Estimated un-ionized ammonia at small incremental pH value and temperatures: practical option for fish farmers

Ammonia as the primary product of nitrogen metabolism causes mortality due to ammonia toxicity produced in a culture system. Effect of pH and Temperature was calculation and expanded using the acid dissociation constant (pka) for equation: pka = 0.09018+ 2729.92/T. Ammonia values (f) expressed in percents for intervals of 1.0 degree from 0 - 30~'C and pH increasing from pH 6-10 where T is the Temperature and acid dissociation constant (pka). Ammonia (f) was calculated using the equation: f= 1/(10pka-pH+1).Small increments of 0.5 were considered from pH values of 3.0 - 7.0 for Temperature range of 20 - 34~'C as experienced now in most farms in Lagos. Casio scientific calculator fx-82TL (12 Digits) with four significant figures was used for the calculation. The acid dissociation constant (Pka) calculated for 31-34~'C was 9.0702, 9.0407, 9.0115 and 8.9824 respectively. pH and Temperature can be monitored and used for ammonia estimation by cross-marching with the extended pH -Temperature Emerson monogram. This will show the estimated ammonia as observed for pH and Temperature at pH 6.0 - 7.0. The use of this management protocol (Monogram) will reduce mortality in culture systems serving as a prompt management tool for fish farm operation. The understanding of the usage of this monogram will reduce the cost of production usually necessitated by non availability and high cost of imported water quality, which many farmers cannot afford

Nutrient and pH stability in liquid manure production and usage for pond fertilization

Nutrient content of organic manure vary according to the composition which determines the fertility and efficiency. The effectiveness of liquid manure depends on the N.P.K value of the manure source. One kilogram of each manure source was weighed and loaded into a polyethylene bag for ten (10) days anaerobic fermentation. pH was monitored for five consecutive days after the second day using Digital pH meter (Model PHeP NOVO Illkirch Cedex France) with values ranging between 5.6-6.3 and 5.7-6.9 for both liquid manures slurry. The liquid manure was produced from Pig and Poultry manure slurry with N.P.K values range between 4.80-5.96, 4.10-4.66,0.47-0.80 and 7.50-8.80, 3.25-5.60, 0.79-0.85 for Pig and poultry manures respectively. Organic manure loose nitrogen when exposed to extreme temperature due to volatilization of NH3. Therefore, in liquid manure production, anaerobic fermentation enhances nutrient stability through immobilization of ammonia-nitrogen compounds. The interaction of N.P.K and pH shows the availability, stability and quality of nutrient in the liquid manure produced. Anaerobic fermentation produces better quality liquid manure than the manure due to immobilization of ammonia nitrogen. Both liquid manure had positive correlation (R2) of 0.6977 and (R2) of 0.2370 for Poultry and Pig liquid manure. Liquid manure application in ponds can reduce cost of pond fertilization especially in the integrated fish farming system than the use of organic manure directly serving as a better means of pond fertilization and pollution control in the farm environment under a stressed economy

Water recirculating aquaculture systems: management by-pass and trouble shooting

Water Recirculating Aquaculture system (WRAS) as a culture system can be simply configured to combine both mechanical and biological filteration mechanism. This system can be regarded as a fish factory being an intensive culture technology system with high-density stocking and carrying capacity. Recirculating systems has some production advantages over other culture systems especially in intensive production. This production system achieves good and stable water quality management and enables the farm manager to trouble shoot as management protocol is easier to determine in a more business manner. Challenges in running this system in Nigeria include poor design, irregular power supply alter failure, high cost of quality feed, poor water quality management and high cost of water quality kits. Similarly, unavoidable continuous daily stress on fish stocked, low biosecurity understanding and lack of expertise coupled with inadequate financing are common issues in running this system. Therefore, necessary by-pass protocols become necessary in the management of this system in Nigeria for profitable production

The nature of fishing community in Nigeria: a case study of Itowolo fishing community, Lagos

