Mormyrus Rume Research Articles

Assessment of Some Selected Heavy Metals Concentration in the Organs of Two Different Fish Species (Clarias gariepinus and Mormyrus rume) of River Gidin Dorowa

This study was aimed to assess selected heavy metals concentration in the organs of Clarias gariepinus and Mormyrus rume from River Gidin Dorowa, Wukari, Taraba State, Nigeria. The liver, muscles and Gills of the fish species and water were collected. During dry (September, October and November,) and wet (December, January and February) seasons. Cadmium, Lead, Zinc and Copper were analyzed using Atomic Absorption Spectrometer. Sampling of fish was carried out monthly for six (6) months. The results showed that heavy metals mean were high in the muscles followed by the liver and low in the gills of Clarias gariepinus, while heavy metals were highest in the gills followed by the liver and lowest in the muscles of Mormyrus rume. High heavy metals concentration (1.900mg/kg) was recorded for Zinc (Zn) in the gills follow by copper (Cu) with a mean of (0.00917mg/kg) recorded in the liver of Mormyrus rume, Pb recorded the high mean of (0.2932mg/kg) in the liver while low lead (Pb) mean (0.1855mg/kg) was recorded in the muscle. However, Zn (1.6250mg.kg) and Pb (0.2882mg/kg) was high in the muscle than in other tissues of C. gariepinus. In other to avoid serious health hazards, there is need to institute effective fisheries pollution control measures and management of River Gidin Dorowa fisheries resources. Continuous monitoring of the pollution levels of the River Gidin Dorowa using fish species as bioindicators can provide adequate information necessary for its effective management.

Assessment of Organochlorines Pesticides Residues in Water, Fish and Sediment Samples from Wurbo Lake, Bali, Taraba State, Nigeria

Organochlorines pesticides (OCPs) have been used worldwide, particularly in many African countries as in Nigeria for the control of pests. OCPs are characterized by their bioaccumulation in the environment, especially in the food chain, where they find their way into the human body. The research was aim to estimate the residual concentrations of different OCPs in water, fish and sediment from Kundi Lake to find out the extent of pesticide contamination and accumulation. The water sample was subjected to liquid-liquid extraction method while the fish and the sediment samples were subjected to soxhlet extraction. The extracts were later analysed for organochlorines pesticide residues using Gas-Chromatography coupled with mass spectrometer (GC-MS). The average length, average weight and condition factor of the studied fish species were measured. The Mormyrus rume had the highest average length of 17.12±0.05 cm, and average weight of 195.36±0.05 g follow by Clarias gariepinus which had the average length of 16.83±0.01 cm, and average weight of 189.43±0.03 g. Tilapia zilli was the least species of fish sample with a length of 12.75±0.03 cm and average weight of 102.21±0.02 g. Also, all the fish species sampled in this present study had condition factors>1. Based on the results obtained from all samples, it was found that the levels of organochlorine pesticides residues in water were generally below MRL as compared with FAO/WHO (0.5ppm). In fish samples, highest concentration of pesticide residues in Mormyrus rume follow by Clarias gariepinus, while the Tilapia zilli recorded low concentration of the pesticide residues. The Endosulfan II recorded high concentration of 4.68 ppm in Mormyrus rume follow by Endrin which recorded the concentration of 2.75 ppm, Aldrin 1.78 ppm and Atrazine 1.72 ppm all in Mormyrus rume. In Clarias gariepinus, Simazine 1.56 ppm follows by Endosulfan I 1.28 ppm while In Tilapia zilli, Endosulfan II 1.16 ppm follows by Atrazine 0.91 ppm and Beta Lindane 0.81 ppm. The results indicate that the area is contaminated with high levels of these pesticides in fish and sediment which may pose a great danger to the environment. Regular monitoring is therefore required to control the levels of pesticide residues in the water bodies.

Ontogeny reveals the origin of Gemminger bones in Mormyridae.

