Worms provide early warning
A polychaete of the family Terebellidae, genus Reteterebella. Image: Gary Cranitch.
7 September 2010
If you ever thought worms were unattractive or dirty, think again, says Dr Pat Hutchings of the Australian Museum. Not only are many of the marine worms she studies brightly-coloured, delicate and quite beautiful, they also play an essential role in keeping marine environments clean, and can be used to monitor the health of coral reef ecosystems.
Dr Hutchings is one of a team of researchers focusing on polychaetes on the CReefs field trip to Lizard Island this month.
Polychaetes, or segmented worms, are amongst the most common and widespread invertebrates found in the oceans. They provide a food source for fish and crustaceans, but perhaps most importantly, polychaetes' own feeding patterns act as a filtering system for ocean sediment.
"They are a bit like the earthworms in your compost bin," explains Dr Hutchings.
"They are very good at breaking down organic matter. A good population of worms helps to ensure a healthy marine environment," she says.
Polychaetes are also very good monitoring devices for pollution.
Because they tend to be widespread and appear in large numbers throughout the oceans, tracking changes in polychaete biodiversity on coral reefs could provide scientists with an early warning system of potential degradations to these ecosystems.
A polychaete of the family Terebellidae, genus Lanicedes. Image: Gary Cranitch.
"There are some worms that can live in heavily contaminated sediment, but a lot can't. If a sample of mud has no worms in it, I know that it's heavily contaminated. It's not a healthy situation," Dr Hutchings says.
The polychaete research team is working to establish a baseline for the diversity and abundance of polychaetes in Australian waters. This information is being used in the management and conservation of marine areas.
"How do you decide which areas need to be conserved, which are the richest in biodiversity?" Dr Hutchings asks.
"Until recently, proxies were used, such as sediment, depth, presence of seagrass beds or mangroves, and the abundance and diversity of fish. These are important considerations, but we also need to monitor the invertebrate creatures living in the sediment.
"There are 80 or more families of polychaetes; more than can be studied by the few researchers in Australia. Our team has targeted five families, each with many species, and each with different reproductive and feeding strategies. These can reasonably be used as surrogates for the biodiversity of other polychaete families," she says.
"Through CReefs field trips and other research, we now have thousands of records of polychaete populations around the coast of Australia. We are beginning to see patterns of which species are present in which environments. Where species are absent, we can consider the reasons why this may be the case, including whether the habitat is degraded due to pollution," she says.