Abstract Available information on the insect fauna of freshwater bogs, fens, and marshes is reviewed. These habitats are extensive and important in Canada. The fauna of marshes is diverse, and appears to consist chiefly of generally distributed lentic species. The fauna of bogs has some specialized elements, but most bog species are generalists. The fauna of Canadian fens is little known, but from limited data for a few groups appears to be moderately rich. Features expected in generalist and specialist species from peatlands and marshes are summarized, and the possible roles of insects in these ecosystems are outlined. Particular needs for future research include the following: careful definition of different kinds of wetland habitats; meticulous sampling of defined habitats to distinguish residents from incidental visitors; and detailed study of the life histories and habits of individual species. Further sampling, and studies of larvae, undoubtedly will increase the numbers of insects known from Canadian peatlands and marshes. About 4000 aquatic insect species are known from Canada. So far only 22% of the species in groups for which detailed information is available have been reported to occur in marshes, and only half as many in peatlands, even though some of the recorded species probably do not breed in all of the habitats from which they have been collected.
The difficulty of hand-sorting aquatic invertebrates from sphagnum moss led to the development of a behavioral extraction procedure. The method involves vertical temperature and dissolved oxygen gradients in a column of water with a sphagnum sample immersed at the top. When sphagnum was used as an artificial substrate in Southern Indian Lake, Manitoba, overall extraction efficiency was 85% (SD ± 1.5%, n = 4). Invertebrates in samples from the edge of the floating sphagnum mat surrounding bog ponds in New Brunswick were extracted with an overall efficiency of 75% (SD ± 15%, n = 17). Taxa not extracted by the procedure were represented by an average of fewer than two organisms in samples containing 289 (SD ± 153) organisms. Efficiencies for the more abundant groups of aquatic invertebrates ranged from 73 to 96%. Mean sorting time was reduced from >16 hr to <2 hr per sample. The method's high efficiency allows both quantitative and qualitative assessment of aquatic invertebrate populations in sphagnum and other substrates.
Profundal macrobenthos in Southern Indian Lake, Manitoba, were surveyed to determine effects of hydroelectric manipulations in 1972 (preimpoundment), 1977 (postimpoundment), and 1979 (postdiversion). Lakewide average standing crops increased following impoundment and decreased by 3 yr after impoundment. Regional changes in standing crops usually could be related to additions of nutrients leached from flooded vegetation, additions of particulate organic matter resulting from shoreline erosion, and changes in integral primary production and suspended solids concentrations before and after impoundment. Greater increases in standing crops of macrobenthos in shallower compared with deeper depth zones of the lake after flooding were attributed to preferential deposition of organic materials in the shallow areas of the lake. Mean standing crops of macrobenthos were higher in regions through which the Churchill River flowed than in regions isolated from the flow before and after impoundment. After diversion, greatest decreases in standing crops occurred in isolated regions, whereas those of regions in the flow declined much less or increased. Responses of the most abundant taxa of macrobenthos (Pontoporeia brevicornis grp., Chironomidae, Oligochaeta, Sphaeriidae) differed in many ways from those recorded for other new reservoirs. Pontoporeia brevicornis grp. remained the most abundant benthic organism, there was no evident succession of macrobenthic taxa, and a high diversity of profundal species was maintained. These results, together with the slight changes in standing crop observed after flooding, indicated only a marginal impact on macrobenthos caused by the low-level flooding of Southern Indian Lake.
Wiens, A.P., and D.M. Rosenberg. 1994. Churchill River diversion: effects on benthic invertebrates in lakes along the lower Churchill and the diversion route. Can. Tech. Rep. Fish. Aquat. Sci. 2001: iv + 29 p. Benthic invertebrates were surveyed in 12 northern Manitoba lakes in 1973, prior to Churchill River diversion, and then every two years after diversion until 1987. Severely reduced flow's caused dewatering of three lakes in the lower Churchill River. A control structure on the Rat River caused water levels to rise in five lakes that comprised the new Notigi Reservoir, and substantially increased flows caused water levels to rise in two lakes downstream of the Notigi Reservoir. The water levels of two lakes used as reference systems were unaffected. Along the lower Churchill, benthic standing crops decreased by half in the remnant lakes; combined with the loss of the original littoral zone (:46% of the lakes' areas), overall benthic standing crops declined to about 25% of preimpact values. Invertebrate standing crops increased in impounded lakes of the Notigi Reservoir; these standing crops have remained high because of nutrient additions from the new flow of the Churchill' River. Qualitative changes also occurred in the benthic invertebrate community ofNotigi Reservoir lakes. Invertebrate standing crops increased in lakes below the Notigi Reservoir immediately after diversion but returned to, or below, preimpact levels by 10 years after diversion. Responses of benthic invertebrates in the different parts of the system generally were accurately predicted by a preimpact environmental assessment.