Itowolo is a fishing village being boarded with Lagos lagoon on nearly every side except the southern part which opened to the Ikorodu road from Mile 12 part of Agboyi - Ketu Local Council Development Area. During the raining season, the water level increases which possibly cause flood at heavy down pour while low water level of higher salinity during the dry season. The indigenes are primarily fisherfolks and they are effective in their fishing activities by having individual functional canoe ranging from small unmotorised paddled dugout type to outboard ones. The main gears used for fishing in the area are cast nets, gill nets, traps, hooks and lines among which cast net is prominently used Their landings during the raining season involve different species of fishes such as Heterobranchus species, Heterotis species, Channa species including others while tilapia of different species take the greatest percentage of their catches during the dry season. The shrimps top the population of catches between the months of July September. The dwellers during off fishing season engage in other economic activities that generate income such as petty trading, palm tapping, fuel wood trading, transport business, mat making, hairdressing, fashion designing, computer business centres and telecommunication vendors. In general, fishing activities are characterized by low unit productivity, intensive labour, relative low capital, low operational costs and limited gear coverage. High post harvest losses are usually experienced due to lack of suitable storage facilities which eventually lead to relative low profit

Antimicrobial effect of slow release chlorine dioxide disinfectant, in comparison with sodium dichloroisocyanurate

MSc (Med), Clinical Microbiology and Infectious Diseases, Faculty of Health Sciences, University of the WitwatersrandThe goal of infection control is to minimize the risk of exposure to potential pathogens and to create a safe working environment in which patients can be treated. Use of disinfectants in is an integral part of infection control. The rate of killing of microorganisms depends upon the type, concentration and time of exposure of the killing agent (disinfectant). Chlorinated compounds are frequently used in healthcare settings but chlorine dioxide has only been used in industries on a large scale. Aseptrol® is newly developed slow release chlorine dioxide and noncorrosive formula which can be used on a smaller scale basis. This study assessed the antimicrobial properties of Aseptrol® (48ppm and 24ppm) in comparison with previously used sodium dichloroisocyanurate containing formula, Presept® (10 000ppm). Both disinfectants killed more susceptible bacteria, such as Staphylococcus aureus, Pseudomonas. aeruginosa and Streptococcus mutans within 30 seconds and proved to be fungicidal by killing Candida albicans within 30 seconds. Aseptrol® and Presept® killed less susceptible mycobacteria such as Mycobacterium tuberculosis, Mycobacterium avium subsp. avium and blood borne organism Hepatitis B virus within 30 seconds. Highly resistant B. subtilis spores were killed in 2 and 2.5 minutes by Aseptrol® and Presept® respectively. Although manufacturers recommend that the disinfectant solutions should be prepared daily, when the shelf-life of prepared solutions stored in screw cap bottles was studied, the results showed that Aseptrol® can be effectively used for 27 day and Presept® for more than 37 days. The goal of infection control is to minimize the risk of exposure to potential pathogens and to create a safe working environment in which patients can be treated. Use of disinfectants in is an integral part of infection control. The rate of killing of microorganisms depends upon the type, concentration and time of exposure of the killing agent (disinfectant). Chlorinated compounds are frequently used in healthcare settings but chlorine dioxide has only been used in industries on a large scale. Aseptrol® is newly developed slow release chlorine dioxide and noncorrosive formula which can be used on a smaller scale basis. This study assessed the antimicrobial properties of Aseptrol® (48ppm and 24ppm) in comparison with previously used sodium dichloroisocyanurate containing formula, Presept® (10 000ppm). Both disinfectants killed more susceptible bacteria, such as Staphylococcus aureus, Pseudomonas. aeruginosa and Streptococcus mutans within 30 seconds and proved to be fungicidal by killing Candida albicans within 30 seconds. Aseptrol® and Presept® killed less susceptible mycobacteria such as Mycobacterium tuberculosis, Mycobacterium avium subsp. avium and blood borne organism Hepatitis B virus within 30 seconds. Highly resistant B. subtilis spores were killed in 2 and 2.5 minutes by Aseptrol® and Presept® respectively. Although manufacturers recommend that the disinfectant solutions should be prepared daily, when the shelf-life of prepared solutions stored in screw cap bottles was studied, the results showed that Aseptrol® can be effectively used for 27 day and Presept® for more than 37 days. Chlorinated disinfectants, such as Aseptrol® and Presept®, have potential to be used as intermediate to high level disinfectants in medical and dental settings, where above test organisms are primary contaminants. It is also possible to use them as sterilants, where semicritical conditions are required. Aseptrol® has an additional advantage because it is noncorrosive and can be used on metal instruments

