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1.
V. Obanda F. Gakuya I. Lekolool S. Chege B. Okita T. Manyibe 《African Journal of Ecology》2008,46(2):144-148
The aim of this study was to survey ciliated intestinal protozoa of the black rhinoceros ( Diceros bicornis michaeli ) and white rhinoceros ( Ceratotherium simum simum ) in Kenyan National Parks. Faecal samples from 28 rhinoceroses that were chemically immobilized for translocation were opportunistically collected. Presence of ciliates was assessed using faecal floatation and sedimentation techniques. The ciliates were identified using cellular morphological features. Ophryoscoleciidae, Cycloposthiidae and Blepharocrythiidae were the three ciliate families represented. Ophryoscoleciidae had nine genera, Cycloposthiidae six genera and Blepharocorythiidae 1 genus. The dominant ciliate genus in all the rhinoceroses that were sampled was entodinium . It was found that the nutrient composition of the diet influences the diversity and numbers of intestinal ciliates, which in turn regulates the nutrient available to the animal. This interplay of nutrient composition of diet, ciliate diversity and nutritional benefits to the host has been used as an index to assess the nutritional state of ruminants. Because of the occurrence of rumenal ciliates in the hindgut fermentative chamber of the rhinoceros, such an index can be used to guide the formulation of feed mixtures for rhinoceros in captivity and remote nutritional assessments of rhinoceros both in free-range and in captivity. 相似文献
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Trends in rhinoceroses (rhinos) in Kruger National Park (Kruger) is of key concern. Poaching drives trends in the Park. Reconciling annual population estimates with yearly reports of poached carcasses fuels public critique. We account for trends in rhinos by extracting time series of estimates. Progressively modelling influences of management introductions and removals, effects of environmental variation and rhino density, direct impacts of poaching, consequences of imperfect carcass detection, and indirect impacts of deaths of dependent calves form the basis of accounting for rhinos. Models that considered all these influences explained 93% of white and 83% of black rhino population trends. In addition, the models predicted 2,515 white and 225 black rhinos, similar to estimates of 2,607 (95% CI: 2,475–2,752) and 202 (95% CI: 172–237) during 2020 respectively. The best model, however, predicts slow recovery with a white rhino population equivalent to pre-poaching achieved between 2030 and 2040. For black rhinos, recovery to pre-poaching population size would be between 2040 and 2050. The poaching onslaught in Kruger disrupted eruptive white rhino dynamics and prevented black rhinos from transitioning into eruptive dynamics. Authorities require innovative approaches within and beyond Kruger to help re-ignite rhino conservation. 相似文献
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Tim CARO Jason RIGGIO 《动物学报(英文版)》2014,(4):486-499
We examine the conservation status of Africa＇s ＂Big Five＂： lion, leopard, buffalo, black and white rhinoceros and elephant, and the role of behavioral knowledge in their conservation. Efforts to conserve these flagship species consist of in situ conservation, captive breeding and reintroductions. With a few exceptions, we find limited evidence that knowledge of behavior informs conservation programs targeted at these species. For management in the wild, knowledge of infanticide and ranging can provide guidelines for realistic hunting quotas and corridors between protected areas, respectively. For ex situ and reintroduction programs, behavioral knowledge is chiefly focused on improved animal husbandry. Despite a formidable understanding of these species＇ behavior, the practicalities of using such knowledge may be diminished because exploitation of these species is so forceful and the bulk of efforts aimed at conserving these species （and indeed most other African species） are primarily in situ where behaviorally driven interventions are limited. Our comparative findings suggest that behavior has been of rather narrow use in the conservation of these flagship species [Current Zoology 60 （4）： 486--499, 2014]. 相似文献
5.
