INVESTIGADORES
DALEO Pedro
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.
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.