Effects of the dominant SW Atlantic intertidal burrowing crab Chasmagnathus granulatus on sediment chemistry and nutrient distribution

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 341:177-190 (2007) - doi:10.3354/meps341177 Effects of the dominant SW Atlantic intertidal burrowing crab Chasmagnathus granulatus on sediment chemistry and nutrient distribution Eugenia Fanjul1,*, María A. Grela2, Oscar Iribarne1 1Departamento de Biología (FCEyN) (CONICET), Universidad Nacional de Mar del Plata, CC 573 Correo Central, B7600WAG, Mar del Plata, Argentina 2Departamento de Química (FCEyN) (CONICET), Universidad Nacional de Mar del Plata, Funes 3350, Mar del Plata, Argentina *Email: mefanjul@mdp.edu.ar ABSTRACT: Through field experiments and chemical analysis of the sediment and pore water, we investigated the effect of the burrowing crab Chasmagnathus granulatus on the distribution and availability of electron acceptors in mudflat sediments. The results show that the presence and activity of C. granulatus and its burrows determine the chemical characteristics of pore water and the redox state of mudflat sediments. Crabs enhance the transport of particulate material in the sediment column, completely mixing the upper 7 cm of sediment in a few days. Comparative analyses of pore water from areas (1) with crabs and burrows, (2) with unoccupied burrows, and (3) without burrows or crabs reveal a large increase in sediment oxygenation, modification of pore water salinity and the distribution of dissolved inorganic nitrogen and sulphate when crabs are present. Denitrification and organic matter (OM) degradation rates were estimated by a diagenetic model that searches for simultaneous agreement between measured and model-calculated depth profiles. OM degradation rates (kG) were found to be greater in bioturbated (kG = 10.6 ± 6.1 [SD] µM s–1) than in non-bioturbated sediments (kG = 4.9 ± 17.8 µM s–1 if unoccupied burrows were present; kG = 0.02 ± 0.013 µM s–1 without burrows). Model-estimated denitrification rates revealed that OM degradation pathways are also affected by C. granulatus activities and their burrows. These changes in the sediment chemistry that are directly and indirectly produced by C. granulatus could comprise the force that drives the pathways of microbial processes and nutrient flows to neighbouring systems. KEY WORDS: Biogeochemistry · Bioturbation · Chasmagnathus granulatus · Intertidal sediments Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 341. Online publication date: July 04, 2007 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2007 Inter-Research.