MULTIVARIJATNE ANALIZE RIBLJIH VRSTA I OKOLINSKIH FAKTORA U VODI MORSKE OBALE GVINEJSKOG ZALJEVA U JUGOZAPADNOJ NIGERIJI

The multivariate relationship between fish species and environmental variables was studied at three landing sites along the coast of the Gulf of Guinea, Southwest Nigeria. Fish species were sampled for abundance once per month per site for twenty-four months and eight environmental variables were measured. Five fish species (Sardinella maderensis, Ilisha africana, Pentanemus quinquarius, Chloroscombrus chrysurus, Ethmalosa fimbrata and Pterioscion peli) were observed to be very abundant, which contributed 77.6% of the total abundance. Fish species composition depicted tropical waters fishery with few dominant species having large number of individuals. Dendogram of cluster analysis revealed five fish communities. Canonical correspondence analysis was used to elucidate the relationships between assemblages of fish species and their environment. S. maderensis, the most abundant species, was observed to be influenced by pH, total dissolved solids (TDS) and nitrate. Clustering and ordination techniques provided very similar results based on the fish species composition. Water pH, total dissolved solids (TDS), nitrate and conductivity were shown to be most influencing environmental variables in decreasing order of vector projections, influencing fish assemblages in marine coastal waters of the Gulf of Guinea, Southwest, Nigeria.Ovim istraživanjem proučavan je multivarijatni odnos vrsta riba i varijabli iz okoline na tri mjesta duž obale Gvinejskog zaljeva u jugozapadnoj Nigeriji. Uzorci riba prikupljani su jednom mjesečno na odabranim lokacijama tijekom 24 mjeseca, pri čemu je mjereno i osam varijabli iz okoline. Najčešće vrste riba, sa 77,6 % udjela ukupne riblje populacije, bile su: Sardinella maderensis, Ilisha africana, Pentanemus quinquarius, Chloroscombrus chrysurus, Ethmalosa fimbrata i Pterioscion peli. Sastav ribljih vrsta prikazuje ulov u tropskim vodama s nekoliko dominantnih vrsta koje imaju veliki broj jedinki.. Dendrogram klaster analize prikazuje pet ribljih zajednica. Kanonička korelacijska analiza korištena je kako bi se razjasnio odnos između sastava vrsta riba i njihove okoline. Utvrđen je vidljiv utjecaj pH, ukupnih otopljenih tvari (TDS) i nitrata na S. maderensis, najbrojniju riblju vrstu. Tehnike grupiranja i koordinacije dale su vrlo slične rezultate temeljene na sastavu ribljih vrsta. pH vrijednost vode, ukupne otopljene tvari (TDS), nitrati i provodljivost najutjecajnije su varijable okoline u opadajućem redoslijedu vektorske projekcije, a znatno utječu na riblji sastav u moru na obalama Gvinejskog zaljeva u jugozapadnoj Nigeriji

Application of Diatom-Based Indices in River Quality Assessment: A Case Study of Lower Ogun River (Abeokuta, Southwestern Nigeria) Using Epilithic Diatoms

Diatom indices have been extensively applied in the bioassessment of surface waters and wetlands in many countries except Nigeria. This pioneer study aimed at investigating the use of epilithic diatom-based indices in the assessment of the Ogun River quality. Water and epilithic diatom samples were collected fortnightly from four sampling stations for a period of four consecutive months (March–June 2015). Water samples were analysed for pH, temperature, electrical conductivity, total dissolved solids (TDS), dissolved oxygen, chemical oxygen demand (COD), nitrite, nitrate, ammonium, phosphate, sulphide, chloride, iron, manganese, silicate, total alkalinity, total hardness, total suspended solids (TSS), transparency and total organic carbon using standard methods. Epilithic diatom samples were collected by scraping the surfaces of rocks or stones using an 18 mm toothbrush and analysed following the standard methods. Data collected were subjected to descriptive (frequency, mean) and inferential statistics (diatom indices, Pearson correlation) using OMNIDIA and SPSS statistical packages. Results showed that the water quality of the Lower Ogun River ranged between bad and high qualities during the study period. The diatom indices (trophic diatom index (TDI), biological diatom index (IBD), generic salinity index (GSI1), generic trophic index (GTI), generic saprobity index (GTI)) were correlated with physical and chemical parameters, thereby indicating their effectiveness in water quality ranking