Virginia W. Wang'ondu Jared O. Bosire James G. Kairo Jenesio I. Kinyamario Francis B. Mwaura Farid Dahdouh‐Guebas Nico Koedam 《Restoration Ecology》2014,22(6):824-831
Mangrove forests are active carbon sinks and important for nutrient cycling in coastal ecosystems. Restoration of degraded mangrove habitats enhances return of ecosystem goods and services, including carbon sequestration. Our objective was to assess the restoration of primary productivity of reforested mangrove stands in comparison with natural reference stands in Gazi Bay, Kenya. Litter fall data were collected in nine Rhizophora mucronata and Sonneratia alba monospecific stands by use of litter traps over 2 years. Litter was emptied monthly, dried, sorted, and weighed. The reforested and natural stands showed seasonality patterns only in the production of reproductive material. Leaves constituted the highest percentage to total litter fall. Litter productivity rates for the R. mucronata stands were not significantly different and ranged from 6.61–10.15 to 8.36–11.02 t ha?1 yr?1 for the restored and natural stands, respectively. The productivity of 5 years R. mucronata stands reached 5.22 t ha?1 yr?1 and was significantly different from other stands. Litter productivity rates for S. alba stands was 7.77–7.85 for the restored stands and 10.15 t ha?1 yr?1 for the natural stand but differences were not significant. Our results indicate that plantations of at least 11 years have attained litter productivity rates comparable to the natural forests. This suggests that productivity of replanted mangroves is likely to reach complete recovery by this age under the prevailing environmental conditions. 相似文献
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Dir. Dr. Bernhard Blaszkiewitz 《Der Zoologische Garten (in deutscher Sprache / in German)》2008,77(4):207-218
The first Black rhino was kept in Berlin Zoo in 1870. After second world war the keeping of Diceros bicornis started in 1954. Between 1981 and 2006 16 births occurred in Berlin Zoo, of which 14 calfs were raised. 相似文献
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Franz Schwarzenberger Kristina Tom&#x;ov Dana Hole
kov Bernd Matern Erich Mstl 《Zoo biology》1996,15(2):159-171
The metabolism and excretion of progesterone in different animal species results in several fecal 5-reduced progesterone metabolites (pregnanes), which in recent studies were quantified using progesterone antibodies. To increase the accuracy of fecal 20-oxo-pregnane evaluations in the black rhinoceros, enzyme immunoassays (EIA) using antibodies against 5α-pregnane-3β-ol-20-one 3HS:BSA (5α-20-one EIA) and 5β-pregnane-3α-ol-20-one 3HS:BSA (5β-20-one EIA) were developed. The assays showed high crossreactivities with pregnanes containing a 20-oxo group and are referred to as group-specific; results of these assays were compared with an EIA using an antibody against 6HS-progesterone (4-ene-20-one EIA). Fecal samples of both subspecies of the black rhinoceros (Diceros bicornis michaeli, n = 5, and Diceros bicornis minor, n = 1) during pregnancy were collected 1–3 times/week. HPLC separation showed three major immunoreactive fecal 20-oxo-pregnane peaks; their elution profiles and different crossreactivities in the three EIAs provided strong evidence that these peaks are 5α-pregnane-3, 20-dione, 5α-pregnane-3α-ol-20-one, and 5α-pregnane-3β-ol-20-one. Pregnane values in the pregnant animals continuously increased between months 3–7 and were significantly (P < 0.01) elevated above the levels of nonpregnant animals (0.2 μg/g) by week 11. During months 6–13 concentrations in the 5α-20-one and in the 5β-20-one EIA (5–11 μg/g) were significantly (P < 0.01) higher than in the 4-ene-20-one EIA (1.5–3 μg/g). In conclusion, the immunoreactive fecal 20-oxo-pregnane metabolites in the black rhinoceros are determined more accurately with antibodies against pregnane-20-one-C3 conjugates, as compared with a progesterone antibody. © 1996 Wiley-Liss, Inc. 相似文献
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The seasonal abundance and reproductive cycle of the flyingfish Hirundichthys affinis was studied near Barbados. H. affinis shows large seasonal variation in abundance. They are common between December and June and scarce from July to November. The population size structure of H. affinis was determined by fishing with four different mesh sizes throughout one year. There appear to be two cohorts of H. affinis present in May and June, one of immature fish with a mean size of 19.8cm FL, and one of mature fish with a mean size of 21.7cm FL. From September to April there is only a single cohort of maturing fish with a mean size that increases from 20.4cm FL in September to 22.0cm FL in April. H. affinis spawns throughout the fishing-season (December–June) and shows a peak in spawning activity from March to June. Immature fish are present in Barbados waters from July to November but in very low abundance. Surface water temperature, wind speed and swell height are the only environmental factors with which catch rate of H. affinis showed significant correlation. Catch rate appears to be negatively correlated with temperature, whereas for wind speed and swell height there are optima. Three hypotheses for the seasonal variation in abundance of H. affinis were examined. The hypothesis that this species remains dispersed near Barbados during the off-season was rejected. The other hypotheses were refined. Both post-spawning mortality, resulting in an interval of low abundance between cohorts (non-overlapping generations), and migration of fish away from Barbados at the end of the fishing season, remain possible explanations for the observed seasonal variation in abundance of this species. 相似文献
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Lindsey Nielsen Dawn Meehan-Meola Annelisa Kilbourn Acacia Alcivar-Warren 《Conservation Genetics》2008,9(1):239-242
