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A new look at the Lake Superior biomass size spectrum
Citation:
Yurista, P., D. Yule, M. Balge, J. VanAlstine, J. Thompson, A. Gamble, T. Hrabik, J. Kelly, J. Stockwell, AND M. Vinson. A new look at the Lake Superior biomass size spectrum. CANADIAN JOURNAL OF FISHERIES AND AQUATIC SCIENCES. NRC Research Press, Ottawa, Canada, 71(9):1324-1333, (2014).
Impact/Purpose:
This paper describes a synthesis of the pelagic biological community (algae through fish) in Lake Superior across a common theme of biomass. This work provides a common structure for evaluating the overall status of the biological community of Lake Superior and presents a bench mark in time as an indicator of the current state of condition. The methodology can be used in future trend analyses to assess the trajectory of the biological community. The work was a collaborative effort of multiple agencies and universities.
Description:
We synthesized data from multiple sampling programs and years to describe the Lake Superior pelagic biomass size structure for two time periods separated by 5 years. The data consisted of water analyzed on a Coulter counter for algae, in situ measurements with a laser optical plankton counter (LOPC) for zooplankton, and acoustic surveys for prey fish assessment. The size spectrum was stable over the 5 year time frame. The primary scaling or overall slope of the normalized biomass size-spectra (NBSS) for the combined years was -1.113. The slope was consistent with a previous estimate for Lake Superior (-1.10) based on phytoplankton and zooplankton (Sprules and Munawar 1986). Periodic dome structures within the overall biomass size structure were fit to polynomial regressions based on the observed sub-domes within the classical taxonomic positions (algae, zooplankton, and fish). Re-interpretation of dome delineation based on sub-domes aligned more closely with predator-prey size relationships that exist within the zooplankton (herbivorous, predacious) and fish (prey fish, top predator) taxonomic positions. Domes were spaced approximately every 3.78 log units along the axis and with a decreasing peak magnitude of -4.1 log units. This spacing was consistent with the theory for multi-spectrum interpretation of regular-repeating but offset domes. The relative position of the algal and herbivorous zooplankton domes predicted well the subsequent biomass domes for larger predatory zooplankton and prey fish. We made a prediction of piscivore biomass that was consistent with a recent trawl survey finding.
URLs/Downloads:
http://www.nrcresearchpress.com/doi/abs/10.1139/cjfas-2013-0596?src=recsys#.VAXixqM6e8o