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Population Dynamics of two Species of Tardigrada, Macrobiotus hufelandii (Schultze) and Echiniscus (Echiniscus) testu do (Doyere), in Roof Moss from Swansea

Clive I. Morgan
Journal of Animal Ecology
Vol. 46, No. 1 (Feb., 1977), pp. 263-279
DOI: 10.2307/3960
Stable URL: http://www.jstor.org/stable/3960
Page Count: 17
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Population Dynamics of two Species of Tardigrada, Macrobiotus hufelandii (Schultze) and Echiniscus (Echiniscus) testu do (Doyere), in Roof Moss from Swansea
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Abstract

(1) Between March 1971 and June 1973, 32 552 individuals and four species of Tardigrada were extracted from the mosses Bryum argenteum L. and Ceratodon purpureus Brid. collected at three roof locations 1.2, 12 and 30 m above ground level, on the campus of University College of Swansea. (2) The dietary requirements of Macrobiotus hufelandii Schultze, Milnesium tardigradum Doyere, Hypsibius (Hypsibius) oberhaeuseri (Doyere) and Echiniscus (Echiniscus) testudo (Doyere) are discussed together with notes on their susceptibility to fungal and protozoan attack. (3) Population densities of up to 823 individuals per gram of moss were recorded, with a range of fluctuation between lowest and highest montly estimates of X 10 to X 17. (4) Temporal variation in numbers of Macrobiotus hufelandii and Echiniscus (E.) testudo was cyclical. The annual cycle of population fluctuation was positively correlated with daylight hours and temperature. Evidence is presented suggesting the existence of a secondary, long-term cycle. (5) Increases in humidity and rainfall, ten to twenty days prior to sampling, produced a decrease in tardigrade numbers but a corresponding increase in the average size of individuals. Increased rainfall also reduced the number of Macrobiotus hufelandii with pigmentation. (6) Size frequency analysis of monthly population samples indicated a lifespan between three and seven months for M. hufelandii and up to three months for Echiniscus (E.) testudo. Rapid development of juveniles led to early recruitment into the middle size classes which were slower growing and persisted longer. (7) Egg production in E. (E.) testudo continued throughout the year but proceeded at an increased rate during spring/early summer.

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