Gambusia holbrooki is a small, aggressive fish introduced into Australia in 1925 to control mosquitoes. It has been suggested that this species may also prey on tadpoles and be a contributing factor in the decline of some Australian frog populations. We examined the influence of tadpole body size (10 mm. 15 mm and 20 mm). predator prey ratio (1 : 1, 1 :2 and 1 :4) and nutritional status of the predator on the level of predation by G. holbrooki on tadpoles of Limnodynasfas peronii. Unfed fish attacked all three size classes of tadpoles without any significant preference but did so more vigorously when the predator/prey ratio was densest. Predator/prey ratio had no significant overall effect on attack of tadpoles by fed fish but there was a preference for the smaller tadpoles during the first six hours of the experiment. Unfed fish also consumed more of the tadpoles they attacked than did the fed fish.

Field surveys were carried out on 10 permanent water bodies in north-west Sydney to examine any correlation between the abundance of G. holbrooki and frog species richness or abundance. The most abundant species was C. signifera. Regression analysis showed a negative relationship between density of G. holbrooki and the abundance of frogs. A positive relationship between the abundance of tree frog species and the cover of aquatic vegetation was also found. While this study did not investigate other factors contributing to declining frog populations, the results of the laboratory experiments and field surveys are consistent with the hypothesis that G. hoibrooki is contributing to declining frog populations.

Alford, R. A., 1989, Variation in predator phenology affects predator performance and prey community composition. Ecology 70: 206-19.
Variation in predator phenology affects predator performance and prey community composition
, 
Ecology
, vol. 
70
 (pg. 
206
-
19
)
Allen, G. R., 1989. Freshwater Fishes of Australia, T. F. H. Publications: Brookvale.
, 
Freshwater Fishes of Australia
Barinaga, M., 1990. Where have all the froggies gone? Science 247: 1034-034.
Where have all the froggies gone?
, 
Science
, vol. 
247
 (pg. 
1034
-
034
)
Beadle, I. C., 1982. The vegetation of Atrstralia. Cambridge University Press: Sydney.
, 
The vegetation of Atrstralia
Beattie, R. C. and Tyler-Jones, R., 1992. The effect of low pH and aluminium on breeding success in the frog Rang temporaria. J. Herpetol. 26: 353-60.
The effect of low pH and aluminium on breeding success in the frog Rang temporaria
, 
J. Herpetol.
, vol. 
26
 (pg. 
353
-
60
)
Begon, M., Harper, J. L. and Townsend, C. R., 1990. Ecology: Individuals, populations and communities. Blackwell Scientific Publications: Boston.
, 
Ecology: Individuals, populations and communities
Bence, J. R. and Murdoch, W. W., 1986. Prey size selection by the mosquitofish: relation to optimal diet theory. Ecology 67: 24-36.
Prey size selection by the mosquitofish: relation to optimal diet theory
, 
Ecology
, vol. 
67
 (pg. 
24
-
36
)
Blaustein, A. R. and Wake, D. B., 1990. Declining Amphibian Populations: A Global Phenomenon? TREE 5: 203-04.
Declining Amphibian Populations: A Global Phenomenon?
, 
TREE
, vol. 
5
 (pg. 
203
-
04
)
Booth, D. J., 1980. Investigations into the extent and mechanisms of prey-size selection by the fish species Pseudomugil signifer (KNER) and Gambusia affinis (Baird and Girard). unpublished B. Sci (Hoes) thesis. University of Sydney.
Bradford, D. F., 1989. Allotropic distribution of native frogs and introduced fishes in high Sierra Nevada Lakes of California: Implication of the negative effects of fish introductions. Copeia 1989(3): 775-78.
Allotropic distribution of native frogs and introduced fishes in high Sierra Nevada Lakes of California: Implication of the negative effects of fish introductions
, 
Copeia
, vol. 
1989
 (pg. 
775
-
78
)
Brodie, E. D., Formanowicz, D. R. and Jr., 1983. Prey size preference of predators: Differential vulnerability of larval anurans. Herpetologica 39: 67-75.
Prey size preference of predators: Differential vulnerability of larval anurans
, 
Herpetologica
, vol. 
39
 (pg. 
67
-
75
)
Bronmark, C. and Edenhamn, P., 1994, Does the presence of fish affect the distribution of tree frogs (Hyla arborea)? Consent. Biol. 8: 841-45.
Does the presence of fish affect the distribution of tree frogs (Hyla arborea)?
, 
Consent. Biol.
, vol. 
8
 (pg. 
841
-
45
)
Caldwell, J. P., Thorp, J. Ii. and Jervey, T. Q., 1950. Predator-prey relationships among larval dragonflies, salamanders and frogs. Decologia 46: 285-89.
Predator-prey relationships among larval dragonflies, salamanders and frogs
, 
Decologia
, vol. 
46
 (pg. 
285
-
89
)
Grump, M. L., 1984. Ontogenetic changes in vulnerability to predation in tadpoles of Hyila pseudopuma. Herpetologica 40(3): 265-71.
