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Two new papers look at growth variation in steelhead and Antarctic krill


Puget Sound Institute Visiting Scientist Marc Mangel has co-authored two recent papers examining variations in growth in species such as steelhead and Antarctic krill.

In a paper in the June issue of The American Naturalist, Mangel is part of a team of authors who describe a new framework for modeling species growth. The model allows for intrinsic among-individual variation in traits, and was applied to two populations of steelhead trout (Oncorhynchus mykiss). The paper describes strong evidence for differences between populations in response to variable environments and heterogeneity among individuals within populations.

Mangel has also looked at vital rates of growth and survivorship in wild krill populations. In the Marine Ecology Progress Series, Mangel and his co-authors used length-frequency distribution data collected over a span of 19 years to document among-year growth variation of Euphasia superba in the Southern Ocean of Antarctica. They observed a positive relationship between krill growth and chlorophyll density in one of the studied regions, but did not find many strong relationships between krill growth and other environmental variables. Their results, which show biologically significant among-year variation in growth that is not explained by environmental covariates, are meaningful for understanding krill biology and management of existing populations.


2013 Shelton, A.O., Satterthwaite, W.H., Beakes, M.P., Munch, S.B., Sogard, S.M., and M. Mangel. Separating intrinsic and environmental contributions to growth and their population consequences. The American Naturalist 181: 0003-0147/2013/18106-53990

2013 Shelton, A.O., Kinzey, D., Reiss, C., Munch, S., Watters, G. and M. Mangel. Among-year variation in growth of Antarctic krill Euphausia superba based on length-frequency data. Marine Ecology Progress Series 481:53-67