New records and invasive potential of the poeciliid fish Phalloceros caudimaculatus

ISSN: 28-833 (Print) 117-88 (Online) Journal homepage: https://www.tandfonline.com/loi/tnzm2 New records and invasive potential of the poeciliid fish Phalloceros caudimaculatus J. J. L. Rowley, T. S. Rayner & G. H. Pyke To cite this article: J. J. L. Rowley, T. S. Rayner & G. H. Pyke (2) New records and invasive potential of the poeciliid fish Phalloceroscaudimaculatus,, 39:, 113-122, DOI: 1.18/28833.2.917372 To link to this article: https://doi.org/1.18/28833.2.917372 Published online: 3 Mar 21. Submit your article to this journal Article views: 229 Citing articles: View citing articles Full Terms & Conditions of access and use can be found at https://www.tandfonline.com/action/journalinformation?journalcode=tnzm2

New Zealand Journal of Marine and Freshwater Research, 2, Vol. 39: 113-122 28-833//39-113 The Royal Society of New Zealand 2 113 Short communication New records and invasive potential of the poeciliid fish Phalloceros caudimaculatus J. J. L. ROWLEY 1,3 T. S. RAYNER 2,3 G. H. PYKE 1 1 Frog Ecology and Behaviour Group Australian Museum 6 College Street, Sydney NSW 2, Australia 2 Office of Conservation NSW Fisheries Port Stephens Fisheries Centre Taylors Beach Road, Taylors Beach NSW 2316, Australia 3 Present address: School of Tropical Biology, James Cook University, Townsville, QLD 4811, Australia, email: Jodi.Rowley@jcu.edu.au Abstract Many species from the family Poeciliidae have been transported around the world by the aquarium trade, often establishing populations in areas far outside their natural range. The one-spot livebearer, Phalloceros caudimaculatus is one such poeciliid species. In March 22, a nonindigenous population of P. caudimaculatus was discovered at Collaroy, in the Sydney metropolitan area, the first record of this species in eastern Australia. Following this discovery, electrofishing and light-trap surveys were conducted at the site, and dip-netting and visual surveys were conducted in surrounding water bodies. P. caudimaculatus was widespread and abundant at the Collaroy site, but no further populations were discovered. Another pest poeciliid species, Gambusia holbrooki, originally present at the site, was absent and, although the mechanism remains unclear, may have been displaced by P. caudimaculatus. Both P. caudimaculatus and G. holbrooki share the characteristics of successful invasive species, with extremely broad physical M414; Online publication date 22 July 2 Received 24 November 24; accepted 8 April 2 tolerances and high reproductive outputs. Given the well-documented negative ecological effects of poeciliids, especially G. holbrooki, we recommend that a precautionary approach should be adopted for the management of P. caudimaculatus and its eradication from the site be attempted. Keywords Australia; invasion; nonindigenous fishes; pest; Phalloceros caudimaculatus; poeciliidae INTRODUCTION The Poeciliidae is a large family of fish indigenous to North, Central and South America and includes many species that have been transported around the world, primarily by the aquarium trade. Many members of this family have established nonindigenous populations, often to the detriment of indigenous species (Jubb 1976/77; Welcomme 1998; FAO 22). Six such poeciliid species have established nonindigenous populations in Australia: plague minnow Gambusia holbrooki, one-spot livebearer Phalloceros caudimaculatus, sailfin molly Poecilia latipinna, guppy Poecilia reticulata, swordtail Xiphophorus helleri, and platy Xiphophorus maculatus (Allen et al. 22). To date, only one of these species, G. holbrooki, is widespread and abundant in Australia, but potential exists for the further establishment and spread of other members of this family (Arthington & McKenzie 1997; Arthington et al. 1999). Of the six nonindigenous poeciliids, P. caudimaculatus presently has one of the most restricted distributions. The species has previously been recorded at a number of sites near Perth (Allen et al. 22; Morgan et al. 24), and in Lesmurdie Falls on the Swan-Avon Rivers system (Arthington et al. 1999), Western Australia; Trephina Gorge, in the Todd River Drainage, Northern Territory (Victorian Museum records); and outdoor ponds in South Australia (Arthington et al. 1999). The recent discovery of P. caudimaculatus in ponds within