Mormyridae are well known and intensively studied for their weak electric organ discharges, which facilitate communication and orientation. The Gemminger bones of Mormyridae are located next to the electrical organ in the caudal peduncle; however, they have not attracted much interest until recently. Therefore, we investigated the diversity of Gemminger bones in mormyrids and studied their ontogenetic development in Mormyrus rume proboscirostris. Gemminger bones are paired, thin, elongated ossifications lying on the dorsal and ventral sides of the caudal peduncle, and usually reach anterior well below the dorsal and anal fin bases. Ontogeny revealed that they are not intermuscular ossifications, as suspected based on the anatomical position of this structure and the systematic position of the mormyrids. Instead, they are membrane ossifications that originate from the fin stays of the dorsal and anal fins.

Determination of organochlorine pesticides residues in water, fish and sediment samples from River Tella, Gassol, Taraba State, Nigeria

The study was aimed at determining the levels of organochlorine pesticides residues in water, sediment and fish species at River Tella to find out the extent of pesticide contamination and accumulation in the river. Total of fourteen (14) organochlorine pesticide residues were analyzed which include Delta lindane, Alpha Lindane, Beta Lindane, Gamma Lindane, Heptachlor, Aldrin, Heptachlor Epoxide, Endosulfan I, Endosulfan II, P’P-DDE, P’P-DDD, P’P-DDT and Methoxychlor. The water sample was subjected to liquid-liquid extraction method while the fish and the sediment samples were subjected to soxhlet extraction. The extracts were later analyzed for organochlorine pesticide residues using Gas-Chromatography coupled with mass spectrometer (GC-MS). The study has revealed that the level of pesticides residues in water was less than that of fish and sediment which was also below the WHO/FAO values. It was also observed that high concentrations recorded were recorded in high in Gamma Lindane (24.71), follow by Alpha Lindane (23.70) and Beta Lindane (4.50). Mormyrus rume follow by Claria gariepinus while the Tilapia zilli recorded low concentration of the pesticide residues. The Aldrin recorded high concentration of 5.11 ppm in Mormyrus rume follow by Endosulfon II which recorded the concentration of 25.03 ppm also in Mormyrus rume. Endrin also recorded the concentration of 4.88 ppm in Clarias. gariepinus. The lowest pesticide residues was recorded in p,p'-DDD (0.01 ppm), p,p'-DDT (0.03 ppm), Methoxychlor (0.01 ppm). The Heptachlor epoxide and P’P-DDE were not detected in water sample. The presence of high concentration in fish may pose a great danger when these fish are being consumed over time. Regular monitoring is therefore required to control the levels of pesticide residues in the water bodies. The measurement of the fish showed that Clarias gariepinus had the average length of 15.89 cm, and average weight of 179.87 g. Mormyrus rume had the average length of 15. 18 cm, and average weight of 210. 54g. Tilapia zilli was the least species of fish sample with a length of 12.96 cm and average weight of 96.88 g. The water quality parameters of the river were also studied, which recorded the temperature of 28.89 oC was recorded, pH value of 9.01, Conductivity value of 40.11, DO value of 6.14 and TDS of 2.35.

Studies on fish species diversity, abundance and Distributon along Onitsha axis of River Niger, Anambra State of Nigeria

