INVESTIGADORES
BRUSCHETTI Carlos Martin
congresos y reuniones científicas
Título:
Ecosystem-engineering by burrowing crabs in a salt marsh and consequences for carbon export.
Autor/es:
GUTIERREZ, J,L; CLIVE, J.; GROFFMAN, P.M; STUART E.; FINDLAY, S.E.; IRIBARNE, O.O; RIBEIRO, P.; BRUSCHETTI, C.M.
Lugar:
Portland, Oregon. USA
Reunión:
Congreso; Ecological Society of America. 89th Annual Meeting.; 2004
Resumen:
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Geomorphology,
vegetation and tidal fluxes are usually identified as the factors introducing variation
in the export characteristics of tidal marshes. Such variables may, however, be
insufficient to explain export characteristics in marshes inhabited by
ecosystem engineers if their habitat modification significantly affects
detritus retention. Salt marshes located from Southern Brazil to Northern
Patagonia (Argentina)
support high densities (up to 60 ind
m-2) of burrowing crabs Chasmagnathus granulata. Studies conducted in
Mar Chiquita coastal lagoon (37º S, Argentina) show that both the
burrowing activity of crabs and the physical presence of their burrows have
important consequences for the retention/export of detritus and sedimentary
organic carbon within the marsh. Burrows function as sediment and detritus
traps, collecting an important proportion (.30 %) of the macrodetritus produced in the marsh. Although crabs
excavate macrodetritus from their burrows during burrow maintenance, most (ø90 %) detritus is retained for several months in sediment mounds that
result from crab excavation. Furthermore, mound production by crabs leads to
the burial of detrital fragments that would otherwise remain as litter on the
marsh surface (50% of the litter standing stock is buried under mounds in a month).
While the excavation of sedimentary organic carbon by crabs exceeds its
deposition into their burrows, sediments excavated by crabs have a lower
content of readily (10 d) labile carbon relative to these collected by their
burrows. Collectively, these findings indicate that ecosystem engineering by
burrowing crabs (1) increase retention and in situ processing of macrodetritus
within the marsh by increasing burial rates, and (2) increase the probability
of export of sedimentary organic carbon by increasing total carbon
availability, and decreasing the proportion of readily labile carbon in
surficial marsh sediments. Incorporating the activities of ecosystem engineers
in current models of marsh export emerges as important for a more adequate understanding
of the function of marshes in the fluxes of nutrients and materials in estuarine
ecosystems.
