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Disjunct distributions of two aquatic predators 1
Author(s) -
Williams Ernest H.
Publication year - 1980
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.1980.25.6.0999
Subject(s) - midge , instar , biology , copepod , predation , planktivore , ecology , disjunct , larva , crustacean , phytoplankton , population , demography , sociology , nutrient
Two planktonic predators found in high altitude ponds of the Rockies are distributed locally in a disjunct fashion. Larvae of Chaoborus americanus are well known planktivores and can eliminate the semipredacious copepod Diaptomus shoshone from a pond; but in spite of the close proximity of many of these ponds, early instars of Chaoborus are rarely found in the presence of D. shoshone, and the densities are extremely low in the few cases of coexistence. Feeding experiments show that D. shoshone adults prey on early instar Chaoborus , but the later the midge instar, the greater its survivorship in the presence of D. shoshone. The copepods are in turn preyed upon by 4th instar midge larvae. The life cycles of the two species are offset so that midge eggs hatch in the presence of D. shoshone adults. It is suggested that reciprocal predatory interactions such as this one are unstable.