Print PageThermal heterogeneity is known to affect the growth and physical condition of aquatic organisms. Differences in the preferred thermal habitat of Lake Superior lake trout morphotypes create alternative growth scenarios for the invasive parasitic sea lamprey (Petromyzon marinus) which feed upon them. We characterized thermal regimes for two lake trout morphotypes, with siscowet lake trout (Salvelinus namaycush) inhabiting consistently cold, deep water (4 – 6 °C) and lean lake trout occupying temperatures between 8 – 12 °C during summer thermal stratification. We contrasted the growth potential of sea lampreys attached to siscowet and lean lake trout hosts using bioenergetics models to determine how host temperature influences the growth and ultimate size of adult sea lamprey.
Results/Conclusions
Sea lampreys simulated under the thermal regime of siscowets are capable of reaching sizes within the range of adult sea lamprey sizes observed in Lake Superior tributaries. Despite limitations on lamprey growth imposed by cold temperatures, siscowets appear to serve as important lamprey hosts. Further evidence from wounding rate studies support the hypothesis that large, abundant siscowet lake trout are utilized by sea lampreys. Studies of the impacts of thermal heterogeneity on sea lampreys are especially important given the rapid warming rate of Lake Superior observed in recent decades. Given the ability of lampreys to grow to adult size when feeding on siscowets, more attention should be paid to these interactions as thermal regimes change in the lake.
