Towards assessing managerial competencies and leadership styles required for successful game ranch management in the Eastern Cape, South Africa24

Given the importance of the agricultural sector in the South African economy and the emerging importance of game farming, long term sustainability is critical. One way of achieving long term sustainability of game ranches in South Africa is to ensure the effective and efficient management of these ranches. Effective and efficient management is largely determined by managerial competencies and leadership styles. The problem statement addressed in this research can be stated as follows: ¡§Which management competencies and leadership styles are required to assist game ranch managers/owners in the effective and efficient management of their game ranches in the Eastern Cape, South Africa?¡¨The purpose of this study is to development a framework to assess the management competencies and leadership styles needed by game ranch managers/owners in order to enhance the game ranch¡¦s prospects of survival, continuity and success. To achieve this, the objectives are to identify whether there is a significant relationship between the:•current and ideal (future required) managerial competencies;• current managerial competencies, transactional and transformational leadership styles; and• managerial competencies and selected biographical variables.Data was collected using a five-point Likert scale questionnaire. The data was analyzed using Statistica V.8. Sample T-testing, Cross Tabulations (Chi Square) and Analysis of Variance (ANOVA) tests were used to assess the research objectives. The reliability and validity the research instrument were also tested by using Cronbach Reliability Analysis and Confirmatory Factor Analyses. It was found that there was a significant difference between current and ideal managerial competencies and that teamwork, planning and administration as well as strategic action needed to be improved. Findings suggest that a strategic relationship exist between gender, current teamwork and self management competencies. Another strategic relationship was found between the number of employees and current strategic action

Antagonistic activity of Aeromonas media strain A199 against Saprolegnia sp., an opportunistic pathogen of the eel, Anguilla australis Richardson

A bacteriocin-like inhibitory substance (BLIS) produced by Aeromonas media strain A199 inhibited the growth of Saprolegnia sp. in vitro, an opportunistic pathogen isolated from affected eels, Anguilla australis (Richardson). The presence of BLIS in solid media inhibited the growth of the vegetative state of the aquatic mould as well as the germination of cysts. Uninhibited growth was, however, observed in the presence of inactive BLIS, suggesting that the in vitro antagonism derived from the BLIS of A199. In four independent in vivo tank observations of fish affected with saprolegniosis, the daily addition of A199 to tank water contributed to the subsequent swift recovery of affected hosts from invasion by this opportunistic pathogen.7 page(s

Is cotton-strip tensile strength a surrogate for microbial activity in groundwater?

The cotton strip assay uses the loss of tensile strength of cotton strips as a measure of microbial cellulolytic activity. Its suitability for measuring general microbial activity in groundwater was tested by examining the relationship of tensile strength, abundance of cellulolytic organisms and general microbial activity on cotton strips deployed in bores. The hypothesis was that the strength of cotton strips would decline with increasing abundance and activity of cellulolytic organisms, and as cellulolysis makes resources available to other microbial groups, cotton strength loss should also be related to increased overall microbial activity. The correlation between the abundance of cellulolytic organisms and cotton strength was not significant. Two main factors influenced this relationship: (i) effectiveness of the media in detecting cellulolytic moulds and (ii) inter-community interactions. After accounting for the presence of moulds through partial correlation, the relationship between tensile strength and abundance of cellulolytic organisms was stronger and significant. Both cotton strength and abundance of cellulolytic organisms correlated significantly with general microbial activity. These results support the use of the cotton strip assay, and cotton tensile strength as a surrogate for microbial activity in groundwater.6 page(s

Biocontrol of saprolegniosis in silver perch Bidyanus bidyanus (Mitchell) by Aeromonas media strain A199

The potential of Aeromonas media strain UTS A199 as a candidate for the biocontrol of winter saprolegniosis was tested during a winter outbreak in a farm and in a laboratory challenge trial on silver perch, Bidyanus bidyanus Mitchell. The daily addition of A199 to tanks during the winter outbreak of saprolegniosis resulted in a significant increase (p<0.05) in fish survival. Close monitoring of fish revealed that A199 treatments halted the progress of the disease by inhibition of hyphal growth within lesions and cyst germination. In a laboratory-based challenge of perch by exposure to high numbers of cysts and zoospores of Saprolegnia parasitica, the presence of A199 in the tank water delayed the onset of the disease but, ultimately, could not protect the fish from the disease under these conditions. © 2003 Elsevier B.V. All rights reserved

Control of saprolegniosis in the eel Anguilla australis Richardson, by Aeromonas media strain A199

The probiotic activity of Aeromonas media strain A199 for the control of saprolegniosis at low water temperatures was trialled in a laboratory-based challenge using the eel, Anguilla australis Richardson. Eels were challenged in the presence of a physiological and physical stress akin to that preceding the winter outbreaks of saprolegniosis in farms. The concentration of Saprolegnia parasitica cysts was 9±1.2 cysts/ml for the initial challenge. Morbidity due to saprolegniosis was low, at 27% in A199-treated tanks, in comparison to the 44% recorded for the non-treated control tanks. The subsequent addition of live A199 cultures to the treatment tanks resulted in the recovery of fish suffering from saprolegniosis (p=0.038), with temperature appearing to be a factor regulating the effect of A199. It was concluded that A199 is a potential agent for the management of winter outbreaks of saprolegniosis in eels. © 2004 Elsevier B.V. All rights reserved