114 New Zealand Journal of Marine and Freshwater Research, 2, Vol. 39 Fig. 1 Location of survey sites on the northern beaches of Sydney, Australia. sy, Point Creek son 'Park Creek Narrabeen Lagoon ^Jtendy Creek Dee Why)tjagoorr Qrains jplong Reef Golf Course Grdetidele BrookvaleiCreek I Dee Why Lagoon Curl Lagoon urnt Bridge Creek 12 3 Kilometres Long Reef Golf Course (LRGC), in the Sydney suburb of Collaroy (Fig. 1), constitutes the first record of this species from eastern Australia. As part of a programme to establish a population of the endangered green and golden bell frog (Litoria aurea) at LRGC (Pyke 1999), regular monitoring for tadpoles and fish has been undertaken since January 1998 (G. Pyke unpubl. data). G. holbrooki was collected from LRGC in December 1997, and specimens were deposited in the Australian Museum collection (AMS I.387333). No other species of non-indigenous fish were observed or captured at LRGC at this time. In March 22, it was observed that the poeciliid present at LRGC resembled P. caudimaculatus and, shortly afterwards, several individuals captured at LRGC were formally identified as P. caudimaculatus. Observations at this time indicated that P. caudimaculatus was abundant in the majority of ponds at LRGC, and that G. holbrooki was either rare or absent. The aims of this paper were to document the current distribution of P. caudimaculatus in the northern beaches area of Sydney, and to assess the invasive potential of P. caudimaculatus. METHODS Study areas Long Reef Golf Course (33 43'S, 11 18'E) is located c. 18 km northeast of the Sydney central business district, in the suburb of Collaroy (Fig. 1). An unnamed creek drains a small, contained, urban catchment before flowing eastward across LRGC to

Rowley et al. Invasive potential of Phalloceros caudimaculatus 11 Fig. 2 Location of ponds at Long Reef Golf Course (LRGC), Collaroy, Australia. Bridge Pumphouse Pipeline f\f LRGC boundary Road Pond o 1 2 Meters discharge across the northern end of Long Reef beach. On the golf course, a series of 12 interconnected ponds acts as water storage and landscape features (Fig. 2). All of the ponds have been created since 1996, when an ongoing wetland regeneration programme began (except for pond 9 which was already present), and were numbered by LRGC based primarily upon their position downstream. The ponds vary in size, substratum, and extent of terrestrial and aquatic vegetation. Pond is the largest pond with an estimated maximum capacity of 12 ML, whereas pond 11 is the smallest at.2 ML. Although all of the ponds fluctuate in water level, only ponds 1 and 11 dry out completely during periods of low rainfall. All ponds are connected either above-ground or via underground pipes, but obstacles to the dispersal offish between ponds exist between ponds 1 and 2, ponds 2 and 11 (shallow, ephemeral drainage lines), and ponds 2 and 3 (ephemeral waterfall). Since their creation, the ponds at LRGC have changed from simple, sparsely-vegetated ponds to more complex, densely-vegetated ponds. Most ponds have a clay or loam substratum, include indigenous aquatic vegetation (e.g., Juncus spp., Eleocharis sphacelata, and Typha orientalis), and are surrounded by golf course fairway (consisting of closely mown grass) or golf course rough (consisting of unmown grass, herbs, and occasional shrubs). None of the ponds have overhanging terrestrial vegetation. In addition to ponds at LRCG, sites in the local area were sampled to determine the regional distribution of P. caudimaculatus (Fig. 1). Sixteen sites within 12 locations were selected, representing both lentic and lotic water bodies likely to contain P. caudimaculatus (Fig. 1). Many of the sites were streams or ponds on golf courses, where habitat features such as surface area, depth, and aquatic vegetation were similar to those at LRGC. Fish surveys A comprehensive fish survey was conducted at LRGC in July 22 during daylight hours (9-16 h). This survey used backpack electrofishing (Smith-Root POW Model 12 backpack electrofishing unit generating 4V, pulsed DC). A total of 61,2-min electrofishing shots was conducted around the perimeter (-3 m from the bank) of ponds 1-1 and 12 at LRCG. All fish captured were identified in the field and counted. All indigenous fish were measured to the nearest 1 mm total length (TL) and returned to the ponds. All P. caudimaculatus were euthanased with Benzocaine (1 mg/litre) and retained by NSW Fisheries for later inclusion in the Australian Museum collection. In the laboratory, P. caudimaculatus were measured to the nearest 1 TL and divided into one of three size classes (<1 mm, 1-24 mm, and 2 mm). The survey investigating the distribution of P. caudimaculatus in 16 water bodies surrounding and

