首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 328 毫秒
1.
T. Hecht 《African Zoology》2013,48(4):222-228
Otoliths and scales were used for age and growth determinations of Sarotherodon mossambicus In the Luphephe-Nwanedzi impoundment, a subtropical man-made reservoir in Venda, northern South Africa. Two rings are deposited annually on the otolith whereas only one ring Is deposited on the scales. Using otoliths the growth of S. mossambicus is described by Lt = 27,3 (1 - e-0,425(t + 0,299))cm and using scales by Lt = 26,8 (1 - e-0,389(t + 0,045)) cm. These two curves differ significantly (P<0,01). The adequacy of these curves was tested by means of Ford-Walford plots. It is postulated that otoliths provide a more reliable estimate of age and growth than scales in subtropical and temperate regions. Males grow faster than females. Based on otoliths the growth of male S. mossambicus in the Luphephe-Nwanedzi impoundment is described by Lt = 27,0(1 - e-0,417(t + 0,504)) cm SL and that of females by Lt = 25,8(1 - e- 0,370(t + 0,497)) cm SL. The growth of S. mossambicus in the Luphephe-Nwanedzi impoundment is compared to other S. mossambicus populations in South Africa.  相似文献   

2.
Estimated expenditures by Nectarinia violacea and Promerops cafer vary throughout the day, with highest rates occurring during the morning when nectar availability is greatest. Energy storage needed to satisfy overnight requirements by these nectarivores probably occurs only during the morning, with deficits being incurred at other times, although the ingestion of insects may help to reduce these deficits. Male and female P. cafer are frequently territorial, showing a clear preference for foraging at partially opened inflorescences of Mimetes hirtus. Smaller male N. violacea are usually excluded from M. hirtus and obliged to forage on less rewarding Erica perspicua.  相似文献   

3.
This study investigated dip-tank use effects on herbaceous vegetation and soil, and relationships between environmental and species variables. Eight dip-tanks, three each in sandy (DPBS) and loamy (DYRL) soils, and two in stony (ROSG) soils were used. Data were collected at 50, 100, 150, 300, 500, 700 and 900 m from each dip-tank. In DPBS, phosphorus and potassium contents were highest (P ? 0.05) on approaching dip-tanks. In all soils, forb and perennial grass abundances showed significant differences but there were no significant trends with distance. These variables are not sufficiently sensitive to form gradients or the gradient is diminished with heavy grazing. In DPBS, the canonical correspondence analysis showed negative correlation of distance with bareness, the abundance of Aristida rhiniochloa and Cynodon dactylon, which may suggest these variables may respond to grazing gradients around dip-tanks, but this pattern was not established on the other soil types. Therefore, caution is required in drawing conclusions of the piosphere effect around focal points. The abundance of highly palatable species was low except for Panicum maximum in DPBS. It is concluded that vegetation and soil changes are driven by abiotic (site and soil) and biotic (livestock) factors that have different influences at different scales. Therefore, any rangeland utilisation and management program should consider these drivers.  相似文献   

4.
《African Zoology》2013,48(2):150-155
A new freshwater eutardigrade, Dactylobiotus luci is described from a permanent marsh pool (Zaphania’s Pool) at 4225 m elevation in the Alpine zone of the Rwenzori Mountains, Uganda. The new species is most similar to D. dervizi Biserov, 1998 in the shape of the egg processes, absence of papillae and absence of eyes, but differs from it mainly by a different appearance of macroplacoids, by having tips of the egg processes usually sharp, not divided and more slender, and by several morphometric characters of eggs and adults. The new species was found in fairly acidic (pH < 6) Sphagnum-Carex fens bordering/extending into the pool. So far, it has only been recorded in one other high-elevation water body in Rwenzori in a similar habitat.  相似文献   

5.
Extract

The treatment of sheep specifically for tapeworm infestation has generally not been advocated, most authorities maintaining that Moniezia expansa is rarely pathogenic when not associated with concurrent nematode infestations. Most sheep develop a good immunity to these parasites which are usually expelled within three months of the host contracting the infestation. On the other hand, there are numerous scattered references to loss of condition and occasionally to deaths attributed to Moniezia infestation in lambs.  相似文献   

6.
  相似文献   

7.
The egg and larval development of the Cape silverside, Atherina breviceps, are described and illustrated from material collected in the Swartvlei estuary. The eggs are spherical, 1,40-1,65 mm in diameter, with 6-12 uniformly spaced chorionic filaments attached at both ends to the chorion. TTie latter condition and the small size of the eggs are unique among the Atherina species. The larvae examined (5,1-15,7 mm) are elongate, have a yolk sac at hatching and are characterized by distinct body pigmentation and a prominent gas bladder. Flexion occurs between 7,6-11,2 mm, all fin elements are formed by 15,7 mm and scales develop by 20,0 mm. We compare the larval development of A breviceps with that of other atherinids and discuss the spawning of this species and the seasonal occurrence of larvae along the southern coast of Africa.  相似文献   

