scholarly journals The Remnant Leiopelma Pakeka (Anura: Leiopelmatidae) Population on Maud Island: Population Size, Distribution and Morphology

2021 ◽  
Author(s):  
◽  
Jacqueline Valerie Phoebe Le Roux
Keyword(s):  
Population Size ◽  
Size Structure ◽  
Vegetation Type ◽  
Bootstrap Method ◽  
Island Population ◽  
The South ◽  
North East ◽  
Forest Remnant ◽  
Population Size Estimates ◽  
Recent Estimate

<p>Leiopelma pakeka is an archaic frog native to New Zealand, and until recently was restricted to a 15ha forest remnant on the south-east face of Maud Island. The L.pakeka population appears to be growing and spreading out from the forest remnant. This study investigated the population size, structure, and distribution of L. pakeka on Maud Island in 2006. The forest remnant was searched using 106 randomly placed 25m2 plots. Population size was estimated using a bootstrap method repeated 10,000 times, adjusted for likelihood of emergence, likely maximum plot population size, and area. The average population size was 34,449 frogs, which is much higher than a 1994 minimum number alive estimate of 19,312. The new figure, however, is similar to another recent estimate of 39,563, based on an update of the 1994 figure. Distributional patterns within the forest remnant were similar to the 1994 study, with most frogs between 90-170m above sea level. The comparability of the population size estimates indicates that L. pakeka numbers have reached the carrying capacity of the forest remnant. The distribution of the remnant L. pakeka population was determined by thoroughly searching the south-east face of Maud Island, thereby minimising the possibility of missing frogs. A total of 232 frogs were found. Frogs generally colonised areas within 50m of the remnant; movement was greater in regenerating forest (75m in the southwest and 100m in the north east) than in pastoral areas (<25m). The size of frogs increased with distance from the forest remnant (weight, girth, condition index, and average snout-vent and tibio-fibula lengths). The size increases may be indications of competitive release, as frog density decreased with distance from the forest remnant. The size range of Leiopelma pakeka was extended by the current study from 50.5mm to at least 52mm snout-vent length. A total of 15 L. pakeka were found on Fort Road, approximately 350m from the remnant. These frogs were most likely in the area before 1994. The Fort Road frogs were compared to the forest remnant L. pakeka, and were not morphologically distinct as only patterning differed significantly. Fort Road L. pakeka may belong to a separate subpopulation. L. pakeka distribution was significantly affected by habitat. Important variables were vegetation type, and rock, canopy, sub-canopy, and leaf litter cover. The size of emergent frogs (tibio-fibula length) was significantly and positively correlated with relative humidity.</p>

scholarly journals The Remnant Leiopelma Pakeka (Anura: Leiopelmatidae) Population on Maud Island: Population Size, Distribution and Morphology

2021 ◽  
Author(s):  
◽  
Jacqueline Valerie Phoebe Le Roux
Keyword(s):  
Population Size ◽  
Size Structure ◽  
Vegetation Type ◽  
Bootstrap Method ◽  
Island Population ◽  
The South ◽  
North East ◽  
Forest Remnant ◽  
Population Size Estimates ◽  
Recent Estimate

