A triage framework for managing novel, hybrid, and designed marine ecosystems

Abstract

The novel ecosystem (NE) concept has been discussed in terrestrial restoration ecology over the last 15 years but has not yet found much traction in the marine context. Against a background of unprecedented environmental change, managers of natural marine resources have portfolios full of altered systems for which restoration to a previous historical baseline may be impractical for ecological, social, or financial reasons. In these cases, the NE concept is useful for weighing options and emphasizes the risk of doing nothing by forcing questions regarding the value of novelty and how it can best be managed in the marine realm. Here, we explore how the concept fits marine ecosystems. We propose a scheme regarding how the NE concept could be used as a triage framework for use in marine environments within the context of a decision framework that explicitly considers changed ecosystems and whether restoration is the best or only option. We propose a conceptual diagram to show where marine NEs fit in the continuum of unaltered to shifted marine ecosystems. Overall, we suggest that the NE concept is of interest to marine ecologists and resource managers because it introduces a new vocabulary for considering marine systems that have been changed through human actions but have not shifted to an alternate stable state. Although it remains to be seen whether the concept of marine NEs leads to better conservation and restoration decisions, we posit that the concept may help inform management decisions in an era of unprecedented global marine change.

Keywords: climate change; conservation; human values; marine ecosystem; marine phase shifts; novel ecosystem; restoration.

Figure 1

A marine ecosystem decision‐making framework setting out decisions relating to different types of alteration. A: addition of marine habitat through man‐made structures. B: application of novel ecosystems concepts as derived from terrestrial systems (Hobbs et al., 2014). Additional social dimensions relating to values are indicated in bold text. C: marine ecosystem management in a “business‐as‐usual” scenario using commonly used marine conservation measures. *Values refer to the end‐state values defined in Wallace et al. (2018)

Figure 2

Conceptual diagram proposing a place for novel ecosystems (NEs) in relation to phase‐shifted ecosystems: (a) a phase‐shift scenario where the threshold separating a historical system and a shifted system is biological only and (b) an NE scenario where the historical/hybrid/novel state is separated from the hybrid/novel/shifted state by biological or social thresholds. Note that the troughs are not quantitatively representative. The hybrid state is stable when the drivers of change and the conservation and restoration efforts are equal. The state can be pushed back to a historical state through restoration efforts