116 New Zealand Journal of Marine and Freshwater Research, 2, Vol. 39 including LRGC was also carried out in July 22 (Fig. 2). At each site, -min observations were made of the water body and dip-netting was conducted at the sites where fish were observed. Dip-netting consisted of 1 m sweeps through the water with a dip-net (6 x 4 x x.3 cm). The number of sweeps performed was proportional to the size of the water body. RESULTS AND DISCUSSION Distribution, abundance, and population characteristics of P. caudimaculatus in NSW A total of 473 fish of three different species was caught during the LRGC electrofishing survey, with P. caudimaculatus comprising c. 88% of the total catch (Table 1). The indigenous migratory species Anguilla australis and Galaxias maculatus were much less abundant. Gambusia holbrooki was not captured or observed during the survey (Table 1). Phalloceros caudimaculatus was widespread at LRGC, and found in all ponds sampled except for ponds 1 and 2. Fish were observed at 9 of the 16 sites in the area including LRGC, however. P. caudimaculatus was not recorded from any site outside of LRCG (Table 2). Phalloceros caudimaculatus caught at LRGC ranged between 11 and 41 mm TL, with a mean of 26 mm. Phalloceros caudimaculatus >2 mm TL were the most abundant size class caught, followed by the 1-24 mm and <1 mm size classes respectively. Risk assessment Continuing introductions and range expansions of nonindigenous freshwater fishes into and among Australian waters pose a substantial threat to indigenous species (Kohen & McDowall 24). Identifying and assessing the variables involved in nonindigenous species becoming established and widespread risks can be a complex and difficult process, one hampered by the paucity of data in the majority of instances (Pascual et al. 22; Kolar 24). The risk posed by P. caudimaculatus, however, may be estimated by assessing the invasive ability and ecological impacts of the species. Invasive ability The invasive ability of P. caudimaculatus is perhaps best demonstrated by comparing the species with the closely related and highly invasive species, G. holbrooki. Apart from similarities in size, morphology and appearance, both P. caudimaculatus and G. holbrooki share the characteristics of successful invaders, with extremely broad physical tolerances and high reproductive outputs (Table 3). Further, as the natural distribution of P. caudimaculatus encompasses a similar range of latitude and elevation to G. holbrooki (Rosen & Bailey 1963; Ramshorst 1978; Bisazza & Pilastro 1997; Dawes 21; Allen et al. 22) it is likely that the former species is Table 1 Number of individuals of Galaxias maculatus and Phalloceros caudimaculatus caught and Anguilla australis observed in each water body at Long Reef Golf Course, Collaroy, Australia during July 22 electrofishing survey. Water body Pond 1 Pond 2 Pond 3 Pond 4 Pond Drainage line between ponds 6 and 7 Pond 7 Drainage line between ponds 7 and 8 Pond 8 Pond 9 Pond 1 Pond 12 Total (% of catch) A. australis 3 7 4 9 8 9 6 1 2 (1.99) G. maculatus 4 1 1 6 (1.27) P. caudimaculatus 12 7 16 4 8 368 41 (87.74)

