DOI: 10.5061/dryad.1v244
title: Data from: Effects of predatory ants within and across ecosystems in bromeliad food webs

description: Predation is one of the most fundamental ecological processes affecting
 biotic communities. Terrestrial predators that live at ecosystem
 boundaries may alter the diversity of terrestrial organisms, but they may
 also have cross-ecosystem cascading effects when they feed on organisms
 with complex life cycles (i.e. organisms that shift from aquatic juvenile
 stages to terrestrial adult stages) or inhibit female oviposition in the
 aquatic environment. The predatory ant Odontomachus hastatus establishes
 its colonies among roots of Vriesea procera, an epiphytic bromeliad
 species with water-filled tanks that shelters many terrestrial and aquatic
 organisms. Ants may impact terrestrial communities and deter adult insects
 from ovipositing in the water of bromeliads via consumptive and
 non-consumptive effects. Ants do not forage within the aquatic
 environment; thus, they may be more efficient predators on terrestrial
 organisms. Therefore, we predict that ants will have stronger effects on
 terrestrial than aquatic food webs. However, such effects may also be site
 contingent and depend on the local composition of food webs. To test our
 hypothesis, we surveyed bromeliads with and without O. hastatus colonies
 from three different coastal field sites in the Atlantic Forest of
 southeast Brazil, and quantified the effect of this predatory ant on the
 composition, density and richness of aquatic and terrestrial metazoans
 found in these bromeliads. We found that ants changed the composition and
 reduced the overall density of aquatic and terrestrial metazoans in
 bromeliad ecosystems. However, effects of ants on species diversity were
 contingent on site. In general terms, the effects of the ant on aquatic
 and terrestrial metazoan communities were similar in strength and
 magnitude. Ants reduced the density of virtually all aquatic functional
 groups, especially detritivore insects as well as metazoans that reach
 bromeliads through phoresy on the skin of terrestrial animals (i.e.
 Ostracoda and Helobdella sp.). Our results suggest that the
 cross-ecosystem effect of this terrestrial predator on the aquatic
 metazoans was at least as strong as its within-ecosystem effect on the
 terrestrial ecosystem, and demonstrates that the same predator can
 simultaneously initiate cascades in multiple ecosystems.
description: Aquatic
 metazoansAbundance of aquatic
 metazoans collected in Vriesea procera bromeliads with and without nests
 of the ant Odontomachus hastatus at Parque Estadual da Serra do Mar
 (Picinguaba), Estação Ecológica Juréia-Itatins (Juréia) and Parque
 Estadual da Ilha do Cardoso (Cardoso), São Paulo State, Brazil. Metazoans
 were identified to the lowest possible taxonomic level, to their classes,
 orders or families, and were separated into functional
 groupsTerrestrial
 metazoansAbundance of terrestrial
 metazoans collected in Vriesea procera bromeliads with and without nests
 of the ant Odontomachus hastatus at Parque Estadual da Serra do Mar
 (Picinguaba), Estação Ecológica Juréia-Itatins (Juréia) and Parque
 Estadual da Ilha do Cardoso (Cardoso), São Paulo State, Brazil. Metazoans
 were identified to the lowest possible taxonomic level and were separated
 in guilds