Gone fishing - for parasites

Holly Heiniger and Terry Miller diving to collect fish.
Image: Gary Cranitch.


23 May 2010
From the beach or a boat, with a snorkel or on scuba, using nets, lines, spear guns or clove oil, Holly Heiniger and Dr Terry Miller of the University of Queensland and the Queensland Museum spend most afternoons on the CReefs Ningaloo expedition going fishing.
Fishing may be an art, but the science starts when Holly and Terry bring their catch back to the field lab and examine the fish species they have targeted for internal parasites.
Holly and Terry are documenting and describing the biodiversity of internal parasites in Indo-Pacific coral reef fishes.
Holly is looking for microscopic parasites of the phylum Myxozoa, which can be found in various tissues, including the gall bladder, brain, muscle and heart of fish.
Terry's focus is on trematodes, which are parasitic flatworms of the phylum Platyhelminthes, that can be found in the internal organs of fish, particularly the intestines and stomach. Parasites of these phyla also inhabit the gills, body cavity, liver, spleen, and urinary bladder of certain fish species.
"The diversity and richness of parasitic taxa on coral reefs is fascinating. Every fish species has a parasitic fauna of some kind, whether internal or external – some fish may host up to five or 10 different species," Terry says.
"Based on what we know already about host preferences and distributions of many of the parasite families we have recovered so far, we are certain that we have found new species on this expedition. Although, until we sequence the DNA and analyse the morphometrics of the parasites, we can't definitively say how many species we have found," Holly adds.
The work will contribute to the overall knowledge of parasitic taxa, host-parasite relationships and their ecological interactions in coral reef ecosystems. Another major component of their study is to explore the evolution and biogeography of parasites in marine fishes.
"We have found parasite species that are genetically and morphologically identical between Ningaloo Reef and the Great Barrier Reef and even wider in the Indo-West Pacific, so we're interested in how these parasites have dispersed over large geographic ranges," Terry explains.
"These expeditions have provided us an unprecedented chance to explore the taxonomy and systematics of internal parasites of reef-associated fishes, which together form a major component of the overall biodiversity found in coral reef ecosystems," he says.