Donna J. Giberson

Species diversity and emergence patterns of nematocerous flies (Insecta: Diptera) from three coastal salt marshes in Prince Edward Island, Canada

Emerging insects were monitored every 10 days between early May and late August 1993, from tidal pools in three coastal salt marshes on Prince Edward Island, Canada. The salt marsh pools ranged from about 1 m2 to > 1,000 m2 in surface area, and had salinities ranging from 11–27‰ Water temperatures through the study period ranged from 4–46°C. Most of the emerging insects were flies (Diptera; 85%), and two-thirds of these were in the sub-Order Nematocera, mainly Chironomidae, Ceratopogonidae, and Culicidae. Forty-three species of Nematocera were identified, although most of these were rare occurrences, and twelve of the species are undescribed. No consistent relationships were found between abundance or diversity and pool size or marsh for Nematocera species overall, although some species showed a statistical preference for a particular marsh or pool size. Emergence patterns were consistent between marshes for species found in different marshes, but overall patterns were highly variable, depending upon species.

Life history of the northern mayfly Baetis bundyae in Rankin Inlet, Nunavut, Canada, with updates to the list of mayflies of Nunavut

Mayflies (Ephemeroptera) were collected from 35 sites (streams and tundra ponds) across southern Nunavut in 2002–2005. Nine mayfly species were previously reported for Nunavut: Acentrella feropagus Alba-Tercedor and McCafferty, Acerpenna pygmaea (Hagen), Baetis bundyae Lehmkuhl, B. flavistriga McDunnough, B. foemina McDunnough, Diphetor hageni (Eaton) (Baetidae), Ephemerella aurivillii (Bengtsson) (Ephemerellidae), Leptophlebia nebulosa (Walker) (Leptophlebiidae), and Metretopus borealis (Eaton) (Metrotopidae). We add 7 species to this list, bringing the total to 16: Ameletus inopinatus Eaton (Ameletidae), Acentrella lapponica Bengtsson, Baetis hudsonicus Ide, B. tricaudatus Dodds, Heptagenia solitaria McDunnough (Heptageniidae), Rhithrogena jejuna Eaton (Heptageniidae), and Parameletus chelifer Bengtsson (Siphlonuridae). Based on numbers collected, the dominant mayfly family was Baetidae. Baetis bundyae was the most common mayfly collected, particularly in coastal areas, where larvae were found in perman...

Effects of an azinphos-methyl runoff event on macroinvertebrates in the Wilmot River, Prince Edward Island, Canada

High levels of azinphos-methyl (0.4–0.8 μg/L) were detected in the Wilmot River, Prince Edward Island, Canada, following runoff from an agricultural field after a heavy rainfall on 19 July 2002. Benthic macroinvertebrate abundance and diversity were sharply lower in samples collected 1 d after the event compared with samples collected in the same manner in July or October 2001. The greatest effects were noticed on the aquatic insects, whose abundance declined from >10 000 individuals per 3-min kick sample in July 2001 to <900 individuals per 3-min kick sample in July 2002. One family of Diptera, one family of Plecoptera, and three families of Trichoptera disappeared entirely from the study reach after the runoff event, and several other families were severely depleted in number. This led to low taxonomic similarity values between the communities before and after the runoff event and a change relative to reference streams on PEI. Examination of biological metrics (including indices such as % EPT (Ephemeroptera, Plecoptera, or Trichoptera), % chironomids, % burrowers, etc.) confirmed that aquatic insects were more heavily targeted by the insecticide than non-insect invertebrates. This resulted in a shift in the community towards non-insect taxa that were better able to avoid or tolerate this type of pollution.