Slow and unsteady: growth of the Australian eastern long-necked turtle near the southern end of its natural range

2018 ◽  
Vol 66 (1) ◽  
pp. 77 ◽  
Author(s):  
Bruce C. Chessman
Keyword(s):  
Growth Rates ◽  
Growth Models ◽  
Logistic Models ◽  
Individual Growth ◽  
Freshwater Turtles ◽  
Turtle Species ◽  
Adult Growth ◽  
Eastern Australia ◽  
Natural Range ◽  
Chelodina Longicollis

Knowledge of growth rates and maturation times of freshwater turtles is important in assessing population viability. I analysed growth of Australian eastern long-necked turtles (Chelodina longicollis) from individual capture–recapture records spanning periods of up to 17 years for a population in Gippsland, Victoria, close to the high-latitude end of the species’ natural range. Juvenile growth was rapid and similar among individuals but adult growth was usually slow, highly variable among individuals and erratic within individuals over time. In addition, asymptotic body lengths were disparate among individuals for both males and females. Von Bertalanffy growth models fitted separately to males plus unsexed juveniles and females plus unsexed juveniles performed better than logistic models but tended to underestimate growth rates for very small and very large turtles and overestimate growth for medium-sized individuals. Sexual maturity was estimated to be achieved at 10 years in males and 16 years in females, which is late compared with most estimates for other populations of C. longicollis and for other turtle species in south-eastern Australia. The high variability of individual growth in this population makes age estimation from body size unreliable beyond the first few years of life.

Demographic analysis of the Port Jackson shark Heterodontus portusjacksoni in the coastal waters of eastern Australia

2008 ◽  
Vol 59 (5) ◽  
pp. 444 ◽  
Author(s):  
David Mark Powter ◽  
William Gladstone
Keyword(s):  
Growth Rates ◽  
Life History Strategy ◽  
Intrinsic Rate ◽  
Biological Information ◽  
Intrinsic Rate Of Increase ◽  
Underwater Visual Census ◽  
Adult Growth ◽  
Rate Of Increase ◽  
Eastern Australia ◽  
Port Jackson

Demographic analyses are used to assess the status and vulnerability of elasmobranchs but their accuracy is often affected by limited basic biological information. Although the Port Jackson shark Heterodontus portusjacksoni (Meyer) is currently not considered at threat, there is insufficient data for eastern Australia to assess this rigorously. The present study determined vital demographic rates of adult and juvenile H. portusjacksoni at four locations on the central and southern coast of New South Wales, Australia from January 2002 to December 2005 using underwater visual census, tag–recapture and samples obtained from a commercial fishery. Natural mortality was low in adults (0.063–0.074 year–1) and juveniles (0.225 year–1), but substantial at the embryonic stage (0.783–0.896 year–1). Adult growth rates (31.4–32.7 mm year–1) were slightly less than that of juveniles (36.8–37.5 mm year–1). Males at both stages grew slightly faster than females. However, H. portusjacksoni had slower growth rates than many other elasmobranch species. Having a low intrinsic rate of increase (r = 0.069 year–1), long generation times (μ1 = 22.5 year) and a low rebound potential, adults are the stage with the greatest impact on population growth. Hence, their life history strategy makes them susceptible to serious decline under exploitation, and management should strive to maintain the adult reproductive stock as a priority.

Growth rates of juvenile southern rock lobster (Jasus edwardsii) estimated through a diver-based tag - recapture program

2012 ◽  
Vol 63 (2) ◽  
pp. 110 ◽  
Author(s):  
Adrian Linnane ◽  
David Hobday ◽  
Stewart Frusher ◽  
Caleb Gardner
Keyword(s):  
Growth Rates ◽  
South Australia ◽  
Individual Growth ◽  
Rock Lobster ◽  
South Eastern ◽  
Growth Increments ◽  
Eastern Australia ◽  
Significant Difference ◽  
Jasus Edwardsii ◽  
South Eastern Australia

Despite being one of the most economically important fisheries in south-eastern Australia, growth rates of juvenile southern rock lobster (Jasus edwardsii) have not previously been quantified in the wild. This study utilised a diver-based tag–recapture program to estimate growth rates of individuals between 40–80 mm carapace length (CL) in temperate reef sites across south-eastern Australia. Of the 7064 lobsters tagged and released, 978 (14%) were recaptured with recapture rates of 23, 5 and 7% in the States of Tasmania, South Australia and Victoria respectively. Although individual growth increments were similar between the sexes, differences in annual growth rates were evident at 50 mm CL, with males growing ~1.4 times faster than females. Increased levels of growth in males resulted from a higher moult frequency, which was found to significantly reduce in females as they reached sexual maturity at ~70–80 mm CL. No significant difference was found in growth rates of males or females between the States when all sites within each State were combined. The growth estimates from this work contribute to the understanding of juvenile lobster population dynamics and will improve current fishery models by confirming relationships between early juvenile, pre-recruit abundance and entry to the fishable biomass.

