Notes on the size structure of a population of the Jacky Dragon Amphibolurus muricatus in a small fragmented urban remnant

2010 ◽  
Vol 16 (4) ◽  
pp. 237 ◽  
Author(s):  
Dennis Hitchen ◽  
Shelley Burgin ◽  
Danny Wotherspoon

The Jacky Dragon Amphibolurus muricatus (White, ex Shaw) is a widespread and abundant species in eastern Australia. Its range overlaps some of the more heavily populated urban areas of Australia where natural habitat is being rapidly lost and/or fragmented. We collected Jacky Dragons over four years in extremely fragmented native remnant vegetation at the edge of an urban golf course in Sydney. The size structure of the population remained similar over the study period. However, there was a lack of large individuals, both male and female. The sex ratio of adult males and females was equivalent rather than conform to the expectation that there would be more females than males in this temperature-dependent sex determined species. Increased sexual aggression and loss during migration were the most likely causes for the loss of larger individuals and for the loss of female bias. These imbalances are predicted to threaten the longer term viability of this urban reptile population.

2021 ◽  
Vol 11 (1) ◽  
pp. 9-23
Author(s):  
JOHN MADIN ◽  
BALU-ALAGAR VENMATHI MARAN ◽  
SUET-MUN HO

Intertidal gastropods provide numerous ecological benefits and are responsible for the dynamics of the intertidal shores habitat and its community assemblages. This study examined the community structure of gastropods in the intertidal shore located near the city of Kota Kinabalu, the capital of Sabah where coastal areas are rapidly developed for various purposes and consequently destroying natural habitats.  A total of 36 gastropods species from 15 families were recorded.  The Planaxis sulcatus was the most abundant species with a density of 480 ind. m-2 followed by Nodilittorina pyramidalis (182 ind. m-2) and Cellana radiata (97 ind. m-2) respectively.  The number of species and their abundance, respectively, are almost three times lower than the number ever recorded for intertidal shores located in non-urban areas or remote locations.  This suggests that the rapidly growing coastal urban areas threatening the diversity and abundance of intertidal gastropods. The density of gastropod (i.e. P. sulcatus & N. pyramidalis) was significantly (p<0.05) high at the lower intertidal shore where slope gradient is steeper with rocks and crevices are the major component of substrates compared to the upper or middle zone which is flatter and composed mainly of coral rubble and sand. Our study suggests that gastropod communities in intertidal shores located adjacent to the urban areas are threatened especially by anthropogenic factors such as frequent human visitations and modification of natural habitat. Future development in the intertidal shore should minimise habitat destruction and should consider infrastructures that encourage gastropod populations to grow and highlighting their ecological role for conservation reasons.


2021 ◽  
Vol 64 (3) ◽  
pp. 217-224
Author(s):  
Nadia Noureen ◽  
Mubashar Hussain ◽  
Muhammad Faheem Malik ◽  
Muhammad Umar ◽  
Zaheer Abbas ◽  
...  

Dung beetles are ecologically important taxa to study the assessment of habitat modification and disturbance across the globe. This study was aimed to explore community composition, species richness and abundance of dung beetles in response to Gujrat, Punjab, Pakistan. Dung beetle assemblage were sampled from four habitat (natural rangeland, cropland, roadside and housing colonies) during 2014-2016 by placing pitfall traps baited with cattle dung. A total number of 540 specimens representing 17 species belonging to seven genera and four tribes were collected. We calculated species relative abundance in natural habitat (34.8%), cropland habitat (40.4%) and in road side areas (25.2%) was recorded, whereas no specimens were recorded in urban areas. Aphodius contaminatus (42.96%) was the most abundant species followed by Onitis castaneous (26.29%) and Onitis singhalensis (20.74%). Tunnellers (50.58%) and dwellers (49.01%) were dominant in all habitats, whereas rollers were least abundant (1.37%). The values of Shannon-Wiener (H) diversity and evenness (E) showed variations among different habitats i.e. natural habitat (H=1.20; E=0.55), cropland habitat (H=1.41, E=0.32) and roads-side (H=0.80, E=0.37). The study showed that cropland served as a major habitat for dung beetles due to its uniformity and close association with mammalian fauna. The results emphasized that natural habitats within the agro-ecosystem have become isolated and fragmented habitat with lesser stability and low resources thus resulting into less diverse habitat. Roadside areas are in close proximity with cropland and act as corridors for efficient species flow within ecosystem due to cattle movement through these areas.      


