Riparian Patchiness Plays Important Role in Ant Trophic Dynamics

New article from STRIVE lab links riverine landscape heterogeneity to ant trophic position and breadth:

Tagwireyi, P. and S.M.P. Sullivan. 2016. Riverine landscape patches influence trophic dynamics of riparian ants. River Research and Applications. doi: 10.1002/rra.3009

ABSTRACT: Food webs in riparian corridors are increasingly viewed as embedded in complex riverine landscapes characterized by an amalgam of aquatic, semi-aquatic, and terrestrial habitats. However, the influence of riverine landscape pattern on trophic dynamics of riparian consumers remains largely unknown. We used naturally abundant stable isotope ratios (δ15N) to compare trophic structure of ants (Formica subsericea) among riparian patch types (crop, grass/herbaceous, gravel bar, lawn, mudflat, shrub, swamp, and woody vegetation) at 12 riverine landscapes distributed along an urban-rural landscape gradient of the Scioto River, Ohio, USA. We expected that the diet of F. subsericea, a common generalist consumer, would reflect local prey availability and thus differences in trophic dynamics among patch types. Mean ant δ15N was higher in crop patches than in any other patch type, and was lowest in grass/herbaceous, lawn, shrub, and woody vegetation patches, sugges- ting that patch type was associated with trophic position of F. subsericea. We also found that the range of δ15N, and thus trophic breadth, was significantly different by patch type, with woody vegetation exhibiting the greatest spread. Variability in canopy, tree and shrub cover, and the degree of urban development was positively correlated with δ15N range (R2 = 0.78), pointing to the role of habitat structure in mediating trophic breadth of riparian ants. These findings provide evidence that riverine landscape pattern can strongly influence trophic dynamics of riparian arthropods.

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