The experimental flooding of Lake (L) 979, a small wetland lake at the Experimental Lakes Area (ELA) in northwestern Ontario, provided an opportunity to study effects on the chironomid fauna emerging from the surrounding peatland. Nearby L632 was used as a reference system. The nature of the peatland chironomid fauna in L979 changed dramatically. Most true peatland species were eliminated by the flooding. They were quickly replaced by lacustrine species whose numbers emerging from the flooded peatland increased substantially. In contrast, qualitative and quantitative changes in emergence were minimal from the open-water zone of the lake and from L632. Intensive study of L979 and L632 revealed 12 species of true peatland chironomids in common with other peatlands at the ELA, and added another 18 species to the 37 peatland species already identified from previous studies at the ELA. Most of the 55 species have wide zoogeographic distributions, and probably occur in peatlands all across the boreal zone of Canada, but confirmatory studies are needed.
Formation of the Southern Indian Lake reservoir, northern Manitoba, added an estimated 5.4 × 10 5 t of Picea mariana (black spruce) needles to the lake. The breakdown of needles in the lake was measured by stringing needles on monofilament line, placing the strings into 3-mm mesh bags, and situating the bags along four shorelines representing high and low shoreline erosion rates (clay vs. bedrock) and wave exposures (highly exposed vs. protected). Sampling was done in phases of 0–41 and 328–384 d. Effects of excluding macroinvertebrates were tested by using needle strings placed in 50-μm mesh bags at the clay low exposure shoreline. Needle breakdown apparently occurred in two stages. Initially, weight losses were due primarily to leaching and microbial conditioning. Subsequently, weight losses were due primarily to feeding by macroinvertebrates. Processing coefficients (k) ranged from 0.0011∙d −1 for the 50-μm mesh bags to 0.0097∙d −1 for the 3-mm mesh bags at the bedrock high exposure shoreline. The presence of macroinvertebrates and exposure to waves enhanced needle breakdown. Macroinvertebrate colonization of needle strings occurred rapidly [Formula: see text] and was mainly by chironomid larvae. Phaenopsectra punctipes (Wied.) and Brillia flavifrons (joh.) larvae fed directly on needle tissue. Macroinvertebrates accounted for ~ 40% of total weight losses and, apparently, were active over the winter. Leaching and microbial conditioning each accounted for ~ 30% of total weight losses. Values of k for Southern Indian Lake most resembled those for conifer needle breakdown recorded in streams, indicating the significance of wave action in the lake. The breakdown of P. mariana needles in Southern Indian Lake appeared to be a significant source of carbon during the year following impoundment, and needles may have been an important habitat for macroinvertebrates within localized areas.
1. Collaboration means actively working together to achieve things which could not be done alone. This article attempts to provide an overall, unified, guiding framework for collaboration in freshwater ecology by discussing aspects of collaboration at individual and organizational levels, and addressing international linkages. 2. The essential elements of collaboration are communication and trust, and effective project management. Barriers to effective collaboration include competition, organizational cultures and organizational instabilities. 3. The success of collaboration can be measured by tangible benefits such as increased numbers of peer‐reviewed publications, the production of working models and a number of intangible benefits. 4. Interactions between individuals lie at the heart of an effective collaboration; organizational arrangements should facilitate this interaction. Some governments are encouraging collaboration to increase cost efficiency and allocate accountability. This trend should continue on an international level. 5. Collaboration is a key to future research in freshwater ecology.
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