8.
Abstract

The purpose of this study was to examine the capacity of live brine shrimp Artemia spp. to accumulate metronidazole at different developmental life stages. Metronidazole is used in fish as an antiparasitic medication. An effective drug delivery method is to enrich the Artemia with metronidazole and offer them as live feed to the infected fish, usually ornamental species and other small fishes. Artemia cysts were hatched and then soaked in a metronidazole solution (0.05%) at instars 1–3 of larval development. Our findings indicated that Artemia were able to accumulate metronidazole at levels considered therapeutic to other animals and humans (25–100 mg/kg). However, the levels varied depending on the stage of larval development. Artemia accumulated the highest levels of metronidazole (137–143 mg/kg) when they started filter feeding (instar 2), whereas newly hatched Artemia (instar 1) contained the lowest level (85 mg/kg). Based on this study and a review of the literature, a new protocol recommended for enriching Artemia with metronidazole consists of soaking the Artemia in a 0.05% metronidazole solution for 3 h at room temperature. Because metronidazole is relatively insoluble in water, it must first be dissolved in warm water with continuous stirring.

Received December 5, 2010; accepted January 30, 2011  相似文献   

9.
Abstract

An enzootic caused by bacteria occurred among cultured giant gourami in two freshwater fish farms in Kagoshima, Japan, in 1982. Typical external characteristics of the diseased fish were sloughed scales, exophthalmia, and opaque eyes. Internally, numerous creamy white nodules were found in the gills, spleen, kidney, and liver and a lesser number in the bladder and stomach. Nocardia sp. was isolated from spleen and kidney tissues of all diseased fish examined. To clarify the taxonomic position of the isolates, 164 tests were performed, and results were compared to reference strains of six species of Nocardia and one species of Rhodococcus. The isolates formed a homogenous group in a single taxon at a similarity of 98.7% based on an average linkage analysis and were clearly separated from the reference strains. The isolated strains were more similar to Nocardia kampachi than to the other representative species. However, 12 distinct differences were found between the isolates and N. kampachi, including growth on nutrient agar, sensitivity to 250 and 500 μg hydroxylamine/mL and 0.01% phenol, tolerance of 0.05% salicylate and 0.1% picric acid in brain-heart infusion medium, hydrolysis of starch, nicotinamidase reaction, and acid from fructose, sucrose, and dextrin. Accordingly, the isolates from the diseased giant gourami were classified as a new species of Nocardia.  相似文献   

10.
《African Zoology》2013,48(2):358-362
The suitability of scales for ageing Micropterus salmoides was determined by comparing the precision of growth zone counts on scales with those obtained from sectioned sagittal otoliths from a sample of 496 fish collected from Wriggleswade and Mankazana Impoundments in the Eastern Cape, South Africa. Otoliths (1.4% rejected) were more readable than scales (41.7% and 7.5% rejected) for Wriggleswade and Mankazana Impoundments respectively. Otolith readings were more precise (average percentage error (APE) = 13.6%; coefficient of variation (CV) = 15.8%) than scales (APE = 18.0%; CV = 21.9%) for the total sample. Growth zone counts between structures were not symmetrically distributed around the agreed ages (otolith age = scale age) of the fish from Wriggleswade Impoundment (Bowker’s test H2: χ2 = 136, d.f. = 27, P < 0.05) and graphical comparison showed that scales tended to underestimate age, particularly for fish older than five years. Scales are therefore not suitable structures for ageing South African M. salmoides which may attain ages of up to 13 years.  相似文献   

11.
Forty-six species were recorded in association with Patella spp., but most of these are casual associates, seeking temporary shelter. The shell surface offers an important substrate for algae.

The amphipod Hyale grandicornis is often associated with Patella, particularly in the juvenile stages. It is a facultative inquiline which vacates its hosts at high tide. The isopods Dynamenella australis and D. scabricula are predominantly associated with limpets and complete their life cycles under limpets. Choice chamber experiments demonstrate their preference for sheltering under limpets. The copepod Scutellidium patellarum is similar, but the association is more marked.