As the population sizes of the black and white rhinoceroses continues to decline, more efforts are needed in multiple areas to help with the conservation efforts. One area being explored is the use of genetic diversity information to aid conservation decisions. In this study, we designed 21 microsatellite primers for white and black rhinoceroses, 16 and 17 of which amplified bands in the white and black rhinoceros, respectively. Out of these primers all 16 were polymorphic in the white rhinoceros and 12 of the 17 were polymorphic in the black rhinoceros. The mean number of alleles was 3.31 and 2.12, the expected heterozygosities were 0.420 and 0.372, and the observed heterozygosities were 0.436 and 0.322 for the white and black rhinoceroses, respectively. Seven of the primers produced different allele sizes and variations that distinguished between black and white rhinoceroses. Further genetic analyses with larger wild population sample sizes and markers are recommended to obtain a better understanding of the genetic structure of the black and white rhinoceros populations in order to be useful in the conservation efforts of these critically endangered species. A. Kilbourn—In memoriam. 相似文献
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M. Njiru P. Nzungi A. Getabu E. Wakwabi A. Othina T. Jembe S. Wekesa 《African Journal of Ecology》2007,45(3):315-323
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Charles C. Ngugi Julius O. Manyala Murithi Njiru Chrisestom M. Mlewa 《African Journal of Ecology》2009,47(4):606-613
A study on some biological parameters of the mountain catfish, Amphilius uranoscopus Pfeffer 1889 (Silurifomes: Amphiliidae), was carried out in the Thego stream on the slopes of Mount Kenya from February to December 2002. Physical and chemical profiles of the Thego show that the water quality parameters is typical of high altitude streams with temperatures rarely exceeding 18°C, DO ranging from 7.9 to 8.2 mg l?1 and relatively high conductivity (97–137 μS cm?1) typical of perturbed lotic environments. A total of 1010 fish were caught by an electro‐fisher, with sizes ranging between 8 and 24 cm fork length. The population structure had a unimodal distribution with maxima at 14–16 cm. The length–weight relationship showed relatively narrow range in the slope ranging from 2.61 in April to 2.98 in February 2002, thereby suggesting isometric growth pattern. The fitted growth pattern of A. uranoscopus showed an asymptotic length (L∞) of 28.5 cm and a growth curvature (K) of 0.56 year?1 resulting in an estimated natural mortality coefficient (M) of 0.90 year?1. The Fulton’s condition factor (K) was also relatively stable with a peak in April (0.92 ± 0.21) and lowest value in June (0.86 ± 0.10). As A. uranoscopus is not under commercial exploitation, the seemingly depressed population is possibly attributed to the introduced exotic rainbow trout that heavily predates on the species and environmental perturbations arising from changes in land use. The implications of such changes on A. uranoscopus are discussed. 相似文献
14.
J. F. Talling 《Hydrobiologia》1986,138(1):139-160
Although some study of the subject began in 1899, wide-ranging information from African water-bodies has only become available since 1950. Important developments included the establishment of long-term centres of research, the adoption of improved methods for quantitative algal sampling, the more intensive study of environmental conditions, the beginnings of experimental testing, and the improvement of taxonomic knowledge.At higher latitudes (> 20 °) examples of pronounced algal seasonality are long-established; they are accompanied and influenced by marked changes in radiant energy income and so water temperature, and often by effects of seasonal water input. Illustrations are given from lakes in Morocco and South Africa.More generally in Africa, including the tropical belt, annual patterns of phytoplankton seasonality are usually either dominated by hydrological features (water input-output) or by hydrographic ones (water-column structure and circulation). Examples of both types are discussed, together with instances (e.g. L. Volta) of combined hydrological and hydrographic regulation. In both the seasonal abundance of diatoms is often distinct and complementary to that of blue-green algae, with differing relationships to vertical mixing and water retention.Horizontal variability in the seasonal cycle is especially pronounced in the larger or morphometrically subdivided lakes. Some inshore-offshore differentiation is also known to affect phytoplankton quantity (e.g. L. George) and species composition (e.g. L. Victoria). Longitudinal differentiation is common in elongate basins especially when with a massive or seasonal inflow at one end (e.g. L. Turkana, L. Nubia, L. Volta); occasional terminal upwelling can also be influential (e.g. southern L. Tanganyika). Such examples grade into the longitudinally differentiated seasonality of flowing river-reservoir systems, as studied on the Blue and White Niles.The annual amplitude of population density, expressed in orders of magnitude (=log10 units), is one measure of seasonal variability. It can exceed 3 orders both in systems subject to hydrological wash-out (e.g. Nile reservoirs) and in the more variable species components of lakes of long retention (e.g. L. Victoria). Low amplitudes can be characteristic of some components (e.g. green algae in L. Victoria) or of total algal biomass (e.g. L. George, L. Sibaya).Seasonal changes may be subordinated to inter-annual ones, especially in shallow and hydrologically unstable lakes (e.g. L. Nakuru). 相似文献
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Nícholas F. de Camargo Hernani F. M. de Oliveira Juliana F. Ribeiro Amabílio J. A. de Camargo Emerson M. Vieira 《Ecology and evolution》2019,9(7):3946-3957
- Spatial and temporal variation in networks has been reported in different studies. However, the many effects of habitat structure and food resource availability variation on network structures have remained poorly investigated, especially in individual‐based networks. This approach can shed light on individual specialization of resource use and how habitat variations shape trophic interactions.
