Similar effects on sediment structure and infaunal community of two competitive intertidal soft-bottom burrowing crab species

MARTINETTO P.,; PALOMO, M. G.; BRUSCHETTI M; IRIBARNE, O.

JOURNAL OF THE MARINE BIOLOGICAL ASSOCIATION OF THE UNITED KINGDOM

CAMBRIDGE UNIV PRESS

Año: 2011 vol. 91 p. 1385 - 1393

0025-3154

The intertidal crabs Neohelice granulata and Cyrtograpsus angulatus arecommon in the SW Atlantic coast but they rarely sharing the same microhabitat. They aresimilar in size and in several life history traits which promote competition. Neohelicegranulata is the dominant species in intertidal soft-sediment and salt-marsh areas fromsouthern Brazil to northern Patagonia Argentina, where it forms extensive burrowingbeds. Its burrowing activity affects sediment characteristics as well as the infaunalcommunity. When both species coexist N. granulata constrains the distribution andmodifies some population characteristics and burrowing behavior of C. angulatus.However, C. angulatus live in burrows forming dense burrowing beds in soft-bottomintertidal areas where N. granulata is absent. Where both species coexist, C. angulatusrarely constructs burrows and N. granulata clearly dominate soft-sediment areas formingconspicuous burrowing beds. This suggests that these crab species could have similarecological roles in some effects on sediments related to burrowing activities. In thisstudy, we experimentally compare their effects on sediment characteristics and infaunalcommunity. The results of the experiment showed that C. angulatus modify sedimentwater and organic matter contents and grain size frequency distributions similarly to N.granulata. Neither N. granulata nor C. angulatus affected the mean abundance of infaunalorganisms during the experiment but their variances showed the same patterns in manycases, indicating similar effects. These results indicate that C. angulatus can modifysediment characteristics similarly to N. granulata, and has similar interactions withinfaunal species.