Changes in abundance of burrowing mayflies in Southern Indian Lake: lessons for environmental monitoring

Surveys of benthic invertebrates in subarctic Southern Indian Lake, Manitoba, before and after manipulation of the lake for hydroelectric development, revealed that Hexagenia (Insecta: Ephemeroptera) populations collapsed following the diversion phase. Initial conclusions attributed the collapse to lake manipulation, but intensive life-history studies indicated that the cause was a series of cold years immediately following diversion. A simple model relating air temperature during the open-water season to Hexagenia abundance was successful in predicting burrowing mayfly abundance in the lake. This indicated the significance of temperature in regulating these populations, which are near their northern limits of distribution in Manitoba. The difficulty in discriminating between natural ecosystem variability and anthropogenic effects during the course of an environmental monitoring program is illustrated by this study.PT: J; CR: 1987, CAN J FISH AQUAT SCI, V44, P1737 BOWMAN RS, 1973, MAR POLLUT B, V9, P269 CULLINANE JP, 1983, ESTUAR COAST SHELF S, V17, P479 FLANNAGAN JF, 1979, ADV EPHEMEROPTERA BI HAMILTON AL, 1974, ZOOBENTHOS SURVEY SO HECKY RE, 1984, CAN J FISH AQUAT SCI, V41, P579 HECKY RE, 1984, CAN J FISH AQUAT SCI, V41, P720 HEISE BA, 1987, J N AM BENTHOL SOC, V6, P230 HUDSON PL, 1972, STUD NAT SCI E, V1 HUNT BP, 1953, B I FISH RES, V4 KOHLER A, 1986, HELGOLANDER MEERESUN, V40, P431 MCCULLOUGH GK, 1981, MS1620 CAN REP FISH NEWBURY RW, 1984, CAN J FISH AQUAT SCI, V41, P548 ROSENBERG DM, 1985, 33RD ANN M N AM BENT WIENS AP, 1984, CAN J FISH AQUAT SCI, V41, P638; NR: 15; TC: 3; J9: AMBIO; PG: 4; GA: FR881Source type: Electronic(1