INVESTIGADORES
IRIBARNE Oscar Osvaldo
artículos
Título:
Positive plant-animal interactions in the high marsh of an Argentinean coastal lagoon
Autor/es:
BORTOLUS, A.; E. SCHWINDT; O. IRIBARNE,
Revista:
ECOLOGY
Editorial:
ECOLOGICAL SOC AMER
Referencias:
Lugar: new york; Año: 2002 vol. 83 p. 733 - 742
ISSN:
0012-9658
Resumen:
Although plant?plant facilitations have been shown to be important structuring
forces in salt marshes, less attention has been given to the potential role played by
plant?animal facilitations in structuring these communities. We used a combination of
sampling and field experiments to evaluate the effect of microenvironmental changes produced
by plant cover on the distribution of the burrowing crab Chasmagnathus granulata,
a dominant macroinvertebrate of high marshes of the southwestern Atlantic coast. Four
questions were explored. Is there a relationship between the spatial distribution of C.
granulata and the spatial distribution of rooted macrophytes or distance from the marsh
edge? How important is plant cover for the establishment and survival of crabs in the high
marsh? Does plant cover affect critical physical variables for crab establishment? How
important are environmental conditions for the survival of crabs in the high marsh?
Surveys of the marsh surface showed that: (1) there was a strong relationship between
the presence of plant cover and the spatial distribution of Chasmagnathus granulata in the
high marsh, and (2) both mean crab size and burrow density decreased from the marsh
edge to high-marsh levels. By shading the substrate, live plants and experimental plant
mimics were found to be equally efficient at buffering high temperature, dehydration, and
soil hardness in the high marsh. Experimental amelioration of these harsh physical conditions
led to higher crab densities. Crab burrows also buffered harsh environmental conditions,
diminishing surface air temperature from ;468C to 238C. Finally, tethering experiments
showed that stressful heating in the high marsh is lethal for crabs, and that plant
cover is crucial for the establishment and long-term success of crabs in the high marsh.
No predation was observed in tethering experiments.
Our results suggest that plant cover is largely responsible for determining the spatial
distribution of this dominant crab in the high marsh through facilitation. Thus, our work
shows that plant?animal facilitations as well as plant?plant facilitations are important structuring
forces in salt marsh communities.