Australonuphis parateres is an annelid beachworm, found in the interdial to subtidal zone of beaches in eastern Australia. It is a common species used as bait for both recreational and commercial anglers. A. parateres is commonly known as the slimy beachworm becuase of the mucus it secretes for its burrowing activity. Onuphidae is the most derived family of polycahetes with the jaw mechanism the autapomorphic trait, defining the phylogeny. There are no significant conservation concerns for this species, however little is known about their population, behaviour and ecology. A small study was conducted to determine if beach traffic (vehicular) had an affect on the abundance of Australian beachworms, but no conclusive evidence was found.  

Australian beachworms are Polychaete worms, belonging to the Genus Australonuphis, from the family Onuphidae which also consists of genera Onuphis and Hirsutonuphis (Paxton 1979). Australonuphis parateres is one of three Australian species of beachworm and is otherwise known as slimy beach worm, appropriately named due to its slimy external morphology. A. parateres is bilaterally symmetrical, coelomate and triploblastic, distinctive of an annelid. It has a prostomium with 5 anterior antennae and enlarged parapodia for burrowing (Paxton 1986). A. parateres is virtually indistinguishable from its counterpart A. teres except for a lack of brown pigment on anterior segments. 

Local distribution and habitat

A. parateres occupy intertidal and subtidal habitats on sandy beaches. This habitat is generally highly dynamic which, in addition to the fact that beachworms are highly mobile as they are not restricted to permanent tubes like their counterparts in the order, is reason for limited study on this species to date (Fielder 2004). Typically members of the family Onuphidae build permanent tubes. A. parateres along with its sister species A. teres however, uniquely secrete a mucus to strengthen the surrounding burrow sediment which is only temporary (Paxton 1979). 

Whilst there is not much information on the biological interactions of A. parateres, studies have shown macro-invertebrates on sandy beaches to be important in benthic community structure, competition and predation as well as sediment structural support (Fielder 2004). Australian beachworms are known to be a common source of food for fish and birds (Status of Fisheries resources in NSW 2010).

Reproduction

A. parateres reproduce by external fertilization, releasing gametes into the water column and spawning much larger numbers of eggs than other genera of Onuphidae (Paxton 1986). The larvae have a planktonic stage, feeding on phytoplankton before they settle as juveniles in the sand at about 3cm (Paxton 1979, 1986). 

Fielder (2004) suggests the possibility of larval stages to preferentially settle in areas with adult species already established based on studies of other polychaetes planktotrophic larvae. 

A. parateres is the largest of the Australian beachworms and can grow up to 300 cm long and 1.5 cm wide (Status of Fisheries resources in NSW 2010). Australonuphis sp. reach sexual maturity at approximately 40cm in length. 

Australonuphis sp. derive those traits of a typical polychaete worm, with a segmented body that absorbs oxygen. The internal anatomy of Onuphidae has had limited study (Fauchald 1997). The gut is a straight tube and there are dorsal and ventral blood vessels present however the remaining circulatory system is unknown (Rouse 2001). 

Prostomium: 

Australonuphis sp. possess five dorsal antennae and a pair of frontal and ventral labial palps and in A. parateres the bands on frontal palps are brown (Paxton 1986). The five antennae consist of proximal ceratophores (circular rings) and distal styles. Chemoreceptors called Nuchal organs are located on the prostomium (Paxton 1986). 

Eversible Pharynx:

The onuphid family all possess an eversible pharynx (Fig. 2); a ventral muscular sack that extends backwards under the oesophagus (Dales 1962 in Paxton 1986). Within the pharynx is a complex jaw mechanism that contains a pair of ventral mandibles (composition of cutting plates and shafts) as well as 4 to 6 pairs of dorsal maxillae. 

Parapodia:

Onuphidae have modified enlarged parapodia with different lengths but are typically biramous (Fig. 4). Australonuphis sp. second to fourth parapodia are longest (Paxton 1986). Anterior parapodia possess ventral cirri, with the posterior converted to ventral pads (Paxton 1986). 

Seven species belong to the Australonuphis genera, five of which occur in Central and South American coastlines; Australonuphis beltrani, Australonuphis casamiquelorum, Australonuphis hartmane, Australonuphis violacea (Paxton 1986) and more recently described Australonuphis paxtonae (De León-González et al. 2008). In Australia, two species of Australonuphis are present (Australonuphis parateres and Australonuphis teres) and are what are known as ‘beachworms’ in addition to a third species belonging to the genera Hirsutonuphis (Paxton 1986) all within the Onuphid family. Within Australia, A. parateres biogeography ranges from Yeppoon in Queensland southwards to South Australia but is restricted to the intertidal and subtidal zone of sandy beaches (Paxton 1986; Fielder 2004) (Fig. 5). 

Australonuphis sp. are the second most common bait used by recreational and commercial fisherman after pipis (Fielder 2004). To date, there is no evidence the fishery for beachworms is unsustainable and the Status of Fisheries resources in NSW (2010) suggested it would be unlikely as the harvest method is labour intensive. However recreational rates of collection are not accurately known and complaints have been put forward of localised depletion (Status of Fisheries resources in NSW 2010). In Queensland however, CPUE is three time greater than New South Wales, thus making it a more profitable fishery but also more likely to overexploit the resource (Fielder 2004). 

There is not much known about the spatial and temporal variability in beachworm abundance in Australia (Fielder 2004), or how anthropogenic activity influences this. Because of limited time and resource constraints, a small field study was conducted to identify how anthropogenic impacts of increasing vehicle use on sandy beaches effects the abundance of A. parateres. In this case, because of the indiscernibility between Australonuphis sp. for this observational study, the observations included both occurring species (A. parateres and A. teres) assuming that their mutual habitat preferences and behaviour would not skew the results by species. 

Materials and Methods

The study was conducted during May at North Stradbroke Island (Fig. 7), located in South East Queensland, Australia. Flinders beach and Main beach both allow vehicular access whilst Deadman’s and Frenchmans Beach do not. Over two consecutive days at low tide, two  1 x 1m quadrats were set out randomly at each site. Beachworms were baited with a fish (mullet) carapace within these quadrats and counted when they emerged briefly from the sand for a period of 6 waves. 

Results and Discussion

There was a higher mean abundance of beachworms present on the non - traffic beaches than there were on vehicle access beaches but this was not significant (P<0.05). This may be due to the vibrations the vehicles make through the sand potentially causing the beach worms to be less likely to seek food in presence of danger. Whilst there have been no scientific studies explicitly identifying this behaviour, it is generally known amongst fisherman that early morning collection of beachworms for bait is best before traffic increases as the beach worms can be ‘shy’ (Perham 2006). There was potential bias in this experimental study as multiple environmental variables may have altered the results and inferences should only be interpreted as conjecture. Fielder (2004) conducted a study on the abundance of beach worms north of Noosa Heads. He identified zones with little swash and no large frontal dunes to be less suitable habitat for beachworms. This was not taken into account when choosing the study locations and may have implicated the results. Fielder (2004) recorded data on the number of vehicles on the study beaches but did not correlate any results from this. Further study should be undertaken to come to any conclusive statements. 

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