Diet, size and reproductive biology of the silver catfish, Chrysichthys nigrodigitatus (Siluformes: Bagridae) in the Cross River, Nigeria

The silver catfish, Chrysichthys nigrodigitatus (Lacépède: 1803) is a highly valued food-fish included among the dominant commercial catches exploited in major rivers of Africa. To provide useful biological data for management, samples were collected monthly between January (2005) and December (2007) in three zones: I: Upper Cross River (grassland), II: Middle Cross River (mixed forest and grassland), and III: Lower Cross River (rainforest)] along 200 km length of the Cross River, Nigeria. Data from 1248 specimens were processed using: allometric coefficient (b), gonado-somatic index, Fulton's condition factor and diversity indices. Male dominance was observed in all populations; C. nigrodigitatus reached maturity at 11.5cm (male) and 16.7cm (female) total length. Gonado-somatic index was higher for females with a peak in the early rains. The breeding period was between April and August with mean fecundity ranging between 4522 ± 1924 eggs and 20321 ± 5543 eggs. This was directly related to total length and weight by the regression models: F = 2365.88 + 560.22 log L and F = 5025.81 +56.34 log W respectively. Exponential equations for length-weight relationships were Wt= -1.997 Lt2.206 (Zone I), W = -2.831 Lt3.040 (Zone II) and Wt= -2.245 Lt2.995 (Zone III). The mean allometric coefficient (b) showed significant departure from cubic value (negative allometry) for Zone I while Zones II and III showed no difference, indicating isometry. Dominant items in the diet were fish and fish parts constituting 21.6% with Food Richness and Gut Repletion Index of 18 and 100% respectively, in all zones. Diet Breadth of 0.802 (Zone I), 0.922 (Zone II) and 0.910 (Zone III) indicate a high trophic flexibility that enables switching from one diet to another according to availability. Mean condition factor for males varied from 0.718 ± 0.117 minimum in Zone I to 0.996 ± 0.062 maximum in Zone III. Forest inland wetlands (Zone II and III) of Cross River provided better condition for C. nigrodigitatus

LETHAL EFFECTS OF 2,2-DICHLOROVINYL DIMETHYL PHOSPHATE (DDVP) ON FINGERLING AND JUVENILE Clarias gariepinus (BURCHELL, 1822)

This study investigated the lethal toxicity of 2,2-dichlorovinyl dimethyl phosphate (DDVP) on African mud catfish, Clarias gariepinus fingerlings (mean weight 7.02 ± 2.56 g) and juveniles (mean weight 13.54 ± 1.46 g) in a static renewable bioassay. DDVP, also known as Dichlorvos is an organophosphate pesticide. Each treatment in the lethal test was in triplicates with bioassay media concentrations (fingerlings: 0, 250, 275, 300, 325 µgL-1) and (juveniles: 0, 400, 450, 500, 600 µgL-1). Data on fish mortality as well as the physico-chemical parameters (temperature, pH, dissolved oxygen and electrical conductivity, EC) of water were collected and subsequently subjected to a one way analysis of variance (ANOVA) at 5% probability level. Duncan Multiple Range Test (DMRT) was used to separate differences between means. The median lethal concentration (LC50) and median lethal time (LT50) were determined by probit analysis. The water quality parameters of the treatment tanks showed no significant difference with those of the control except for conductivity and pH. Behavioural responses in the fishes included erratic and uncoordinated swimming which were observed to be more pronounced in the juveniles. Bleached body was the only external change observed and this was more pronounced in the fingerlings. The 96-hr LC50 for fingerlings and juveniles were 275.2 and 492.0 µgL-1 respectively. The LT50 values for fingerlings were 48.10 and 7.77 hrs for concentrations 250 and 325 µgL-1 respectively; while those of juveniles were 25.54 and 5.34 hrs for 400 and 600 µgL-1 respectively. The results indicated that DDVP was 1.79 times more toxic to the fingerlings than the juveniles

