Changes in the distribution and abundances of juvenile fishes on intertidal soft sediment areas dominated by the burrowing crab Chasmagnathus granulatus

PAULINA MARTINETTO; PABLO RIBEIRO; OSCAR IRIBARNE

MARINE AND FRESHWATER RESEARCH

CSIRO Publishing, Australia

Año: 2007 vol. 58 p. 194 - 203

1323-1650

Intertidal estuarine areas located between southern Brazil and northern Argentinean Patagonia are characterized by extended beds of the burrowing crab Chasmagnathus granulatus. Their activity leads to profound changes on the structure, quality and dynamics of sediments, affecting the entire benthic community and creating a patchy distribution of resources for other species. In this study, we evaluate differences in habitat use by juvenile fishes above soft sediments inhabited by C. granulatus. We sampled adjacent areas with (“crab beds”) and without crab burrows in intertidal mudflats of the Mar Chiquita coastal lagoon (37° 32’ S, 57° 19’ W) seasonally from 2000 to 2002. There were more fish species in crab bed areas. Abundance of benthivores and planktivores fishes were also higher in crab beds during flood tide, but during ebb tide planktivorous fishes were more abundant outside crab bed areas while benthivores did not vary between areas. This study indicates that species composition and abundance of juvenile fishes can be affected by the presence of bioturbator species such as Chasmagnathus granulatus.