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Title: Factors affecting the distribution and abundance of chironomids in three Shropshire meres, with special reference to the larval tracheal systems
Author: Bowman, Catriona Morag Tait
Awarding Body: Keele University
Current Institution: Keele University
Date of Award: 1976
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Newton Mere, Crose Mere and Blake Mere (Shropshire) are warn monomictic lakes which show thermal stratification and clinograde oxygen curves in summer but which return to isothermal conditions in winter. Crose Mere is the most eutrophic mere and Newton Mere relatively the most dilute. The physico-chemical environment of each mere is determined by the lithology and morphology of the lake basin. The principal factors affecting distribution of diironomid larvae are the oxygen content of the water, the time of initiation of thermal stratification, both of which are dependent on the temperature regime; and the types of tradieal systems possessed by the larvae. Four apneustic tradieal patterns have been described and show sequential development. Progressive reduction of the tradieal system is associated with an increase in the concentration of haemoglobin and a decrease in the activity levels of the larvae. Hydrogen sulphide produced by profundal sediments in Crose Mere is responsible for low abundance of diironomids in the profundal; the life-less profundal zone in Blake Mere is due to the onset of anoxic conditions before emergence and oviposition occur. Newton Mere supports the largest population of the predominant larval form, Chironcmus anthracinus Zett., whose distribution is positively related to increasing depth. Abundance in the tubiculous larvae is related to the type of substratum, its food value and the space available for eadi larva; and in the carnivorous Procladius choreus Mg. abundance is related to the availability of prey. No relationship was found between the ability of larvae of C. anthracinus. P. choreus and Cricotopus sylvestris Fab. to withstand adverse temperature and oxygen conditions and the levels of stored tissue glycogen. However, monthly monitoring of natural populations of C. anthracinus and P. choreus showed that the amount of stored tissue glycogen increases during the last larval instar and is greatest immediately prior to pupation. The rate of respiration (Q02) was found to increase with rising temperatures. A key to common larval chironomids has been compiled.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QH301 Biology