Rowley et al. Invasive potential of Phalloceros caudimaculatus 117 adapted to and able to persist in similar climatic regimes worldwide. The present distribution of the two species, however, differs substantially. Nonindigenous populations of G. holbrooki and/or the closely related G. affinis occur through broad areas of every continent except Antarctica (Krumholz 1948; Lloyd 1984, 1986; Lloyd & Tomasov 198; Murdoch & Bence 1987), and in Australia, G. holbrooki is found in most freshwater systems (Lloyd et al. 1986; Arthington & Lloyd 1989; Arthington 1991; Arthington & McKenzie 1997). In contrast, nonindigenous populations of P. caudimaculatus only occur in Africa (e.g., Malawi (Jubb 1976/77), New Zealand (McDowall 1999), and Australia (Arthington & McKenzie 1997; Morgan et al. 24; present study)). The relatively limited distribution of P. caudimaculatus compared with G. holbrooki is likely to reflect the widespread, deliberate and persistent release of G. holbrooki as a mosquito control agent (NSW NPWS 23), rather than any difference in invasive ability. Such widespread anthropogenic dispersal has not occurred with P. caudimaculatus. The nonindigenous population of P. caudimaculatus at LRGC probably originated from the release of aquarium fish shortly before the summer of 1999/ 2, just before the large and rapid increase observed in poeciliid numbers at LRGC (G. Pyke unpubl. data). During summer 1999/2, fish that resembled P. caudimaculatus were observed at LRGC for the first time, but considered unusual colour variants of G. holbrooki. The nearest known nonindigenous populations of this fish are at least 16 km away and so dispersal of the fish without human aid to LRGC would seem to be impossible. The fish has been available locally through the aquarium community and is maintained by some local fish hobbyists (M. Robinson pers. comm.). Analysis by mtdna sequencing may provide more information about the origin of the LRGC population. The ecological impacts of nonindigenous populations of P. caudimaculatus remain unknown. However, given the well-documented negative effects of the closely related G. holbrooki (Gill et al. 1999; NSW NPWS 23) such impacts could be substantial and unpredictable. For example, there is some evidence to suggest that P. caudimaculatus may be capable of displacing G. holbrooki. Although G. holbrooki was the only nonindigenous species identified at LRGC in 1997, G. holbrooki is presently locally extinct at LRGC. Ongoing fish surveys conducted at LRGC since the identification of P. caudimaculatus, have failed to capture any G. holbrooki (R. Creese pers. comm.). Further, the first observation of P. caudimaculatus coincided with a rapid increase in its abundance (G. Pyke unpubl. data), suggesting the possibility of a rapid change in the relative abundance of P. caudimaculatus and G. holbrooki at this time. A very similar displacement has been reported at several locations in Western Australia (Maddern 23; Morgan et al. 24). During backpack electrofishing surveys, Maddern (23) collected over 9 P. caudimaculatus individuals from sites near Perth. At two of these sites, Bull Creek and Lesmurdie Brook, P. caudimaculatus was reported to have displaced G. holbrooki. At present, the mechanism behind these displacements can only be speculated. Maddern (23) proposed that, as there is little dietary overlap or agnostic behaviour between P. caudimaculatus and G. holbrooki (Table 3), the most likely explanation for the apparent displacement in Bull Creek and Lesmurdie Brook was greater tolerance for lower temperatures by P. caudimaculatus (McDowall Table 2 Abundance of fish species collected during dip-netting survey, July 22. Site name No. sweeps Phalloceros caudimaculatus Gambusia holbrooki Hypseleotris galii Bayview Golf Course Mona Vale Golf Course Pipeclay Point Creek Hendy Creek Long Reef Golf Course Dee Why Lagoon Drain 2 Dee Why Lagoon Drain 3 Dee Why Lagoon Drain Dee Why Lagoon Drain 6 Dee Why Lagoon Drain 7 1 31 38 31 131 14 16 2 12 7

o GO Table 3 Comparative morphology, behaviour and ecology of Gambusia holbrooki and Gambusia affinis to Phalloceros caudimaculatus. Home range Morphology Reproduction Diet Habitat Physico-chemical limits Ecological impacts Gambusia holbrooki and G. affinis North and Central Both species are American rivers drainin into the Gulf of Mexico (Allen 22) sexually dimorphic, with females attaining 6 cm, and males growing to c. 3. cm (Allen 22). Drab, pale olive-greenish dorsally, becoming grey with blue sheen on sides and silvery on belly (Allen 22) Phalloceros caudimaculatus South America between Yellowish overall with Brazil and Uruguay a black blotch on caudal (Rosen & Bailey 1963; peduncle edged with Bisazza & Pilastro 1997; silver or gold (Endler Allen 22) 1984; Allen 22). Variable coloration depending on location, generally mottled yellow with black spots Both species have large brood sizes, short gestation periods, and multiple broods per year (Milton & Arthington 1983; McKay 1984; Wheeler 198; Arias & Reznick 2; Dawes 21) Breeding season may be longer than for G. holbrooki (Maddern 23) Aggressive carnivore (Dionne 198; Arthington & Marshall 1999) and cannibal (Sokolov 1936; McKay 1984; Merrick & Schmida 1984; Meffe 198) Non-aggressive (Griffiths 1972; Merrick & Schmida 1984; McDowall 1999) algivore (Sterba 1962; Sabinoetal. 199; Aranhaetal. 1998; Aranha & Caramaschi 1999; Esteves & Lobon- Cervia21; Maddern, 23) Both species abundant in a wide variety of still or slow-flowing water bodies (Jubb 1976/77 ;Unmack 199; Aranhaetal. 1998; McDowall 1999; Esteves & Lobon- Cervia21; Allen et al. 22) Phalloceros genera may be better able to withstand variable hydological regimes (Meffe 1984) Tolerant of both freshwater and marine conditions (NSW NPWS 23). Temperatures from. to 38 C (Swanson & Chech 1996; Clarke et al. 2). Able to survive in anoxic conditions owing to upturned mouth and flattened head (Lloyd 1984) Fresh and brackish waters (Ramshorst 1978; Wischnath 1993). Temperatures as low as C (Hoedman 1974) and as high as 38 C (Rietzler et al. 1981). May survive low oxygen content as it displays the morphological adaptation of an upturned mouth (Culley & Ferguson 1969) Adverse affects on native wildlife caused by direct predation on tadpoles, eggs and fry of indigenous species and interspecific competition for food (NSW NPWS 23) Relatively unknown possibly detrimental (FAO 22; Jubb 1976/77) 2; :al; a g 8- a' B- s* < % o "to