Coral Reefs ◽  
2021 ◽  
Author(s):  
Liam Lachs ◽  
Brigitte Sommer ◽  
James Cant ◽  
Jessica M. Hodge ◽  
Hamish A. Malcolm ◽  
...  

AbstractAnthropocene coral reefs are faced with increasingly severe marine heatwaves and mass coral bleaching mortality events. The ensuing demographic changes to coral assemblages can have long-term impacts on reef community organisation. Thus, understanding the dynamics of subtropical scleractinian coral populations is essential to predict their recovery or extinction post-disturbance. Here we present a 10-yr demographic assessment of a subtropical endemic coral, Pocillopora aliciae (Schmidt-Roach et al. in Zootaxa 3626:576–582, 2013) from the Solitary Islands Marine Park, eastern Australia, paired with long-term temperature records. These coral populations are regularly affected by storms, undergo seasonal thermal variability, and are increasingly impacted by severe marine heatwaves. We examined the demographic processes governing the persistence of these populations using inference from size-frequency distributions based on log-transformed planar area measurements of 7196 coral colonies. Specifically, the size-frequency distribution mean, coefficient of variation, skewness, kurtosis, and coral density were applied to describe population dynamics. Generalised Linear Mixed Effects Models were used to determine temporal trends and test demographic responses to heat stress. Temporal variation in size-frequency distributions revealed various population processes, from recruitment pulses and cohort growth, to bleaching impacts and temperature dependencies. Sporadic recruitment pulses likely support population persistence, illustrated in 2010 by strong positively skewed size-frequency distributions and the highest density of juvenile corals measured during the study. Increasing mean colony size over the following 6 yr indicates further cohort growth of these recruits. Severe heat stress in 2016 resulted in mass bleaching mortality and a 51% decline in coral density. Moderate heat stress in the following years was associated with suppressed P. aliciae recruitment and a lack of early recovery, marked by an exponential decrease of juvenile density (i.e. recruitment) with increasing heat stress. Here, population reliance on sporadic recruitment and susceptibility to heat stress underpin the vulnerability of subtropical coral assemblages to climate change.


2003 ◽  
Vol 30 (3) ◽  
pp. 281 ◽  
Author(s):  
David S. Dique ◽  
Jim Thompson ◽  
Harriet J. Preece ◽  
Deidré L. de Villiers ◽  
Frank N. Carrick

Koala dispersal was investigated as part of a detailed ecological study of a nationally significant koala population located 20 km south-east of Brisbane, Queensland. From 1996 to 2000, 195 koalas from three sites were captured and fitted with radio-collars. A total of 40 koalas (23 males and 17 females) dispersed from these sites. Most (93%) dispersing individuals were 20–36 months of age. Three adult females (more than 36 months old) dispersed and no adult males dispersed during the study. A significantly higher proportion of young males dispersed than females. Dispersal occurred between June and December, with most dispersal of males commencing in July and August and that of females commencing between September and November prior to, and early in, the annual breeding season. The mean straight-line distance between the natal and breeding home ranges for males and females was similar and was measured at 3.5 km (range 1.1–9.7 km) and 3.4 km (range 0.3–10.6 km) respectively. Dispersing males and females tended to successfully disperse south and west of their natal home ranges and were generally unable to successfully disperse to urban areas within the study area, as a high proportion of the mortality of dispersing koalas was associated with attacks by domestic dogs and with collisions with vehicles on roads. Information from other studies indicates that most young koalas disperse from their natal areas. It is likely that the social behaviour and mating systems of koala populations provide mechanisms for young koalas to disperse. The potential role of dispersal in the dynamics of regional koala populations is discussed.


