298 M. Butler etal. 



Ph. D. thesis at the University of Michigan by M. Butler. We are grateful 

 for Dr. Bierle's permission to use his data and samples in this account. 



Benthic Studies 



Research on arctic macrobenthos has been sparse and primarily 

 descriptive. The earliest detailed work was Andersen's (1946) study of 

 several shallow lakes in Greenland. He pointed out the relatively great 

 importance of soft-bottom benthos and particularly the Chironomidae in 

 northern waters. He observed large populations but comparatively few 

 species, primarily Chironomidae in the groups Tanytarsini, Chironomus, 

 Phaenopsectra, Psectrocladius, Cricotopus, Corynoneura, and Procladius, 

 and related their abundance and distribution to environmental features 

 such as dissolved oxygen over winter, macrophytes, development of 

 dissolved H2S, and depth of water. He mentioned also Acari, Turbellaria 

 and Lepidurus. He believed most Chironomidae to have one-year life 

 cycles. A brief survey of lakes in the mid-1950's (Livingstone et al. 1958) 

 also emphasized the low diversity and moderate standing crops of benthos 

 and littoral insects and the importance of chironomids in the arctic 

 standing waters, but provided little direct data on their ecology. They 

 found an unusual Tanytarsini preserved in lake sediments, Corynocera (or 

 Dryadotanytarsus) and remarked on the very high density of chironomid 

 remains in some lakes. Their higher standing crops of macrobenthos were 

 similar to those in Barrow ponds. 



The classic studies of Scholander et al. (1953) on physiology of arctic 

 animals showed how Chironomus larvae from Barrow ponds were able to 

 freeze and return to activity with the subsequent thaw. Oliver (1968) and 

 Danks and Oliver (1972), working in the Lake Hazen area of extreme 

 northeast Canada, showed that metamorphosis and emergence of 

 Chironomidae adults were extremely synchronous but varied between 

 ponds and to a lesser extent between habitats within ponds. The 

 Chironomidae in those studies were in the same genera but were often 

 different species than the Barrow midges. Oliver (1968) summarized a 

 number of other features of arctic Chironomidae, including the occurrence 

 of copulation on surfaces rather than in aerial swarms in several species, 

 and mechanisms controlling emergence, oogenesis, and long life cycles. 

 Oliver found that water temperature regulated the time of emergence in 

 shallow environments. In Cape Thompson ponds (Watson et al. 1966a), 

 macrobenthos densities were high (38,000 m ") and chironomids were the 

 most numerous taxon, followed by oligochaetes. Turbellaria, Polychaeta, 

 Isopoda, Amphipoda, Acari, and the insect orders Plecoptera, 

 Trichoptera, Ephemeroptera, and Coleoptera were well represented, 

 especially in beds of the macrophyte Arctophila. Unfortunately they were 

 unable to give more taxonomic detail. 



