• Body size in E. m. macquarii differed markedly between populations. Femalesranged in maximum sizes (carapace length) of 180 mm in the Macleay River to over 300 mm in the Murray River. E. m. macquarii was sexually dimorphic across allpopulations with females larger than males in all cases.
  • Nesting season began as early as mid-September in the Brisbane River andas late as December in the Hunter River, and continued until early January. Populationsin the Hunter and Murray Rivers are likely to produce only one clutch per season while populations from the Macleay and Nepean Rivers can produce two, and on someoccasions, three clutches annually. The majority of females would appear to reproduceevery year.
  • Research fromNorth American studies have demonstrated that many species of freshwater turtlesdisplay large variation in life history attributes across their range
  • Even within a population, life history traits can vary due to fluctuations inenvironmental condition
  • E. macquarii is unable to migrate between waterbodies, as it is largely restricted to permanent waters (Chessman 1978, 1984, 1998). Therefore, populations of Em. macquarii are reproductively isolated […] as a result, Em. macquarii is genetically and morphologically more variable […]
  • Turtles in the genus Emydura are the best studied species of freshwater turtle in Australia
  • Emydura macquarii is a short-necked species of turtle with a carapace that islight brown to black in colour. Body size is highly variable, with reported maximumsizes for females ranging from 180 mm in the Macleay-Hastings rivers (Cann, 1998) toover 320 mm in the Murray River (Chessman, 1978). Similarly, body shape is alsovariable, both within and amongst populations.
  • Adult males are easily distinguished from adult females by their longer, thicker tail. Em. macquarii prefersdeep permanent still waterbodies such as rivers and its backwaters (swamps andlagoons) where they are generally the pre-dominant turtle species (Chessman, 1988).The high rate of evaporative water loss under desiccating conditions prevents Em.macquarii from migrating overland (Chessman, 1984), thereby restricting them topermanent waterholes.
  • Emydura macquarii is omnivorous consuming a wide range of food types suchas filamentous algae, periphyton, aquatic macrophytes and invertebrates, terrestrial insects and carrion (Georges, 1982b; Chessman, 1986). Juveniles tend to be more carnivorous than adults (Georges, 1982b).
  • Age determination: “Growth ring data was only used for juveniles and young adults, as rings became intermittent and undetectable in older individuals” scute annuli (costal scutes)
  • [Figure 3.5 shows age-length relationship from age 0 (~25 mm) until age 7 years (~200 mm)]
  • The results of our study demonstrated that C. expansa andE. macquarii have adaptive behavioural and physiologicalmechanisms reported previously only from euryhaline estuar-ine turtles living with periods of elevated, hypertonic envir-onmental salinity (Dunson, 1986), despite the species studied here being widely distributed through the largest freshwatercatchment in Australia. This suggests that there has been along history of evolutionary adaptation to the fluctuatingsalinities of the Murray–Darling system in these species […]
  • our study indicated a high adaptive fitness of the species to acutesalinity events, from which physiological recovery appears tobe rapid. Those adaptations evident in the species that weinvestigated include a behavioural reduction in food intake, which would reduce the ingestion of salt, which is rapidly reversed on return to freshwater. […] the increase in plasma electrolytes (especially sodium and chloride) and nitrogenous osmolytes (urea and uric acid) […] The behavioural reduction in food intake may be associated with a reduced metabolic rate, because digestive activity is reduced, and is probably associated with a reduction, if not cessation, inexcretion (a water-conserving mechanism) […]
  • The freshwater treatment tur-tles were kept in tap water with a salinity of 0%o for theduration of the experiment. Animals in the brackish treat-ment were acclimated by placement into water of 5, 7, 10 and 13%o progressively every 2 days, followed by 15%o untilfor 50 days
  • […] this species is an opportunistic omnivore. In order of decreasing importance the main food types were filamentous algae, vertebrate (mainly fish) carrion, detritus, periphyton (including sponges), mobile aquatic invertebrates, aquatic macrophytes and terrestrial invertebrates. There was a degree of dietary shift with turtle size, small specimens containing moredetritus and periphyton and less filamentous algae, macrophytes and carrion than bigger ones.
  • Frequency of atmospheric basking was significantly positively correlated with operative environmental temperature (Te).
  • Operative environmental temperatures(Te) associated with atmospheric baskingwere estimated from the equation Te = 0.017R + 1.18Ta - 2.88 log V - 11.2 derived by Crawfordet al. (1983) for Pseudemys scripta, which is similar to E. macquarii in gross morphology. In this equa-tion, R is total radiationin watts per square meter, Ta is air temperature (C), and V is wind velocity in meters per second.