Author(s):  
Sally Babidge

Water governance refers to the material and regulatory control of water and waters. It involves questions such as who makes decisions about water and how; at what scale such decisions are made in relation to different waters; and who and which water or ecosystem benefits. Classical work in anthropology considered how irrigation practices may have given rise to the development of state forms, and in response to early-21st-century privatization regimes, anthropologists have considered how different groups have challenged the apparent global dominance of commodity values and water as property. Infrastructures for water distribution in urban areas (such as systems of canals, pipes, and faucets), and considerations of the sociocultural effects of hydrological unit delineation and definition (e.g., groundwater or river “basins”) have become key sites for the ethnographic investigation of water governance, emerging forms of personhood, and societal inequalities. The diversity in anthropologies of water unsettles generalized models in global regimes of water governance. The anthropology of water governance and ownership considers the context and contingencies of water and power. It reveals the global dominance of markets, rights, and technical approaches to water management, such as the case of “private water” in Chile, in which water markets have failed to provide equity and environmental health, but also how certain groups avoided complete privatization of water under this extreme example. Ethnographic studies of the cultural organization of resource scarcity over topographically complex and remote terrain, such as that of irrigators in the Andean cordillera, express the diversity of human innovation at the intersection of politics and ecology. In arid South Eastern Australia, basin plans that treat water as a unit of calculation and economic trade place social and ecological relations in peril. Infrastructures of development provide a narrative of unsettled state and development ideologies, and the problem of groundwater management reveals governance challenges in the face of unstable, unknown, and invisible material. Anthropological studies of water contribute to knowledge of earth’s diverse humanity, knowledge practices, and ecologies. Researchers propose that water governance might engage with human differences articulated at multiple scales, as well as in understanding water’s material agency and waters as dynamic, especially in an ever-changing climate.


2018 ◽  
Vol 10 (8) ◽  
pp. 2733 ◽  
Author(s):  
Yang Li ◽  
Hua Shao ◽  
Nan Jiang ◽  
Ge Shi ◽  
Xin Cheng

The development of the Yangtze River Economic Belt (YREB) is an important national regional development strategy and a strategic engineering development system. In this study, the evolution of urban spatial patterns in the YREB from 1990 to 2010 was mapped using the nighttime stable light (NSL) data, multi-temporal urban land products, and multiple sources of geographic data by using the rank-size distribution and the Gini coefficient method. Through statistical results, we found that urban land takes on the feature of “high in the east and low in the west”. The study area included cities of different development stages and sizes. The nighttime light increased in most cities from 1992 to 2010, and the rate assumed an obvious growth tendency in the three urban agglomerations in the YREB. The results revealed that the urban size distribution of the YREB is relatively dispersed, the speed of urban development is unequal, and the trend of urban size structure shows a decentralized distribution pattern that has continuously strengthened from 1990 to 2010. Affected by factors such as geographical conditions, spatial distance, and development stage, the lower reaches of the Yangtze River have developed rapidly, the upper and middle reaches have developed large cities, and a contiguous development trend is not obvious. The evolution of urban agglomerations in the region presents a variety of spatial development characteristics. Jiangsu, Zhejiang, and Shanghai have entered a phase of urban continuation, forming a more mature interregional urban agglomeration, while the YREB inland urban agglomerations are in suburbanization and multi-centered urban areas. At this stage, the conditions for the formation of transregional urban agglomerations do not yet exist, and there are many uncertainties in the boundary and spatial structure of each urban agglomeration.


2021 ◽  
Vol 8 ◽  
Author(s):  
Jhostin Ramos ◽  
Marco Boto ◽  
Juan Felipe Blanco-Libreros ◽  
José M. Riascos

Periwinkles (Littorinidae: genus Littoraria) are one of the very few molluscan clades showing an adaptive radiation closely associated to the mangrove habitat. However, pervasive land use changes associated to urbanization is prompting mangrove loss or degradation, with unknown consequences for mangrove-associated fauna. In the southern Colombian Caribbean, mangrove ecosystems have been encroached by human settlements and different populations of Littoraria angulifera (Lamarck, 1822) now inhabit anthropogenic intertidal substrates in urban areas, but the demographic traits of populations thriving in these novel environments are unknown. We studied the relative abundance and size structure of L. angulifera in remnant mangrove patches, woody debris and anthropogenic substrates (boulder seawalls and built structures) in 13 locations throughout the Urabá Gulf, a human-transformed tropical estuarine system. The abundance of L. angulifera was up to two orders of magnitude higher in anthropogenic than in quasi-natural or natural substrates. Snails also displayed a significant preference for wave protected positions in boulder seawalls and built structures exposed to heavy wave action, which was not previously reported in mangrove forests. Moreover, snail populations in anthropogenic substrate were consistently dominated by individuals of small sizes in comparison with mangroves or driftwood. We argue that the anthropogenic disturbances caused by the expansion of Turbo city during nearly one century in a coast formerly dominated by mangrove forests are providing novel and expanding habitats, whose quality might be good enough as to support high-density populations of L. angulifera. However, we hypothesize that shifted thermal regimes in hard and novel wave-exposed urban seascapes might also be prompting behavioral adjustments and the selection of smaller size ranges than those observed in mangrove forests.


