Hypoxia Tolerance of Two Haplochromine Cichlids: Swamp Leakage and Potential for Interlacustrine Dispersal

摘要: The ability to tolerate hypoxia in some haplochromine cichlid fishes contributes the richness of habitats occupied by lineage and may be important interlacustrine dispersal through swampy channels. Lacustrine members genus Astatotilapia tend ecologically plastic but are rarely encountered interior dense swamps. A notable exception is seen swamp corridor that joins Lake Kabaleka with George, Uganda, where one species (Astatotilapia ‘wrought-iron’) abundant, a second species, A. aeneocolor, rare. Both abundant open waters main lake. In this paper, we compare physiological (oxygen consumption) behavioral indicators tolerance between ‘wrought-iron’ from open-water two Astatotilapia. When exposed progressive hypoxia, all fish used aquatic surface respiration (ASR); however, swamp-dwelling showed lower gill ventilation rates prior initiation ASR, higher pre-ASR aggression rates, swimming speed during rate bubble exchange than both group aeneocolor. These differences reflect interpopulational variation selection pressure for low-oxygen habitats. Several lines evidence suggest was general more tolerant include ASR90 threshold, drop onset equilibrium loss under extreme ‘wrought-iron’. routine metabolic critical oxygen tension did not differ ‘wrought-iron’, or Comparative data on ASR thresholds tensions other East African cichlids intermediate tolerance. Nevertheless, our study suggests generalized lacustrine haplochromines ‘leak’ corridors even relatively conditions.