Lars G. Rudstam
Kelly L. Bowen
Brian Weidel
James M. Watkins
Patrick F Sullivan
Jeremy P. Holden
Michael J. Connerton
Toby J. Holda
2019
<p><i>Mysis diluviana</i><span> is a major component of prey fish diets in the Great Lakes, so annual production of </span><i>M. diluviana</i><span> is important for understanding and modeling energy flow through Great Lakes food webs. However, only three lake-wide measurements of </span><i>M. diluviana</i><span> annual production in Lake Ontario are currently available (1971, 1990, 1995). During 2013, lake-wide coverage of Lake Ontario was achieved during four periods from April to November. Annual mean density and biomass of </span><i>M. diluviana</i><span> in 2013 were 99 #/m</span><sup>2</sup><span> (SE: 8) and 318 mg dw/m</span><sup>2</sup><span> (SE: 28) – approximately half of values observed in 1990s. </span><i>M. diluviana</i><span> comprised 13–30% of offshore zooplankton biomass in each period. Reproduction peaked in fall, with mean brood size of 32 embryos (range: 11–49), at least 10% larger than in 1990s. Generation time was two years from embryo to initial reproduction. Growth rates were 0.052 mm/d for the age-0 cohort and 0.027 mm/d for the age-1 cohort. Age-0 growth rate was significantly higher than in 1980s–90s (0.035 mm/d). Annual production in 2013 was 0.85 g dw/m</span><sup>2</sup><span>/yr (SE: 0.03) which was 30–40% of values observed in 1990 and 1995 (2.23 and 2.53 g/m</span><sup>2</sup><span>/yr). Annual production to biomass ratio (P/B) in 2013 was 2.65 /yr which was 80–85% of values observed in 1990 and 1995 (3.24 and 3.11 /yr), but this difference was not statistically significant. Our results suggest that changes in annual production over time can be estimated using changes in biomass over time and a mean P/B ratio.</span></p>
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10.1016/j.jglr.2019.01.007
en
Elsevier
Status of Mysis diluviana in Lake Ontario in 2013: lower abundance but higher fecundity than in the 1990s
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