scholarly journals Population demography of Oldham’s leaf turtle (Cyclemys oldhamii) in protected and disturbed habitats in Thailand

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7196
Author(s):  
Sengvilay Seateun ◽  
Nancy E. Karraker ◽  
Bryan L. Stuart ◽  
Anchalee Aowphol
Keyword(s):  
Population Structure ◽  
Sexual Dimorphism ◽  
Anthropogenic Impacts ◽  
Size Class ◽  
Freshwater Turtle ◽  
Class Structure ◽  
Population Demography ◽  
Conservation Actions ◽  
Constructed Ponds ◽  
Survival Density

Background Freshwater turtle populations are vulnerable to a range of human activities because of particular life history attributes, and anthropogenic impacts can cause shifts in demographic traits, including survival, density and population structure. Asian freshwater turtles have undergone dramatic population declines in recent decades principally because of collection for food, pet, and traditional medicine markets. Despite this, few studies have been conducted on the population demography of these turtles, thereby limiting our understanding of population trends and the development of conservation actions. Oldham’s leaf turtle (Cyclemys oldhamii) is one of the most commonly traded turtles in Asian markets, but previous published studies have focused solely on systematics. Methods We conducted a mark-recapture study of C. oldhamii at three sites in northeastern Thailand—a protected stream, a degraded stream, and human-constructed ponds—and evaluated differences in survival, density, population structure, and sexual dimorphism among sites. Results We captured 77 turtles at the protected stream, 67 at the constructed ponds, and two in the degraded stream. Survival was 12% lower and density was 35% lower in the constructed ponds than in the protected stream. Size class structure was skewed toward smaller individuals at the constructed ponds, and both sites exhibited subadult-skewed age class structure. Sex ratios were not statistically different than 1:1 at either site and did not differ between sites. We did not document sexual dimorphism in either population. Discussion Explanations for lower survival, lower densities, and skewed size class structure at the constructed ponds include collection for consumption or Buddhist prayer release locally, collection for illegal export from Thailand, predation by domestic dogs associated with humans living nearby, or lower habitat quality. Evidence from our study suggests that collection, either for local use or export, is the most likely explanation for differences in demographic characteristics between the two sites. The information gained from this study may contribute to a status assessment for C. oldhamii and development of conservation actions should they become necessary to protect populations in Thailand.

scholarly journals A Newly Discovered Forest of the Whip Coral Viminella flagellum (Anthozoa, Alcyonacea) in the Mediterranean Sea: A Non-Invasive Method to Assess Its Population Structure

Biology ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 39
Author(s):  
Giovanni Chimienti ◽  
Ricardo Aguilar ◽  
Michela Maiorca ◽  
Francesco Mastrototaro
Keyword(s):  
Population Structure ◽  
Ad Hoc ◽  
Anthropogenic Impacts ◽  
Tyrrhenian Sea ◽  
Non Invasive ◽  
The Status ◽  
Conservation Actions ◽  
Population Structures ◽  
Invasive Method ◽  
Southern Tyrrhenian Sea

Coral forests are vulnerable marine ecosystems formed by arborescent corals (e.g., Anthozoa of the orders Alcyonacea and Antipatharia). The population structure of the habitat-forming corals can inform on the status of the habitat, representing an essential aspect to monitor. Most Mediterranean corals live in the mesophotic and aphotic zones, and their population structures can be assessed by analyzing images collected by underwater vehicles. This is still not possible in whip-like corals, whose colony lengths and flexibilities impede the taking of direct length measurements from images. This study reports on the occurrence of a monospecific forest, of the whip coral Viminella flagellum in the Aeolian Archipelago (Southern Tyrrhenian Sea; 149 m depth), and the assessment of its population structure through an ad-hoc, non-invasive method to estimate a colony height based on its width. The forest of V. flagellum showed a mean density of 19.4 ± 0.2 colonies m−2 (up to 44.8 colonies m−2) and no signs of anthropogenic impacts. The population was dominated by young colonies, with the presence of large adults and active recruitment. The new model proved to be effective for non-invasive monitoring of this near threatened species, representing a needed step towards appropriate conservation actions.

scholarly journals Population biology of the crab Armases angustipes (Crustacea, Decapoda, Sesarmidae) at Brazilian tropical coast