Rowley et al. Invasive potential of Phalloceros caudimaculatus 119 24). This would allow the species to breed during months when G. holbrooki is reproductively restricted by cold weather. Such a situation might be exacerbated under hydrologically variable regimes, which P. caudimaculatus appears to be better adapted to withstand (Meffe 1984). At LRGC we speculate that a trophic cascade (Power 199) may possibly be involved. As an algivore (Table 3), P. caudimaculatus may have an effect on the biomass of algae available for consumption by invertebrates, upon which G. holbrooki prey (Arthington & Marshall 1999). However, there appears to be little impact of P. caudimaculatus on native species, in either Western Australia or at LRGC, some of which are likely to consume similar aquatic invertebrates to G. holbrooki (Kennard et al. 21). Alternatively, differences in coloration between P. caudimaculatus and G. holbrooki may have an influence on their relative susceptibility to predation from both fish (such as A. australis at LRGC) and bird species, as there is a highly significant correlation between rank predation intensity and the colour pattern characteristics of South American poecillids (Endler 1982, 1984). Further research is required to determine the ecological impacts of P. caudimaculatus, with particular reference to the possible displacement of G. holbrooki. CONCLUSION Any nonindigenous species has the potential to become a major pest under suitable conditions (Arthington & Marshall 1999). Species such as P. caudimaculatus, with broad physical tolerances and high fecundities, pose a particular risk. That P. caudimaculatus is so similar in biology to the renowned pest species G. holbrooki indicates the potential threat of the spread of P. caudimaculatus through Australia's waterways. Theoretically, P. caudimaculatus could inhabit all areas currently occupied by G. holbrooki. In practice, however, the risk of the species becoming established in NSW waterways beyond the closed system of LRGC, without being transported by humans, appears to be minimal. Importation of aquarium fish is a major potential source of invasive species in many countries (McDowall 24), including Australia (Kohen & MacKenzie 24). To the extent that P. caudimaculatus is maintained in captivity by aquarists there is a risk that it will be released, deliberately or inadvertently, into the wild. Therefore, minimisation of the risks to the Australian environment from P. caudimaculatus will require minimisation of its abundance amongst fish hobbyists. This may include the listing of this species as "noxious" pursuant to section 29 of the Fisheries Management Act 1994 (NSW) in Australia. Such minimisation should occur in concert with education programmes advising inexperienced aquarists of their responsibility in the conservation of Australia's aquatic environment (Kohen & MacKenzie 24). The elimination of the P. caudimaculatus population at LRCG, and any other nonindigenous populations that are discovered, is highly recommended. As the P. caudimaculatus population at LRGC is contained within a defined area, control measures appear to be practical, but continuous release of the fish species into the wild remains a constant threat. Any additional nonindigenous fish established in Australia have the potential to threaten Australian aquatic fauna, and a precautionary approach is necessary (Simberloff 23; McDowall 24). Every effort should be made to eradicate populations of nonindigenous fishes as soon as they are detected. ACKNOWLEDGMENTS This study was supported by the Australian Museum, NSW Fisheries, and Long Reef Golf Club. The tadpole/ fish monitoring was carried out under Scientific Licence issued by the NSW National Parks and Wildlife Service to G. H. Pyke as approved by the Australian Museum Animal Care and Ethics Committee. The fish surveys in June and July 22 were carried out under ACEC no. 98/ 14, NSW Fisheries Project "Survey and Control of New Pest Fish" and NPWS Section 9(2) Certificate (No. CPPD/2/24). Many helpful comments on earlier drafts of this manuscript were provided by Bob Creese, Greg Gowing, James Knight, Anne Miehs, Angela Arthington, and Gerry Closs. Kathryn Wem, Craig Murrell, and Jillian Macintyre helped with the tadpole/fish monitoring. Mark McGrouther from the Australian Museum identified the specimens. Maps were prepared with the assistance of Simon Kirkness from NSW Fisheries. For all this assistance we are most grateful. REFERENCES Allen GR, Midgley SH, Allen M 22. Freshwater fishes of Australia. Perth, Western Australian Museum. 394 p. Aranha JMR, Caramaschi EP 1999. Population structure, reproductive aspects and feeding of Cyprinodontiformes fishes (Osteichthyes) from a coastal stream in southeastern Brazil. Revista Brasileira de Zoologia 16: 637-61.

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