A project undertaken at Murdoch University, and supervised by Storm Martin.
Healthy ecosystems are characterised by high richness and diversity of parasites. Parasites are ubiquitous, abundant and important. Most links in trophic networks involve parasites and most animal species are parasitic, at least for some stage of their life cycle, yet parasites are usually poorly surveyed in natural systems and frequently overlooked in ecological studies and biodiversity surveys. Parasites almost certainly comprise the majority of the animal species remaining unknown or uncharacterised, as well as most of the animal species that have or will be lost in the Anthropocene without ever being known to science. It is against this context that surveys of parasite biodiversity are important. Taxonomy of marine parasites in the Indian Ocean region lags far behind progress in the Atlantic and Pacific, and in Western Australia there has never been a research programme dedicated to surveys and identification for these groups. This APSF project enabled established of the first such programme, at Murdoch University.
The richest lineage of parasitic animals are the flatworms, which comprise three major groups: the trematodes (flukes), cestodes (tapeworms) and monogeneans. Monogeneans are the richest group of ectoparasites on fishes and have direct life cycles. Trematodes are endoparasites and the richest of all parasite lineages. They have complex life cycles requiring trophic transmission and multiple host species, and involving both sexual and asexual reproduction and multiple parasitic and free-living larval stages. Trematodes exploit essentially all vertebrates as definitive hosts, as well as many invertebrate groups as intermediate hosts, but are at their richest in bony fishes. Our best estimates of total richness remain crude but suggest perhaps one-fifth to one-tenth of the trematodes and monogeneans in fishes are known to science, though the vast majority of “known” species have never been reported again since they were initially described.
The initial focus for this project was to survey, identify and characterise the trematodes parasitic in fishes at Ningaloo Reef, and to use genetic barcode data to compare the species composition at Ningaloo Reef to that of the Great Barrier Reef, where the fauna is much better known due to focussed taxonomic efforts for over three decades. We conducted three intensive field surveys via Murdoch University’s Coral Bay Research Station. We dissected and examined 505 individual fishes across 130 species and 33 families, a modest sample (more than 20,000 fishes have been examined on the Great Barrier Reef) but representative of much of the taxonomic breadth of fish species in the area. We caught fishes directly from the reef and examined them fresh on site. Our catch was supplemented by frames donated by commercial fishing charters operating out of Coral Bay. Thousands of trematode and monogenean specimens were collected, as well as many specimens of other parasite groups including acanthocephalans, nematodes, copepods, isopods, larval cestodes, and marine leeches. Based on parallel morphological study and genetic sequencing, we currently consider this material to include approximately 238 species of trematodes across 32 families, and at least 80 species of monogeneans. This more than doubles the number of species for each of these groups known previously from Ningaloo Reef, and includes more than 100 species suspected to be new to science. We are currently working to characterise these taxa, though completing this task will take years of effort.
Taxonomists working on parasite faunas are few, especially relative to the enormous richness of these organisms. In Western Australia, there are no other dedicated taxonomists working on parasitic animals of wildlife. Similarly, there are few marine trematode taxonomists in the broader Indian Ocean region. For these reasons, this APSF research programme has rapidly expanded in scope, to include taxonomy of other parasites in wildlife of Western Australia, and to include collaboration and taxonomy capacity-building around the Indian Ocean. In particular, through conservation initiatives for the western ground parrot and green sawfish, both critically endangered, we discovered and described new, host-specific and critically co-endangered parasites, a feather louse and monogenean, respectively. We have also commenced the first intensive marine parasite surveys in Sri Lanka, working with local research students, and have delivered three taxonomy and wildlife parasitology workshops to develop local capacity.
