ABSTRACT
Chironomids are useful quantitative indicators of climatic change. The larval head capsules are well-preserved, abundant and diverse in lake sediments; they are readily identifiable, usually to genus- or species-group level, using identification keys to modern larvae; chironomids respond rapidly and characteristically to climate change; they occur in a wide variety of environmental conditions; and many taxa are stenothermic. Temperature has an important influence on many aspects of chironomid biology and ecology including rate and success of egg-hatching, larval development time, time of adult emergence and swarming behaviour of adults. Several low-error chironomid-air temperature inference models have now been developed and these have produced good climatic reconstructions for the Late Glacial. However, reconstructing Holocene temperatures is more problematic because expected temperature changes are close to the error margins of the models. In addition, the influence of the relatively small-scale temperature changes during the Holocene on chironomid assemblages can be overwhelmed by the impact of changes in other environmental variables, especially pH, water-level and dissolved oxygen, and this may compromise chironomid-inferred temperature reconstructions. Despite these problems, responses to many of the significant climatic fluctuations during the Holocene have been detected in many chironomid stratigraphies, and chironomid-inferred temperatures have been estimated for these events. Chironomids have also been used successfully to reconstruct quantitatively changes in salinity during the Holocene, which is closely linked to climate change, especially in subtropical regions.
