Can a Single Species Challenge Paradigms of Salt Marsh Functioning?

Abstract

Over the history of ecology, well-established generalizations were refined or even changed after the appearance or consideration of new evidence. Here, we review results obtained in Southwestern Atlantic salt marshes (between southern Brazil −32°1′ S-and the Argentinean Patagonia −53°48′ S-). Most of these salt marshes are inhabited by the intertidal burrowing crab Neohelice granulata, a species that influences many ecological processes through bioturbation and herbivory. The experimental evaluation of these processes shows that in some cases, the results were not consistent with generalizations and models of salt marsh ecological functioning. However, this does not imply that the generalizations grounded mainly on the results from North American sites are not valid. In turn, we suggest that these apparently conflicting results emerged because two major processes, herbivory and bioturbation, have been overlooked until recently. Thus, their relative contribution has not been included in the models of salt marsh functioning. In conclusion, we believe that there is a need for performing parallel and simultaneous experiments comparing distant sites with varying environmental (i.e., abiotic and biotic) conditions to be able to uncover common processes and causes of contingencies. Particularly, Southwestern Atlantic salt marshes could lead the way in providing information to better incorporate herbivory and bioturbation into current models or paradigms about how salt marshes work.

Pattern and scale: evaluating generalities in crab distributions and marsh dynamics from small plots to a national scale

“…Tidal inundation strongly affects marsh distribution, so historically, academic and management emphasis has been placed on physical factors, such as sediment supply and marsh elevation, and how both can affect resilience to sea-level rise, another critical physical stressor (Kirwan and Murray 2007). In particular, herbivory and bioturbation by crabs can exert strong negative effects on marshes (e.g., Holdredge et al 2009, Smith and Tyrrell 2012, Bertness et al 2014, Alberti et al 2015. In particular, herbivory and bioturbation by crabs can exert strong negative effects on marshes (e.g., Holdredge et al 2009, Smith and Tyrrell 2012, Bertness et al 2014, Alberti et al 2015.…”

Reimagining South American coasts: unveiling the hidden invasion history of an iconic ecological engineer

“…In a period perhaps as short as 200 years, the invasion of South America by S. alterniflora has had catastrophic consequences, with this plant entirely reshaping coastal systems. For example, how did the addition of S. alterniflora influences the abundance, distribution and ecological roles of the native bioengineers such as the burrowing crab Neohelice granulata (Dana, 1851) (Bortolus & Iribarne, 1999;Botto et al, 2005;Spivak, 2010;Alberti et al, 2015) and the razor clam Tagelus plebeius (Lightfoot, 1786) (Addino et al, 2015)? 2), originally largely devoid of the dense meadows of intertidal halophytes that now characterize them.…”

A View From the South on the Changing Coastal and Estuarine Environments

“…In this issue, salt marsh results collected over the past three decades from the Southwest Atlantic coast of Argentina are compared to results from northern salt marsh ecology studies (Alberti et al 2014). The authors provide an excellent example of how generalities in ecological theory based on extensive (over 100 years) research carried out in northern salt marshes may not apply to the functioning of salt marshes located elsewhere.…”