<p>Leiopelma pakeka is an archaic frog native to New Zealand, and until recently was restricted to a 15ha forest remnant on the south-east face of Maud Island. The L.pakeka population appears to be growing and spreading out from the forest remnant. This study investigated the population size, structure, and distribution of L. pakeka on Maud Island in 2006. The forest remnant was searched using 106 randomly placed 25m2 plots. Population size was estimated using a bootstrap method repeated 10,000 times, adjusted for likelihood of emergence, likely maximum plot population size, and area. The average population size was 34,449 frogs, which is much higher than a 1994 minimum number alive estimate of 19,312. The new figure, however, is similar to another recent estimate of 39,563, based on an update of the 1994 figure. Distributional patterns within the forest remnant were similar to the 1994 study, with most frogs between 90-170m above sea level. The comparability of the population size estimates indicates that L. pakeka numbers have reached the carrying capacity of the forest remnant. The distribution of the remnant L. pakeka population was determined by thoroughly searching the south-east face of Maud Island, thereby minimising the possibility of missing frogs. A total of 232 frogs were found. Frogs generally colonised areas within 50m of the remnant; movement was greater in regenerating forest (75m in the southwest and 100m in the north east) than in pastoral areas (<25m). The size of frogs increased with distance from the forest remnant (weight, girth, condition index, and average snout-vent and tibio-fibula lengths). The size increases may be indications of competitive release, as frog density decreased with distance from the forest remnant. The size range of Leiopelma pakeka was extended by the current study from 50.5mm to at least 52mm snout-vent length. A total of 15 L. pakeka were found on Fort Road, approximately 350m from the remnant. These frogs were most likely in the area before 1994. The Fort Road frogs were compared to the forest remnant L. pakeka, and were not morphologically distinct as only patterning differed significantly. Fort Road L. pakeka may belong to a separate subpopulation. L. pakeka distribution was significantly affected by habitat. Important variables were vegetation type, and rock, canopy, sub-canopy, and leaf litter cover. The size of emergent frogs (tibio-fibula length) was significantly and positively correlated with relative humidity.</p>

Population estimates and size structure of Plectropomus leopardus (Pisces : Serranidae) in relation to no-fishing zones: mark-release-resighting and underwater visual census

2000 ◽  
Vol 51 (3) ◽  
pp. 221 ◽  
Author(s):  
D. C. Zeller ◽  
G. R. Russ
Keyword(s):  
Great Barrier Reef ◽  
Population Size ◽  
Size Structure ◽  
Barrier Reef ◽  
Visual Census ◽  
Underwater Visual Census ◽  
Coral Trout ◽  
Population Size Estimates ◽  
Lizard Island ◽  
Plectropomus Leopardus

A mark–release–resighting (MRR) technique was used to estimate population size of the coral trout, Plectropomus leopardus, on coral reefs fringing Lizard Island, Great Barrier Reef, Australia. Fish were captured by hook-and-line fishing, and marked with individual freeze-brand numbers in August 1995. An underwater visual census (UVC) technique was used during September and October 1995 both for resighting of marked fish and to make an independent estimate of fish density and thus population size. The study area was 750 966 m2 . The UVC sampled 154 000 m2 (20.5%) of this area. Six different methods of analysis of MRR gave similar population size estimates (e.g. Petersen 12 873; 95% CI 9989–15 754) extrapolated to the 4.5 million-m2 reef area from datum to 20-m depth around Lizard Island. UVC gave a population size estimate (24 182; 95% CI 21 860–26 504) twice that of MRR. The lower estimate derived from MRR may be the result of tag-induced mortality, or of the relative difficulty in discriminating between marked and unmarked trout by UVC. This is only the second estimate of population size of coral trout on an area of the Great Barrier Reef.

scholarly journals Waterbird population estimates for a key staging site in Kazakhstan: a contribution to wetland conservation on the Central Asian flyway

2008 ◽  
Vol 18 (1) ◽  
pp. 71-86 ◽  
Author(s):  
Holger Schielzeth ◽  
Götz Eichhorn ◽  
Thomas Heinicke ◽  
Johannes Kamp ◽  
Maxim A. Koshkin ◽  
...  
Keyword(s):  
Population Size ◽  
Conservation Status ◽  
Steppe Zone ◽  
Wetland Conservation ◽  
Conservation Strategies ◽  
Population Estimates ◽  
The South ◽  
Migration Routes ◽  
South West ◽  
Population Size Estimates

AbstractRealistic population size estimates for waterbirds are crucial for the application of wetland conservation strategies, since the identification of internationally important wetlands is based on local numbers relative to the population size of the respective species. Central Asia is a poorly surveyed region that is situated at the intersection of migration routes that lead waterbirds from Western Siberia to the south-west (South-West Asia, East Africa) and to the south-east (South Asia, India). We calculated waterbird population estimates for the Tengiz–Korgalzhyn region, a large wetland complex in the steppe zone of Central Kazakhstan, based on waterbird surveys conducted between 1999 and 2004. For 20 of 43 species analysed the region supported more than 5% of the relevant flyway populations. Five species occurred with more than 40% of the flyway totals, including the Endangered White-headed Duck Oxyura leucocephala and the Vulnerable Dalmatian Pelican Pelecanus crispus. Peak numbers were recorded in summer and autumn and for most species numbers were more than an order of magnitude lower on spring migration compared with autumn migration. We identified 72 individual sites that held more than 20,000 waterbirds or more than 1% of a particular flyway population at least once. These sites are likely to constitute priorities for conservation. The general conservation status of the region is favourable, since many of the important sites are located within a strict nature reserve. However, outside the reserve hunting, fishing and powerline casualties represent conservation issues that should be monitored more carefully in the future.

