You are here:
Big Numbers for the Big Lake: A Lower Food Web Assessment of Lake Superior (2004-2006)
Citation:
KELLY, J. R., P. M. YURISTA, J. STOCKWELL, E. J. ISAAC, S. E. MILLER, J. V. SCHAROLD, T. D. CORRY, T. JOHNSON, O. JOHANSSEN, M. MUNAWAR, AND V. RICHARDSON. Big Numbers for the Big Lake: A Lower Food Web Assessment of Lake Superior (2004-2006). Presented at 52nd Annual Conference of IAGLR, Toledo, OH, May 18 - 22, 2009.
Impact/Purpose:
These studies are strong foundation for: a) provision of quantitative estimates and related uncertainties for the lower food web, b) comparison to conditions comprehensively assessed in the 1970s, and c) evaluation of large lake bioassessment strategies.
Description:
Our collaborative binational studies focused on lower trophic levels (plankton, mysids, benthos) of Lake Superior based on comprehensive sampling (2004 to 2006). Information is integrated for a lakewide summary, but also to display patterns among lower food web components by depth. There were > 40 trillion individuals of the principal benthic prey, Diporeia, which had an aggregate biomass of ~66 thousand metric tons wet weight. For reference, this biomass is larger than that of the humans living within the Lake Superior basin. As big as those numbers are, the benthos was the least contributor among measured lower food web components. An estimated Diporeia-to-mysids-to-zooplankton (DMZ) biomass ratio was ~1 : 5 : 19 for the lakewide summary. The 20-80 m depth zone was replete with Diporeia and low in mysids a DMZ ratio was ~1 : 0.6 : 4. In contrast, a DMZ ratio was ~1 : 9 : 38 in midwaters (80-200 m) which represent a majority (~53%) of the lake area. Further offshore (>200 m) zooplankton and mysids dominate the biomass; the DMZ ratio was ~1 : 69 : 178. These studies are strong foundation for: a) provision of quantitative estimates and related uncertainties for the lower food web, b) comparison to conditions comprehensively assessed in the 1970s, and c) evaluation of large lake bioassessment strategies.