A study on biodiversity, abundance and distribution was carried out in Onitsha Axis of River Niger in Onitsha North and South Local Government Area, Anambra State, Nigeria for a period of three months. The area was partitioned into Station I (Emejuru), Station II (Bridge Head) and Station III (Akpaka). Fish samples were collected weekly from July to September, 2019 with the aid of fisher folks using gill nets, cast nets, hook and lines and local traps. The results showed a total composition of 4,645 individuals belonging to 15 families and 31 species. Momyridae showed significance (p<0.05) species diversity with seven (7), followed by Bagridae (5) spp. with the remaining 13 families having one and two spp. Station III Akpaka recorded the highest fish diversity of 37%, followed by Station I Emejuru 34% and Station II Bridge head 29%. In terms of species abundance, Bagrus bayad 13.9% >bagrus docmak 8.8% >Chryschythys Nigrodigitatus7.2% >Bargus filamentous 4.5% >Malapters electricus 4.4% >Heterotis niloticus 4.0% >Orochromis niloticus 3.8% >Mormyrus macrophatalmus 3.3%) recorded the highest, followed by Heterobranchus bidorsalis, Mormyrus rume, Mormyrus tarpirus, Mormyrus senegalensis, Schibe mystus Synodontis clarias and Cithrinus citharus had 2.2%, 2.3%, 3.0%, 1.7%, 2.9%, 1.6% and 3.2% respectively, and Hypothermirus pissitacus the least with 0.4%. This research shows that the Onitsha axis of the River Niger is still rich in fish species diversity and abundance; hence concerted efforts should be made by the various government agencies to see that laws guiding the proper use of water bodies are enforced in the Onitsha axis of the River Niger, to enhance economics, conservation and sustainability.

Heavy Metal Bioaccumulation and Histopathological Studies of Fish Tissues from Ose River, Ondo State, Nigeria

The exposure of the aquatic ecosystem to heavy metal from both natural and anthropogenic activities are on the rise and have harmful health effects on all aquatic organisms and human. This study assessed the concentrations of heavy metals (Fe, Pb, Cd, Cr, As and Zn) in surface water, sediments and fish tissues of Ose River and examined the histopathological changes of the tissues of two fish species (Mormyrus rume and Clarias garienpinus). Surface water, sediments and fish samples were collected and procured from Ose River in Ondo State, Nigeria from February to April 2021. Heavy metal digestions were done in the laboratory using HNO3/HCl while the concentrations were determined using Atomic Absorption Spectrometer. Histopathological alterations in the fish tissues were also assessed. Bioaccumulation factor (BAF), ecological risk index and potential ecological risk level were used to assess the investigated metal concentrations. In the surface water, the concentration of Cd (0.010–0.030 mg/l) and As (0.010–0.05 mg/l) exceeded the WHO limits of 0.01mg/l respectively while Fe, Pb, Cr and Zn were within the limits. In the sediments, all metals exceeded the limits except Pb and As. The concentrations of Pb (0.30±0.000–4.12±0.030 mg/l), Zn (9.970±0.010–30.77±0.023 mg/l), Cd (0.026±0.002–0.331±0.004 mg/l) and Cr (ND-0.331±0.004 mg/l) in the fish tissues were seen to be higher than the permissible limits of 0.5 mg/l, 5 mg/l, 0.005 mgl and 0.05-0.15 mg/l respectively. The BAF showed no probability. The alterations observed in the kidneys of the fish were cholestasis, necrosis, loss of glomeruli structure and tubular necrosis. While the gills showed congestion of the central veins and interlamellae hyperplasia caused by the presence of a monogenean parasite. The livers however revealed loss of hepatocytes nuclei, necrosis in hepatocytes and lymphocytic infiltrate. The study showed that the study site was polluted with heavy metals and may pose serious health issues to fishers, those using the water and people feeding on fish from the river. This study therefore suggests good indicators for bio-monitoring of heavy metals in Ose River. Seeing that the site was polluted with heavy metals hence, a more comprehensive assessment of the river is recommended.

Pollution Status and Health Risk Assessment of Polycyclic Aromatic Hydrocarbons in Surface Water, Sediment and Fish from Ezu-River, Anaku, Anambra State, Nigeria