The Archaean Atâ intrusive complex (Atâ tonalite), north-east Disko Bugt, West Greenland

1999 ◽  
pp. 103-112
Author(s):  
Feiko Kalsbeek ◽  
Lilian Skjernaa
Keyword(s):  
Intrusive Complex ◽  
The South ◽  
Original Series ◽  
Early Proterozoic ◽  
West Greenland ◽  
North East ◽  
The North ◽  
Southern Border ◽  
Area North ◽  
Igneous Layering

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Kalsbeek, F., & Skjernaa, L. (1999). The Archaean Atâ intrusive complex (Atâ tonalite), north-east Disko Bugt, West Greenland. Geology of Greenland Survey Bulletin, 181, 103-112. https://doi.org/10.34194/ggub.v181.5118 _______________ The 2800 Ma Atâ intrusive complex (elsewhere referred to as ‘Atâ granite’ or ‘Atâ tonalite’), which occupies an area of c. 400 km2 in the area north-east of Disko Bugt, was emplaced into grey migmatitic gneisses and supracrustal rocks. At its southern border the Atâ complex is cut by younger granites. The complex is divided by a belt of supracrustal rocks into a western, mainly tonalitic part, and an eastern part consisting mainly of granodiorite and trondhjemite. The ‘eastern complex’ is a classical pluton. It is little deformed in its central part, displaying well-preserved igneous layering and local orbicular textures. Near its intrusive contact with the overlying supracrustal rocks the rocks become foliated, with foliation parallel to the contact. The Atâ intrusive complex has escaped much of the later Archaean and early Proterozoic deformation and metamorphism that characterises the gneisses to the north and to the south; it belongs to the best-preserved Archaean tonalite-trondhjemite-granodiorite intrusions in Greenland.

Estimating the population size of people who inject drugs in Ho Chi Minh City, Vietnam: A two-survey capture-recapture exercise (Preprint)

2019 ◽  
Author(s):  
Abu Abdul-Quader
Keyword(s):  
Population Size ◽  
Illicit Drugs ◽  
People Who Inject Drugs ◽  
Care Service ◽  
Ho Chi Minh City ◽  
Size Estimation ◽  
Population Size Estimates ◽  
Capture Recapture ◽  
The City ◽  
Size Estimates

BACKGROUND Population size estimation of people who inject drugs (PWID) in Ho Chi Minh City (HCMC), Vietnam relied on the UNAIDS Estimation and Projection Package and reports from the city police department. The two estimates vary widely. OBJECTIVE To estimate the population size of people who inject drugs in Ho Chi Minh City, Vietnam METHODS Using Respondent-driven sampling (RDS), we implemented two-source capture-recapture method to estimate the population size of PWID in HCMC in 2017 in 7 out of 24 districts. The study included men or women aged at least 18 years who reported injecting illicit drugs in the last 90 days and who had lived in the city the past six months. We calculated two sets of size estimates, the first assumed that all participants in each survey round resided in the district where the survey was conducted, the second, used the district of residence as reported by the participant. District estimates were summed to obtain an aggregate estimate for the seven districts. To calculate the city total, we weighted the population size estimates for each district by the inverse of the stratum specific sampling probabilities. RESULTS The first estimate resulted in a population size of 19,155 (95% CI: 17,006–25,039). The second one generated a smaller population size estimate of 12,867 (95% CI: 11,312–17,393). CONCLUSIONS The two-survey capture-recapture exercise provided two disparate estimates of PWID in HCMC. For planning HIV prevention and care service needs among PWID in HCMC, both estimates may need to be taken into consideration together with size estimates from other sources.