LETALNO DJELOVANJE 2,2-DIKLOROVINIL DIMETIL FOSFATA (DDVP) NA MLAĐ I MLADUNCE VRSTE Clarias gariepinus (BURCHELL, 1822)

This study investigated the lethal toxicity of 2,2-dichlorovinyl dimethyl phosphate (DDVP) on African mud catfish, Clarias gariepinus fingerlings (mean weight 7.02 ± 2.56 g) and juveniles (mean weight 13.54 ± 1.46 g) in a static renewable bioassay. DDVP, also known as Dichlorvos is an organophosphate pesticide. Each treatment in the lethal test was in triplicates with bioassay media concentrations (fingerlings: 0, 250, 275, 300, 325 µgL-1) and (juveniles: 0, 400, 450, 500, 600 µgL-1). Data on fish mortality as well as the physico-chemical parameters (temperature, pH, dissolved oxygen and electrical conductivity, EC) of water were collected and subsequently subjected to a one way analysis of variance (ANOVA) at 5% probability level. Duncan Multiple Range Test (DMRT) was used to separate differences between means. The median lethal concentration (LC50) and median lethal time (LT50) were determined by probit analysis. The water quality parameters of the treatment tanks showed no significant difference with those of the control except for conductivity and pH. Behavioural responses in the fishes included erratic and uncoordinated swimming which were observed to be more pronounced in the juveniles. Bleached body was the only external change observed and this was more pronounced in the fingerlings. The 96-hr LC50 for fingerlings and juveniles were 275.2 and 492.0 µgL-1 respectively. The LT50 values for fingerlings were 48.10 and 7.77 hrs for concentrations 250 and 325 µgL-1 respectively; while those of juveniles were 25.54 and 5.34 hrs for 400 and 600 µgL-1 respectively. The results indicated that DDVP was 1.79 times more toxic to the fingerlings than the juveniles.Ovim istraživanjem proučavano je letalno djelovanje 2,2-diklorovinil dimetil fosfata (DDVP) za mlađ (srednja masa 7,02 ± 2,56 g) i mladunce (srednja masa 13,54 ± 1,46 g) afričkog soma Clarias gariepinus u statičnoj obnovljivoj bioanalizi. DDVP (Dichlorvos) je organofosforni pesticid. Svaki tretman letalnog djelovanja vršio se u tri ponavljanja s testnim koncentracijama otopine (mlađ: 0, 250, 275, 300, 325 µgL-1) i (mladunci: 0, 400, 450, 500, 600 µgL-1). Prikupljani su podaci o smrtnosti ribe kao i fizikalno-kemijski parametri vode (temperatura, pH, otopljeni kisik i električna provodnost, EC) te se potom primjenjivala jednosmjerna analiza varijance (ANOVA) s 5% vjerojatnosti. Korišten je Duncan Multiple Range Test (DMRT) kako bi se razdvojile razlike između srednjih vrijednosti. Srednja letalna koncentracija (LC50) i srednje vrijeme smrtnosti (LT50) određeni su probit analizom. Parametri kvalitete vode bazena nisu pokazivali značajnu razliku od kontrolnih, osim za provodljivost i pH. Ponašanje riba se očitovalo u nepravilnom i nekoordiniranom plivanju koje je bilo naglašenije kod mladunaca. Izbijeljeno tijelo je jedina uočena vanjska promjena, a bila je naglašenija kod mlađi. 96-satne vrijednosti LC50 za mlađ i mladunce iznosile su 275,2 µgL-1, odnosno 492,0 µgL-1. Vrijednosti LT50 za mlađ su bile 48,10 i 7,77 sati za koncentracije 250 µgL-1, odnosno 325 µgL-1; dok su za mladunce bile 25,54 i 5,34 sati za 400 µgL-1, odnosno 600 µgL-1. Rezultati su pokazali da je DDVP 1,79 puta više toksičan za mlađ nego za mladunce

