Data and code from: Biological invasions disrupt the relationship between size spectrum and trophic interactions in freshwater fish communities

The size spectrum, which describes the relationship between abundance (or
biomass) and body size, is an ataxic approach that can provide insights
into energy fluxes across trophic levels. However, anthropogenic
perturbations can alter the relationship between body size and trophic
position, and therefore the predator-prey mass ratio (PPMR). In this
study, we used body size distribution and stable isotope analyses to
investigate the relationship between size spectrum and the PPMR in lake
fish communities across various eutrophication and invasion levels. Our
results revealed that, although size spectrum and PPMR co-varied (i.e.,
resulting in a flatter size spectrum when PPMR was low), this effect was
modulated by the level of biological invasion in the community. This was
likely caused by differences in trophic niche between native and
non-native species: small non-native species exhibited higher trophic
positions than small native species, while large non-native species can
have lower trophic positions than their native counterparts. These
findings suggest that the relationship between size structure and trophic
interactions in lake fish communities may be blurred by anthropogenic
perturbations, challenging core assumptions of size-based ecology in
estimating energy fluxes within freshwater food webs.