Kelp Forest Restoration in Australia

Abstract

Kelp forests dominate the rocky coasts of temperate Australia and are the foundation of the Great Southern Reef. Much like terrestrial forests, these marine forests create complex habitat for diverse communities of flora and fauna. Kelp forests also support coastal food-webs and valuable fisheries and provide a suite of additional ecosystem services. In many regions of Australia and around the world, kelp forests are in decline due to ocean warming, overgrazing, and pollution. One potential tool in the conservation and management of these important ecosystems is habitat restoration, the science and practice of which is currently undergoing substantial expansion. We summarize the present state of Australian kelp forests and emphasize that consideration of the initial drivers of kelp decline is a critical first step in restoration. With a focus on Australian examples, we review methods, implementation and outcomes of kelp forest restoration, and discuss suitable measures of success and the estimated costs of restoration activities. We propose a workflow and decision system for kelp forest restoration that identifies alternative pathways for implementation and acknowledges that under some circumstances restoration at scale is not possible or feasible. As a case study, we then apply the Society for Ecological Restoration's 5-star evaluation to Operation Crayweed, Australia's primary example of kelp forest restoration. Overall, no single method of kelp forest restoration is suitable for all situations, but outcomes can be optimized by ameliorating the driver(s) of kelp decline and achieving ongoing natural recruitment of kelp. Whilst scalability of kelp forest restoration to the seascape-scale remains a considerable challenge, the present review should provide a platform for future restoration efforts. However, it is also crucial to emphasize that the challenges of restoration place a high value on preventative conservation and protection of existing kelp forest ecosystems -prevention is invariably better than cure.

Restore or Redefine: Future Trajectories for Restoration

“…Instead, kelp forests have been replaced by alternate habitats including turf algae (Filbee-Dexter and or urchin barrens (Filbee-Dexter and Scheibling, 2014; Ling et al, 2015) which create strong reinforcing feedbacks that prevent natural recovery of kelp. This provides strong impetus and motivation to apply interventions such as restoration, especially where the initial stressor no longer occurs (e.g., Coleman et al, 2008) or can be controlled (e.g., Sanderson et al, 2015;Layton et al, 2020).…”

“…In Sydney, Australia, a project is also ongoing that aims to re-establish lost forests of P. comosa at the scale of the initial degradation −70 km of metropolitan coastline 1 (Campbell et al, 2014;Wood et al, in review). The projects that have seen sustained success have generally been well financed, have often been coordinated by regulatory bodies, carried out over a sustained periods of time, or harnessed the power of local community engagement to deliver lasting results (Eger et al, 2019;DeAngelis et al, 2020;Layton et al, 2020). While these projects are currently in the minority, interest in kelp restoration is accelerating and we are at the point where we can adequately learn from our past mistakes and enhance restoration of our underwater forests (Eger et al, 2019).…”

Using Propagules to Restore Coastal Marine Ecosystems

“…Kelp restoration typically involves transplanting adult or subadult kelp from donor wild or cultured populations, attaching them either directly to the reef or to artificial structures (e.g., Wilson and North, 1983;Hernández-Carmona et al, 2000;Falace et al, 2006;Haraguchi et al, 2009;Campbell et al, 2014). Kelp grow on hard surfaces and are not easily attached, so sometimes this requires labor-intensive drilling or installation of attachment surfaces (reviewed in Fredriksen et al, 2020;Layton et al, 2020). Propagules (spores, gametophytes, zygotes or germlings) have not been widely used.…”

Operation Crayweed: Ecological and sociocultural aspects of restoring Sydney’s underwater forests

“…We have estimated our Crayweed ‘revegetation’ costs at US $46 250 per hectare (2018 year of evaluation). This figure includes materials, transport and personnel, but excludes project management and monitoring, and also excludes the initial and ongoing scientific research done to develop and optimise the restoration methods (Layton et al 2020). This estimate sits well towards the lower end of coral reef restoration programmes (which vary between US$6000 and US$4M per hectare; Bayraktarov et al 2016) and could likely be reduced through continued method development and optimisation.…”