Kelp‐boulder transplants for habitat restoration
Tyson J. Bessell, Victor Shelamoff, Cayne Layton, Jemina Stuart‐SmithAbstract
Introduction
Degraded habitats present a major barrier to the survival and recovery of threatened marine species, particularly where structural or biogenic complexity has been lost, and natural regeneration ability is uncertain. Despite growing interest in habitat restoration, techniques rarely deliver rapid improvements at the necessary scales, especially where habitat loss threatens site‐attached or range‐restricted species.
Objectives
This study evaluated whether transplanting kelp‐bearing boulders can deliver rapid, localized improvements in habitat condition and assessed the potential of this approach as a tool for targeted habitat enhancement in support of habitat restoration for the Critically Endangered Red handfish ( Thymichthys politus ).
Methods
We transplanted kelp‐bearing boulders to a degraded temperate reef in southeastern Tasmania and compared benthic habitat composition and associated communities in restored and unrestored areas over 12 months.
Results
Areas transplanted with kelp‐bearing boulders showed rapid and persistent increases in desirable macroalgal cover, alongside reductions in undesirable turf algae, leading to more structurally complex benthic habitats compared to surrounding unrestored areas. However, restoration effects remained spatially constrained, with limited evidence of spill‐over into neighboring areas. Macroinvertebrate assemblages changed significantly through time, driven by the appearance of a small number of taxa, whereas responses of cryptic fishes showed no clear treatment effects.
Conclusions
These findings demonstrate that kelp‐bearing boulder transplants can deliver rapid, localized improvements in habitat condition in degraded reef systems. However, the ecological significance of these habitat changes, particularly for threatened species conservation, will likely depend on restoration scale, duration, and the recovery of additional habitat components beyond canopy‐forming algae.