Limnodynastes Peronii Research Articles

Life in acid: interactive effects of pH and natural organic acids on growth, development and locomotor performance of larval striped marsh frogs (Limnodynastes peronii)

The low pH of naturally acidic aquatic environments is the result of soft-water with low buffering capacity and high concentrations of natural organic acids. Our current understanding of the influence of pH on aquatic organisms is largely limited to laboratory studies conducted under controlled conditions with little incorporation of these organic acids. Recent studies suggest natural organic acids may influence the physiology of aquatic species independent of low pH. We examined the effects of pH and varying concentrations of natural wallum water, which is high in organic acids on the hatching success, growth and locomotor performance of larval striped marsh frogs (Limnodynastes peronii). Based on previous studies, we predicted that the detrimental effects of low pH would be further exacerbated by higher concentrations of naturally occurring organic acids (high concentrations of wallum water). In artificial soft-water, embryos experienced both reduced growth and reduced survival when exposed to low pH. However, greater concentrations of natural organic acids did not exacerbate these effects of low pH on growth and development. Instead, we found some evidence that the natural organic acids within wallum water improved growth and swimming performance across all pH treatments. Using path analyses to investigate the effects of pH and natural organic acid concentration on burst swimming performance, we found performance was directly affected by both body length and organic acid concentration. Our data further highlight our limited understanding of the importance of natural organic acids for aquatic organisms and the need to incorporate greater ecological relevance into these studies.

Living in the 80s - seasonality and phenology of frog calling activity at Darkes Forest from 1987-1989

We recorded the calling activity of frogs at a permanent pond 80 km south of Sydney between 1987 and 1989, documenting the calling seasons of five species and relating calling activity (within calling seasons) to temperature, humidity, barometric pressure and rainfall. Three species commenced calling in August/September with Litoria peronli and Uperokia laevigata calling consistently throughout the summer months and Umnodynastes dumerilil calling more sporadically. Limnodynastes peronii appeared capable of calling at any time of the year, but did not call continuously. Litoria verreauxii called very consistently from January to September. Random effects models indicated that the probability of males calling increases with increasing temperatures in Limnodynastes peronli, Litoria peronii and Uperoleia laevigata. Increasing barometric pressure was positively associated with calling in Umnodynastes peronii. Calling was not related to either rainfall or humidity for any species. The calling seasons were similar to expectations based on published information. The lack of relationships between calling and rainfall and humidity may be related to the presence of permanent water and or the regular rainfall experienced throughout the study period. Historical data from this study may provide a baseline for future studies to assess changes in calling phenology linked to climate change.

Comparison of frog assemblages between urban and non‐urban habitats in the upper Blue Mountains of Australia

Summary1. World wide, and in Australia, many frog populations have declined over the last two decades. The present study was undertaken to determine whether urbanization has affected frog diversity and abundance.2. Five urban sites were paired with non‐urban sites. Urban sites were in Katoomba and Blackheath, and were subject to physical environmental disturbance and impacted by storm water pollution due to urban runoff. Non‐urban sites were in the Blue Mountains National Park and were effectively subject to no human impact.3. Water quality at urban sites was typical of sites polluted with sewage, while non‐urban sites exhibited water quality typical of ‘pristine’ natural bushland streams.4. Six species were found at urban sites (Litoria peronii, Litoria dentata, Litoria verreauxii, Limnodynastes dumerilii, Limnodynastes peronii, Crinia signifera), with up to four species present at a site. Only one species (C. signifera) was recorded at non‐urban sites, and frogs were absent from most non‐urban sites.5. The situation in non‐urban sites mirrors the trend of decline observed in other montane regions. Surprisingly, frog abundance and diversity were higher in urban habitats, running counter to this trend.6. We hypothesize that the salts, detergents and other chemicals in urban wastewaters provide frogs with a level of protection against disease, particularly chytridiomycosis.

