Revista Chilena de Historia Natural 85 (1): 123-135, 2012
RESEARCH ARTICLE
Trophic ecology of the chiton Acanthopleura echinata on Chilean
rocky Shores
PATRICIO A. CAMUS, ARTURO H. NAVARRETE, ÁLVARO G. SANHUEZA & L. FELIPE
Polyplacophorans are common herbivores on rocky shores, but basic aspects of
their ecology remain scarcely studied and their role within communities could be more complex than previously
considered. Such is the case of Acanthopleura echinata (Barnes), one of the largest and most conspicuous
chitons in the world, and at the same time, one of the least known intertidal species in the southeastern Pacifi c. To
improve the basic ecological knowledge of this potentially important intertidal consumer, we studied the diet of A.
echinata and its variation among sites of varying levels of coastal upwelling spread over 1000 km along the coast of
northern Chile. A seasonal evaluation of diet, body size distribution and density at sites expected to vary in overall nutrient
loadings, benthic algal productivity and sea surface temperature, allowed us to examine plasticity in Acantholeura
diet and body size. Overall, A. echinata consumed 85 items of algae (64.7 %, mainly fleshy and
calcified encrusting thalli) and invertebrates (35.3 %, mainly barnacles). Diet was always dominated by encrusting
corallines, although the proportion of algae increased with body size suggesting an ontogenetic variation in feeding habits.
Although the number and occurrence frequency of dietary items varied significantly in time and space, there were no
consistent seasonal patterns and the dominant items in the diet remained the same at all places. The density of A.
echinata showed no significant spatial variation, but its body size and diet breadth correlated positively among sites
and both tended to increase with latitude. Our results show that A. echinata is a generalist,
polyphagous consumer with a high potential for affecting the space-occupancy dynamics in the intertidal system, and also
that among site variation in diet bears no simple relationship with variation in sea surface temperature and upwelling
intensity.
body size,
intertidal, niche breadth, omnivory, upwelling
