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Free keywords:
flood resistance; Acari: Oribatida; inundation; floodplains; soil mites; Amazon; Neotropics
Abstract:
Specimens of Rostrozetes foveolatus were obtained from two inundated forest areas ("varzea" and "igapo") and from two nonflooded secondary forests in the Central Amazon Region. The survival rates of their populations under submerged and nonsubmerged conditions were compared in laboratory conditions. The "igapo" population was sampled during three periods in 1992: before (February: litter nonsubmerged), in the beginning (April: litter submerged) and in the peak of the inundation phase (July: litter submerged). At "igapo", the animals survived better when submitted to nonsubmerged conditions, meaning that submersion is a stress factor. The same result did not occur at "varzea", signifying a better adaptation of this population to the submersion stress. The lowest flood resistance (27 days) was found in animals from "terra firme" secondary forest, away from the igapo. A considerable submersion resistance in the population sampled in the secondary forest, near the igapo forest, was comparable to the populations of the inundated areas and greater than the resistence at "terra-firme", far away from the "igapo". Animals sampled in February of 1996 (reared individually in plastic containers), from the flooded forests had significantly higher survival rates than those from secondary forests. Three situations in relation to the submersion period were registered: a) one of "varzea", with a more resistant population, b) one of "igapo", with a intermediate resistance and c) one of "terra-firme", away from the "igapo", with a lower resistant population. In twelve of the fifteen species studied, a high resistance to submersion was also registered.
