Ellison Abstract- 1998 Bledzki and Ellison

Bledzki, L. A. & A. M. Ellison. 1998. Population growth and production of Habrotrocha rosa Donner (Rotifera: Bdelloidea) and its contribution to the nutrient supply of its host, the northern pitcher plant, Sarracenia purpurea L. (Sarraceniaceae). Hydrobiologia 385: 193-200.

Abstract

The population growth and biomass production of the pitcher-plant (Sarracenia purpurea L.) inquiline, Habrotocha rosa Donner (Rotifera: Bdelloidea), its consumption by other pitcher-plant inqulines, and its excretion of phosphorus (PO₄-P) and nitrogen (NO₃-N and NH₄-N), were investigated in laboratory experiments. Observed population growth and production rate of H. rosa were higher at pH 4 (2.3 rotifers d^-1) than at pH 3 (1.3 rotifers d^-1), 5 (1.9 rotifers d^-1), or 6 (0.8 rotifers d^-1). Populations of H. rosa are an abundant and reliable food source for larvae of the dipteran inqulines Wyeomyia smithii (Coq.) and Blaesoxipha fletcheri (Aldrich) that co-occur with H. rosa in S. purpurea pitchers. Abundance of H. rosa within a pitcher is negatively associated with abundance of dipteran larvae, and these larvae consume rotifers in direct proportion to rotifer density (Type I functional response). Habrotrocha rosa may also account for the majority of the plant's supply of N and P. An average population of rotifers in the field (~400 per pitcher) can excrete ~5.2 mg NO₃-N, ~3.91 mg NH₄-N, and ~18.4 mg PO₄-P per day into a single leaf, and excretion rate is independent of water pH. Over the six-month growing season of pitcher-plants in Massachusetts, U.S.A., we estimate that rotifers could supply 8.8-43 mg of N and 18.2-88 mg of P. These values far exceed the amount of N and P previously estimated to be supplied annually to the plants through insect capture or rainfall.

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