The distribution of the sixteen polycyclic aromatic hydrocarbons (PAHs) was studied in surface water, sediment and three fish species (African catfish (Clarias gariepinus), Trout fish (Mormyrus rume) and Hetrobranchus longefilis) from Ezu-river, Anaku, Anambra State, Nigeria. The samples were analysed for PAHs by means of Gas chromatography-mass spectrometry. The results of PAHs showed that, in surface water, the highest concentration was related to benzo(a)pyrene whereas benzo(k)fluoranthene was the most important pollutant in sediment. For the fish samples, Hetrobranchus longefilis recorded the highest concentration in Naphthalene while Anthracene was the most dominant pollutants in Mormyrus rume and in Clarias gariepinus benz(b) fluoranthene was the highest pollutants. The Health and exposure risk assessment was conducted for carcinogenic and non-carcinogenic exposure in adults and children which shows that the cumulative cancer risk and hazard index were within USEPA regulatory standard. Calculated Hazard Index for fish and water samples were less than one and thus be recommended for consumption.

Heavy Metal Concentrations in Fish from River Tano in Ghana and the Health Risks Posed to Consumers.

Appreciable levels of trace metals have been reported in the Tano basin, but data on the corresponding levels in fish and the risk they pose to consumers are limited. The levels of 7 trace metals in 18 fish muscles were assessed between November 2016 and October 2017 using acid digestion and PerkinElmer (PinAACle 900T) Atomic Absorption Spectrophotometry. Apart from Cu, all the metals studied were detected in all fish samples. The levels of Cr, As, and Hg were higher than the acceptable levels of fish muscles. Cr concentration ranged from 16.10 ± 0.2 mg/kg in Clarias gariepinus to 57.9 ± 4.2 mg/kg in Sarotherodon galilaeus. The levels of As ranged from 1.01 ± 0.08 in Clarias gariepinus to 3.00 ± 0.01 mg/kg in Mormyrus rume. Hg level was 0.58 ± 0.69 mg/kg in Oreochromis niloticus and 2.52 ± 0.70 mg/kg in Ctenopoma kingsleyae. However, Pb, Zn, and Cd concentrations were below the Food and Agriculture Organization limits with low target hazard quotients in all fish samples, suggesting no possible noncarcinogenic risks to adult consumers. Possible noncarcinogenic and carcinogenic health risks were recorded for As, Hg, and Cr in all fish species. Strong associations were observed between Hg, As, Zn, and Cr and between Pb and Cd suggesting a possible common source. Mormyrus rume fish species was under stress in the river, but the remaining species were in good condition. Periodic monitoring of trace metal concentrations in fish and enforcement of the buffer zone policy are recommended.

From fin rays to DNA: supplementary morphological and molecular data to identify Mormyrus subundulatus Roberts, 1989 (Pisces: Mormyridae) from the Bandama River in Côte d'Ivoire

The genus Mormyrus Linnaeus, 1758 has been well studied in western Africa where five species are currently recognized. Mormyrus subundulatus Roberts, 1989 was described in 1989, and, although morphologically and genetically close to Mormyrus rume Valenciennes, 1847, is still considered by the most recent studies as a distinct species. It is endemic to the Côte d'Ivoire and Ghana River systems. It was historically recorded from only three locations but is today very likely extirpated from one of them and threatened in the remaining two. It is categorized as “Vulnerable B1ab(iii)” by the IUCN Red List (Dankwa 2020). Although a few papers describe precisely the morphology and electric signal of the species, they are based on a very limited number of samples. In this paper, we present new data on the morphological characteristics of the species (extending the dorsal fin rays count range, which is the main morphometric criterium to distinguish M. subundulatus and M. rume) based on Museum samples and samples collected recently a few kilometers away from the type locality. Determination of the newly collected material was confirmed by the analysis of a fragment of the Cytochrome b gene, and we produced the first sequence fragment of the cytochrome oxydase subunit 1 (COI) for this species.