- To test hypotheses related to habitat variability on trophic interactions, we investigated seasonal and spatial variation in network structure of four populations of the marsupial Gracilinanus agilis in the highly seasonal tropical savannas of the Brazilian Cerrado.
- We evaluated such variation with network nestedness and modularity considering both cool‐dry and warm‐wet seasons, and related such variations with food resource availability and habitat structure (considered in the present study as environmental variation) in four sites of savanna woodland forest.
- Network analyses showed that modularity (but not nestedness) was consistently lower during the cool‐dry season in all G. agilis populations. Our results indicated that nestedness is related to habitat structure, showing that this metric increases in sites with thick and spaced trees. On the other hand, modularity was positively related to diversity of arthropods and abundance of fruits.
- We propose that the relationship between nestedness and habitat structure is an outcome of individual variation in the vertical space and food resource use by G. agilis in sites with thick and spaced trees. Moreover, individual specialization in resource‐rich and population‐dense periods possibly increased the network modularity of G. agilis. Therefore, our study reveals that environment variability considering spatial and temporal components is important for shaping network structure of populations.
16.
Richard M. Cowling Abigail Kamineth Mark Difford Eileen E. Campbell 《African Journal of Ecology》2010,48(1):135-145
African elephant and black rhinoceros – both megaherbivores – impact negatively on the abundance of succulent plants, including tree succulents, in South Africa's subtropical thicket. We sampled 35 sites in subtropical thicket to assess historical and contemporary impacts of African elephant and black rhinoceros on the population structure of three species of succulent tree euphorbia. Population age structures were highly variable and showed no species-specific effects. Almost half the sites had growing populations dominated by young individuals. Sites having contemporary impacts had significantly fewer individuals in the 30–75 years age range, but this effect declined with increasing terrain slope. Eighty-one percent of sites assumed to have been impacted by megaherbivores historically had individuals that predated rhino and elephant extirpation in the region. This and other population age structure data indicate that megaherbivores and tree euphorbias coexisted historically on terrain of low relief. However, in areas not subject to contemporary impacts, euphorbia populations are likely to be much higher now than historically, owing to population relaxation after the extirpation of megaherbivores in the mid 1800s. Given the sensitivity of tree euphorbias to megaherbivore impacts, managers should consider monitoring the population structure of these species in order to identify thresholds of potential concern regarding megaherbivore impacts. 相似文献
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Renal weights of 430 adult black subjects coming to medicolegal autopsy at the Diepkloof State Mortuary, a large urban area southwest of Johannesburg, South Africa, were analyzed. The subjects were from 10 southern African black ethnic groups-Zulu, Sotho, Tswana, Xhosa, Shangaan, Swazi, Venda, Ndebele, Kalanga, and Malawi. The aims of the study were: 1) to ascertain the anatomical \"norm\" as it pertains to renal weights in this diverse population group; 2) to formulate standard reference tables that might be of use to the practicing pathologist in the southern African arena; 3) to provide a range of values that take into account the variables of age, sex, race, body weight, and body height; and 4) to provide a standard of comparison with anthropological and anatomical studies conducted on North American black, North American Caucasian, Indian subcontinent, Burmese, and Jamaican population groups. In each of the 430 subjects, age, sex, ethnic group, supine body length, body weight, individual left and right renal weights, and causes of death were noted. The latter were divided into 6 categories: 1) penetrating incised wounds; 2) multiple injuries; 3) gunshot wounds; 4) craniocerebral injuries; 5) various miscellaneous nonnatural causes of death; and 6) natural causes of death. The above variables were analyzed by computer and compared with respect to renal weights. No statistically significant differences were observed between the sexes or the age groups.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
