Keynote Presentation 2024 Australian Marine Sciences Association Annual Meeting combined with NZMSS

Anchor scour from ships as a disturbance agent to temperate rocky reef fish assemblages: BRUVs reveal marked impacts on across species, taxonomic and functional guilds (#73)

Allison Broad 1 , Matt Rees 2 , Tim Ingleton 3 , Brad Morris 3 , Andy Davis 1
  1. University of Wollongong, Wollongong, NSW, Australia
  2. Marine Ecosystem Unit, Fisheries Research, NSW Department of Primary Industries, Huskisson, NSW, Australia
  3. Waters, Wetlands and Coasts, New South Wales Department of Planning, Industry and Environment, Lidcombe, NSW, Australia

Anchoring impacts to marine environments from large, ocean-going ships is increasingly recognised as a global threat to marine biota. To date, no replicated assessment examining anchor disturbance to fish assemblages exists at the scale of ocean-going vessels. Here we aim to fill this important knowledge gap, using the Port Kembla Anchorage in SE Australia as a case study. We predicted that demersal fish on temperate rocky reefs (>30m) would differ significantly to those that were ‘anchor-free’. Using Baited Remote Underwater Video (BRUV) we assessed species and functional groups using a full-subsets generalised additive mixed modelling approach, including fine-scale reef variables as covariates to account for natural spatial variability and to improve estimates. Reefs exposed to anchoring (ie. disturbed) was the most important predictor for the total abundance of fish, with twice as many individuals. Abundance measures were largely driven by the shoaling zooplanktivore; Atypichthys strigatus, with near four-fold increases of this trophic group on anchored reefs. In contrast, the abundance of other taxa including, Latro­­piscis purpurissatus, Meuschenia freycineti and demersal elasmobranchs decreased two to four-fold on disturbed reefs. Our results indicate anchoring activities can have ecosystem-wide impacts to fish assemblages underscoring the importance of better managing anchoring near ports globally.