NSW Department of Primary Industries, Lord Howe Island Marine Park News
The International Union for Conservation of Nature (IUCN) established its Red List of Threatened Species in 1964 as a tool for identifying the extinction risk of species worldwide. Species are assessed based on their population size, population trends, global distribution, and any known threats to the species. These assessments help to guide and inform conservation priorities and drive awareness of conservation issues.
Whilst almost every species of mammal and bird has been assessed, only a small percent of marine invertebrates (such as sea snails, sea star, sea urchins etc) have been subject to assessment, largely due to the lack of available data. Often overlooked, marine invertebrates contribute significantly to the biodiversity, function and values of the marine park, and many only occur here.
Recent efforts to address this include comprehensive assessments of all abalone species. Globally, abalone are under threat from multiple impacts including overfishing, disease, habitat destruction, and climate change. Climate change poses a threat to abalone because marine heatwaves compromise their immunity, making them susceptible to disease, and ocean acidification can reduce the survival rate of juveniles by dissolving their shells. Abalone are also especially vulnerable because their reproduction relies on individuals being less than 2m apart, so if the population is thinned out it can trigger further rapid declines in numbers.
The Lord Howe Abalone (Haliotis rubiginosa) was included in the assessments. This small species (up to 5cm long) is endemic to the Lord Howe Island Marine Park and lives under calcium carbonate boulders and coral rubble in the intertidal and shallow subtidal reefs. Recent data from PhD surveys by Marine Ranger Caitlin Woods was included in the assessment and indicated that the population density of this species on intertidal reefs was very low.
Due to its incredibly small population size, population density, and distribution, this species faces an extremely high risk of extinction from threats including marine pollution – such as an oil spill event – and climate change. As a result, the IUCN assessed the Lord Howe Abalone to be Critically Endangered. Of the 37 worldwide abalone species, it was one of only two given this status, with another two species assessed as Endangered and four as Vulnerable. This internationally recognised listing highlights the conservation significance of the Lord Howe Island Marine Park and the endemic marine invertebrates that inhabit it.
Marine Park staff will continue to support monitoring efforts and surveys of intertidal and subtidal reef communities.
The full IUCN assessment of the Lord Howe Abalone is available via: https://www.iucnredlist.org/species/78771575/78772563
For more information please contact Marine Park staff on 6563 2359.
This article appeared in The Lord Howe Island Signal, 31 July 2021.
