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Salamander predation and vertical distributions of zooplankton
Author(s) -
HOLOMUZKI JOSEPH R.
Publication year - 1989
Publication title -
freshwater biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.297
H-Index - 156
eISSN - 1365-2427
pISSN - 0046-5070
DOI - 10.1111/j.1365-2427.1989.tb01378.x
Subject(s) - daphnia pulex , limnetic zone , biology , zooplankton , salamander , ecology , daphnia , predation , diel vertical migration , branchiopoda , zoology , cladocera , littoral zone
SUMMARY. 1. The impact of different predation regimes of zooplanktivorous larval tiger salamanders, Ambystoma tigrinum nebulosum , on the vertical temporal distributions of Daphnia pulex, Diaptomus nudus and larval Chaoborus flavicans was studied in limnetic enclosures in a pond in east‐central Arizona. Zooplankton densities were monitored 1‐2 h before sunset, at sunset, and 1‐2 h after sunset at three depths (0‐0.4, 1.0 and 2.0 m) in four salamander treatments (0, 20, 40 salamanders per enclosure, and unenclosed limnetic areas). 2. Densities and body size of Daphnia pulex were consistently greater in salamander‐free enclosures than in other treatments. More Daphnia were generally nearer the surface (0‐1.0 m) than along the bottom before and at sunset than after sunset in enclosures without salamanders. After sunset, Daphnia was by far most dense along the bottom. Densities were uniform among depths and sample times in treatments with salamanders. Salamanders moved throughout the water column. Frequencies of D. pulex spined morphs (with prominent dorsal crest) did not differ among salamander treatments. 3. Chaoborus densities were positively correlated with D. pulex distributions among depths and sample times in treatments. Spatio‐temporal distributions of Chaoborus were influenced more by their daphnid prey than by risk of predation from larval salamanders. 4. Densities of Diaptomus nudus were highest in open water controls and lowest in enclosures without salamanders. Diaptomus was generally more dense between 0 and 1 m than at 2.0 m depths in all treatments, and vertical distributions were not dependent on salamander density.