IIMYC   23581
INSTITUTO DE INVESTIGACIONES MARINAS Y COSTERAS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Comparison of stressors on herbivory of Spartina spp. by marsh crabs in North and South American salt marshes
Autor/es:
ELMER, W.; DALEO, P.; ALBERTI, J.; IRIBARNE, O.
Lugar:
Mar del Plata
Reunión:
Congreso; CERF's Inaugural International Conference of the Americas; 2012
Resumen:
Disturbances in salt marshes are frequently caused by multiple stressors including prolonged flooding, elevated salinity, extended droughts, and disease from pathogens. Herbivory by marsh crabs [(Sesarma reticulatum in the North West Atlantic (NA) and Neohelice granulata in South Atlantic (SA)] caused considerable grazing in salt marshes recovering from disturbance. In North America, along Connecticut?s Long Island Sound, salt marshes that experienced dieback presumably over 10 years ago have not recovered in many sites, in part, due to crab herbivory. On the perimeter of these sites, a higher incidence of a pathogenic fungus called Fusarium palustre, was found than in healthy marshes. We hypothesized that marsh crabs were more attracted to stressed S. alterniflora. Plants were exposed to different irrigation regimes and inoculated with the fungus or left un-inoculated and placed with adult marsh crabs in mesocosms and in situ where dieback had occurred. Visual estimates of loss and missing leaves due to consumption were greatest on drought- and flood-stressed plants and/or plants that were inoculated with the fungus In South West Atlantic (SA) marshes, there is also a relationship between recovery from disturbance and herbivory. In most SA salt marshes, herbivorous crabs preferentially consume plants surrounding disturbed areas, slowing down marsh recovery. While salinity stress does not seem to affect crab herbivory, flood stress enhances crab consumption of Spartina spp. plants. Finally, as in NA salt marshes, there is a strong association between pathogenic fungi and crab herbivory. Crab-induced wounds on Spartina spp. leaves promote fungal infections and subsequent plant mortality. Even though these findings reveal some region-specific abiotic and biotic mechanisms that enhance crab herbivory in NA and SA, they also suggest that these two regions might share some common processes.