TY - JOUR
T1 - Fish predators, food availability and diel vertical migration in Daphnia
AU - Dini, Michael L.
AU - Carpenter, Stephen R.
N1 - Funding Information:
design and logistics of bag experiments; Tom Frost made available the fluorometer, pump and generator at the Trout Lake Research Station; He Xi, Russell Wright and Dave Benkowski provided the yearling bass and supplied the larval fish nets. We thank Clyde Goulden for advice concerning the lipid-ovary-egg index. We also thank Peter Leavitt, Ann St Amand, Martin Berg, Pat Soranno, Neil MacKay, Carol Blanchette, Mary Bremigan and the UNDERC Class of 1988 for their assistance in the field. David Lodge, Peter Leavitt and Ann St Amand provided helpful reviews of the manuscript. This work was funded by NSF grant BSR-86-06271 and by a research grant from the Indiana Academy of Science. This paper is a contribution from the University of Notre Dame Environmental Research Center.
PY - 1992
Y1 - 1992
N2 - Diel vertical migration of zooplankton is a highly variable and complex behaviour which apparently cannot be explained by any single factor. We determined the relative importance of fish predation, food availability and water depth in shaping the migratory behaviour of Daphnia. A modified 2×2×2 factorial experiment provided two levels of fish density (present/absent), food availability (ambient/high) and depth (4-10 m); shallow treatments with fish were excluded. Triplicate 1.2 m diameter enclosures for each of the six treatments were held in an 18 unit array in Peter Lake, Gogebic Co., MI, USA. Repeated measures ANOVA identified significant trends in daphnid density, migration and fitness (determined by lipid-ovary-egg index, LOE) as well as in chlorophyll a content of the water column for part of a 4-week experiment in July 1988. In deep enclosures with fish, Daphnia performed significantly more intense migrations than in fishless enclosures, save those in fishless ambient-food enclosures. Daphnia in deep fishless enclosures without abundant food at depth performed significantly reduced migrations. Daphnid LOE index was significantly influenced only by food content. Our results were consistent with the predator-avoidance hypothesis as well as with observations of greatest migrations where large vertical differences in food abundance exist. They support a hierarchical view of vertical migration, with presence of fish the primary factor, and food availability the secondary factor.
AB - Diel vertical migration of zooplankton is a highly variable and complex behaviour which apparently cannot be explained by any single factor. We determined the relative importance of fish predation, food availability and water depth in shaping the migratory behaviour of Daphnia. A modified 2×2×2 factorial experiment provided two levels of fish density (present/absent), food availability (ambient/high) and depth (4-10 m); shallow treatments with fish were excluded. Triplicate 1.2 m diameter enclosures for each of the six treatments were held in an 18 unit array in Peter Lake, Gogebic Co., MI, USA. Repeated measures ANOVA identified significant trends in daphnid density, migration and fitness (determined by lipid-ovary-egg index, LOE) as well as in chlorophyll a content of the water column for part of a 4-week experiment in July 1988. In deep enclosures with fish, Daphnia performed significantly more intense migrations than in fishless enclosures, save those in fishless ambient-food enclosures. Daphnia in deep fishless enclosures without abundant food at depth performed significantly reduced migrations. Daphnid LOE index was significantly influenced only by food content. Our results were consistent with the predator-avoidance hypothesis as well as with observations of greatest migrations where large vertical differences in food abundance exist. They support a hierarchical view of vertical migration, with presence of fish the primary factor, and food availability the secondary factor.
UR - http://www.scopus.com/inward/record.url?scp=0027039536&partnerID=8YFLogxK
U2 - 10.1093/plankt/14.3.359
DO - 10.1093/plankt/14.3.359
M3 - Article
AN - SCOPUS:0027039536
VL - 14
SP - 359
EP - 377
JO - Journal of Plankton Research
JF - Journal of Plankton Research
SN - 0142-7873
IS - 3
ER -