Effects of Bioturbation of the Sandprawn Callichirus Major on Nutrient Fluxes from Sediments of a Subtropical Sandy Beac
Coastal sediments are sites of active recycling of organic matter and, therefore, a nutrient source for microalgal photosynthesis (Nixon 1981). Growing evidence suggests that bioturbating macrofauna has an important role in sedimentary carbon and nutrient
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Effects of Bioturbation of the Sand prawn Callichirus Major on Nutrient Fluxes from Sediments of a Subtropical Sandy Beach, Brazil E. C. Machado· J. R. B. Souza· C. A. Borzone . N. Brandini . C. B. Daniel
23.1
Introduction
Coastal sediments are sites of active recycling of organic matter and, therefore, a nutrient source for micro algal photosynthesis (Nixon 1981). Growing evidence suggests that bioturbating macrofauna has an important role in sedimentary carbon and nutrient dynamics (Andersen and Kristensen 1991; Aigars 200l; Sun et al. 2002), sediment turnover (Colin et al. 1986; Rowden and Jones 1993, Rowden et al. 1998a; Berkenbusch and Rowden 1999; Hughes et al. 1999), geotechnical and geophysical properties of the surficial sediments (Rowden et al. 1998b) and benthic community structure (Botto and Iribarne 1999). The fate of contaminants and pollutants in sediments, such as oil and metal trace, can also be largely influenced by these organisms (Bosworth and Thibodeaux 1990; Felder and Griffis 1994; Petersen et al. 1998). Due to the cryptic lifestyle of burrowing shrimps, many aspects of their biology are poorly understood or unknown (Coelho et al. 2000a). However, recently sampling techniques have improved the study of their burrow morphology and behaviour (Stamhuis et al. 1996; Coelho et al. 2000a), growth and reproduction (Felder and Lovett 1989; Tamaki et al. 1997; Nates and Felder 1999), physiological and behavioural mechanisms (Felder 1979; Dworschak 1987; Nates and Felder 1999; Strasser and Felder 1999;Taylor et al. 2000; Bourgeois and Felder 200l), trophic strategies and morphology (Coelho et al. 2000b). Bioturbation by members of the crustacean, decapod family Callianassidae ("mud" or "ghost" shrimps), which are widely distributed in coastal waters, influences sediment dynamics and ecosystem functions (Rowden and Jones 1993). The activities of these crustaceans affect a variety of important processes such as nutrient exchange, community structure and biogeochemical cycling (Aller et ai.I983; Ziebis et al. 1996; Bird et al. 1999, Berkenbush et al. 2000). Burrow irrigation provides an efficient mechanism for active transport of solutes across the sediment-water interface (Andersen and Kristensen 1991). Moreover, tube- and burrow-dwelling of fauna increase the area of the sediment-water interface, extending the oxic sediment surface by constructing burrows (Waslenchuk et al. 1983; Ziebis et al. 1996; Coelho et al. 2000a). The availability of oxygen as an electron acceptor for aerobic decomposition of organic matter and oxidation of reduced inorganic substances in the sediment increases as a consequence (Forster and Graf 1995). The sandprawn Callichirus major occurs in high densities in the lower intertidal and subtidal regions of several Brazilian sandy beaches, and has been the subject of different studies on distribution (Souza and Borzone 1996), population dynamics (Rodrigues and Shimizu 1997; Souza et a1.1998) and fisheries (Borzone and Souza 1996). L. D. de Lacerda et al. (eds.), Environmental Ge
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