Itambi A.C.,University of Bremen |
von Dobeneck T.,University of Bremen |
Adegbie A.T.,Nigerian Institute for Oceanography and Marine Research
Journal of Quaternary Science | Year: 2010
We combine environmental magnetism, geochemical measurements and colour reflectance to study two late Quaternary sediment cores: GeoB 4905-4 at 2° 30′ N off Cameroon and GeoB 4906-3 at 0° 44′ N off Gabon. This area is suitable for investigating precipitation changes over Central and West Africa because of its potential to record input of aeolian and fluvial sediments. Three magnetozones representing low and high degree of alteration of the primary rock magnetic signals were identified. The magnetic signature is dominated by fine-grained magnetite, while residual haematite prevails in the reduced intervals, showing increase in concentration and fine grain size at wet intervals. Our records also show millennial-scale changes in climate during the last glacial and interglacial cycles. At the northern location, the past 5.5ka are marked by high-frequency oscillations of Ti and colour reflectance, which suggests aeolian input and hence aridity. The southern location remains under the influence of the Intertropical Convergence Zone and thus did not register aeolian signals. The millennial-scale climatic signals indicate that drier and/or colder conditions persisted during the late Holocene and are synchronous with the 900 a climatic cycles observed in Northern Hemisphere ice core records. © 2009 John Wiley & Sons, Ltd.
Jerome F.C.,Nigerian Institute for Oceanography and Marine Research |
Human and Ecological Risk Assessment | Year: 2016
Metals such as cadmium (Cd), lead (Pb), zinc (Zn), and copper (Cu) were estimated in the flesh of the edible blue crab Callinectes amnicola from selected areas of the Lagos Lagoon, Nigeria (i.e., Makoko, Iddo, Okababa, Ikoyi, and Ajah) for 18 months between March 2011 and August 2012. Estimated average daily intake (EADI) and target hazard quotient (THQ) were used to determine the risk implications for adult and child consumer populations. Range of Cd, Pb, Zn, and Cu across sites was 0.16–0.46, 1.48–3.17, 2.21–3.65, and 9.48–12.76 mg kg−1 crab flesh wet weight, respectively. Lead concentrations in crab flesh from Makoko (3.16 ± 1.44 mg kg−1) and Iddo (5.17 ± 1.26 mg kg−1) exceeded the maximum accepted limits recommended by the Food and Agriculture Organization/World Health Organization for food fisheries. The EADI across sites for the adult consumer population exceeded the reference dose (RfD) recommended by the U.S. Environmental Protection Agency for most metals with magnitude of ≤7-fold while EADI of Pb among child consumer population across sites exceeded RfD by a maximum of 4.5-fold. THQs for adult population were >1 for all metals across all sites, and >1 for Pb and Cd for selected sites for the child consumer population. Findings from this study indicate higher health risks of metal toxicity to adult consumer populations, and risks of lead toxicity to child consumer populations around the Lagos Lagoon, Nigeria. © 2016 Taylor & Francis Group, LLC.
Edun O.M.,Nigerian Institute for Oceanography and Marine Research
Journal of Fisheries and Aquatic Science | Year: 2012
Global aquaculture production has grown rapidly over the last 50 years. It is generally accepted that there is limited potential to increase trahtional fisheries; consequently, increased aquaculture is required in order to maintain global per capita fish consumption at the present level. With nearly half of all fish eaten today coming from farms and some 12 million people dependent on fish farming for their daily income, ensuring that farmed fish products are safe to eat and of the highest possible quality is crucial. Most of the work reviewed in this article describes the safety and quality issues in farmed fish, implications for consumers and presents methods to improve product characteristics. © 2013 Academic Journals Inc.
Ajiboye O.O.,Nigerian Institute for Oceanography and Marine Research |
Yakubu A.F.,Nigerian Institute for Oceanography and Marine Research
Reviews in Fish Biology and Fisheries | Year: 2010
The paper emphasizes on the several attempts made to raise the brackish water tilapia species, Tilapia guineensis both on an experimental and production basis by researchers and fish farmers in Nigeria. Besides, the aquaculture potentials of Tilapia guineensis have been reported by several authors. However, problems exist which are not found with the culture of other tilapia species. Even under most favourable conditions (e. g. the monosex culture of Tilapia guineensis), a poor growth rate and a mediocre feed conversion do not presage profitable aquaculture exploitation. The present review therefore throws light on areas of further research to enhance the growth performance of Tilapia guineensis with emphasis on fish larvae nutrition and first feeding (development of bio-encapsulated feed for larval fish based on nutritionally enriched nematodes and Calanoid copepods), digestibibilty of the feed ingredients, elucidation of the dietary protein requirements, improved culture technique through the use of the Recirculating Aquaculture Systems and the adoption of the most recent technology (The YY Male technology) that produces Genetically Male Tilapia through genetic manipulation. Specific recommended areas for further research are also proffered. © 2009 Springer Science+Business Media B.V.