First record of hatchling overwintering inside the natal nest of a chelid turtle

2015 ◽  
Vol 63 (4) ◽  
pp. 287 ◽  
Author(s):  
Bruno O. Ferronato ◽  
John H. Roe ◽  
Arthur Georges
Keyword(s):  
Small Sample Size ◽  
First Record ◽  
Small Sample ◽  
Future Research ◽  
Freshwater Turtles ◽  
Physiological Mechanisms ◽  
Natal Nest ◽  
Eastern Australia ◽  
Winter Temperatures ◽  
Chelodina Longicollis

Hatchling overwintering inside the natal nest is a strategy used by several Northern Hemisphere species of freshwater turtles. We recorded hatchling overwintering in the nest by Chelodina longicollis (Chelidae) in south-eastern Australia, during three reproductive seasons. Hatchlings spent, on average, 320 days inside the nest from the date eggs were laid until emergence. Some nests were carefully opened adjacent to the nest plug, one during winter and one in spring, to confirm that eggs had hatched and were not in diapause, although we could not precisely confirm hatching dates. Despite our small sample size, we observed a dichotomous overwintering strategy, with hatchlings from one nest emerging in autumn and spending their first winter in the aquatic environment, and hatchlings from three nests overwintering in the nest and emerging in spring. These findings expand the phylogenetic range of turtles exhibiting hatchling overwintering behaviour. Future research should evaluate whether this strategy is widespread among other long-necked turtles in temperate regions and examine physiological mechanisms involved in coping with winter temperatures.

Body growth in one montane population of Sceloporus grammicus (Sauria, Phrynosomatidae) in Central México

2008 ◽  
Vol 29 (1) ◽  
pp. 127-134 ◽  
Author(s):  
Fausto Méndez-de la Cruz ◽  
Orlando Cuellar ◽  
Jaime Zúñiga-Vega
Keyword(s):  
Growth Rates ◽  
Growth Pattern ◽  
Logistic Models ◽  
Body Growth ◽  
The Body ◽  
Individual Growth ◽  
Central Mexico ◽  
Lower Altitude ◽  
Sceloporus Grammicus ◽  
Region Growth

Abstract We conducted an analysis of the body growth pattern of the viviparous lizard Sceloporus grammicus in one of its montane populations in Central México. We calculated 177 individual growth rates for the period comprised between June 1991 and June 1997. Von Bertalanffy growth model provided the best fit to our data in comparison with logistic models. No intersexual differences were found in the growth pattern. The constructed growth curve estimated an age at maturity of 12 and a half months for females and 14 months for males. In spite of marked seasonality in the region, growth rates were not significantly different between seasons. Our results, together with previous studies on the growth ecology of other populations of S. grammicus, suggest that in the volcanic mountains of Central México body growth, and therefore age and size at maturity, are relatively more limited during the whole year in comparison with populations inhabiting northern or lower-altitude localities.

Reproduction, growth and maturity in the black flying-fox, Pteropus alecto (Megachiroptera : Pteropodidae)

1998 ◽  
Vol 46 (4) ◽  
pp. 329 ◽  
Author(s):  
M. J. Vardon ◽  
C. R. Tidemann
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Growth Curves ◽  
Day Length ◽  
Individual Growth ◽  
Young Males ◽  
Weight Growth ◽  
Eastern Australia ◽  
Juvenile Males ◽  
Flying Fox