Pond attributes influence competitive interactions between tadpoles and mosquito larvae

Abstract Tadpoles and mosquito larvae often coexist in natural freshwater bodies. We studied competitive interactions between: (i) tadpoles of the striped marsh frog (Limnodynastes peronii) and larvae of the mosquito Culex quinquefasciatus; and (ii) tadpoles of the common eastern froglet (Crinia signifera) and larvae of the mosquito Aedes australis. These two sets of taxa occur in natural water bodies in the Sydney region. Laboratory trials revealed competition between mosquito larvae and tadpoles in both systems. For example, mosquitoes displayed reduced rates of survival, growth and development, and smaller size at metamorphosis, when they were raised with tadpoles. The intensity of competitive suppression was influenced by attributes such as pond size (and hence, larval density), the location of food (on the water surface vs the substrate), and the extent of opportunities for direct physical interactions between the two competing organisms. These effects differed between the two study systems, suggesting that the mechanisms of suppression also differed. Limnodynastes peronii tadpoles suppressed C. quinquefasciatus even when the two types of organisms were separated by a physical partition, suggesting that chemical or microbiological cues may be responsible. Pond attributes also affected the impact of C. signifera tadpoles on Aedes larvae, but (unlike the Limnodynastes–Culex system) these effects disappeared when densities were lowered or when the tadpoles and mosquito larvae were physically separated. Thus, direct physical interactions may suppress mosquitoes in the Crinia–Aedes system. Our results suggest that tadpoles suppress the viability of larval mosquitoes by multiple pathways.

Mining a museum frog collection for environmental bio-indicators using specimens of the Striped Marsh Frog Limnodynastes peronii

Museum specimens of the Striped Marsh Frog, (Limnodynastes peronii; Myobatrachidae), were examined to evaluateits potential role in providing bio-indicators of environmental quality and change. I hypothesized that chemical pollutionof their breeding habitat would have peaked during the 1960s or 1970s, and that the levels of physical abnormality and morphological asymmetry for this frog species would tend to increase with increasing pollution. Consistent with this, I found that both the proportion of frogs with physical abnormalities and the average difference in length between the left and right lower legs peaked for specimens collected during the 1960s or 1970s and were lower for specimens collected during earlier and later decades. I also found that the overall proportion of specimens of this species with physical abnormalities was high relative to presumed background levels, which is consistent with relatively elevated levels of pollution in the degraded habitats where this species generally occurs. In this and similar ways, biological collections may be mined to provide environmental bio-indicators.

Interactions between tadpoles of Green and Golden Bell FrogLitoria aureaand Striped Marsh FrogLimnodynastes peronii

Abstract: Experiments with tadpoles have been used to distinguish between intra- and inter-specific interactions and between interactions that arise through direct physical contact or indirectly through water-born movement of chemicals or micro-organisms. In the case of two Australian frog species, the Green and Golden Bell Frog Litoria aurea and the Striped Marsh Frog Limnodynastes peronii, it has been suspected that there are negative chemical interactions between the tadpoles of these two species, and that management of the former species, which is considered ‘threatened’ with extinction, may have to consider such interactions. We therefore sought to evaluate the nature of any interactions between tadpoles of these two species using three experimental treatments in which each tadpole species occurred on its own (i.e., “separate”), in the same water as the other species but separated by a mesh partition (i.e., “adjacent”), and intermingling together in the same water (i.e., “mixed”). We minimized any ef...

Cooler temperatures increase sensitivity to ultraviolet B radiation in embryos and larvae of the frog Limnodynastes peronii

AbstractRecent studies suggest that complex interacting processes are driving global amphibian declines. Increased ultraviolet B (UVB) radiation in the solar spectrum associated with ozone depletion has been implicated in declines, and evidence suggests that the effects of UVB radiation on amphibians may be greater at cooler temperatures. We tested the thermal sensitivity of UVB effects on amphibians in a controlled factorial experiment using the striped marsh frog, Limnodynastes peronii as a model species. We compared survival, growth and locomotor performance of embryonic and larval L. peronii reared under low and high UVB exposures at both 20 and 30 °C. Embryonic and larval L. peronii proved extremely sensitive to UVB damage and exhibited greater sensitivity at 20 °C compared with 30 °C. Embryonic survival to Gosner stage 25 was unaffected by UVB exposure at 30 °C, but at 20 °C survival was reduced to 52% under high UVB. Larval survival exhibited a similar trend. At 20 °C, all tadpoles survived under low UVB, whereas under high UVB there was 100% mortality after 15 days of exposure. At 30 °C, 86% survived under low UVB, but only 46% survived under high UVB. Sublethal effects such as, embryonic malformation, retarded larval growth and reduced larval swimming performance were also greater at 20 °C compared with 30 °C. Our results strongly indicate that UVB damage in amphibians is markedly increased at cooler temperatures. Thus, populations of UVB sensitive species occurring at cold climates may be at greater risk of declines due to increased solar UVB radiation.

