Arctic Research Meade River

Aquatic insects were surveyed in 1952 in a small study site in the Meade River valley (70.45° N 156.30° W) of Alaska about 80 km south of the Arctic Ocean and about 320 km north of the nearest timberline. Temperatures ranged from -23.9°C to 23.3°C (May 10-August 8), with July being the warmest month as it typically is throughout the taiga and tundra. River volume is greatest just after spring thaw in June, and then dwindles to a low just before freeze-up. Undoubtedly, some sections freeze solid over winter, a situation not favorable for fishes. Nevertheless, at least four species were present in the river: ninespine stickleback, Pungitius pungitius; Alaska blackfish, Dallis pectoralis; whitefish, Coregonus sp.; and grayling, Thymallus sp. Stomach content analyses of grayling and whitefish from the North Slope contained representatives of all the insect orders commonly present in that region.

Water temperatures reached 9.4°C in the oxbow lake by mid-July; water temperatures in nearby smaller ponds ranged from 9.4°C to -15°C. All the observed insects showed marked adaptations permitting activity in a range of temperatures much lower than would be expected in temperate or tropical regions. Adult caddisflies were observed on June 12 (maximum temperature on that day, 5.6°C), and larval caddisflies were observed crawling about under the ice of the oxbow lake on June 18. Larval caddisflies were found only in the oxbow lake. Smaller, warmer ponds produced predaceous diving beetles (Dytiscidae), larval mayflies (Baetidae), stoneflies (Plecoptera), and various flies (Diptera), especially mosquitoes. A small, water-filled crack in the tundra produced specimens of all these insect groups as well as several kinds of Crustacea (Diaptomus sp.; Eurycercus lamellatus; Daphnia pulex; Polyartemiella sp.; circumpolar fairy shrimp, Branchinecta paludosa), a water mite (Hydrachnidia), and a snail (Physa sp.).

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