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Paul K. Ndang'ang'a Fred M. Barasa Mercy N. Kariuki Paul Muoria 《African Journal of Ecology》2016,54(1):76-86
The coastal forests of Kenya are conservation priorities hosting high levels of biodiversity. Monitoring of biodiversity in these forests is therefore necessary to understand and reverse negative trends in good time. Using the Important Bird Area (IBA) monitoring framework, a participatory approach, state (habitat condition), pressure (threats) and response (conservation action) indicators of twelve coastal Kenya forest IBAs were assessed from 2004 to 2011. Trends for these indicators were assessed at six sites for which sufficient data existed: Arabuko‐Sokoke, Dakatcha Woodlands, Gede Ruins, Lower Tana River, Shimba Hills and Taita Hills, and baselines were described for remaining six. Changes were always small, but state deteriorated in Gede, Lower Tana and Shimba Hills, remained the same (unfavourable) in Arabuko‐Sokoke and Dakatcha, and improved in Taita Hills. Pressure reduced in Arabuko‐Sokoke, Dakatcha and Taita Hills, deteriorated in Lower Tana and Shimba Hills and remained the same (medium) in Gede. Response improved in Dakatcha, remained the same (medium) in Shimba Hills, and deteriorated in the rest. As there was an apparent overall deterioration in the forests assessed, improved management of the protected sites and increased conservation action through community engagement around protected areas and within the nonprotected IBAs are recommended. 相似文献
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Trevor A. Jackson Miguel N. Rincón Laura F. Villamizar Sulav Paudel 《Journal of Applied Entomology》2023,147(1):19-22
The coconut rhinoceros beetle (CRB: Oryctes rhinoceros L.) is one of the most damaging pests of coconut and oil palms in the Asia/Pacific region but has not been reported from the Western Hemisphere. Here, we report a possible establishment of CRB in Nayarit, Mexico, based on an analysis of social media reports and photographs indicating the presence of the beetle and the distinctive v-shaped notches in palm fronds caused by the beetle feeding. CRB populations are destructive once established, therefore, urgent actions are required to contain the pest and prevent damage to coconut and oil palm in the Americas. 相似文献
20.
Insight into demographic processes that operate at larger spatial scales can be achieved through studying local populations when a particular species of interest is examined over time, by many investigators, in a variety of locations. On the west coast of North America, Mazzaella splendens (Setchell et Gardner) Fredericq is such a species of interest. A synthesis of local demographic studies of M. splendens from the late 1960s to the present reveals a pattern that is potentially common to the larger natural populations. This is the pattern: population density is high in summer and low in winter for both alternate free‐living life history phases of M. splendens. The magnitude of this seasonal change decreases in increasingly wave‐exposed habitats. In wave‐sheltered habitats there is a seasonal alternation from summer haploid to winter diploid dominance. This alternation gradually changes to constant diploid dominance as wave exposure in the habitat increases. Changes in population density are primarily a function of appearances and disappearances of perennating basal crusts (genets), as modules are produced or lost, rather than differential module production by genets of one phase over those of the other. To test the generality of this pattern, we examined seasonal changes in density, in local populations of M. splendens, in both a wave‐sheltered and a wave‐exposed habitat at Second Beach, Barkley Sound. Greater seasonal fluctuation in population density at wave‐sheltered, compared to wave‐exposed habitats is supported as a pattern potentially common to the natural populations of M. splendens. A change from summer haploid dominance in wave‐sheltered areas to summer diploid dominance in wave‐exposed areas is similarly supported. All changes in population density were the result of appearances and disappearances of genets rather than differential module production by haploid versus diploid basal crusts, also consistent with previous observations. A seasonal alternation in phase dominance, however, was absent from the wave‐sheltered site at Second Beach, Barkley Sound for 3 consecutive years. Seasonal alternation in phase dominance of M. splendens appears dependent on local conditions and is not common to all natural populations. 相似文献