Feeding efficiencies of Chironomus plumosus (L.) and C. anthracinus Zett. (Diptera: Chironomidae) in mesotrophic Lake Erken

Abstract

Absorption efficiencies of nitrogen and carbon in twoChironomus species found dominating in the profundal zone of mesotrophic Lake Erken were determined gravimetrically.2. Absorption efficiencies for C. plumosus showed greater seasonal variation than those of C. anthracinus, with low efficiencies coinciding with the summer dominance of flagellate phytoplankton and with high C:N ratios.3. Overall mean absorption efficiencies {±SE) for carbon and nitrogen, respectively, were 26.8% (±1.9) and 29.3% (±1.9) for C plumosus, 24.6% (±1.7) and 28.1% (±1.8) for C anthracinus.4. Significant differences were found to exist between the C:N ratios of the superficial 2 cm sediment layers and those of Chironomus anterior midgut contents. 5. C. anthracinus appears to be a deposit feeder ingesting particulate matter scraped from the recently deposited surface sediments. The greater seasonal variation found in the absorption efficiencies of C. plumosus, together with the lower C:N ratios, support the contention that this species is a filter feeder with the nutritional quality of ingested matter depending primarily on pelagic inputs.

Possible sources of methane-derived carbon for chironomid larvae

“…These larvae exhibit a flexible feeding mode, switching between deposit-and filterfeeding, depending on food availability (McLachlan 1977, Johnson 1985, Berg 1995, Goedkoop et al 1998). Thus, they could feed on microbial biomass from the sediment as well as from the water directly above the sediment surface, a region in which in many lakes oxic/anoxic interfaces occur, providing the preferred habitat for MOB (Hanson & Hanson 1996).…”

The role of chironomids (Diptera) in the profundal macrozoobenthos in Finnish reservoirs

“…1, an interesting continuum from lake profundal to reservoir profundal to reservoir littoral to natural pools is obvious for Chironomus species and their ecology. The filter-feeding Chironomus plumosus dominates the lake profundal zone (McLACHLAN and CANTRELL, 1976) and gives way to the deposit-feeding Chironomus anthracinus in the reservoir profundal zone (JOHNSON, 1985). Chironomus aberratusgroup larvae co-occur with C. anthracinus and become common species in the shallow organic littoral in these reservoirs.…”

Effect of Larval Density on Temporal Variation in Life Cycle Patterns of Chironomus plumosus(L.)(Diptera: Chironomidae) in the Profundal Zone of Eutrophic Lake Suwa during 1982-1995.

“…In 1992, C. plumosus pupae were not found in Ekmann-Birge samples during this period, but exuviae exhibiting the emergence of adult midges were collected from the sediment. In 1982In , 1983In , 1984In , 1985In , 1986In and 1991, a second emergence period was not clearly observed.…”

“…Several investigators have reported the importance of newly deposited organic matter at the sediment surface in the diet of C. plumosus larvae (e.g., JOHNSON, 1985JOHNSON, , 1989. Therefore, chl-a concentrations at 6 m depth do not necessarily reflect the amount of available food resources for C. plumosus.…”