Body-weight variations in four week old Clarias gariepinus

The variation in size and weight of fry and fingerlings of Clarias gariepinus has been a major factor affecting the success of hatchery production of the species. It encourages cannibalism, thus reducing the overall survival. The disparity in weight and population was assessed to determine the necessity of sorting as a reliable method of controlling size disparity and mortality in hatchery production. Two-week-old fry with average weight of 15mg and length range of 0.8-0.9cm were randomly sampled and stocked at 200 fry/litre in 30 litre circular tanks. The fish were fed for four weeks on 45% crude protein diet, ad libitum. At the end of four weeks, there were three groups; large, medium and small with mean weight of 4.02g, 1.24g and 0.17g, respectively. The cumulative mean weight was 1.8g, population ratio was 1:8:10 for large, medium and small, respectively

Improving breeding performance of fingerlings of Clarias gariepinus through intraspecific hybridization

The scarcity of genetically improved fish seed is a major constraint to rapid development of aquaculture in Nigeria due to inbreeding. The study was conducted to monitor breeding indices from intra-specific mating combinations of wild stocks of Clarias gariepinus. Broodstock of C. gariepinus were collected from Lokoja (LK), Makurdi (MK), Agenebode (AG) and Onitsha (ON) and compared with domesticated strain. 16 mating combinations of parental and intraspecific mating combinations were conducted in triplicates. Results were subjected to one way analysis of variance (ANOVA) (α= 0.05). The results showed collection from Onitsha had highest values of fertilization (95.2%), hatchability (87.6 %) and survival (66.0 %), followed by crosses from female from Onitsha : ♀ON X ♂LK, ♀ON X  ♂MK and ♀ON X  ♂AG having 95.8 %, 91.1 % and 88.8 % (fertilization), 68.7 %, 61.9 % and 60.7 % (hatchability) and 61 %, 57 % and 63 % (survival) respectively. Domesticated strain had least values (81.9 %, 59.4 % and 51 %) fertilization, hatchability and survival respectively. ANOVA (α< 0.05) showed variation in fertilization, hatchability and survival. The better performing strains could be explored for genetic development. However, protein and gene profiling of these natural populations may be necessary to identify the proteins and genes responsible for these variations in breeding performances.Key Words: Breeding, performance, Clarias gariepinus, hybridizatio

Culture trial of (Peneaus) Penaeus monodon in concrete tank

Culture trial of the Tiger Shrimp (Peneaus monodon) was carried out in one of the grow-out concrete tanks at Nigerian Institute for Oceanography and Marine Research, Victoria Island, Lagos. A total of 264 post larvae of P. monodon (PL 30) produced at the Institute’s shrimp hatchery complex were used for the experiment which lasted for 157 days. Coppens Catco feed of 0.8 - 1.2mm size was used to feed the post larvae throughout the duration of the experiment. The results showed that the shrimps grew from an initial mean body weight of 1.763g at stocking to 19.538g at the end of the experiment. The daily growth rate was 0.113g/day while specific growth rate was 1.532 %. Food Conversion Ratio (FCR) was 3.362 while survival rate was 90%. The study has shown that P. monodon can be successfully cultured in concrete tanks. However further studies aimed at improving growth rate will be undertaken

Corrigendum: The intersection of age, sex, race and socio-economic status in COVID-19 hospital admissions and deaths in South Africa

The following terminology was erroneously reported: “non-white race” should be “people of colour”, or “black African, coloured and people of Indian descent”

Design and construction of a shrimp hatchery for the breeding of the black tiger shrimp Penaeus monodon

A shrimp hatchery for the breeding of the black tiger shrimp, Penaeus monodon was constructed by the Nigeria Institute for Oceanography and Marine Research in 2008 by the reconstruction of an existing old shrimp hatchery. The new shrimp hatchery comprises of the following: water treatment, water storage, broodstock maturation, spawning/incubation, nursery and micro-algae units. The design included the construction of a concrete sump for the collection and treatment of wastewater before disposal, in addition to an aeration unit equipped with root blower for adequate supply of dissolved oxygen. The reconstructed NIOMR shrimp hatchery has been successfully used for the production of post larvae, which are presently being reared to adult shrimp in concrete tanks. The successful completion of the shrimp hatchery and breeding of P. monodon has confirmed that the species can be spawned and reared to adult size in Nigeria for local and export markets