Short‐ and long‐term consequences of thermal variation in the larval environment of anurans

1. To survive adverse or unpredictable conditions in the ontogenetic environment, many organisms retain a level of phenotypic plasticity that allows them to meet the challenges of rapidly changing conditions. Larval anurans are widely known for their ability to modify behaviour, morphology and physiological processes during development, making them an ideal model system for studies of environmental effects on phenotypic traits. Although temperature is one of the most important factors influencing the growth, development and metamorphic condition of larval anurans, many studies have failed to include ecologically relevant thermal fluctuations among their treatments. 2. We compared the growth and age at metamorphosis of striped marsh frogs Limnodynastes peronii raised in a diurnally fluctuating thermal regime and a stable regime of the same mean temperature. We then assessed the long-term effects of the larval environment on the morphology and performance of post-metamorphic frogs. 3. Larval L. peronii from the fluctuating treatment were significantly longer throughout development and metamorphosed about 5 days earlier. Frogs from the fluctuating group metamorphosed at a smaller mass and in poorer condition compared with the stable group, and had proportionally shorter legs. 4. Frogs from the fluctuating group showed greater jumping performance at metamorphosis and less degradation in performance during a 10-week dormancy. Treatment differences in performance could not be explained by whole-animal morphological variation, suggesting improved contractile properties of the muscles in the fluctuating group.

Predator-induced phenotypic plasticity in tadpoles: extension or innovation?

Phenotypic plasticity, the ability of a trait to change as a function of the environment, is central to many ideas in evolutionary biology. A special case of phenotypic plasticity observed in many organisms is mediated by their natural predators. Here, we used a predator-prey system of dragonfly larvae and tadpoles to determine if predator-mediated phenotypic plasticity provides a novel way of surviving in the presence of predators (an innovation) or if it represents a simple extension of the way noninduced tadpoles survive predation. Tadpoles of Limnodynastes peronii were raised in the presence and absence of predation, which then entered a survival experiment. Induced morphological traits, primarily tail height and tail muscle height, were found to be under selection, indicating that predator-mediated phenotypic plasticity may be adaptive. Although predator-induced animals survived better, the multivariate linear selection gradients were similar between the two tadpole groups, suggesting that predator-mediated phenotypic plasticity is an extension of existing survival strategies. In addition, nonlinear selection gradients indicated a cost of predator-induced plasticity that may limit the ability of phenotypic plasticity to enhance survival in the presence of predators.

TADPOLES OF FOUR COMMON AUSTRALIAN FROGS ARE NOT EFFECTIVE PREDATORS OF THE COMMON PEST AND VECTOR MOSQUITO CULEX ANNULIROSTRIS

In a laboratory investigation of tadpoles of 4 Australian frogs, Limnodynastes peronii, Limnodynastes tasmaniensis, Litoria aurea, and Litoria peronii, there was no evidence of active predation on larvae of Culex annulirostris. The mortality of larvae was greatest when exposed to the tadpoles of Litoria spp., which may have been the result of specific foraging behavior. Results indicate that Litoria spp. tadpoles may have a minor impact on mosquito populations, but they are unlikely to be useful biological control agents in Australia.

Predator‐mediated phenotypic plasticity in tadpoles of the striped marsh frog, Limnodynastes peronii

Abstract We tested the phenotypic responses of larval striped marsh frogs (Limnodynastes peronii) to the odonate nymph predator, Aeshna brevistyla. When reared in the presence of dragonfly nymphs feeding upon conspecifics of L. peronii larvae the tadpoles showed a strong change in morphology. Morphological changes included an increase in total tail height, but also an unexpected marked change in head‐body shape. In addition, we examined how tadpole development, as well as mass and length at metamorphosis, was affected by exposure to dragonfly nymphs. Larval development of L. peronii was strongly influenced by exposure to the predatory behaviour of dragonfly nymphs. Predator‐induced tadpoles had significantly slower developmental rates than control larvae. Although metamorphs of non‐exposed L. peronii were approximately 33% lighter than predator‐exposed metamorphs and possessed lower jump distances, after adjusting for mass there was no difference in jump distance. The newly described morphological response may assist in more accurately relating morphological plasticity to fitness.

