I am generally interested in the biotic interactions and abiotic conditions that determine community structure and function. My research has focused on the role of historical and contemporary human impacts in altering trophic interactions and the effects of that trophic dysfunction on community structure. I am interested in understanding how novel trophic interactions, triggered by historical and current human impacts, effect biotic and abiotic feedbacks.
My work on Cape Cod, MA has focused on how the interaction between historical mosquito ditching and contemporary overfishing by recreational anglers has triggered widespread salt marsh die-off in the last three decades (2,4). Using historical aerial photographs and a variety of manipulative field experiments I have reconstructed a 70 year history of salt marsh change on Cape Cod (4). This research has elucidated the role of impact debts, dormant human impacts that accumulate unrealized before triggering community-wide shifts, in driving patterns of coastal habitat loss. I have also demonstrated the generality of these hypotheses as crab-driven salt marsh die-off spreads into Long Island Sound (3).
My research has also focused on the role of belowground herbivory in driving patterns of salt marsh die-off on Cape Cod (1). Shifts in the trophic structure of New England’s salt marshes have led to novel feeding behaviors, including an apparent increase in the role of belowground grazing by herbivorous crabs. In 2011, I performed a series of manipulative field experiments to determine the impact and prevalence of belowground grazing on die-off intensity throughout Cape Cod.
My current work on Cape Cod is aimed at elucidating the role of the recently invasive green crab, Carcinus maenas, in driving patterns of recovery from salt marsh die-off (5, see CV for additional manuscripts in progress). This project involves investigating the biotic and abiotic conditions that allow green crabs to invade and persist in salt marshes experiencing die-off, as well as the direct and indirect interactions between Sesarma reticulaturm and Carcinus maenas. In the absence of natural predators, green crabs may play a compensatory role, both through predation and a powerful fear of being eaten response that can dramatically reduce Sesarma herbivory rates. The results of this work have implications for the management of New England’s heavily impacted salt marsh ecosystems, many of which are still experiencing widespread salt marsh die-off (2) while others recover from decades of degradation (5).
1) Coverdale, T. C., A. H. Altieri, and M. D. Bertness. 2012. Belowground herbivory increases vulnerability of New England salt marshes to die-off. Ecology 93(9) 2085-2094. http://dx.doi.org/10.1890/12-0010.1.
2) Altieri, A. H., M. D. Bertness, T. C. Coverdale, N. C. Herrmann, and C. Holdredge. 2012. A trophic cascade triggers collapse of a salt-marsh ecosystem with intensive recreational fishing. Ecology 93(6): 1402-1410. http://dx.doi.org/10.1890/11-1314.1.
3) Coverdale, T. C., N. C. Herrmann, A. H. Altieri, and M. D. Bertness. In press. Latent impacts: the role of historical human impacts in coastal habitat loss. Frontiers in Ecology and the Environment http://dx.doi.org/10.1890/120130.
4) Coverdale, T. C., M. D. Bertness, and A. H. Altieri. In press. Regional ontogeny of New England salt marsh die-off. Conservation Biology.
5) Altieri, A. H., M. D. Bertness, T. C. Coverdale, E. E. Axelman, N. C. Herrmann, and P. L. Szathmary. In press. Facilitation drives the resilience of salt marshes and rapid reversal of die-off. Ecology.
1) “Depression-era drainage ditches emerge as sleeping threat to Cape Cod salt marshes”. January, 2013. Ecological Society of America
2) “Student’s curiosity produces ecological buzz”. January, 2013. Brown University Public Relations