This paper reviews the timing of reproduction, growth rates and age at maturity of the black flying-fox, Pteropus alecto. This species is found from Sulawesi, Indonesia, south to the central east coast of Australia. In northern Australia at 12ºS most young are born in January–March, in contrast to October–November at 27ºS in eastern Australia, but a small percentage of young are born outside the major birth peaks in both areas. The birth peaks of P. alecto appear to be aligned with periods of maximum plant productivity, rather than day length. The plasticity of breeding season is likely to be an important factor enabling P. alecto to colonise areas from near the equator to 29ºS. Individual growth rates were calculated for 27 P. alecto. The weight growth rate of these animals was 2.40 3.14 g day-1 (mean s.d.), while growth rate of the forearm was 0.19 0.18 mm day-1 (mean s.d.). The growth rate of the forearm of females was significantly greater than for males (P = 0.08). From the mean forearm lengths of animals trapped, separate growth curves were developed for juvenile males (n = 566) and females (n = 610); these indicate that growth rate of females is about 8% higher than that of males. Primiparous females had a forearm length of 171.1 3.4 mm (mean s.d.) (n = 5), which is achieved 15–17 months after birth, but about a third of females with forearm lengths of 160–170 mm have suckled young. Males mature at an age greater than females due to their slower growth rate, a phenomenon known from other megachiropteran species.

Freshwater turtles of the TransFly region of Papua New Guinea - notes on diversity, distribution, reproduction, harvest and trade

2006 ◽  
Vol 33 (5) ◽  
pp. 373 ◽  
Author(s):  
Arthur Georges ◽  
Fiorenzo Guarino ◽  
Biatus Bito
Keyword(s):  
Papua New Guinea ◽  
New Guinea ◽  
Management Plan ◽  
Transport Infrastructure ◽  
Sufficient Information ◽  
Freshwater Turtles ◽  
Demographic Information ◽  
Turtle Species ◽  
Western Province ◽  
High Diversity

The Chelidae is a family of side-necked turtles restricted in distribution to South America and Australasia. While their biology in Australia is reasonably well known, species in New Guinea are very poorly known despite high diversity, especially in the southern lowlands. In this paper, we report on the diversity, distribution, habitat and reproductive biology of the freshwater turtles of the TransFly region of the Western Province of Papua New Guinea, with special emphasis on reproduction of Emydura subglobosa, Elseya branderhorsti and Elseya novaeguineae. Seven species were captured, with reliable records of an eighth. A key to the freshwater turtles of the TransFly region is provided. Harvest methods, consumption, and trade in turtles by the TransFly communities are documented. There is mounting pressure to take advantage of revenue opportunities afforded by the Asian turtle trade, but this is impeded by lack of transport infrastructure. There is also insufficient demographic information on any New Guinean turtle species to make a reasoned judgment on the level of harvest that would be sustainable. Nor is there sufficient information on captive rearing for most species, and where it is available it is not accessible by local villagers. These knowledge gaps need to be addressed and factored into a management plan that is implemented before local communities can capitalise on the commercial opportunities provided by the turtle fauna without risking collapse of the resource and the implications for their concurrent subsistence economy that would follow.

scholarly journals Plastic ingestion by freshwater turtles: a review and call to action

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Adam G. Clause ◽  
Aaron J. Celestian ◽  
Gregory B. Pauly
Keyword(s):  
Marine Species ◽  
Marine Turtle ◽  
Freshwater Turtle ◽  
Freshwater Turtles ◽  
Plastic Pollution ◽  
Potential Threat ◽  
Implementation Quality ◽  
Turtle Species ◽  
Marine Turtles ◽  
Conservation Concern

AbstractPlastic pollution, and especially plastic ingestion by animals, is a serious global issue. This problem is well documented in marine systems, but it is relatively understudied in freshwater systems. For turtles, it is unknown how plastic ingestion compares between marine and non-marine species. We review the relevant turtle dietary literature, and find that plastic ingestion is reported for all 7 marine turtle species, but only 5 of 352 non-marine turtle species. In the last 10 years, despite marine turtles representing just 2% of all turtle species, almost 50% of relevant turtle dietary studies involved only marine turtles. These results suggest that the potential threat of plastic ingestion is poorly studied in non-marine turtles. We also examine plastic ingestion frequency in a freshwater turtle population, finding that 7.7% of 65 turtles had ingested plastic. However, plastic-resembling organic material would have inflated our frequency results up to 40% higher were it not for verification using Raman spectroscopy. Additionally, we showcase how non-native turtles can be used as a proxy for understanding the potential for plastic ingestion by co-occurring native turtles of conservation concern. We conclude with recommendations for how scientists studying non-marine turtles can improve the implementation, quality, and discoverability of plastic ingestion research.

