Mapping of benthic ecosystems: Key to improving the management and sustainability of anchoring practices for ocean-going vessels

A global fleet of more than 48,000 vessels conveys >80% of world trade by volume. Anchor damage to benthic habitats by these vessels, along with the burgeoning cruise ship industry, represents a key threat to benthic biodiversity and ecosystem function. Here, we use vessel positional information (Automated Identification System (AIS) data) to map anchoring activity. We then focus on the important role that high resolution habitat mapping will play in understanding the distribution of habitat types which may be impacted by anchoring activities. Many international ports have high-intensity anchor areas that remain unmapped and thus risks to benthic biodiversity are poorly understood and inadequately managed. We use case studies from an anchorage in south-eastern Australia, major trade routes in the Middle East and the anchoring of cruise vessels in the Caribbean to highlight the important role of habitat mapping in reducing anchoring impacts. We contend that mapping represents an important safeguard against anchoring impacts from unexpected events such as the COVID-related redirection of cruise vessels to anchorages and the blocking of the Suez Canal by the Ever Given grounding. With increasing maritime trade expected over coming decades there is a need to transition toward sustainable anchorage management practices and provide public confidence in stewardship of marine ecosystems by the maritime industry into the future.

Widespread bleaching in the One Tree Island lagoon (Southern Great Barrier Reef) during record-breaking temperatures in 2020.

The global marine environment has been impacted significantly by climate change. Ocean temperatures are rising, and the frequency, duration and intensity of marine heatwaves are increasing, particularly affecting coral reefs. Coral bleaching events are becoming more common, with less recovery time between events. Anomalous temperatures at the start of 2020 caused widespread bleaching across the Great Barrier Reef (GBR), extending to southern, previously less affected reefs such as One Tree Island. Here, nine video transects were conducted at One Tree Island, in the Capricorn Bunker Group, and analysed for community composition and diversity, and the extent of bleaching across taxa. Average live hard coral cover across the area was 11.62%, and almost half of this was identified as severely bleached. This bleaching event is concerning as it occurred in an area previously considered a potential refuge for corals and associated fauna from the risks of climate warming. Due to the global impacts of COVID-19 during 2020, this report provides one of potentially few monitoring efforts of coral bleaching.