Ovary structure and oogenesis in internally and externally fertilizing Osteoglossiformes (Teleostei:Osteoglossomorpha)

AbstractIn this study, we assessed the ovary structure and early oogenesis in representatives of Osteoglossomorpha, one of the most basal Teleostei groups. We aimed to perform a comparative analysis between internally fertilizing Pantodon buchholzi (Pantodontidae) and externally fertilizing Osteoglossum bicirrhosum (Osteoglossidae), Marcusenius cyprinoides, Brevimyrus niger, Gnathonemus petersii and Mormyrus rume (Mormyridae). Our results indicated differences in ovary structure between P. buchholzi and the externally fertilizing species, as well as a considerable disparity in oocyte organization in all studied species. All species possess ovaries of the cystovarian type. In P. buchholzi, the epithelium lining the lumen was columnar and formed crypts with ciliated and microvillus cells as well as deep invaginations with secretory cells, whereas in the remaining species epithelium was squamous. The organization of oogonia and one‐nucleolus oocytes did not differ between species, there were variations in oocytes at subsequent steps of primary growth, including symmetry/asymmetry of the inner cell structure, differences in Balbiani body formation, presence/absence of zonation of the ooplasm, and differences in the order in which cortical alveoli and oil droplets appeared. These differences may be caused by a long and separate evolution of the families as well as adaptation to insemination in the family Pantodontidae.

Length-weight relationships of 19 fish species from two tropical artificial reservoirs (Manantali and Selingue) in Mali, West Africa

Length-weight relationships (LWRs) were estimated for 19 fish species sampled from two artificial reservoirs (Manantali and Selingue) in Mali: Brycinus leuciscus, B. macrolepidotus, B. nurse, Chrysichthys auratus, C. nigrodigitatus, Coptodon zillii, Distichodus brevipinnis, D. rostratus, Hemichromis fasciatus, Hydrocynus forskahlii, Labeo coubie, L. senegalensis, Lates niloticus, Mormyrus rume, Sarotherodon galilaeus, Schilbe intermedius, S. mystus, Synodontis schall, S. sorex. The fish were collected between June 2002 and October 2003 during three experimental fishing campaigns using gillnets deployed overnight. All fish were measured (total length) to the nearest mm and weighed to the nearest g (total weight). Coefficients of determination of the LWRs (r²) were mostly high (> 0.9). The values of the allometry coefficient b ranged from 2.651 (Chrysichthys auratus) to 3.270 (Brycinus leuciscus). This study provides new information about LWRs of two fish species, which have been published but are not yet available in Fishbase (Distichodus brevipinnis and Mormyrus rume)

ENDO AND ECTO PARASITE PREVALENCE AND ABUNDANCE IN SOME FISH SPECIES FROM AKOMOJE, OGUN RIVER SOUTH-WEST NIGERIA

Parasites are the second most abundant microorganisms that infect and cause disease in wild and cultured fish after bacteria. The study investigated the parasite prevalence, abundance, mean intensity and dominance in some fresh water fish from Akomoje, Ogun River, Nigeria from February to May, 2016. Eight fish species were collected and identified to the species level. Experimental fish were measured and weighed. Endo- and ecto-parasites were examined for from Skin/scale, dorsal and caudal fins, gills, intestine and stomach of fish. Water sample was collected from shore, mid and extreme of the landing site and also analysed for parasite abundance. Prevalence percentage of parasite in all fish species varied slightly with size. Myxozoan group revealed the highest dominance of ecto- and endo-parasites in virtually all fish species while mean intensity and abundance of Myxozoan spp was highest in Oreochromis niloticus and Hemichromis fasciatus. Highest case of a single species of ecto- and endo-parasite in a fish sample was that of Nematode larva in Chrysicthys nigrodigitatus (41.43 %) and Trichocerca sp (Rotifera) in Mormyrus rume (52.9 %).Water analysis revealed three parasite groups that were present in the sampled fish. Conclusively, Akomoje landing site of Ogun River has a rich burden of parasites.