Ontogenetic changes in vulnerability to predation in tadpoles of Hyila pseudopuma
, 
Herpetologica
, vol. 
40
 (pg. 
265
-
71
)
Ferraro, T. J., 1993. Amphibian decline; a case study in western Sydney. Pp, 197-204 in Herpetology in Australia: A Diverse Discipline ed by D. Lunney and D. Ayers. Royal Zoological Society of New South Wales: Mosman.
, 
Herpetology in Australia: A Diverse Discipline
(pg. 
197
-
204
)
Ferraro, T. J. and Burgin, S., 1993. Review of environmental factors influencing the decline of Australian frogs, Pp. 205-18 in Herpetology in Australia. A Diverse Discipline ed by D. Lunney and D. Ayers. Royal Zoological Society of New South Vales: Mosman.
, 
Herpetology in Australia. A Diverse Discipline
(pg. 
205
-
18
)
Grigg, G. and Barker, J., 1983, Frog Galls of S.E. Australia, (Audio). Australian Museum: Sydney.
Grubb, J. C., 1972. Differential predation by Gambusia of affenis on the eggs of seven species of anuran amphibians. Amer. Midland Natur. 88: 102-08.
Differential predation by Gambusia of affenis on the eggs of seven species of anuran amphibians
, 
Amer. Midland Natur.
, vol. 
88
 (pg. 
102
-
08
)
Hero, J., 1991, A froggy forecast. Wildl. Aust. 28: 14-15.
A froggy forecast
, 
Wildl. Aust.
, vol. 
28
 (pg. 
14
-
15
)
Hurlbert, S. H., Zedler, J., and Fairbanks, D., 1972, Ecosystem alteration by mosquitofish (Gambusia affcnis) predation. Science 175: 639-41.
Ecosystem alteration by mosquitofish (Gambusia affcnis) predation
, 
Science
, vol. 
175
 (pg. 
639
-
41
)
Jutterbuck, J. E., 1994. Comments about the amphibian decline symposium. Herpetol. Rev. 21: 75-76.
Comments about the amphibian decline symposium
, 
Herpetol. Rev.
, vol. 
21
 (pg. 
75
-
76
)
Fats, L. B., Petranka, J. W. and Sih, A., 1988. Antipredator defenses and the persistence of amphibian larvae with fishes. Ecology 69: 1865-870.
Antipredator defenses and the persistence of amphibian larvae with fishes
, 
Ecology
, vol. 
69
 (pg. 
1865
-
870
)
Leger Moss, J. T., 1988. A preliminary report for Queensland National Parks and Wildlife Service on the freshwater fishes of Morton Island, Queensland with special comment on the exotic “mosquito fish”, Gambusia affinis, Dept. Recreation and Health: Brisbane City Council.
Littlejohn, M. J., 1965. Frogcalls and the species problem, Aust. Zool. 14: 259-64.
Frogcalls and the species problem
, 
Aust. Zool.
, vol. 
14
 (pg. 
259
-
64
)
Lloyd, L. N., Arthington, A. H. and Milton, D. A., 1986, The mosquitofish - a valuable mosquito-control agent or a pest? Pp. 7-25 in The Ecology of Exotic Animails and Plants: some Australian case histories ed by R. L. Kitching. John Wiley and Sons: Gladesville.
, 
The Ecology of Exotic Animails and Plants: some Australian case histories
(pg. 
7
-
25
)
Lloyd, L., 1989. Ecological interactions of Gambusia hoibrooki with Australian native fishes. Pp, 94-97 in Introduced and Translocated, fishes and their ecological effects ed by D. AA. Pollard. Australian Government Publishing Service; Canberra.
, 
Introduced and Translocated, fishes and their ecological effects
(pg. 
94
-
97
)
Mahony, M. J., 1993. The status of frogs in Watagan Mountains area of the Central Coast of New South Wales. Pp. 257-64 in Herpetology in Australia: A Diverse discipline ed by D. Lunney and D. Ayers. Royal Zoological Society of New South Wales: Mosman.
, 
Herpetology in Australia: A Diverse discipline
(pg. 
257
-
64
)
Martin, G., 1990. Froggy Bottom. Discover 1990: 36-37.
Froggy Bottom
, 
Discover
, vol. 
1990
 (pg. 
36
-
37
)
McDowall, R. M., 1980. Freshwater Fishes of South-eastern Australia. Reed Publishing: Terrey Hills.
, 
Freshwater Fishes of South-eastern Australia
Merrick, J. R., and Schmida, G. E.,1984. Australian Freshwater Fishes: Biology and Management. Griffin Press Ltd: Netley.
, 
Australian Freshwater Fishes: Biology and Management
Morin, P. J., 1981. Predatory salamanders reverse the outcome of competition among three species of Anuran tadpoles. Science 212: 1284-286.
Predatory salamanders reverse the outcome of competition among three species of Anuran tadpoles
, 
Science
, vol. 
212
 (pg. 
1284
-
286
)
Moyle, P. B. and Cech, J. J., 1982. Fishes. Air introduction to Ichthyology. Prentice-Hall Inc: New Jersey.
