Counting marmots…
Non-native species and habitat degradation are two major catalysts of environmental change and often occur simultaneously. In freshwater systems, degradation of adjacent terrestrial vegetation may facilitate invasion by altering resource availability. Here we examine impacts of an invasive herbivorous snail, T. granifera, on nitrogen (N) cycling in tropical stream systems. We also investigate the potential for riparian canopy removal to create hotspots of snail N excretion by altering food resource quantity and quality. In a set of Trinidadian streams, we measured snail biomass and N excretion in open and closed canopy habitats to generate estimates of mass- and area-specific N excretion by invaders. Snail biomass was 2 to 8 times greater and areal N excretion ranged from 3 to 9 times greater in open canopy relative to closed canopy habitats. Snails foraging in open canopy habitat also had access to more abundant food resources and exhibited greater growth and mass- specific N excretion rates. Estimates of ecosystem NH4 demand indicated that snail N excretion supplied 2%, 11%, and 16% of demand in closed, intermediate, and open canopy habitats, respectively. We conclude that under some ecological conditions riparian canopy loss can generate hotspots of snail biomass, growth, and N excretion along tropical stream networks, thereby exacerbating invasive snail impact on an important biogeochemical cycle.
Knowledge graph centered on Ecological stoichiomety of consumer-resource inter with 43 nodes and 118 connections. Top connected: Prey exchange rates and the impact of predators on, Engelmann Spruce, Salix lucida subsp. lasiandra, Diptera, Bacteria.
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