Calliopiella michaelseni (Amphipoda) is commensal and show a preference for certain limpet species. Its colour changes in relation to the host species. Feeding occurs on limpet faeces and algal fragments. The life cycle is completed under the limpet, two reproductive peaks occurring each year. Adults usually occur in pairs and there is a positive correlation between host and amphipod size. Juveniles remain with their parents initially, and then disperse to other limpets. Adult pairs may defend their host, excluding other amphipods. Calliopiella is strongly photonegative and thigmotactic.

The turbellarian Notoplanapatellarum is preferentially commensal with Patella oculus. This can be experimentally demonstrated. It feeds on small Crustacea, including Scutellidium.  相似文献   

12.
This study documents the fauna associated with two common comatulid crinoid species, Comanthus wahlbergi and Tropiometra carinata, in False Bay, South Africa, and describes the patterns of infestation of obligate associate species. A total of 11 invertebrate species was found associated with one or both crinoids. Of these, three were considered obligate: the myzostomidans, Myzostoma fuscomaculatum and Myzostoma n.sp., and the shrimp, Hippolyte catagrapha, all of which only occurred on T. carinata. Both frequency and density of infestation were higher for the two myzostomes than for the shrimp. The majority of crinoids infested with myzostomes hosted two or more individuals, while H. catagrapha usually occurred singly. A total of 67.5% of all T. carinata collected were infested by symbionts. Of these 45% hosted only one species, 17% hosted two species and 5.8% hosted all three. Most M. fuscomaculatum (85.2%) and H. catagrapha (82.1%) matched their hosts’ colouring, while Myzostoma n. sp. were all yellowish incolour. Infestation by Myzostoma n. sp. increased in both frequency and density with depth. All three obligate symbiont species are new to science, illustrating the biodiversity that can still be uncovered by investigating new niches.  相似文献   

13.
The starfish Marthasterias glacialis is a generalized predator, feeding particularly on Choromytilus meridionalis, but also on several limpets, notably Patella longicosta. Thais dubia (Gastropoda) feeds mainly on barnacles, mussels, and Patella granulans. The gastropods Burnupena delalandii and B. cincta are principally scavengers, feeding on damaged or dead animals. The responses of Patella spp. to these predators are described. P. granulans, P. concolor, P. compressa and P. miniata all retreat rapidly on contact. Small P. granatina and P. oculus respond similarly, but larger specimens react aggressively, smashing their shells downwards and often damaging the predator. The territorial species (P. longicosta, P. cochlear and P. tabularis) all retreat to their scars and remain clamped there. P. argenvillei and P. tabularis are usually unresponsive, possibly because they are too large to fall prey. Cellana capensis rolls its mantle upwards to cover the shell, preventing predators from attaching. The responses and their effectiveness are discussed in relation to other behavioural patterns displayed by limpets. There is no correlation between the intensity of a prey’s response to a predator and the degree of contact between the two in the field.  相似文献   

14.
Reasons for performing study: There is minimal published information on equine oromaxillary fistulae that are unrelated to cheek teeth (CT) repulsion or on the conservative treatment of these atypical fistulae. Objectives: To report equine oromaxillary fistulae unrelated to CT extraction and describe their management in standing horses. Methods: Case details of oromaxillary fistulae of atypical aetiology occurring at 2 referral centres between 2002–2006, including their treatment and response to treatment were examined. Results: Nine cases of oromaxillary fistula were recorded, mainly in aged horses (median 22 years). Fistulae were associated with CT diastemata in 7 cases, fractured CT in one and a central defect in a worn CT in another. After removing food and exudate from the sinuses, 6 cases were treated successfully by filling the diastema or dental defect with polymethylmethacrylate (PMMA). Following dental extraction, the other 3 cases were treated successfully by use of PMMA alveolar packing. Conclusion: Older horses can spontaneously develop oromaxillary fistulae, usually secondary to CT diastemata. In the absence of apical infection, this disorder can usually be treated successfully in standing horses by treating the sinusitis and sealing the oral aspect of the diastema with PMMA. Potential relevance: Older horses with sinusitis should be assessed for the presence of CT diastemata and oromaxillary fistulae. If detected, these disorders can be treated successfully in the standing horse.  相似文献   