, 
Fishes. Air introduction to Ichthyology
Myers, G. S., 1965. Gambnsia, the fish destroyer. Aust. Zool. 13: 102.
Gambnsia, the fish destroyer
, 
Aust. Zool.
, vol. 
13
 pg. 
102
 
Petranka, J. W., 1989. Response of toad tadpoles to conflicting chemical stimuli: Predator avoidance versus “ioptima1” foraging. Herpetologica 45, 283-92.
Response of toad tadpoles to conflicting chemical stimuli: Predator avoidance versus “ioptima1” foraging
, 
Herpetologica
, vol. 
45
 (pg. 
283
-
92
)
Phillips, K., 1990. Where have all the frogs and toads gone? BioScience 40: 422-24.
Where have all the frogs and toads gone?
, 
BioScience
, vol. 
40
 (pg. 
422
-
24
)
Resetarits, W. J., Wilbur, Jr, and H. M., 1989. Choice of Oviposition Site by Hyla Chrysoscelis: Role of Predators and Competitors. Ecology 70: 220-28.
Choice of Oviposition Site by Hyla Chrysoscelis: Role of Predators and Competitors
, 
Ecology
, vol. 
70
 (pg. 
220
-
28
)
Richards, S. J. and Bull, C.M. 1990. Size-Limited Predation on Tadpoles of Three Australian Frogs. Copeia 1990: 1041-046.
Size-Limited Predation on Tadpoles of Three Australian Frogs
, 
Copeia
, vol. 
1990
 (pg. 
1041
-
046
)
Robinson, L., 1991. Fief Guide to the Native Plants of Sydney. Kangaroo Press; Kenthurst.
, 
Fief Guide to the Native Plants of Sydney
Robinson, M., 1993. A Field Guide to Frogs of Australia. Reed Publications: Chatswood.
, 
A Field Guide to Frogs of Australia
Sainty, G. R. and Jacobs, S. W. L., 1981. Waterplants of New South Wales. C. C. Merritt Pty Ltd: Chiswick.
, 
Waterplants of New South Wales
Semlitsch, R. D., 1993. Effects of different predators on the survival and development of tadpoles from the hybridogenetic Rana esculenta complex. Oikos 67: 40-46.
Effects of different predators on the survival and development of tadpoles from the hybridogenetic Rana esculenta complex
, 
Oikos
, vol. 
67
 (pg. 
40
-
46
)
Semlitsch, R. D. and Gibbons, J. W., 1958. Fish predation in size-structured populations of treefrog tadpoles. Oecologia 75: 321-26.
Fish predation in size-structured populations of treefrog tadpoles
, 
Oecologia
, vol. 
75
 (pg. 
321
-
26
)
Slater, K., 1978. Fauna:reptiles and amphibians. Pp. 80-86 in Land use on the South Coast of New South Wales, Vol 2. ed by R. H. Guon. CSIRO: Melbourne.
, 
Land use on the South Coast of New South Wales
, vol. 
2
 (pg. 
80
-
86
)
Smith, D. C., 1983. Factors controlling tadpole populations of the Chorus Frog (Pseudacris triseriata) on Isle Royale, Michigan. Ecology 64: 591-10.
Factors controlling tadpole populations of the Chorus Frog (Pseudacris triseriata) on Isle Royale, Michigan
, 
Ecology
, vol. 
64
 (pg. 
591
-
10
)
Southwood, T. R. E., 1966. Ecological Methods with Crticu1ar reference to the study of insect populations. Chapman Hall: London.
, 
Ecological Methods with Crticu1ar reference to the study of insect populations
Travis, J., Keen, H. and Juilianna, J., 1985. The role of relative body size in a predator-prey relationship between dragonfly naiads and larval anurans. Oikos 45: 59-65.
The role of relative body size in a predator-prey relationship between dragonfly naiads and larval anurans
, 
Oikos
, vol. 
45
 (pg. 
59
-
65
)
Tyler, M. J., 1991. Our vanishing frogs. Habitat 19: 20-25.
Our vanishing frogs
, 
Habitat
, vol. 
19
 (pg. 
20
-
25
)
Tyler, M. J., 1992. Encyclopedia of Australian Animas: Frogs. Angus and Robinson: Pymble.
, 
Encyclopedia of Australian Animas: Frogs
Tyler. M. J. and Davis, M., 1985. The gastric brooding frog Rheobatrachus silus. Pp. 469-70 in The Biology of Australian Frogs and Reptiles ed by G. Grigg, R. Shine and H. Ehmann. Surrey Beatty & Sons: Chipping Norton.
, 
The Biology of Australian Frogs and Reptiles
(pg. 
469
-
70
)
Warner, S., Travis, J. and Dunson, W. A., 1993. Effect of pH on interspecific competition between two species of Hylid tadpoles. Ecology 74: 183-94.
Effect of pH on interspecific competition between two species of Hylid tadpoles
, 
Ecology
, vol. 
74
 (pg. 
183
-
94
)
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