Diversity of Bacteria and Fungi Associated with Freshwater Fishes from Mijawal River, Nasarawa, Nigeria

Understudying the presence of bacteria and fungi population on freshwater fishes, provides the knowledge and understanding of their diversity and potential roles they may play in the health of the aquatic and terrestrial ecosystems. The present study was conducted to evaluate the diversity of bacteria and fungi species of identified fish samples from River Mijawal, Nasarawa State. The fishes were sampled from the only landing for three months (October to December, 2019) for this study. During the sampling periods, thirteen (13) different fish species were identified; they were swabbed with sterilized swab stick from the skin surface for bacteria and fungi identification. The Dominant fish species were Tilapia zillii, Labeo senegalensis, Mormyrus rume and Mormyrus tapines. The total number of thirteen (13) bacterial and five (5) fungi species were isolated and identified. Eight (8) of the bacteria isolates, were gram negative bacteria (Pseudomonas sp, Aeromonas sp, Serratia mercescenes, Proteus sp, Salmonella spp, Escherichia coli, Klebsiella sp, and Enterobacter sp.); whilst the other five (5) were gram positive bacteria (Bacillus sp, Micrococcus sp, Staphylococcus sp, Enterococcus sp and Listeria monocytogenes).The five isolated fungi species were Aspergillus niger, Rhizopus sp, Penicillium sp, Trichoderma viridae and Geotrichum candidum. The frequency of occurrence of the isolated bacteria indicated that Staphylococcus sp had the highest frequency of occurrence (16.67%) while Serratia mercescens had the least occurrence (2.78%). The highest number of occurrence of the isolated fungi species was observed in Rhizopus sp while the least was recorded in Geotricum candidum. It was observed that Tilapia zillii and Mormyrus rume had the most frequent bacteria and fungi isolates. It can therefore be deduced from the results that fish samples identified from River Mijawal has high bacteria and fungi diversity that may be pathogenic to man. The occurrence of these microbes may be attributed of human and animal faeces in the River 
 Keywords: Freshwater fishes, Microbes, River Mijawal, Nasarawa

Population dynamics of Mormyrus rume (Valenciennes, 1847; Osteoglossiformes; Mormyridae) Of Ikere-Gorge, Iseyin, Oyo State, Nigeria

The structure of a fish population is determined by the equilibrium between growth, recruitment and total mortality. But, there is paucity of information on the growth and mortality of Mormyrus rume in Nigeria. Therefore this study is needful to determine its population parameters, with a view of evolving management strategies for its sustainable exploitation. Estimates of population parameters of Mormyrus rume were obtained from length-frequency data of 836 individuals collected monthly for a period of 24 months from January 2017 to December 2018. The estimated growth parameters were: asymptotic length (L∞) was 100.8cm; growth coefficient (K) was 0.62/year; growth performance (Ɵ) was 3.8; length at maturity (Lm) was 52.57cm; reproductive load (Lm/L∞) was 0.52 and optimum length (Lopt) was 65.10cm. Likewise, natural, fishing and total mortalities were 0.93, 1.46 and 2.39 respectively. The values of exploitation rate (0.61) and ratio of total mortality and growth coefficient (3.85) showed that Mormyrus rume is most exploited in Ikere-gorge. Therefore, appropriate fishing regulations should be enforced to regulate fishing gears and mesh size that will fish Mormyrus rume at sustainable level.
 Keywords: Recruitment, mortality, growth, exploitation, length

Comparative analysis of some metallic elements in selected body part of some fishes (Mormyrus rume and Heterobranchus longifilis) captured from Igbokoda River, Okitipupa, Ondo State, Nigeria

Fishes are important for the maintenance and growth of living things, particularly human beings. Due to the nutritional value of fish, people are encouraged to include it into their diet. Fish is consumed in almost every house in Igbokoda, Nigeria and in the surrounding communities and is typically consumed in either (smoked, fried, cooked) condition. When these fish are polluted with heavy metals, they bioaccumulate and cause certain human organs to malfunction. The content of toxic elements in two different species (Mormyrus rume and Heterobranchus longifilis) of fish captured from the Igbokoda River of Ilaje was analyzed using Energy Dispersive X-ray Fluorescence (EDXRF). The result obtained showed that the mean values of all the elements were higher than the recommended FAO/WHO and International Atomic Energy Agency (IAEA) 407 standards, except for K, Ca, Sr and As, which were lower than the IAEA 407. Generally, the concentration of elements in muscle and head was higher than that of tail for each species for both M. rume and H. longifilis. The target hazard quotient (THQ) of each element through the consumption of Igbokoda fish for both adults and children increases in this order Mn > Cu > Ni > Zn > Fe > As > Pb and Mn > Cu > Ni > Zn > Fe > As > Pb for M. rume and H. longifilis respectively.