2014 ◽  
Vol 104 (2) ◽  
pp. 150-161 ◽  
Author(s):  
Marina de Sá Leitão C. de Araújo ◽  
Deusinete de O. Tenório ◽  
Daniela da S. Castiglioni
Keyword(s):  
Population Structure ◽  
Sexual Dimorphism ◽  
Sex Ratio ◽  
Population Biology ◽  
Carapace Width ◽  
Reproductive Activity ◽  
Coastal Regions ◽  
Phytoplankton Productivity ◽  
Number Of Individuals ◽  
Tropical Coast

The semi terrestrial crabs are important elements of the fauna of coastal regions. The aim of this study was to analyze the population structure of Armases angustipes (Dana, 1852) at estuaries of the Ariquindá River, considered a non impacted area, and Mamucabas River, considered a few impacted area, on the south coast of state of Pernambuco, Brazil. The species occurred in all months of the year. The number of individuals per month varied, being higher in the months of transition between the seasons. This is probably due to significant seasonal variations of air and burrow temperature and burrow salinity. There was no sexual dimorphism in size of A. angustipes in the mangrove of Ariquindá River, but males were larger than females in the mangrove of Mamucabas River. In both estuaries, the sex ratio did not differ from Mendelian proportion, but showed a deviation for females. The analysis of temporal variation in sex ratio showed significant differences in some months of the year. These variations are due to cyclical events that act distinctly on each sex. In both estuaries, size classes of carapace width were equally represented by both sexes. The ovigerous females of A. angustipes occurred only in some months of the year, especially in summer, in both estuaries. Probably the high phytoplankton productivity observed in summer favors the reproductive activity, since these algae serve as food for the larvae. Specimens of the population of Rio Ariquindá are largest and wider than those of Mamucabas River. This fact, associated with the low abundance of crabs and the lower frequency of ovigerous females observed in Mamucabas River, is an indication that this population may be influenced by the environmental impacts that this estuary has received.

scholarly journals Use of nursery areas by the extinct megatooth shark Otodus megalodon (Chondrichthyes: Lamniformes)

2020 ◽  
Vol 16 (11) ◽  
pp. 20200746
Author(s):  
Jose L. Herraiz ◽  
Joan Ribé ◽  
Héctor Botella ◽  
Carlos Martínez-Pérez ◽  
Humberto G. Ferrón
Keyword(s):  
Middle Miocene ◽  
Spatial Scales ◽  
Gaussian Mixture Models ◽  
Marine Species ◽  
Gaussian Mixture ◽  
Size Class ◽  
Class Structure ◽  
Nursery Areas ◽  
First Time ◽  
Slow Growing

Nursery areas are fundamental for the success of many marine species, particularly for large, slow-growing taxa with low fecundity and high age of maturity. Here, we examine the population size-class structure of the extinct gigantic shark Otodus megalodon in a newly described middle Miocene locality from Northeastern Spain, as well as in eight previously known formations (Temblor, Calvert, Pisco, Gatún, Chucunaque, Bahía Inglesa, Yorktown and Bone Valley). In all cases, body lengths of all individuals were inferred from dental parameters and the size-class structure was estimated from kernel probability density functions and Gaussian mixture models. Our analyses support the presence of five potential nurseries ranging from the Langhian (middle Miocene) to the Zanclean (Pliocene), with higher densities of individuals with estimated body lengths within the typical range of neonates and young juveniles. These results reveal, for the first time, that nursery areas were commonly used by O. megalodon over large temporal and spatial scales, reducing early mortality and playing a key role in maintaining viable adult populations. Ultimately, the presumed reliance of O. megalodon on the presence of suitable nursery grounds might have also been determinant in the demise of this iconic top predatory shark.

scholarly journals Trophic Redundancy and Predator Size Class Structure Drive Differences in Kelp Forest Ecosystem Dynamics

2020 ◽  
Vol 101 (2) ◽  
Author(s):  
Jacob H. Eisaguirre ◽  
Joseph M. Eisaguirre ◽  
Kathryn Davis ◽  
Peter M. Carlson ◽  
Steven D. Gaines ◽  
...  
Keyword(s):  
Forest Ecosystem ◽  
Kelp Forest ◽  
Size Class ◽  
Ecosystem Dynamics ◽  
Class Structure ◽  
Predator Size

scholarly journals Trophic redundancy and predator size class structure drive differences in kelp forest ecosystem dynamics