2018 ◽  
Author(s):  
Miguel Á. Collado ◽  
Daniel Sol ◽  
Ignasi Bartomeus

ABSTRACTHabitat loss and alteration is widely considered one of the main drivers of the current loss of pollinator diversity. Unfortunately, we still lack a comprehensive analysis of habitat importance, use and preference for major groups of pollinators. Here, we address this gap analysing a large dataset of 15,762 bee specimens (more than 400 species) across northeast USA. We found that natural habitats sustain the highest bee diversity, with many species strongly depending on such habitats. By characterizing habitat use and preference for the 45 most abundant species, we also show that many bee species can use human-altered habitats despite exhibiting strong and clear preferences for forested habitats. However, only a few species appear to do well when the habitat has been drastically modified. We conclude that although altered environments may harbor a substantial number of species, preserving natural areas is still essential to guarantee the conservation of bee biodiversity.


Author(s):  
Radoslav Kojić ◽  
Matija Antić

Meteorological parameters and traffic flows have a direct impact on air quality in large urban areas, and hence on the quality of life in them. A large number of done surveys confirmed the great dependence of the concentration of ground-level ozone (O3) upon meteorological parameters and the size, structure and imbalances of traffic flows. As part of the research conducted in the period from November 5th to December 8th 2014 in Brcko in Muderis Ibrahimbegic St concentrations of ground-level ozone (O3) were measured, meteorological parameters (temperature, humidity, wind speed and intensity of solar radiation) and characteristics of traffic flow of road motor vehicles. The maximum concentrations of ground-level ozone (O3) in the measurement period was 106.54μg/m³, while the minimum concentration was 4.794μg/m³. By analyzing the results of measurements the high coefficient of correlation between wind speed, air temperature and humidity was established. The correlation coefficient between the traffic flows on the one hand and the concentration of ground-level ozone (O3), on the other hand is very low and does not exceed the value of 0.301. A negative correlation coefficient between traffic flows and concentrations of ground-level ozone (O3) is also observed in the certain time of the day.


2019 ◽  
Vol 119 ◽  
pp. 00012 ◽  
Author(s):  
Caterina Mele

The human habitation of the surface of the planet has led, especially since the mid-twentieth century, to an enormous increase in the built up area. This phenomenon concerns both the oldest industrialised countries, such as European Union and the United States, and the so-called emerging countries in Asia, Africa and Latin America.The urbanised built area has increased in different ways, but has led everywhere to the destruction of large portions of virgin soil, the loss of biodiversity in the number and type of species in fauna and flora, and often the total or partial impairment of ecosystem functions of enormous environmental value (such as the evapotransportive mechanisms of soil and vegetation). Although the curve of global population growth is slowing, the growth of urban areas continues to expand, even in countries which have long been industrialised, where the spread of building has given rise to cities dispersed over a territory so that there is no longer a recognisable clear division between the city and the countryside. In fact, contemporary cities are the main consumers of all environmental resources, from water to food, including energy and environmental stressors, and are responsible for 80% of CO2 emissions into the atmosphere. The ecosystem surface required to sustain a large city on the planet today canbe about 200 times larger than its physical size. The urban civilisation of the 21st century, which at a superficial glance may appear as a symbol of the human capacity to radically adapt and transform the natural habitat toits own needs, is also a witness to the unsustainability of the human footprint on earth. Radically rethinking cities and human settlements entails an equally radical rethinking of our economic and development model, but it is a necessary and strategic task if we really want to face the challenge of sustainability with appropriate instruments.


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