Biodiversity of Fish Fauna in River Niger at Agenebode, Edo State, Nigeria

The River Niger is blessed with diverse fish species and aquatic life. The study of the fish fauna and biodiversity along the River Niger was conducted from October 2016 to December 2018. A total of 35 species belonging to 18 families were obtained from this study. New to this River as regards literature are the family Solidae and Catostomidae. The sole fish (Solea solea) (0.16%) with only 1 representation while the Catastomids were represented by 3 species; Ictiobus niger (1.73%), Ictiobus cyprinellus (2.20%), Ictiobus bubalus (2.52%). Other species obtained were the Mormyrus rume 3.93%, Polyterus bichir (2.99%) and Protopterus annectens (7.08%). The most abundant of species observed was Gymnarchus niloticus (8.49%) of the family Gymnarchidae while the least was Solea solea (0.16%). The biodiversity indices revealed that Station 2 had the most evenly distributed species and the most of diverse species though Station 1 had the most number of species. Station 3 however had the least of species obtained. It is concluded the River Niger is still productive and in good condition, capable of maintaining and managing fish species according to condition factor.

Comparative studies on the antioxidant potential of hydrolysates of <i>Mormyrus rume</i> muscle protein

This study determined the degree of hydrolysis of Mormyrus rume muscle proteins by digestive proteases and the antioxidant potential of the hydrolysates produced was evaluated. The proteins were extracted with distilled water adjusted to neutral pH. The proteases used include trypsin, chymotrypsin and pepsin and the degree of hydrolysis was determined using trichloroacetic acid precipitation method. The antioxidative activities of the hydrolysates were evaluated using different in-vitro antioxidant assay methods such as 1,1-diphenyl-2- picrylhydrazyl (DPPH) radical scavenging, hydrogen peroxide scavenging, metal chelating capacity and reductive potentials. Degree of hydrolysis was generally low and ranges between 17.68% and 32.20% with pepsin given the highest degree of hydrolysis. The protein hydrolysates obtained with trypsin exhibited the highest antioxidant activities when assessed with metal chelating activity assay with half maximal inhibitory concentration (IC ) of 0.32 ± 0.01 mg/ml; hydrogen peroxide scavenging assay with IC of 0.18 ± 0.01 mg/ml 50 50 and reductive potential of 0.41 ± 0.002 units at the highest concentration tested (1.0 mg/ml). Pepsin-produced hydrolysates showed the highest DPPH radical scavenging potential at all concentrations with IC of 0.35 ± 50 0.003mg/ml. The study concluded that the hydrolysates produced contain bioactive peptides which possessed significant amount of antioxidant activities, which may be a promising health promoting agent if isolated. Keywords : Hydrolysates, Pepsin, Trypsin, Chymotrypsin, Antioxidant, Enzyme, Mormyrus rume .

