摘要:Invasive species introduction and expansion is the second greatest
threat to global biodiversity decline after habitat degradation.
Introduced in the 1930s, the benthivorous Longnose Sucker
(Catostomus catostomus) became established in Yellowstone Lake,
Wyoming, USA, and used tributary streams for spawning. With
this introduction, concerns were raised regarding their possible
competition for food resources with native adfluvial Yellowstone
Cutthroat Trout (Oncorhynchus clarkii bouvieri). Additionally, insufficient
literature exists on Longnose Sucker feeding habits
throughout their range, and there has been no comprehensive
study of Longnose Sucker diet in Yellowstone Lake. The need
exists for understanding the community ecology and food web
dynamics in Yellowstone Lake, especially as non-native Lake Trout
(Salvelinus namaycush) have caused declines in Yellowstone
Cutthroat Trout through predation. The objectives of this study
were to examine possible size-specific shifts in feeding habits,
evaluate feeding strategy, and compare historical and contemporary
diet data of Longnose Suckers in Yellowstone Lake. Diet data collected
during summer of 2018 were analyzed by length-class to test
for size-specific diet shifts. As Longnose Sucker length increased,
copepods (Diacyclops bicuspidatus thomasi, Leptodiaptomus ashlandi
or Hesperodiaptomus shoshone) decreased in proportion by weight. In
contrast, dipterans (Chironomidae) and amphipods (Hyalella spp. or
Gammarus spp.) varied in proportion by weight in the diet across
length classes. We assessed the feeding strategy by evaluating the
relationship between prey-specific abundance and percent frequency
of occurrence. This assessment indicates that Longnose Suckers have
a heterogeneous diet and generalized feeding strategy as all prey
items had a prey-specific abundance value of <50%. Diet composition
differed significantly between historical and contemporary samples, likely related to the differences in sampling locations and
possibly due to a Lake Trout-induced trophic cascade. This study
established the diet composition and feeding habits of Longnose
Suckers residing in Yellowstone Lake, thus, expanding our knowledge
of Longnose Sucker feeding patterns and ecology.