Biochemical acclimation of metabolic enzymes in response to lowered temperature in tadpoles of Limnodynastes peronii

We measured the rate at which the metabolic enzymes lactate dehydrogenase (LDH), citrate synthase (CS), and cytochrome c oxidase (CCO) acclimate in the response to lowered temperature in the axial muscle of tadpoles of Limnodynastes peronii (Anura: Myobatrachidae) over 6 weeks. In addition, we measured growth rates of the tadpoles kept at both temperatures and examined the activities of these enzymes in the liver tissue of the control group and cold-acclimated group at the end of the experiment. We found that LDH acclimates in axial muscle; the differences between the control and cold-acclimated group became apparent after 21 days. After 42 days, the activity of LDH in axial muscle in the cold-acclimated group was 30% greater than the control group. Growth rates were maintained at 0.7 mm/week within both treatments despite the 10 °C difference in temperature between experimental groups. Both LDH and CS were increased in activity in the liver (5 and 1.3 times greater, respectively, in the cold-acclimated group). The thermal sensitivity (Q 10) of LDH was between 20 and 30 °C in the cold-acclimated group (1.2±0.01) when compared to the control group (1.6±0.15). The rate at which acclimation in this species occurs is appropriate for seasonal changes in temperature, and these animals may not be able to respond to a rapid drop in temperature.

Egg temperature modifies predator avoidance and the effects of the insecticide endosulfan on tadpoles of an Australian frog

Summary Attention is shifting from simplistic explanations of global amphibian declines that posit a single cause (such as climate change, pesticide contamination or disease) to more complex scenarios that involve interactive effects. Temperature is a pervasive influence on frog development, particularly during the egg and larval stages. However, the effect of temperatures experienced early in ontogeny on later larval behaviour or response to agrochemicals is little known. Eggs of the Australian frog Limnodynastes peronii were reared at two temperatures that simulate naturally occurring cool and warm temperature regimes (14 ± 3 °C and 20 ± 3 °C). Tadpoles were then exposed to sublethal concentrations of the organochlorine insecticide endosulfan, at a common temperature. Endosulfan often contaminates aquatic environments, yet its effects on Australian frogs are unknown. Tadpoles reduced feeding after 48 h of exposure to endosulfan concentrations that occur in the field (both 0·03 µg l−1 and 1·3 µg l−1). Feeding remained depressed at 1·3 µg l−1 endosulfan up to 9 days after tadpoles were transferred to endosulfan‐free water. Egg‐rearing temperature and endosulfan interacted to affect tadpole length. Further, tadpoles exposed to endosulfan were significantly shorter than control tadpoles. They were also more vulnerable to capture by an invertebrate (odonate) predator than controls of the same size when tested 9 days after transfer to clean water. While warm egg‐rearing temperatures significantly decreased vulnerability to capture, tadpoles were proportionally more adversely affected by endosulfan. Thus, egg‐rearing temperature altered predator avoidance and changed the way in which endosulfan affected growth. Moreover, endosulfan significantly decreased feeding, growth and predator avoidance. Synthesis and applications. Not only can short‐term exposure to endosulfan at levels within regulatory guidelines and frequently reported in natural waterbodies influence tadpole viability, but the sensitivity of the tadpoles to this effect depends upon the thermal regimes that they encounter over their first few days of life. These data therefore suggest that existing water quality prescriptions may not provide adequate protection, while also illustrating how aspects of climate and thermal regimes might interact with pesticides to have cumulative effects on amphibian fitness.

