An energetic evaluation of a predator-prey (leech-amphipod) couple in Montezuma Well, Arizona, USA

McLoughlin, N; Blinn, D; Davies, R

1. The highly stable conditions in Montezuma Well, Arizona, have contributed to a very close predator-prey relationship between the endemic leech, Erpobdella montezuma, and its endemic amphipod prey, Hyalella montezuma, which forms nearly 90% of the leech diet. 2. Using a simple bioenergetic model, it was determined why a benthic opportunistic foraging strategy, typical of most other erpobdellids, is inferior to the specialized foraging behaviour utilized by E. montezuma and why reproduction by the leech is restricted during certain times of the year. 3. Our model demonstrated that to attain a biomass in excess of 2000 mg (maximum field size) during periods of low amphipod densities in the winter E. montezuma must feed on alternative prey types and have a foraging activity < 4 h per day. 4. Leech reproduction 4-6 months prior to the onset of winter food shortages of prey increases juvenile and adult survivorship with highest reproductive success for E. montezuma occurring in June-July. 5. Rather than being an obligate forager on H. montezuma, E. montezuma exploits a periodically abundant amphipod during most of the year in addition to alternate prey types during the winter thereby achieving an overall higher rate of energy gain than could be achievable by other closely related species of erpobdellids utilizing an opportunistic foraging approach.

An energetic evaluation of a predator-prey (leech-amphipod) couple in Montezuma Well, Arizona, USA

Series