  • Overall, atmospheric basking was seen over the following ranges of environ-mental conditions: wind velocity 0-3 m/s, water surface temperature 10.1-31.8 C, air temperature 14.6-43.0 C, estimated Te 11.0-53.3 C, estimated solar radiation 200-1400 W/m2. It was observed only between 0800 and 1900 h
  • E. macquarii was the species most often caught in the river itself and riverbackwaters
  • Relative abundance of E. macquarii was significantly positively correlated with water body depth, transparency, persistence during dry conditions and flow speed, and negatively correlated with remoteness from the river.
  • it is clear that E. macquarii avoids shallow water bodies, because no specimenwas taken from a water body less than 2 m deep
  • E. macquarii [occupied] a middle layer [within water bodies] comprising logs and other debris
  • Oxygen consumption of Chelodina expansa, C. longicollis and Emydura macquarii (Pleurodira: Chelidae) was measured at rest and during induced exercise at 8, 13, 18, 22, 26, 30 and 34°C.
  • In C. expansa and E. macquarii, active and aerobic scope increased over the full temperature range assessed but in C. longicollis these variables reached a plateau above 22°C.
  • I compared various forms of basking in nature, and responses to aquatic and aerial photothermal gradients in the laboratory, among three species of Australian chelid turtles: Chelodina expansa, C. longicollis and Emydura macquarii.
  • [Fig. 1 and 2 show that for E. macquarii, air temperature varies between ~15 and ~37 °C; water surface temperature between 10 and ~32 °C; and water bottom temperature between ~20 and ~25 °C.]
  • C. expansa, C. longicollis and E. macquarii all appeared to consistently avoid raising body temperatures above ~34°C
  • The probability of E. m. macquarii activity was significantly related to mean daily water temperature (P < 0.0001) (Table 4.1). Probability of activity increased with mean daily water temperaturein both habitats, but at water temperatures greater than 19°C, turtles were more likely to beactive in Yellowbelly Creek than Horseshoe Lagoon (Figure 4.2). In Yellowbelly Creek, watertemperatures of 16°C or less were associated with a very low probability of activity.Throughout the 10 days of radiotracking in Horseshoe Lagoon, water temperatures rangedfrom a minimum of 17.5°C in spring to a maximum of 30.5°C in summer. In contrast, watertemperatures in Yellowbelly Creek ranged from 14.5°C in spring to 22.5°C in summer.
  • [Figures 4.2 and 4.3 shows that water temperature ranged between 15 and 30 °C, with activity increasing linearly with temperature.]
  • In summer, water temperatures of around 18°C to 22°C in Yellowbelly Creek still likelyconstituted a thermally challenging environment for E. m. macquarii. Spencer et al (1998) found that consumption rates and rates of food passage in E. m. macquarii were significantlyenhanced at water temperatures of 30°C compared to 20°C. Chessman (1988a) found thatcapture rates of E. m. macqaurii in baited traps were highest at water temperatures of between 25°C and 30°C, indicating that this is an optimal temperature range for feeding activity.
  • Laboratory experiment: Both plants (F1,105 = 10,295, p < 0.001) and turbidity(F1,105 = 11.73, p < 0.001) significantly affected theamount of time (represented by the proportion ofphotographs) that each turtle spent on the left side ofthe tank (Supplementary Table S2). When plants wereavailable (always on the left side of the aquarium),turtles spent significantly more time on the left sideamong the plants (Fig. 1).
  • Hatchling E. macquarii prefer aquatic vegetationover bare habitat in both the laboratory and the field.

Pahuja & Marayan 2021, Evaluating the Stressors Impacting Rescued Reptilian Wildlife, link

  • In this study we identified 4 degrees of stressor categories (preliminary, primary, secondary and tertiary) in rescued reptiles admitted at the Adelaide Koalaand Wildlife Hospital, South Australia. (!)
  • Age determination: [Table 2 shows the sex-specific parameters of the von Bertalanffy age-length relationship, which is illustrated in Fig. 2 and 3]
  • [Table 1 shows an estimated relationship (conditioned on empirical catch-and-release data) from age 1 (plastron length = 68.3 mm) to 10 years (PL = 189 mm)]
  • [Fig. 1 shows that this species stops growing at around 225 mm, after which the growth rate = 0]
  • The generation length of the Murray River Turtle is inferred to be 25 to 30 years. Age of first breeding for females is around 9-11 years (Spencer 2002) and longevity is approximately 40-50 years.