Preprint volume - SIBM

Pre-print Volume – Opening keynote
Fig. 1 - Shoreline development consequences on New England salt marsh plant communities (from
Bertness et al., 2001).
Conseguenze del cambiamento della costa sulle comunità vegetali delle paludi salmastre
(from Bertness et al., 2001).
Is human disturbance shifting salt marsh ecosystems from bottom-up nutrient
control to top-down consumer control - Salt marsh ecosystems have long been
recognized as systems under strong bottom-up control by physical factors. Recent
research on Western Atlantic salt marshes, however, has shown that human
disturbances, primarily overfishing, are shifting these systems to top-down, consumercontrolled
systems, often with catastrophic consequences. Geese herbivory in the
Canadian subarctic (Jefferies 1997), snail grazing on the Gulf of Mexico (Silliman et
al., 2005), and crab herbivory on Argentinean (Alberti et al., 2008) and New England
(Holdredge et al., 2009) salt marshes are all leading to significant die-off of salt
marshes and loss of the ecosystem services they provide. These results challenge the
long-standing paradigm that salt marsh ecosystems are controlled exclusively by
bottom up forces and reveal that human disturbances are shifting salt marshes to top
down control. Salt marsh conservation and management assumes strong, exclusive
bottom-up control, these finding are critical to successful salt marsh conservation and
management.
These examples illustrate the necessary interdependence of experimental marine
community ecology and successful marine conservation.
41 st S.I.B.M. CONGRESS Rapallo (GE), 7-11 June 2010
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