Dynamics of heavy metal Pollution in Tropical lagoon of Gulf of Guinea, West Africa

In this study the accumulation of Iron (Fe), Zinc (Zn), Cobalt (Co), Chromium (Cr), Cadmium (Cd), Lead (Pb) and Nickel (Ni) in sediment, water, some fish samples (Schilbe mystus, Mormyrus rume, Gymnarchus niloticus, Cynoglossus senegalensis, and Chrysichthys nigrodigitatus ) and an aquatic plant Eichhornea crassipes collected from Lekki lagoon, Lagos Nigeria were examined. Heavy metals in the water, sediment, some selected fish and an aquatic plant were determined seasonally across nine sampling Stations; in the gills, liver and muscles of the fish species and in the root stem and leaves of Eichhornea crassipes using an atomic absorption spectrometer (AAS). Heavy metals concentrations in the sediment and water varied significantly, both spatially and seasonally. Metal concentrations varied between species and body parts while Co, Cr and Pb were not detected. Ni was found in the liver and gills of S. mystus and M. rume and Cr in the gills of G. niloticus only. In Eichhornea crassipes , metals detected were in the order: root>leaves>stem for Fe, Zn, Cr, and Cd; root>stem>leaves for Pb and Ni while Co was not detected. Heavy metal presence in Lekki Lagoon calls for monitoring of activities within and around the lagoon and policy development towards the sustainable ecosystem health services. Keywords: Pollutants, Heavy metals, Eichhornia crassipes, Bioaccumulation, Lekki lagoon

Evaluating Heavy Metals Pollution and Exposure Risk Through the Consumption of Four Commercially Important Fish Species and Water from Cross River Ecosystem, Nigeria.

In order to evaluate heavy metals exposure risk in the mid-Cross River, the concentrations of iron (Fe), zinc (Zn), manganese (Mn), copper (Cu), lead (Pb) and chromium (Cr) in water and four commercially important fishes (Chrysichthys nigrodigitatus, Clarias anguillaris, Tilapia zillii and Mormyrus rume) were studied between February 2015 and August 2016. Iron (2.71 ± 0.5mg/L), Mn (0.49 ± 0.06mg/L), Pb (0.05 ± 0.04mg/L) and Cr (0.06 ± 0.03mg/L) in water were above permissible limits. The pattern of heavy metals concentration in fish was T. zillii > M. rume > C. anguillaris > C. nigrodigitatus except for Pb. The estimated daily intake of most heavy metals was below the tolerable daily intake values except Pb. Although the hazard quotient was below one, the total hazard quotient and the carcinogenic risk value for Cr were above acceptable ranges for all fishes.

Effects of Drying Methods on the Biochemical Composition and Organoleptic Properties of Two Freshwater Fish Species (Mormyrus rume and Labeo coubie) of Cross River Obubra, Nigeria

Consumers all over the world are increasingly becoming aware of the health and nutrition status of fish and fishery products. There have develop some preference for fish species and even their processing methods. This study aims to investigate the effects of two drying methods (smoking and oven drying) on the biochemical components and organoleptic properties of two less preferred food fishes abundant in the study area. The fish samples Mormyrus rume and Labeo coubie were purchased from fresh landings of fishermen at Ahaha beach. The biochemical assay of the moisture, protein, fat, carbohydrate, ash, calcium (Ca), magnesium (Mg), phosphorus (P), iron (Fe), sodium (Na) and potassium (K) were conducted in the labouratory using standard methods. The proximate composition of raw M. rume was determined as moisture 70.38%, protein 17.43%, carbohydrate 1.13%, fat 5.93% and ash 2.77% while oven dried were 18.78, 63.85, 3.37, 8.73 and 7.58% respectively. All the proximate parameters and gross energy level investigated were higher (p < 0.05) in M. rume except the moisture content of dried samples of L. coubie. The mineral content were in the order Ca < Mg < Fe < Na < P and < K in both species and were higher in M. rume except Na. The drying methods showed increase in the proximate and mineral compositions in the order raw < smoking and < oven drying except moisture content that decreased respectively is both species. Organoleptic properties revealed that dried samples (smoked and oven) were not significantly different (p < 0.05) in taste, flavour, texture and overall acceptance, however while oven dried had better colour (4.33), smoked dried taste (4.63) better. The drying methods shows concentration of the required nutrients in human diets and were also found to be most palatable by the panellist. To improve fish nutrient quality smoke and oven drying should be encourage.