15.
Culicoides biting midges (Diptera: Ceratopogonidae) are vectors of important diseases affecting wild and domestic animals. During the last decade they have played a major role in the epidemiology of the largest bluetongue epizootic ever recorded in Europe, the disease is transmitted between hosts almost exclusively by bites of Culicoides midges and affects both domestic and wild ruminants however severe disease usually occurs in certain breeds of sheep and some species of deer. An accurate vector identification is of major importance in arthropod borne diseases surveillance, as great differences in vectorial capacity are found even between close species. Unfortunately, specialized taxonomic knowledge of Culicoides identification is rarely available in routine surveillance, mainly based on wing morphology. Recently, some European species of Culicoides belonging to the subgenus Avaritia Fox, 1955 and Culicoides Latreille, 1809 have been described as new bluetongue virus vectors.In the present study, by using a fragment of the barcode region (COI gene) we report the presence of up to 11 species within the subgenus Culicoides in Catalonia (NE Spain), a region recently affected by a bluetongue epizootic. The molecular analysis revealed new non-described cryptic species which were grouped in three complexes of morphologically similar species, two in the Pulicaris complex resembling Culicoides pulicaris, two in the Fagineus complex resembling Culicoides fagineus and three in the Newsteadi complex resembling Culicoides newsteadi. The phylogenetic relationships among them showed that cryptic species detected in both Pulicaris and Fagineus complexes were closely related, whereas those in the Newsteadi complex were more distant. Accurate analysis of all species using morphological and molecular approaches resulted in the detection of diagnostic metric traits for cryptic species and the design of several new species-specific single and multiplex PCR assays to identify unambiguously all the species, most of them still lacking a specific molecular diagnosis.  相似文献   

16.
Habronemiasis, otherwise known as summer sores, is a parasitic disease of horses, donkeys and other equids, commonly encountered in subtropical and tropical regions. It occurs as a result of nematode infestation of the skin and typically manifests as ulcerative granulating lesions or masses. Habronema muscae, Habronema microstoma and Draschia megastoma are the usual invaders, usually transmitted by house flies, face flies and stable flies. In this case report, an eosinophilic granuloma on the urethral process of a 15-year-old gelding is presented, followed by successful surgical excision without further medical treatment. To the authors’ knowledge, equine eosinophilic granuloma on the urethral process associated with habronemiasis has not previously been documented in southern Europe and should be considered as a potential differential diagnosis for penile masses.  相似文献   

17.
Observations on the phylogenetic relationships of Barbus species from the southern Cape Province are made in the light of new data on the post-cranial axial skeleton and other osteological and anatomical features. Particular attention is paid to the relationships of the ‘red fin’ Barbus species, and new evidence on the problematical relationships of the rare African cyprinid species Oreodaimon quathlambae, is presented.  相似文献   

18.
Abstract

Pseudorhabdosynochus kritskyi n. sp. from gag Mycteroperca microlepis (Perciformes: Serranidae) of the Gulf of Mexico is described and differs from all known species of the genus by the shape of the vagina. It may be further differentiated from P. americanum, P. amplidiscatum, P. caballeroi, P. epinepheli, P. latesi, P. monaensis, and Cycloplectanum magnisquamodiscum in having fewer rows of scales in each squamodisc. This new species is most similar to P. beverleyburtonae, P. bocquetae, P. cupatum, P. lantauensis, P. melanesiensis, P. querni, P. serrani, P. summanae, P. vagampullum, and Cycloplectanum riouxi in having 15 or fewer squamodisc rows, but it may be separated by differences in either squamodisc morphology or differently shaped hamuli or bars.  相似文献   

19.
Pneumonia of pigs is one of the more important disease factors limiting pig production. Of the varieties of pneumonia affecting this species enzootic pneumonia caused by Mycoplasma spp. is the most common and most important. The major effects of this disease are lowered food conversion ratio and poor weight gain. Deaths are usually the result of secondary infection by necrotising, pus-forming bacteria. Eradication of the disease is expensive and requires depopulation and restocking. Control and treatment by antimicrobial agents is most effective if the drug combination used takes regard of the bacteria complicating the disease on any particular property. Other forms of pneumonia such as those caused by Haemophilus pleuropneumoniae, Salmonella cholerae-suis and Aujeszky’s disease virus can be important on individual farms. The role of other agents such as Bordetella bronchiseptica and adenoviruses in respiratory disease of pigs remain to be clarified.  相似文献   

20.
This report concerns a collection of parasitic worms from South Africa, and contains a new species of monogenean, Gyrodactylus transvaalensis, six species of adult trematodes, including a new species of Phyllodistomum.P. van der waali, two metacercariae of the Family Clinostomidae and three of the Order Strigeida, as well as two species of cestodes, and larvae of the nematode genus Contracaecum. The adults of previously-known helminths are redescribed, with some remarks on their systematics and biology. Accompanying the material of the new gyrodactylid monogenean there is a specimen which is thought to be a giant of the new form, and this appears to be the first recorded suggestion of the occurrence of gigantism in the Monogenea, and in fact in any kind of helminth.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号