Diet, size and reproductive biology of the silver catfish, Chrysichthys nigrodigitatus (Siluformes: Bagridae) in the Cross River, Nigeria

The silver catfish, Chrysichthys nigrodigitatus (Lacépède: 1803) is a highly valued food-fish included among the dominant commercial catches exploited in major rivers of Africa. To provide useful biological data for management, samples were collected monthly between January (2005) and December (2007) in three zones: I: Upper Cross River (grassland), II: Middle Cross River (mixed forest and grassland), and III: Lower Cross River (rainforest)] along 200 km length of the Cross River, Nigeria. Data from 1 248 specimens were processed using: allometric coefficient (b), gonado-somatic index, Fulton’s condition factor and diversity indices. Male dominance was observed in all populations; C. nigrodigitatus reached maturity at 11.5cm (male) and 16.7cm (female) total length. Gonado-somatic index was higher for females with a peak in the early rains. The breeding period was between April and August with mean fecundity ranging between 4522 ±1924 eggs and 20321 ± 5543 eggs. This was directly related to total length and weight by the regression models: F = 2365.88 + 560.22 log L and F = 5025.81 +56.34 log W respectively. Exponential equations for length-weight relationships were Wt=-1.997 Lt2.206 (Zone I), W = -2.831 Lt3.040 (Zone II) and Wt= -2.245 Lt2.995 (Zone III). The mean allometric coefficient (b) showed significant departure from cubic value (negative allometry) for Zone I while Zones II and III showed no difference, indicating isometry. Dominant items in the diet were fish and fish parts constituting 21.6% with Food Richness and Gut Repletion Index of 18 and 100% respectively, in all zones. Diet Breadth of 0.802 (Zone I), 0.922 (Zone II) and 0.910 (Zone III) indicate a high trophic flexibility that enables switching from one diet to another according to availability. Mean condition factor for males varied from 0.718 ±0.117 minimum in Zone I to 0.996 ±0.062 maximum in Zone III. Forest inland wetlands (Zone II and III) of Cross River provided better condition for C. nigrodigitatus. Rev. Biol. Trop. 56 (4): 1785-1799. Epub 2008 December 12

LETALNO DJELOVANJE 2,2-DIKLOROVINIL DIMETIL FOSFATA (DDVP) NA MLAĐ I MLADUNCE VRSTE Clarias gariepinus (BURCHELL, 1822)

This study investigated the lethal toxicity of 2,2-dichlorovinyl dimethyl phosphate (DDVP) on African mud catfish, Clarias gariepinus fingerlings (mean weight 7.02 ± 2.56 g) and juveniles (mean weight 13.54 ± 1.46 g) in a static renewable bioassay. DDVP, also known as Dichlorvos is an organophosphate pesticide. Each treatment in the lethal test was in triplicates with bioassay media concentrations (fingerlings: 0, 250, 275, 300, 325 µgL-1) and (juveniles: 0, 400, 450, 500, 600 µgL-1). Data on fish mortality as well as the physico-chemical parameters (temperature, pH, dissolved oxygen and electrical conductivity, EC) of water were collected and subsequently subjected to a one way analysis of variance (ANOVA) at 5% probability level. Duncan Multiple Range Test (DMRT) was used to separate differences between means. The median lethal concentration (LC50) and median lethal time (LT50) were determined by probit analysis. The water quality parameters of the treatment tanks showed no significant difference with those of the control except for conductivity and pH. Behavioural responses in the fishes included erratic and uncoordinated swimming which were observed to be more pronounced in the juveniles. