to fill in gaps in species data using iNaturalist. Our goal was to target the gaps in underrepresented freshwater diversity through the “Make a Splash” project (https://www.inaturalist.org/projects/blitz-the-gap-make-a-splash). Many species of aquatic invertebrates are underrepresented on iNaturalist as they can be difficult to find, photograph clearly, and identify to genus/species; however, they make up an incredible diversity of our freshwater species. Therefore, on iNaturalist, aquatic invertebrate species distributions are extremely limited, with even common taxa often having few observations on iNaturalist. 

On July 19^th, a crew of 13 AFS Quebec members set out to capture some of this diversity at two locations near the island of Montreal: Bray Island Park and Île Claude. These locations are both within the Ottawa River at its confluence with the St. Lawrence River. Despite being in close proximity to the city of Montreal, the small invertebrates we were seeking are rarely posted to iNaturalist. With our waders on and nets in hand, we went into the river and collected invertebrates from various substrates – insect larvae and nymphs from stones, fingernail clams and mussels from mud, and snails and hemipterans from weed beds. We set up our IDing station with tubs, magnifying glasses, and ID guides to sort through our specimens and identify them.

At both sites we found several net-spinning caddisflies (Polycentropodidae, Hydropsychidae, and Philopotamidae). These don’t build and carry around a cylindrical case like most other caddisflies, rather they spin nets of silk and set them into the current to catch drifting prey. Net-spinning caddisflies function much like underwater spiders, hiding in retreats at the base of their nets until something is caught, after which they will emerge to feed. Each species will spin a slightly different net – some are straight or curved-trumpet shaped tubes, while others are built within larger stick/stone retreats held together with silk (such as Macrostemum zebratum, see picture below).

Another favourite specimen among the collectors were the water scorpions. Water scorpions are not actually scorpions, rather they are hemipteran insects with a breathing appendage (snorkel) in the back to let them sit just under the water’s surface waiting to seize prey with their raptorial claws.

In total, we made 155 observations of 75 species, and awarded the participants who made the most observations and saw the most taxa. It was our first BioBlitz event with AFS Quebec and it was a great success thanks to the Quebec Centre for Biodiversity Science and the Blitz the Gap Champions Grant!