Nudibranchs are a charismatic and widely distributed group of marine invertebrates that can be useful biological indicators of ocean change, thanks to their responsiveness and dispersal ability. However, these same traits mean nudibranchs are also often detected outside their native ranges. In recent years, two non-native nudibranch species, Polycera capensis and Polycera hedgpethi, have been increasingly observed in south-eas...

Kelp forests provide habitat for many species, but it remains uncertain whether specific kelp forest types support distinct biodiversity. Surface canopy-forming giant kelp ( Macrocystis pyrifera ) forests in Tasmania, Australia, have declined significantly due to climate change, and have been widely replaced by forests dominated by smaller stipitate kelps like Ecklonia radiata . However, there is limited knowledge of the commu...

Introduction To counteract the rapid loss of marine forests globally and meet international commitments of the UN Decade on Ecosystem Restoration and the Convention on Biological Diversity ‘30 by 30’ targets, there is an urgent need to enhance our capacity for macroalgal restoration. The Green Gravel Action Group (GGAG) is a global network of 67 members that are working on the restoration of a diverse range of macroalgal fores...

Marine kelp forests cover 1/3 of our world's coastlines, are heralded as a nature-based solution to address socio-environmental issues, connect hundreds of millions of people with the ocean, and support a rich web of biodiversity throughout our oceans. But they are increasingly threatened with some areas reporting over 90% declines in kelp forest cover in living memory. Despite their importance and the threats they face, kelp...

Global seaweed aquaculture production has more than tripled since 2002 and is dominated by Asian countries with farming operations that typically occur in relatively wave‐protected, nearshore areas. To meet future demand, production must move to “non‐traditional” regions and into less contested waters offshore. However, the technological complexities and uncertainties in the performance of seaweed cultivated in high‐energy off...

The biodiversity benefits of kelp aquaculture and afforestation are increasingly acclaimed as the industry continues to grow and develop globally, however, whether farmed kelp can provide this ecosystem service remains unclear. Using peer-reviewed literature, we evaluated whether kelp farms provide biodiversity benefits, and identified only 23 studies that discussed the effects of kelp aquaculture on biodiversity, half of whic...

Ecosystem engineers often exert strong effects on the recruitment of other species through modification of the local abiotic and biotic environment. In 2015, artificial reefs in eastern Tasmania (− 42.64693, 148.01481) spanning seven different patch sizes (0.12–7.68 m 2 ) and supporting four densities of transplanted kelp ( Ecklonia radiata at 0, 4.1, 8.2 and 16.4 kelp m −2 ) were used to determine how the patch size and densi...

Marine ecosystems and their associated biodiversity sustain life on Earth and hold intrinsic value. Critical marine ecosystem services include maintenance of global oxygen and carbon cycles, production of food and energy, and sustenance of human wellbeing. However marine ecosystems are swiftly being degraded due to the unsustainable use of marine environments and a rapidly changing climate. The fundamental challenge for the fu...

Kelp forests around the world are under increasing pressure from anthropogenic stressors. A widespread consequence is that in many places, complex and highly productive kelp habitats have been replaced by structurally simple and less productive turf algae habitats. Turf algae habitats resist re‐establishment of kelp via recruitment inhibition; however, little is known about the specific mechanisms involved. One potential facto...