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Behavioural responses of different blackfly species to short‐term oxygen depletion
Author(s) -
Kiel E.,
Frutiger A.
Publication year - 1997
Publication title -
internationale revue der gesamten hydrobiologie und hydrographie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.524
H-Index - 52
eISSN - 1522-2632
pISSN - 0020-9309
DOI - 10.1002/iroh.19970820114
Subject(s) - oxygen , biology , larva , ecology , chemistry , organic chemistry
Behavioural changes of four larval blackflies ( Simulium noelleri, S. ornatum (complex), S. trifasciatum [syn. S. spinosum ] and S. variegatum ) to experimental reduction of dissolved oxygen were investigated with videotechniques. Since these species are characterised by different habitat preferences, they were expected to respond differently to oxygen depletion. During experiments lasting 120–140 min., dissolved oxygen (DO) was reduced to 0.3–0.6 mg/1 within the first hour and kept constant for another hour. Water velocity in the laboratory channel was 135 cm/s. Transparent plastic walls allowed video‐recording of larval behavioural responses to oxygen depletion. Blackflies did not engage in undulative or other ventilation movements, and they did not increase locomotory activity, nor did they actively drift. Oxygen depletion mainly altered filter‐feeding activity and non‐locomotory movements (bending and sweeping). With decreasing DO concentrations larvae of all four species reduced and finally ceased filter‐feeding. Non‐locomotory movements first temporarily increased and then also ceased, except in S. variegatum , where these movements were immediately suspended. DO‐threshold values for cessation of filter‐feeding and movements, as well as mortality indicated S. variegatum to be the most sensitive species in respect to oxygen depletion, while S. noelleri seems to be the most tolerant among the four blackfly species tested here.