Crab regulation of cross-ecosystem resource transfer by marine foraging fire ants

GARCIA, E.A.; BERTNESS, M.D.; ALBERTI, J.; SILLIMAN, B.R.

OECOLOGIA

SPRINGER

Año: 2011 vol. 166 p. 1111 - 1119

0029-8549

Permeability of boundaries in biological systems is regulated by biotic and/or abiotic factors. Despite this knowledge, the role of biotic factors in regulat- ing resource transfer across ecosystem boundaries has received little study. Additionally, little is known about how cross-ecosystem resource transfer aVects source popu- lations. We used experiments, observations and stable iso- topes, to evaluate: (1) the proportion of intertidal-foraging black Wre ant (Solenopsis richteri) diet derived from marine sources, (2) how black Wre ant cross-ecosystem resource transfer is altered by the dominant bioengineer in the inter- tidal, a burrowing crab (Neohelice granulata), (3) the top- down impact of these terrestrial ants on a marine resource, and (4) the eVect of marine resources on recipient black Wre ants. We found that more than 85% of the black Wre ant diet is derived from marine sources, the number of intertidal foraging ants doubles in the absence of crab burrows, and that ants cause a 50% reduction in intertidal polychaetes. Also, ant mound density is three times greater adjacent to marine systems. This study reveals that cross-ecosystem foraging terrestrial ants can clearly have strong impacts on marine resources. Furthermore, ecosystem engineers that modify and occupy habitat in these ecosystem boundaries can strongly regulate the degree of cross-ecosystem resource transfer and resultant top down impacts.