Ecology ◽  
2020 ◽  
Vol 101 (5) ◽  
Author(s):  
Jacob H. Eisaguirre ◽  
Joseph M. Eisaguirre ◽  
Kathryn Davis ◽  
Peter M. Carlson ◽  
Steven D. Gaines ◽  
...  
Keyword(s):  
Forest Ecosystem ◽  
Kelp Forest ◽  
Size Class ◽  
Ecosystem Dynamics ◽  
Class Structure ◽  
Predator Size

scholarly journals Honey Bee Diversity is Swayed by Migratory Beekeeping and Trade Despite Conservation Practices: Genetic Evidences for the Impact of Anthropogenic Factors on Population Structure

2019 ◽  
Author(s):  
Mert Kükrer ◽  
Meral Kence ◽  
Aykut Kence
Keyword(s):  
Population Structure ◽  
Gene Flow ◽  
Honey Bee ◽  
Honey Bees ◽  
Anthropogenic Impacts ◽  
Anthropogenic Factors ◽  
Conservation Implications ◽  
The Status ◽  
Bee Diversity ◽  
The Impact

Intense admixture of honey bee (Apis mellifera L.) populations is mostly attributed to migratory beekeeping practices and replacement of queens and colonies with non-native races or hybrids of different subspecies. These two practices are also heavily carried out in Anatolia and Thrace where 5 subspecies reside naturally.Here, we carried out an analysis of population structure of honey bees sampled from six different regions (n = 250) in order to test the genetic impacts of migratory beekeeping, queen and colony trade and conservation efficacy of isolated regions. A total of 30 microsatellite markers were used in four multiplex reactions.Direct genetic impact of migratory beekeeping was demonstrated first time based on a comparison of assignment of individuals to their geographically native populations where migratory colonies showed less fidelity. We found genetic evidence for them acting as a hybrid zone mobile in space and time, becoming vectors of otherwise local gene combinations.The effects of honey bee trade were revealed by the presence of very high introgression levels from the highly commercial Caucasian bees naturally limited to a narrow range. We also measured the direction and magnitude of this gene flow connected with bee trade.Comparison between regions that are either open to migratory beekeeping or not let us evaluate the status of isolated regions as centers of limited gene flow and showed the importance of establishing such regions.Despite signs of gene flow, our findings confirm high levels of geographically structured genetic diversity of four subspecies of honey bees in Turkey and emphasize the need to develop policies to maintain this diversity.Our overall results might potentially bear a wider interest to the community since they constitute an important attempt to quantify the effects of anthropogenic impacts on established patterns of honey bee diversity. Our measurable and justified findings on migratory beekeeping, queen and colony replacements as well as conservation implications will hopefully be of use for the decision makers and other stakeholders.

scholarly journals Size-class structure of the forests of Finland during 1921–2013: a recovery from centuries of exploitation, guided by forest policies

2019 ◽  
Vol 139 (2) ◽  
pp. 279-293
Author(s):  
Helena M. Henttonen ◽  
Pekka Nöjd ◽  
Susanne Suvanto ◽  
Juha Heikkinen ◽  
Harri Mäkinen
Keyword(s):  
Land Use ◽  
Geographical Area ◽  
Species Group ◽  
Size Class ◽  
Class Structure ◽  
Initial State ◽  
Frequency Distributions ◽  
Size Classes ◽  
Growing Stock ◽  
Large Trees

AbstractFrequency distributions of tree diameters are a powerful tool for analyzing changes of tree populations in large areas. We analyzed the densities and mean volume estimates of trees in different size classes for the Finnish forests over the time-span of the National Forest Inventories (1921–2013). The results display a general increase in trees in all size classes, species group and geographical area, mainly after the 1970s. The densities of medium- and large-sized conifers showed large increases in the southern boreal subzone, spruces even more than pines. Small- to medium-sized pines have increased in the middle and northern boreal subzones. The shifts in growing stock are related to changing land use, resulting from the development of the society. The low quantities of both growing stock and large trees during the 1920s reflect a poor initial state of forests. Several land use forms of the former agriculture-based society were detrimental to forests, including slash and burn agriculture, cattle grazing and tar production. The pressure from alternative land use forms was stronger in southern Finland, where the population density (people per km2) is much higher. Between 1971 and 2013, the changes in size-class structure can be attributed mainly to intensified silviculture boosted by actions of the Finnish governments, including both legislation and financial support for management activities. Not only the development of growing stock has exceeded expectations, but the increase has also concentrated in the economically valuable trees in the large size classes.

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