Imagine yourself near a body of water. Where would you look to find fascinating species that you have never seen before? You might check the vegetation, the bank, the water itself or maybe the surface. But what if I told you there is an entire world waiting to be explored at the bottom of the water? You might wonder what could possibly be found in mud or rocks, and what could possibly make them special. But if you had seen benthic macroinvertebrates before, your perspective would likely be different.
What are benthic macroinvertebrates?
Benthic macroinvertebrates (BMIs) are organisms that lack a backbone, are visible to human eyes and are found at the bottom of a body of water. It may come as a surprise, but you might be more familiar with BMIs than you think. Organisms that fall under this category range from larvae of dragonflies, damselflies, moths, and butterflies, to aquatic beetles, snails, crayfish, mussels, and clams.
BMIs are fascinating creatures. Caddisflies, for instance, can create jewelry if you provide them with materials during their cocoon-making phase. Mayflies have been around longer than dinosaurs, dragonflies are the most efficient hunters in the animal kingdom, and many, such as diving beetles, carry their own air supply while submerged.
Small but Mighty Role
Aside from their fascinating adaptations, BMIs play a crucial role in water assessment as significant bioindicators, which means they provide information about the status of an ecosystem. Found in nearly all aquatic ecosystems, they are mostly accessible to scientists. BMIs are generally less capable of avoiding the effects of pollutants than other aquatic inhabitants. Some species are more sensitive to pollution, so the presence and abundance of certain species can indicate pollution levels at sampling sites.
Bioindicators like benthic macroinvertebrates show how organisms react to environmental stressors over a long period, minimizing the impact of pollutant fluctuations on the report.
Brief History of BMIs in Water Monitoring
Water monitoring in North America became prominent around the mid-20th century, with visual observation of the water’s colours and odours as the main indicators of the water quality. By the 1970s, scientists started to use chemistry for testing. Soon afterward, scientists realized water chemistry alone provided poor evidence for water quality, and bioindicators such as benthic macroinvertebrates began to be sampled in water monitoring.
Currently in Ontario, scientists follow the methods from the Ontario Benthos Biomonitoring Network and the Ontario Stream Assessment Protocol when sampling benthic macroinvertebrates.
Benthic study workshop, Ontario Nature Annual Gathering 2015 © Michael Wynia
5 BMIs You Need to Meet
Stonefly
Stonefly larva © Emmett Blanchett-Neheli CC BY-SA 4.0, iNaturalist
Crane fly
Crane fly larva © Bob Hendricks CC BY-SA 2.0
Fishfly
Fishfly larva © Santosh DT CC BY-SA 4.0, iNaturalist
Caddisfly
Caddisfly larva © Andrew Hoffman CC BY-NC-ND 2.0
Aquatic Beetle
Harris’ diving beetle larva © Emily Palahnuk CC BY-SA 4.0, iNaturalist
Get Involved
To learn more about benthic macroinvertebrates, check out EcoSpark’s BMIs Guide and The Atlas of Common Freshwater Macroinvertebrates of Eastern North America.
Test out your skill at EcoSpark’s BMIs ID Quiz.
Volunteer in BMIs community science monitoring like Citizen Scientists.
Resources
The post Below the Surface: The Hidden World of Benthic Macroinvertebrates appeared first on Ontario Nature.