Blood worms – more diverse than fishes can tell

Bloodworms are efficient bait collected by recreational fisherman, or else bought at fishing shops at high prices. The worms are long and compact. The whole worm or sections of it can be attached to the hook in order to catch many different fish species.

Bloodworm here in Australia is the common name for species grouped under the genus Marphysa (Family Eunicidae), which are a type of seaworm or a polychaete, to give it its correct technical name. Live individuals are red in color due to the presence of hemoglobin in the blood. Once the worm is cut, red blood drips, thus the common name of bloodworm.

Traditionally most bloodworms here in Australia have been identified as just one species, Marphysa sanguinea. This species was originally described by Reverend George Montagu in 1813 from Devon in southwest England. The original description was very brief and included a very schematic illustration (Fig. 1), allowing many different but superficially similar species of Marphysa to fit such description. This led to records of this species from all around the world, suggesting it was a cosmopolitan species.

Figure 1: Original illustration of Marphysa sanguinea in Montagu (1813).

Increasingly, we have become suspicious of such “cosmopolitan” status for the species. The urge to investigate such issues and to confirm the true identity of the Australian species started when we looked at the bait industry localized in Moreton Bay (Queensland). The blood worms in Moreton Bay live in seagrass beds and breeds when water temperatures are 27°C. Whereas Marphysa sanguinea was described on English specimens living in intertidal rock crevices in protected bays. This encouraged us to undertake a detailed morphological study of worms from Moreton Bay and Devon. We observed they were two different species and described the species from Moreton Bay as a new species, Marphysa mullawa. Also, another study described a second new species of bloodworm (Marphysa fauchaldi) from the Australia Coast found in barramundi ponds in the Northern Territory.

Later with support of the NSW Recreational Fishers, we investigated the distribution of bloodworms along the NSW coast and how many species were involved using morphological features but also similarities in DNA sequences. First of all, we checked all the records of Marphysa present in the Australian Museum database from the NSW coast. Armed with this information we resampled these sites at which the worms had previously been collected. We collected at low tide using a spade and sieve and any Marphysa found were dropped into clean vials in seawater. Back in the makeshift lab in the back of the car, we removed each worm and cut off the back of the worm and placed it in 95% alcohol and the front of the worm was placed in 7% neutralized formalin. This was repeated for each worm collected and labeled so we knew exactly which back and front end were connected. Over the next 24hrs the 95% alcohol was replaced several times and placed in a chilled esky. After each collecting trip we returned to the Australian Museum. A total of 10 sites were sampled of which revealed two new species of blood worms. At some of the sites at which Marphysa had previously been collected, no worms could be found, this included all the sites in Lake Macquarie and the coastal lagoons of Cochrone. This could be due to increased run off from non sewered sites or in the case of the coastal lagoons the time since they were last open to the sea.

Back in the museum, the back ends were ground up and the DNA extracted, amplified and sent off to be sequenced. The front ends were washed in freshwater and transferred to 70% alcohol. They were then examined under the light microscope and photographed to look at various characters along the body. Some parapodia (legs) were removed at intervals along the body dehydrated and then mounted on stubs for examination under the scanning electron microscope to observe the detailed structure of the chaetae (bristles of the worms, Fig. 2). Using this combination of morphological and molecular data we were able to distinguish two species of bloodworm Marphysa present along the NSW coast and also a smaller species. All species have been formally described.

Figure 2: A, Live specimen of Marphysa mullawa from Careel Bay, Pittwater NSW, rectangle highlights parapodia (“legs”) from four initial segments; Photo Kathy Atkinson. B, Parapodia from four initial segments, top most is the first one, circle highlights chaetae. C, Compound spine chaetae. D. Comb chaetae.

Another two species remain to be described, one from Victoria and one from Adelaide. However, we would like to stress that additional species almost certainly occur, including another two species from Moreton Bay in non-seagrass habitats such as in front of the mangroves. While typically at a site only one species occurs there are some sites at least within the Hawkesbury region where different species co-occur. Not all estuarine areas in NSW have been sampled and as sometimes they only occur in low densities, additional sampling effort may reveal either additional new species or expand the known distribution of a species.

Currently, we know that Australian bloodworms, traditionally thought to be a single species, make up at least seven different species (Marphysa fauchaldi, Marphysa kristiani, Marphysa mossambica, and Marphysa mullawa), none of which are Marphysa sanguinea, plus an undescribed species in Lakes Entrance, Victoria and Adelaide, South Australia (Fig. 3). While it is not easy to distinguish between species in the field, it is important to know that the bait industry is potentially using a mixture of species. Each species will have discrete times of breeding when gametes are released into the water column and the duration of larval life may vary between species as well as life spans. Currently in NSW there is a single plan of management for all eunicids which includes blood worms (see Box) and a limit to the number of worms which can be collected. We have no information on the number of people collecting or the collecting effort and how sustainable this collecting effort. But certainly the first step in developing more targeted plans of management is to actually know how many species we are dealing with and then to look at their reproductive strategies. We also have confirmed that three other smaller Marphysa species also occur in Australia (Marphysa bifurcata, Marphysa sessilobranchiata and Marphysa pseudosessiloa) which are not called “blood worms” and probably not collected for bait.

Figure 3: Map of Australia illustrating distribution of Marphysa species that we have verified. Localities at Kimberley Region are approximate.

With the number of recreational fishers increasing and with it the potential for increasing collecting effort of bait we need to ensure that such collecting is sustainable. To date here in Australia nobody is attempting to breed bloodworms, the only worms being bred are the beachworms in Lake Macquarie, NSW. Blood worms sold in NSW appear to be all frozen and imported from China (pers comm.) and where several species of blood worms have recently been described.

This is an ongoing project and we hope to continue sampling along the coast to determine ranges for each species and we know that additional species still remain to be discovered, including from areas of southern Australia.

Authors

Pat Hutchings, Australian Museum Research Institute, Australian Museum, Sydney NSW 2010

Joana Zanol, Laboratório de Biodiversidade de Annelida, Departamento de Invertebrados, Museu Nacional, Universidade Federal do Rio de Janeiro, Horto Botânico, Quinta da Boa Vista, São Cristovão, Rio de Janeiro, RJ 20940-040, Brazil