IIMYC   23581
INSTITUTO DE INVESTIGACIONES MARINAS Y COSTERAS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Cascading top-down effects on estuarine intertidal meiofaunal and algal assemblages
Autor/es:
ALVAREZ, M FERNANDA; ESQUIUS, K SOLEDAD; ADDINO, MARIANA; ALBERTI, JUAN; IRIBARNE, OSCAR; BOTTO, FLORENCIA
Lugar:
Mar del Plata
Reunión:
Conferencia; CERF 2012. The Changing Coastal and Estuarine Environment: A Comparative Approach.; 2012
Resumen:
Interactions between organisms are important determinants of species distribution and abundance. Due to the high complexity of interactions between species in natural systems, the outcome of a  given interaction can affect others, finally modifying community composition. For example, competition is frequently asymmetric and often the superior competitor displaces the subordinate; however other interaction such as predation or ecosystem engineer through bioturbation, can bealso equally relevant. In intertidal mudflats of the SW Atlantic estuarine environments (37° 40′S, 57° 23′W) the distribution of the burrowing crab Neohelice (= Chasmagnathus) granulata and the intertidal snail Heleobia australis is rarely overlapped, suggesting that both species have negative interactions; and, given that both species have different foraging strategies, these interaction can have top-down impacts on community dynamics. Samples and field experiments revealed that crabs displace snail toward low intertidal areas, but this displacement is caused by bioturbation and not by food competition, given that bioturbated areas showed comparatively high microalgal densities. Moreover, this interaction between crabs and snails, has marked effects on the benthic assemblages, given that each of these two species affect the infaunal species as copepods, flagellates and nauplli larvae. On the other hand, snails trough herbivory and bioturbation modified algal assemblages, specifically cyanobacteria, chlorophytes, and euglenophytes, although diatoms, the most abundant group, was not modified. Our results show that crab activities modify herbivore – primary producers interaction and shows that this system is being controlled by a multi-species interaction controlling microalgae assemblage structures.