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Climate change is leading to novel species interactions and profoundly altering ecosystems. In marine systems, tropical and subtropical species are increasing in higher latitudes. This has been linked to the deforestation of temperate coastlines, as direct effects of ocean warming combine with increased herbivory from tropical and sub-tropical fishes and lead to the decline of canopy-forming kelp. Here, we tested the hypothesis that this deforestation may be facilitated by greater palatability of temperate kelp and other canopy seaweeds compared to tropical taxa. We used multiple-choice filmed feeding field experiments and chemical analyses to measure the palatability of temperate and tropical seaweeds from Tosa Bay (southeastern Japan) and we used single-species feeding assays to measure changes in consumption of the kelp Ecklonia cava throughout the year. We found no evidence that temperate seaweeds are more palatable to herbivorous fish. In the multiple-choice assays, consumption was concentrated on both tropical and temperate Sargassum species, which are ephemeral and peak in abundance in the spring/early summer. Consumption of the kelp Ecklonia cava peaked during the autumn, when Sargassum species are absent. The highest levels of kelp herbivory coincide with the reproductive season for E. cava and may contribute to the long-term decline of these kelp forests in southern Japan., (© 2022. The Author(s).)

Interest in oyster reef conservation and restoration is growing globally, but particularly in Australia, it is unclear the extent to which oyster reefs complement (versus replicate) habitat provisioning by other structured habitats in the seascape. Remote underwater video surveys of two east Australian estuaries revealed that at high tide, oyster reefs not only supported distinct fish communities to bare sediments but also to adjacent seagrass beds and mangrove forests. Fish observations in oyster reefs were close to double that of mangroves and seagrass, with species richness, abundance, feeding and wandering behaviours similar. Several species of blenny and goby were unique to oyster reefs and oyster-containing mangroves, whilst recreationally fished species such as bream and mullet were more abundant on oyster reefs than in other habitats. Resolving the association between oyster reefs and fish species within the broader seascape will assist in developing restoration and management strategies that maximise fisheries benefit., (Crown Copyright © 2022. Published by Elsevier Ltd. All rights reserved.)