IIMYC   23581
INSTITUTO DE INVESTIGACIONES MARINAS Y COSTERAS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Biological and physical factors affecting the colonization of vegetation-free patches in a SW Atlantic salt marsh
Autor/es:
KAMINSKY, J.; ALBERTI, J.; AGUIAR, M.R.; IRIBARNE, O.
Lugar:
Mar del Plata
Reunión:
Congreso; CERF's Inaugural International Conference of the Americas; 2012
Institución organizadora:
Coastal and Estuarine Research Federation
Resumen:
The colonization of vegetation-free zones is one of the key processes in the development of communities where disturbance has initiated a secondary succession. A variety of biotic and abiotic factors can affect the pioneer species, and therefore delay or accelerate the development of the community. Particularly, the recovery of disturbance-generated bare areas occurs within 3 years in many salt marshes from the Northern Hemisphere. However, preliminary observations revealed that the bare patches found on the Mar Chiquita coastal lagoon (37° 44' S, 57° 26' O, Argentina) remain unchanged for more than four years). The aim of this study was to determine which physical and biological factors condition the colonization of the bare patches in these marshes. We evaluated the natural germination of the pioneer plant Sarcocornia perennis taking into account the distance to mature plants, as well as the herbivory/bioturbation pressure exerted by the intertidal crab Neohelice granulata. Almost no germination was observed in distant patches, while the amount of seedlings in those patches close to mature S. perennis plants showed high mortality rates during higher-temperature months. Although mortality remained high when we used shade cloth to reduce solar radiation, we found increased survival during the summer months in those areas with a combination of shade and crab exclusion. Finally, we analyzed if colonization was favored by increasing the number of S. perennis seeds, and we found that the observed differences in natural germination between patches closer to and further from the pioneer species were dissipated. The mortality pattern stayed constant, but some seedlings established themselves in crab exclusions. In summary, our results suggest that generalizations based on the results from the northern hemisphere are not valid in our system due to a combination of biotic and abiotic factors such as seed dispersion and the presence of crabs.