Variable demographics and consumption requirements of Bythotrephes longimanus (Crustacea, Cercopagididae) along a nearshore to offshore gradient in Lake Michigan
Demographic differences in Bythotrephes longimanus populations are often used to infer the prevalence of different environmental conditions that regulate their population. We collected seasonal data on Bythotrephes abundance and life history at a nearshore (15 m), transitional (45 m) and offshore site (110 m) in Lake Michigan during 2007–2016. Due to higher fish predation requirements and the small size of zooplankton prey at the nearshore site, we expected life-history attributes of Bythotrephes would differ compared to the deeper sites, but body and spine length, percent of growth allocated to the spine, and brood size were similar among depths. Owing to higher abundances in the offshore, the ratio of consumption requirements: prey production (C:P) was relatively high throughout the growing season at the deepest site compared to the two shallower sites, where C:P was generally only high in the fall. However, reproductive characteristics of Bythotrephes at the offshore site did not reflect a food-limited population compared to the other two sites. Rather the proportion of barren females was higher at the nearshore site than those at the deeper sites, leading to much lower birth rates and abundance of Bythotrephes at the shallow site compared to the deeper sites.
KeywordsZooplankton Predation Life history Predatory cladoceran
D. Ruberg, A. Sookhai, J. Elliott, A. Zantello, A. Dunnuck, and GLERL vessel operations provided lab and field support. Original data can be obtained by contacting email@example.com. GLERL Contribution Number 1907.
- Cavaletto, J. F., H. A. Vanderploeg, R. Pichlová-Ptáčníková, S. A. Pothoven, J. R. Liebig & G. L. Fahnenstiel, 2010. Temporal and spatial segregation allow for coexistence of predatory cladocerans, Leptodora kindtii, Bythotrephes longimanus and Cercopagis pengoi, in southeastern Lake Michigan. Journal of Great Lakes Research 36(Suppl. 3): 65–73.CrossRefGoogle Scholar
- Rivier, I. K., 1998. The predatory Cladocera (Onychopoda: Podonidae, Polyphemidae, Cercopagidae) and Leptodorida of the world. Backhuys Publishing, Leiden.Google Scholar
- Therriault, T. W., I. A. Grigorovich, M. E. Cristescu, H. A. M. Ketelaars, M. Viljanen, D. D. Heath & H. J. MacIsaac, 2002. Taxonomic resolution of the genus Bythotrephes Leydig using molecular markers and re-evaluation of its global distribution. Diversity and Distributions 8: 67–84.CrossRefGoogle Scholar
- Vanderploeg, H. A., S. A. Pothoven, G. L. Fahnenstiel, J. F. Cavaletto, J. R. Liebig, C. A. Stow, T. F. Nalepa, C. P. Madenjian & D. B. Bunnell, 2012. Seasonal zooplankton dynamics in Lake Michigan: disentangling impacts of resource limitation, ecosystem engineering, and predation during a critical ecosystem transition. Journal of Great Lakes Research 38: 336–352.CrossRefGoogle Scholar
- Vanderploeg, H. A., S. A. Pothoven, D. Krueger, D. M. Mason, J. R. Liebig, J. F. Cavaletto, S. A. Ruberg, G. A. Lang & R. Ptáčníková, 2015. Spatial and predatory interactions of visually preying nonindigenous zooplankton and fish in Lake Michigan during midsummer. Journal of Great Lakes Research 41(Suppl. 3): 125–142.CrossRefGoogle Scholar
- Yan, N. D., A. Blukacz, W. G. Sprules, P. K. Kindy, D. Hackett, R. E. Girard & B. J. Clark, 2001. Changes in zooplankton and the phenology of the spiny water flea, Bythotrephes, following its invasion of Harp Lake, Ontario, Canada. Canadian Journal of Fisheries and Aquatic Sciences 58: 2341–2350.CrossRefGoogle Scholar