Dispersion and abundance of Maritrema arenaria in Semibalanus balanoides in north-east Ireland

1990 ◽  
Vol 64 (2) ◽  
pp. 151-160 ◽  
Author(s):  
H. Carrol ◽  
W. I. Montgomery ◽  
R. E. B. Hanna
Keyword(s):  
Size Structure ◽  
Background Level ◽  
Host Population ◽  
Parasite Infection ◽  
Semibalanus Balanoides ◽  
Low Background ◽  
Digenean Trematode ◽  
North East ◽  
Parasitic Burden ◽  
A Site

ABSTRACTInfection of the barnacle Semibalanus balanoides with the digenean trematode Maritrema arenaria was investigated at 17 sites along the Co. Down coastline. There was a low background level of infection. Abundance of M. arenaria, however, was substantially greater at sites close to fish factories and at a site close to a sewage works. Aggregation of M. arenaria in S. balanoides was least marked at low mean parasite burdens. The parasitic burden was related more closely to barnacle size at a site of heavy infection than at one with a low abundance. There was a significant association between height on the shore and number of encysted metacercariae in S. balanoides. This was independent of variation in host size. It is concluded that relationships that bring about overdispersion of digeneans, such as that between the size-structure of the host population and parasite infection, may be dependent on the overall abundance of the parasite.

The Metamorphosed Limestones and Associated Contaminated Igneous Rocks of the Carlingford District, Co. Louth

1932 ◽  
Vol 69 (5) ◽  
pp. 209-233 ◽  
Author(s):  
G. D. Osborne
Keyword(s):  
Igneous Rocks ◽  
The South ◽  
Ordnance Survey ◽  
Igneous Complex ◽  
North East ◽  
The North ◽  
South West ◽  
Carboniferous Limestone ◽  
Contamination Effects

THE Carlingford-Barnave district falls within the boundaries of Sheet 71 of the Ordnance Survey of Ireland, and forms part of a broad promontory lying between Carlingford Lough on the north-east and Dundalk Bay on the south-west. The greater part of this promontory is made up of an igneous complex of Tertiary age which has invaded the Silurian slates and quartzites and the Carboniferous Limestone Series. This complex has not yet been investigated in detail, but for the purposes of the present paper certain references to it are necessary, and these are made below. The prevalence of hybrid-relations and contamination-effects between the basic and acid igneous rocks of the region is a very marked feature, and because of this it has been difficult at times to decide which types have been responsible for the various stages of the metamorphism.

The closed-subpopulation method and estimation of population size from mark-recapture and ancillary data

2000 ◽  
Vol 78 (2) ◽  
pp. 320-326 ◽  
Author(s):  
Frank AM Tuyttens
Keyword(s):  
Population Size ◽  
Ancillary Data ◽  
Mark Recapture ◽  
Animal Populations ◽  
Accuracy And Precision ◽  
Population Size Estimates ◽  
Minimum Number ◽  
Flexible Framework ◽  
And Performance ◽  
Better Than

The algebraic relationships, underlying assumptions, and performance of the recently proposed closed-subpopulation method are compared with those of other commonly used methods for estimating the size of animal populations from mark-recapture records. In its basic format the closed-subpopulation method is similar to the Manly-Parr method and less restrictive than the Jolly-Seber method. Computer simulations indicate that the accuracy and precision of the population estimators generated by the basic closed-subpopulation method are almost comparable to those generated by the Jolly-Seber method, and generally better than those of the minimum-number-alive method. The performance of all these methods depends on the capture probability, the number of previous and subsequent trapping occasions, and whether the population is demographically closed or open. Violation of the assumption of equal catchability causes a negative bias that is more pronounced for the closed-subpopulation and Jolly-Seber estimators than for the minimum-number-alive. The closed-subpopulation method provides a simple and flexible framework for illustrating that the precision and accuracy of population-size estimates can be improved by incorporating evidence, other than mark-recapture data, of the presence of recognisable individuals in the population (from radiotelemetry, mortality records, or sightings, for example) and by exploiting specific characteristics of the population concerned.

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