| Summary: | Several studies have shown that distinct compartments of lake ecosystems are coupled
via transportation of organic matter, nutrients and energy across
habitat boundaries. Here we evaluate the potential of the invasive signal crayfish
(Pacifastacus leniusculus (Dana)) to modify energy pathways in large
boreal lakes. Using a stable isotope mixing model and calculation of the isotopic niches
we estimated the contribution of different food sources to the diets of crayfish captured
from different habitats, and from that inferred their potential to transport energy across
the littoral-profundal gradient. The crayfish caught from the littoral area utilized
mainly littoral food sources, whereas the importance of profundal sources increased
consistently with depth. We also found crayfish in deeper habitats with littoral
δ13C label, which indicates significant
use of littoral sources. These results presents evidence that invasive signal crayfish
create a new link in energy transfer from littoral areas to profundal areas and thereby
increase connectivity between these spatially distinct habitats. Our results highlight a
need for better understanding of the role of crayfish in lake energy dynamics and habitat
connectivity.
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