Amphibian decline and fertilizers used on agricultural land in south-eastern Australia

Evidence is provided that fertilizer use increased markedly from the 1960s in New South Wales (NSW), south-eastern Australia. The agrochemicals probably accumulated on agricultural land until 1974, when they were washed or leached after heavy rains into waterbodies that may have been occupied by the endangered green and golden bell frog ( Litoria aurea). The numbers of annual sightings suggest that the range of this species contracted in 1975, following the suspected pulse of fertilizers into aquatic habitats. There was no such decline for the common eastern froglet ( Crinia signifera) and the striped marsh frog ( Limnodynastes peronii), which commonly occur in many agricultural waterbodies. A laboratory study showed that L. aurea, C. signifera, and L. peronii tadpoles exposed to ammonium nitrate and calcium phosphate fertilizers over 150, 21, and 91 days differed in survivorship. Significantly few L. aurea tadpoles survived to metamorphosis in 10 and 15 mg/l ammonium nitrate, and 15 mg/l calcium phosphate, which had no effect on the survivorship of C. signifera and L. peronii tadpoles. Historical and experimental evidence suggests that the elevated nitrate and phosphate concentrations in waterbodies in 1974–1975 contributed to the decline of L. aurea in its former range.

Swimming against the current: the Brown Striped Marsh Frog Limnodynastes peronii success story

Seven potential anuran breeding sites within Western Sydney were sampled between March and August 1997 to assess the effect of habitat disturbance upon species assemblages. The greatest species diversity and abundance was recorded in relatively less human impacted areas, than in more disturbed sites. Of the seven species recorded to chorus during cooler months, only Limnodynastes peronii successfully breed and only in disturbed sites. The species was also more abundant in such areas than more pristine habitat. Oviposition time influenced larval growth rate, although there was no defined trend over time. Intra-clutch variation in weight achieved (over 10 weeks) was greater than among clutches. Ability to take advantage of breeding habitat that is sub-optimal for other species, the ability to breed year around and larval growth plasticity have apparently pre-adapted this species to thrive in urban impacted habitat, in contrast to most local endemic species.

Oviposition site selection by mosquitoes is affected by cues from conspecific larvae and anuran tadpoles

Abstract The oviposition site that a female mosquito selects will influence the fitness of her larvae. We conducted a series of artificial pond experiments to compare the oviposition responses of two species of mosquitoes with the presence of tadpoles, conspecifics and chemical cues from these organisms. The two mosquito species differ markedly in larval ecology. The larvae of one species, Culex quinquefasciatus, co‐occur with numerous freshwater organisms, including tadpoles of Linmodynastes peronii (the striped marsh frog). Larvae of the other mosquito, Ochlerotatus australis, inhabit small brackish rock ponds where the main potential competitors are tadpoles of Crinia signifera (the common eastern froglet). In field trials, females of both mosquito species oviposited significantly more often in water that contained (or had previously contained) conspecific larvae. However, these superficially similar responses were mediated via different pathways: fungicide abolished the response by C. quinquefasciatus but not by O. australis. The two mosquito species also responded differently to cues associated with syntopic tadpoles. The presence of tadpoles did not influence oviposition by C. quinquefasciatus, but O. australis oviposited less often if tadpoles were present. These interspecific differences in oviposition behaviour may be adaptive to differences in larval ecology: competition with tadpoles is likely to be more significant for O. australis than for C. quinquefasciatus. Our findings thus support the hypothesis that mosquitoes oviposit selectively to avoid potential anuran larval competitors.

Biological warfare in the garden pond: tadpoles suppress the growth of mosquito larvae

Abstract. 1. Although tadpoles and mosquito larvae may compete for scarce resources in natural freshwater systems, the mechanisms involved in such competition remain largely unstudied.2. Replicated artificial ponds were set up to examine the role of pathogenic interference (water‐borne growth inhibitors) in two tadpole–mosquito systems from south‐eastern Australia. One system comprised taxa that are commonly sympatric in freshwater ponds (tadpoles of Limnodynastes peronii and larvae of Culex quinquefasciatus) while the other comprised species that co‐occur in brackish water ponds (tadpoles of Crinia signifera and larvae of Ochlerotatus australis).3. Water that had previously contained tadpoles suppressed the rates of survival and pupation of mosquito larvae in both systems. Fungicide reduced or eliminated this effect, suggesting that the growth inhibitors may be fungal organisms (possibly the yeast Rhodotorula glutinis) from tadpole faeces. Fungicide also enhanced growth rates of tadpoles.4. These results suggest that interference competition between tadpoles and mosquito larvae is mediated by other organisms in some ecological systems.

