Occurrence of Labyrinthula spp. in seagrass species of New South Wales, Australia

Seagrasses provide numerous ecosystem services and functions, thus seagrass ecosystems are a critical component of nearshore ecosystems worldwide (Table 1). Unfortunately, seagrass meadows are rapidly being lost in Australia... [ view full abstract ]

Seagrasses provide numerous ecosystem services and functions, thus seagrass ecosystems are a critical component of nearshore ecosystems worldwide (Table 1). Unfortunately, seagrass meadows are rapidly being lost in Australia and around the world (Waycott et al. 2009, Orth et al. 2006). Labyrinthula is a well-known endobiotic and epibiotic parasite found in association with seagrasses globally (Vergeer and den Hartog 1994), and is a putative causative agent of emerging infectious disease in seagrass ecosystems world-wide (Muehlstein et al. 1991). Under increasing stress from the impacts of global climate change, prevalence of disease epidemics in marine species is generally expected to rise in the future (Harvell et al. 2002). Existing studies of Labyrinthula infection, prevalence and pathogenicity have largely focused on species of Zostera and to some extent Thallassia spp. located in Japan, Europe, and the United States (Sullivan et al. 2013). A few isolated studies have confirmed the presence of Labyrinthula in Queensland and Western Australia (Seddon et al. 2000, Kirkman 1978), though specific observations, descriptions of culture methods and documentary photographs are lacking. A more detailed study of Labyrinthula was completed in New Zealand, where cultures confirmed multiple instances of infection and disease symptoms in seagrass beds in both Aukland and Christchurch seagrass meadows (Armiger 1964). Our study provides the first sampling of Labyrinthula in seagrass species of New South Wales, Australia, where we have positively confirmed the presence of Labyrinthula. A discussion of pathogenicity, DNA sampling and photographic imaging is included.