Do damaged marine ecosystems recover?

A recent work involving researchers of the University of Bologna and partially funded by THESEUS (Lotze et al. 2011) made the cover of the November 2011 edition of Trends in Ecology and Evolution. On top of this, the publication was featured twice by the Faculty of 1000 (once as “Recommended” and once as “Must Read”) and was selected for inclusion in the European Commission's environmental news service for policy makers Science for Environment Policy. 


This publication discussed theoretical and practical definitions of “recovery”, and summarized the patterns and drivers of well-documented recoveries in marine populations and ecosystems. In the face of external natural or anthropogenic disturbances, populations or ecosystems can be resistant and remain fundamentally unchanged, or they can be damaged and fully recover to their initial state, partially recover to a reduced, altered or alternative stable state, or irreversibly remain in a damaged state for a long time. In practice, recovery is often measured as some form of increase, improvement or shift in certain response variables, ideally reversing to pre-disturbance conditions.


The work looked at how common recoveries were in marine ecosystems, how long they took, the magnitude of the recovery and the main drivers. It was found that between 10 and 50% of marine species and ecosystems show some recovery from population declines and degradation, but rarely to former levels of abundance. These recoveries are often driven by a synergy of different factors, including the reduction of the original impacts, combined with favourable life-history and environmental conditions. The work also identified strategies for successful recoveries, including raising public and political awareness, legal action and enforcing management plans, reducing human impacts, protecting or restoring biodiversity and complex ecosystems, and long term planning, as recoveries can take many decades, particularly for longer-lived species and complex ecosystems.


UNIBO is currently working in collaboration with other THESEUS partners from the NIOO-KNAW / NIOZ in Yerseke (Netherlands), the UK (Bangor and Plymouth), and Spain (Santander), to study how regional climate and tidal regime are determining the vulnerability of salt-marsh vegetation to environmental changes. This knowledge is important to guide efforts to prevent further loss and enhance future recoveries of these systems, and facilitate their use as soft mitigation options.


Researchers from UNIBO and NIOO-KNAW setting up experiments on salt-marsh vulnerability in Bellocchio, North Adriatic Sea (Italy)


By Laura Airoldi


Source: Lotze, H. K., Coll, M., Magera, A. M., Ward-Paige, C., & Airoldi, L. (2011). Recovery of marine animal populations and ecosystems. Trends in Ecology and Evolution. 26(11): 595-605.