Ukenye E.A.,Nigerian Institute for Oceanography and Marine Research |
Kolade O.Y.,Nigerian Institute for Oceanography and Marine Research
Pakistan Journal of Nutrition | Year: 2015
This study assessed the freezing length effect on the physical and chemical components of fresh croaker fish caught from Badagry beach, Lagos and frozen at -20°C with fresh sample (not frozen) as control. The experimental fish was subjected to different freezing periods of 2, 4 and 6 weeks, respectively. Samples of frozen croaker fish were assessed bi-weekly for physical attributes such as colour, odour, texture and eye colour. Proximate composition was determined using changes in moisture content, crude protein, ash and lipid as well as mineral content in both the frozen fish and the control. A general decline was observed in physical attributes of frozen samples when compared with the control. The result of the proximate composition showed that moisture content reduced (79-74%) after 2 weeks (at weeks 4 and 6) of freezing while lipid content increased (0.3-0.8%) at week 4 and 6 of freezing. Thus, moisture is inversely proportional to lipid. The Protein content reduced (18.69-17.52%) as freezing progresses (during weeks 4 and 6). However, freezing has no effect on ash content and no mineral losses were detected during the period of this study. © Asian Network for Scientific Information, 2015.
Abohweyere P.O.,Nigerian Institute for Oceanography and Marine Research
European Journal of Scientific Research | Year: 2011
A cohort analysis was carried out on a 24-month length-frequency data of Macrobrachium macrobrachion Herklots, 1851 (Brackish River Prawn) from the Lagos - Lekki lagoon system, via modal progression analysis using Bhattacharya's method in FISAT (FAO-ICLARM Stock Assessment Tools) software. A total of 12,168 specimen of M. macrobrachion was used for the analysis. Three cohorts were decomposed from the composite length frequency sample. The residual of the Gulland and Holt plot, from the length at age derived from the linking of cohort means gave the value of the amplitude of growth oscillation C as 0.20 and the winter point WP as 0.58 or July. The amplitude of seasonal growth oscillation and the winter point derivable from the cohort analysis are of paramount importance in the stock assessment and ultimately management of the resource as they revealed the strength of growth oscillation along with the period of slowest growth which can be inferred as the most susceptible period for the stock. Therefore resource sustainability require that fishing mortality be minimized in this period (July) in the Lagos - Lekki lagoon system. © EuroJournals Publishing, Inc. 2011.
Megbowon I.,Nigerian Institute for Oceanography and Marine Research |
Mojekwu T.O.,Nigerian Institute for Oceanography and Marine Research
Biotechnology | Year: 2014
Tilapia is the second leading aquatic crop globally, next to carps and its production has increased tremendously within the last decade. Its production is however affected by stunting, a phenomenon brought about by overpopulation due to precocious reproduction under mixed sex culture system. Several methods such as use of predatory fish, hybridization, polyploidy and sex reversal, using methyl testosterone have been employed with different degrees of success. This study reviews the use of methyl testosterone in sex reversal of tilapia and its consequent effects on fish, man and environment. It established the preference of all-male tilapia due to better and more uniform growth under culture system. It has been demonstrated that the hormone does not have any adverse effect on fish flesh after cessation of treatment of tilapia fry. In like manner, ingestion of fish produced by sex reversal does not therefore harm man. However, one is not too sure of the effect of the hormone or it's by-products on vital organs (liver, kidney, pancreas and gills), metabolic profile and nucleic acids. This may also affect muscle building and perceived libido-enhancement in man. On the environment, the steroid is either biodegraded or mineralized. It must be stated that escape from tilapia hatchery into the natural water may, however, alter the dynamics of the environment due to unforeseen consequences. © Science Alert. All Rights Reserved.
