Photos of a healthy and a degraded giant kelp forest
Giant kelp off eastern Tasmania. Images: Cayne Layton and Matt Doggett.

Dense, giant kelp (Macrocystis pyrifera) forests were once ubiquitous off Tasmania, but now only five per cent remain and they are listed by the Australian Government as an endangered marine community: the first such listing for Australia. The decline is associated with the increased presence off Tasmania of warm and nutrient-poor waters brought by the East Australian Current. Active restoration is a potential approach to the conservation of giant kelp forests, and efforts are focussed on the few remnant individuals.

This research extends a project begun in 2018 by the University of Tasmania to select for thermally tolerant and low-nutrient-tolerant giant kelp genotypes and examine effects of acclimation of selected genotypes by pre-exposure to warm, nutrient-poor conditions. Pre-exposed selected genotypes of giant kelp are being out-planted off eastern Tasmania as micro-sporophytes in an experiment with and without added nutrient. The work will assess the feasibility of this approach as a means to develop minimum patch sizes for giant kelp that can be self-replacing and self-expanding, thus providing restoration and future climate-proofing options for this EPBC-listed marine community.