INVESTIGADORES
PERILLO Gerardo Miguel E.
congresos y reuniones científicas
Título:
Benthic disturbance by foraging predators: effect of White Croaker, Micropogonias furnieri, on sediment stability in SW Atlantic tidal flats
Autor/es:
MOLINA, L.M.; VALIÑAS, M.S.; PRATOLONGO, P.D.; PERILLO, G.M.E.
Lugar:
Bahía Blanca
Reunión:
Congreso; ECSA 44: SCIENCE AND MANAGEMENT OF ESTUARIES AND COASTS: A TALE OF TWO HEMISPHERES; 2008
Institución organizadora:
Estuarine Coastal Science Association-Instituto Argentino de Oceanografía
Resumen:
A common feature of many of large predators is that they cause substantial local sediment disruption and generate obvious patchstructures, such as pits or furrows. These biogenic structures may have different effects on soft sediment communities, alteringpopulation dynamics, creating a temporal mosaic of successional patches, and increasing variability at different spatial scales.Depressions in soft sediments become areas of reduced shear stress, enhanced deposition, and enlarged residence time forsuspended material. Sediment deposition in depressions is enhanced because of a reduced shear, but a remaining question to beresolved is to which extent the sedimentation process into pits is selective for particles of differing settling velocities. Micropogoniasfurnieri(white croaker) is a major predator in SW Atlantic tidal flats that commonly produces elliptical depressions in the soft mud by directattack on benthic infauna. The aim of this study was to test the effects of the M. furnieri feeding activities on the infaunal verticaldistribution, as well as sediment deposition and stability. Six fish exclusion were performed and cages deployed for a month, afterthat sediment corers (10 cm in diameter and 12 cm in depth) were taken and separated in three layers (upper, mid and lower) about4 cm thick. Differences between treatments and depths were tested through a two way ANOVA. Sediment stability was measuredusing a Cohesive Strength Meter device (CSM), by taken one measurement per cage. The Critical Shear Stress thresholds wereestimated and then compared through a one way ANOVA. Sediment samples were also taken in control sites, inside and outsidedepressions, to compare sediment size distributions. Sediment inside depressions showed a higher preponderance of sand, whencompared to sediment outside pits, and sediment stability was greater inside fish exclusions. However, infaunal distribution did notshow significant differences between treatments. These results support the idea that M. furnieri has a great effect on sedimentdynamics and stability, not because of its effect on infaunal communities, but by changing microtopography and alteringsedimentation patterns.