Ministry of Forests, Lands and Natural Resource Operations

Aquatic Ecology

The aquatic invertebrate community in 240, 241 and Dennis Creeks is dominated by the larval stage of aquatic insects, as well as by flatworms and seed shrimp. Diptera (True flies) are the most abundant aquatic insect in these headwater creeks, followed by Ephemeroptera (Mayflies), and Plecoptera (Stoneflies). Only a few Trichoptera (Caddisflies) were collected in the three creeks. The larvae of mayflies, stoneflies and caddisflies are considered intolerant of disturbance, while those of the true flies are considered tolerant of disturbance.

Order Ephemeroptera (Mayflies)

Order Ephemeroptera (Mayflies)

Mayfly larvae have gills located on their abdomen, have one or two “tails”, and have one claw per leg. We collected larvae of the families Ameletidae, Baetidae, Ephemerellidae, Heptageniidae and Leptophlebiidae.

Order Plecoptera (Stoneflies)

Order Plecoptera (Stoneflies)

Stonefly larvae have gills located on their thorax, always have two “tails”, and have two claws per leg. We collected larvae of the families Chloroperlidae, Leuctridae, Nemouridae and Perlodidae.

Order Trichoptera (Caddisflies)

Order Trichoptera (Caddisflies)

Trichoptera were the most taxonomically diverse group of insects collected, but they were also always the least abundant. Families present in our samples were Glossosomatidae, Hydropsychidae, Lepidostomatidae, Limnephilidae, Philopotamidae, Rhyacophilidae and Uenoidae.

Order Diptera (True flies)

Order Diptera (True flies)

The larvae of true flies lack the three pairs of jointed legs on the thorax found on mayflies, stoneflies and caddisflies. The overwhelming majority of diptera larvae were in the family Chironomidae (non-biting midges), but we also collected black fly larvae (Simuliidae; photo), and crane fly larvae (Tipulidae).