Thermal plasticity of skeletal muscle phenotype in ectothermic vertebrates and its significance for locomotory behaviour.

Seasonal cooling can modify the thermal preferenda of ectothermic vertebrates and elicit a variety of physiological responses ranging from winter dormancy to an acclimation response that partially compensates for the effects of low temperature on activity. Partial compensation of activity levels is particularly common in aquatic species for which seasonal temperature changes provide a stable cue for initiating the response. Thermal plasticity of locomotory performance has evolved independently on numerous occasions, and there is considerable phylogenetic diversity with respect to the mechanisms at the physiological and molecular levels. In teleosts, neuromuscular variables that can be modified include the duration of motor nerve stimulation, muscle activation and relaxation times, maximum force and unloaded shortening velocity (V(max)), although not all are modified in every species. Thermal plasticity in V(max) has been associated with changes in myosin ATPase activity and myosin heavy chain (MyHC) composition and/or with a change in the ratio of myosin light chain isoforms. In common carp (Cyprinus carpio), there are continuous changes in phenotype with acclimation temperature at lower levels of organisation, such as MyHC composition and V(max), but a distinct threshold for an effect in terms of locomotory performance. Thus, there is no simple relationship between whole-animal performance and muscle phenotype. The nature and magnitude of temperature acclimation responses also vary during ontogeny. For example, common carp acquire the ability to modify MyHC composition with changes in acclimation temperature during the juvenile stage. In contrast, the thermal plasticity of swimming performance observed in tadpoles of the frog Limnodynastes peronii is lost in the terrestrial adult stage. Although it is often assumed that the adjustments in locomotory performance associated with temperature acclimation enhance fitness, this has rarely been tested experimentally. Truly integrative studies of temperature acclimation are scarce, and few studies have considered both sensory and motor function in evaluating behavioural responses. Developmental plasticity is a special case of a temperature acclimation response that can lead to temporary or permanent changes in morphology and/or physiological characteristics that affect locomotory performance.

Pond attributes influence competitive interactions between tadpoles and mosquito larvae

Abstract Tadpoles and mosquito larvae often coexist in natural freshwater bodies. We studied competitive interactions between: (i) tadpoles of the striped marsh frog (Limnodynastes peronii) and larvae of the mosquito Culex quinquefasciatus; and (ii) tadpoles of the common eastern froglet (Crinia signifera) and larvae of the mosquito Aedes australis. These two sets of taxa occur in natural water bodies in the Sydney region. Laboratory trials revealed competition between mosquito larvae and tadpoles in both systems. For example, mosquitoes displayed reduced rates of survival, growth and development, and smaller size at metamorphosis, when they were raised with tadpoles. The intensity of competitive suppression was influenced by attributes such as pond size (and hence, larval density), the location of food (on the water surface vs the substrate), and the extent of opportunities for direct physical interactions between the two competing organisms. These effects differed between the two study systems, suggesting that the mechanisms of suppression also differed. Limnodynastes peronii tadpoles suppressed C. quinquefasciatus even when the two types of organisms were separated by a physical partition, suggesting that chemical or microbiological cues may be responsible. Pond attributes also affected the impact of C. signifera tadpoles on Aedes larvae, but (unlike the Limnodynastes–Culex system) these effects disappeared when densities were lowered or when the tadpoles and mosquito larvae were physically separated. Thus, direct physical interactions may suppress mosquitoes in the Crinia–Aedes system. Our results suggest that tadpoles suppress the viability of larval mosquitoes by multiple pathways.

Reproduction and larval growth of the urban dwelling Brown Striped Marsh FrogLimnodynastes peronii

Limnodynastes peronii was observed to successfully breed in small urban impoundments. Fecundity, egg viability and hatching success varied significantly, spatially and temporally. The predominant influence on breeding success was therefore deduced to be environmental. In contrast, growth varied more within populations than over time or between waterbodies and the observed results were considered to reflect genetic, rather than environmental, differences. Abnormalities were also hypothesised to reflect genetic differences and not environmental conditions.