An inhibitory substance produced by Aeromonas media A199, an aquatic probiotic

Whether or not the probiotic activity of the Aeromonas media strain A199 derived from the production of an extracellular inhibitory substance was investigated. Ethyl acetate extraction of broth cultures of A199 and preparative thin layer chromatography methodologies revealed a fraction that contained inhibitory activity against bacterial and fungal indicators. Gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance (NMR) analyses identified indole (2,3 benzopyrrole, henceforth referred to as T1) as the major chemical component in this fraction. The presence of inhibitory activity in broth culture extracts of A199 was found to be entirely dependent on the production of T1 by the organism. The inhibitory activity of T1 in vitro against Edwardsiella tarda, Vibrio anguillarum, Yersinia ruckeri, Aeromonas salmonicida and Lactococcus garvieae was found to be concentration dependent (300-600 μg ml- 1). Antifungal activity (75-300 μg ml- 1) was obtained against the vegetative stage and cysts of Saprolegnia parasitica, with cysts showing a higher susceptibility. Morphological changes observed within hyphae suggested that T1 could be a potential cytoplasmic toxin. Equivalent inhibitory activity was obtained from commercial indole against the majority of indicators, but discrepancies were encountered consistently with failure to inhibit particular bacterial indicators as well as decreased antifungal activity. A comparison of the inhibitory activity of A199 and other indole producers, that included various strains of A. media and Escherichia coli, indicated that the ability of a bacterium to produce indole might not necessarily afford it with inhibitory activities. © 2005 Elsevier B.V. All rights reserved

Probiotics in aquaculture: The need, principles and mechanisms of action and screening processes

Aquaculture production of molluscs is worth US$11 billion per year and represents 65% of World mollusc product. A significant limitation to the industry is loss of stock through bacterial disease. Traditional methods to combat disease with antibiotics have been questioned and alternatives have been sought. The field of probiotics as well as the screening methods used to acquire probiotic strains for the alternative management of disease in aquaculture is discussed. This review provides a comprehensive summary of probiotics in aquaculture with special reference to mollusc culture. © 2007 Elsevier B.V. All rights reserved

Two pathogens of greenshell™ mussel larvae, perna canaliculus: Vibrio splendidus and a V. coralliilyticus/neptunius-like isolate

Bacterial pathogens of Greenshell™ mussel (GSM) larvae can cause batch losses during hatchery production. Twenty-two isolates were screened using a larval bioassay. Two strains were identified as potential pathogens. Phenotypic identification of these strains revealed two non-reactive Gram-negative, oxidase positive rods. Sequencing of the 16S rRNA gene identified Vibrio splendidus and a V. coralliilyticus/neptunius-like isolate as pathogens of GSM larvae, with an ability to cause 83% and 75% larval mortality in vitro, respectively, at a concentration of 102 CFU mL-1. Histopathology indicated that the route of infection was via the digestive system. Using healthy larvae as target hosts, Koch's postulates were confirmed for the two isolates. This is the first report on pathogens of GSM larvae. © 2009 Blackwell Publishing Ltd

Alteromonas macleodii 0444 and Neptunomonas sp. 0536, two novel probiotics for hatchery-reared Greenshell™ mussel larvae, Perna canaliculus

Antibiotic management of aquacultured animals, such as Greenshell™ mussel (GSM) larvae, Perna canaliculus, is undesirable because of health concerns and political pressures; hence, alternatives are needed. Herein, two novel probiotic bacteria were identified and trialled in a GSM larval rearing hatchery. Sequencing of the 16S rRNA gene and phylogenetic analysis identified the strains as Alteromonas macleodii 0444 and Neptunomonas sp. 0536. Both probiotics were evaluated separately at the Glenhaven Aquaculture Centre hatchery facility during routine larval rearing and when the larvae were challenged with both a high (107 and 106CFUml-1) and low (106 and 105CFUml-1) pathogenic dose of Vibrio sp. DO1 and V. splendidus respectively. In all experiments, probiotic application improved larval survival significantly when administered prior to pathogen exposure. Across all experiments, larvae that were exposed to the high and low dosages of pathogens averaged 14% and 36% survival respectively on the fourth day following pathogen exposure. The administration of probiotics prior to pathogen challenge resulted in larval survival of 50% and 66% respectively. Non-inoculated control larvae and larvae administered the probiotic alone demonstrated 67% and 79% survival respectively. Neptunomonas sp. 0536 appeared to suppress naturally occurring vibrios in the culture environment of healthy GSM larvae. This is the first report of A. macleodii and Neptunomonas sp. as probiotic bacteria in a large scale production facility. © 2010 Elsevier B.V

Performance of single and multi-strain probiotics during hatchery production of Greenshell ^™ mussel larvae, Perna canaliculus

Earlier work identified two novel strains of probiotic bacteria, Alteromonas macleodii 0444 and Neptunomonas sp. 0536, for Greenshell ™ mussel (Perna canaliculus) larvae. Herein, we investigated whether the combination of the two probiotics in a multi-strain mix provided a) enhanced larval production during routine rearing and b) improved larval protection during two separate pathogen-challenge tests (Vibrio sp. DO1 and Vibrio splendidus). The response of larvae to multi-strain or single-strain probiotic administration was compared to that of larvae without probiotics. Two concentrations of each probiotic were tested (10 7 and 10 8CFUml -1). Addition of 10 8CFUml -1 multi-strain mix in the routine rearing of larvae yielded smaller-sized larvae and a lower feeding rate when compared with the 10 7CFUml -1 and control groups. During the challenge test against Vibrio sp. DO1 and V. splendidus, protection by single-strain probiotic administration was observed at both levels of probiotic administration (10 7 and 10 8CFUml -1), with no apparent added protection from multi-strain probiotics. Although 10 8CFUml -1 levels provided protection against pathogen attack, they were also potentially detrimental to normal larval rearing when administered in combination and, as such, where administration of A. macleodii 0444 and Neptunomonas sp. 0536 would be applied together, a multi-strain mix of probiotics at 10 7CFUml -1, is recommended as the best concentration of each probiotic. © 2012 Elsevier B.V