Ajiboye O.,Nigerian Institute for Oceanography and Marine Research |
Yakubu A.F.,Nigerian Institute for Oceanography and Marine Research |
Adams T.E.,Nigerian Institute for Oceanography and Marine Research |
Olaji E.D.,Nigerian Institute for Oceanography and Marine Research |
Nwogu N.A.,Nigerian Institute for Oceanography and Marine Research
Reviews in Fish Biology and Fisheries | Year: 2011
In spite of the growing interest and success obtained using cultured-copepods, their use in marine aquaculture remains sporadic. Besides, mass culture of several marine copepods has been well established by several authors. However, the upscale of copepod cultures to commercial levels is still a challenge. The practice of using wild copepods from natural ponds which thus increases the risk of parasitic infections of most species has limited their application in aquaculture. The present paper thus emphasizes on recent research efforts focused on the use of chemical treatments and freeze-thawing methods to eradicate procercoids from copepods. Research efforts focused on copepod culture systems which subsequently improved and refined their culture in marine fish larviculture are also well discussed. Advances in the use of copepod eggs as potential source of nauplii for marine fish larvae with special emphasis on the viability, storage conditions and biochemical compositions of the copepod eggs are underscored. Additionally, recent advances in the biochemical compositions (protein, amino acids, pigments, and vitamins) of copepods, which has received relatively little attention compared to researches on the lipid and fatty acid compositions are well emphasized. Specific recommended areas for further research are also proffered. © 2010 Springer Science+Business Media B.V.
Akande G.R.,Nigerian Institute for Oceanography and Marine Research |
Adeyemi R.S.,Nigerian Institute for Oceanography and Marine Research
Agricultural Engineering International: CIGR Journal | Year: 2016
The most widely employed traditional method of processing and preserving fish for human consumption in the third world are smoking and drying. However, the traditional smoking and drying methods restrict the cross border trade of preserved fish due to the associated poor quality of the products, low capacity and poor energy efficiency. A detachable smoking kiln that uses solid biofuel as energy source and enables processing of fish into good quality and highly competitive shelf stable smoked dried fish and fish oil was developed. It consists of insulated walls, segmented compartments and a solar powered fan that circulates heat and smoke. The fan is powered by solar photo voltaic (PV) cell and/or DC cell. The equipment is detachable enhancing its portability feature. It has an overall ground size of 95 cm × 90 cm; the height excluding hood and chimney, is 136 cm and the gross weight is 211 kg. The no-load temperature profiling of the equipment showed an even distribution of heat within the smoke drying chamber. Performance evaluation conducted on the equipment using fresh water catfish (Clarias gariepinus) (average live weight of 350 g ± 50 g per piece) as test organism showed that the kiln has a batch capacity for processing 50 kg live weight (average moisture content, 72% w. b.) of Clarias gariepinus to smoked dried fish (average moisture content, 5.5% w.b.) in 10 h when operated at 110oC ± 10oC. The observed batch capacity agrees with the design calculation. About 57% of the total oil content of the test fish samples was collected using the oil collecting system of the equipment. The equipment reduced frequent rotation of fish by operator and the associated drudgery during smoking operation. The smoked fish were uniformly dried. © 2016, Int. Comm. of Agricultural and Biosystems Engineering. All rights reserved.
Agwu O.A.,Nigerian Institute for Oceanography and Marine Research
African Journal of Aquatic Science | Year: 2013
Antibiotic-resistant bacteria in the aquatic environment are considered reservoirs for drug-resistant genes. Therefore, culturable heterotrophic bacteria isolated from Lagos Lagoon surface waters between 2011 and 2012 were screened for their susceptibility to 14 commonly used antibiotics belonging to six major classes. The sampling stations had temperature, pH and salinity ranges of 28 to 33 °C, 8.2 to 8.1 and 14.6 to 20.1, respectively. The high microbial load of the sampling stations was evident, the mean most probable number being between 400 and 1 100 per 100 ml. The bacteria encountered were Pseudomonas sp., Citrobacter sp., Vibrio sp., Micrococcus sp., Streptococcus sp., Bacillus sp. and Aeromonas sp. Resistance to the tested antibiotics was widespread; the incidences of isolates resistant to ampicillin (55.3%) and amoxicillin (52.6%) were the most common, while all tested isolates were susceptible to the fluoroquinolones, with the exception of sparfloxacin which was resisted by 26.3% of the isolates. The frequency of resistant isolates for aminogylcosides, macrolides, phenicols and sulfonamides ranged between 2.6% and 18.4%. The most resistant strain had a multiple antibiotic resistance value of 0.57. Although susceptibility to some drugs was noted, resistance to the beta-lactam antibiotics suggests that bacteria in Lagos Lagoon harbour genes for resistance. © 2013 Copyright © NISC (Pty) Ltd.