Extreme rainfall events shape food webs across Central and South America

ANTIQUEIRA P.; DE OMENA, PAULA M.; FREIRE R; MARINO, NICHOLAS A. C.; ATWOOD, T.; DÉZERALD, OLIVIER; ROMERO, GUSTAVO Q.; KRATINA, PAVEL; BARBERIS I.M.; PICCOLI, GUSTAVO C. O.; FARJALLA, VINICIUS F.; MACDONALD, A. ANDREW M.; SRIVASTAVA, DIANE S.

Ghent

Congreso; Ecology across borders; 2018

Joint Annual Meeting of BES, NECOV, GFÖ, and EEF

Changes in global and regional precipitation regimes are some of the most pervasive components of climate change. Intensification of rainfall cycles, ranging from frequent downpours to severe droughts1-3, could potentially cause widespread, but largely unknown, alterations to food web structure and ecosystem function. Here we conducted multi-site coordinated experiments to show how components of rainfall (quantity, clustering), habitat hydrology, and their extremes, modulate food web structure in 210 natural freshwater microecosystems across seven sites in Central and South America (18°N to 29°S). Trophic levels were affected differently by rainfall components; detritivores had site-specific responses under rainfall clustering, whereas mesopredators were not affected by either rainfall or hydrology, and the biomass of top predators tended to be highest under clustered rainfall. Consequently, biomass pyramids became more top-heavy (i.e., top predator-detritivore mass ratios increased), or even inverted, under extremely clustered rainfall. This implies that precipitation extremes can exacerbate the strength of biotic interactions and destabilize trophic dynamics. Rainfall-driven shifts in the shape of biomass pyramids were remarkably consistent across all sites, despite their differences in taxonomic composition. This shows that precipitation extremes impact freshwater ecosystems, and highlight that organisms from different trophic levels are variably susceptible to changing in rainfall components.