Geostatistically modeling stem size and increment in an old-growth forest

1994 ◽  
Vol 24 (7) ◽  
pp. 1354-1368 ◽  
Author(s):  
Franco Biondi ◽  
Donald E. Myers ◽  
Charles C. Avery
Keyword(s):  
Spatial Patterns ◽  
Growth Rates ◽  
Spatial Dependence ◽  
Basal Area ◽  
Tree Density ◽  
Individual Growth ◽  
Old Growth ◽  
Model Estimate ◽  
Stem Size ◽  
Old Growth Forest

Geostatistics provides tools to model, estimate, map, and eventually predict spatial patterns of tree size and growth. Variogram models and kriged maps were used to study spatial dependence of stem diameter (DBH), basal area (BA), and 10-year periodic basal area increment (BAI) in an old-growth forest stand. Temporal variation of spatial patterns was evaluated by fitting spatial stochastic models at 10-year intervals, from 1920 to 1990. The study area was a naturally seeded stand of southwestern ponderosa pine (Pinusponderosa Dougl. ex Laws. var. scopulorum) where total BA and tree density have steadily increased over the last decades. Our objective was to determine if increased stand density simply reduced individual growth rates or if it also altered spatial interactions among trees. Despite increased crowding, stem size maintained the same type of spatial dependence from 1920 to 1990. An isotropic Gaussian variogram was the model of choice to represent spatial dependence at all times. Stem size was spatially autocorrelated over distances no greater than 30 m, a measure of average patch diameter in this forest ecosystem. Because patch diameter remained constant through time, tree density increased by increasing the number of pine groups, not their horizontal dimension. Spatial dependence of stem size (DBH and BA) was always much greater and decreased less through time than that of stem increment (BAI). Spatial dependence of BAI was close to zero in the most recent decade, indicating that growth rates in 1980–1990 varied regardless of mutual tree position. Increased tree crowding corresponded not only to lower average and variance of individual growth rates, but also to reduced spatial dependence of BAI. Because growth variation was less affected by intertree distance with greater local crowding, prediction of individual growth rates benefits from information on horizontal stand structure only if tree density does not exceed threshold values. Simulation models and area estimates of tree performance in old-growth forests may be improved by including geostatistical components to summarize ecological spatial dependence.

scholarly journals Comparison of growth models to describe growth from birth to 6 years in a Beninese cohort of children with repeated measurements

BMJ Open ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. e035785
Author(s):  
Shukrullah Ahmadi ◽  
Florence Bodeau-Livinec ◽  
Roméo Zoumenou ◽  
André Garcia ◽  
David Courtin ◽  
...  
Keyword(s):  
Growth Model ◽  
Goodness Of Fit ◽  
Growth Models ◽  
Information Criterion ◽  
Height Growth ◽  
Sub Saharan Africa ◽  
Individual Growth ◽  
Secondary Outcome ◽  
Growth Trajectories ◽  
Best Fitting

ObjectiveTo select a growth model that best describes individual growth trajectories of children and to present some growth characteristics of this population.SettingsParticipants were selected from a prospective cohort conducted in three health centres (Allada, Sekou and Attogon) in a semirural region of Benin, sub-Saharan Africa.ParticipantsChildren aged 0 to 6 years were recruited in a cohort study with at least two valid height and weight measurements included (n=961).Primary and secondary outcome measuresThis study compared the goodness-of-fit of three structural growth models (Jenss-Bayley, Reed and a newly adapted version of the Gompertz growth model) on longitudinal weight and height growth data of boys and girls. The goodness-of-fit of the models was assessed using residual distribution over age and compared with the Akaike Information Criterion (AIC) and Bayesian Information Criterion (BIC). The best-fitting model allowed estimating mean weight and height growth trajectories, individual growth and growth velocities. Underweight, stunting and wasting were also estimated at age 6 years.ResultsThe three models were able to fit well both weight and height data. The Jenss-Bayley model presented the best fit for weight and height, both in boys and girls. Mean height growth trajectories were identical in shape and direction for boys and girls while the mean weight growth curve of girls fell slightly below the curve of boys after neonatal life. Finally, 35%, 27.7% and 8% of boys; and 34%, 38.4% and 4% of girls were estimated to be underweight, wasted and stunted at age 6 years, respectively.ConclusionThe growth parameters of the best-fitting Jenss-Bayley model can be used to describe growth trajectories and study their determinants.

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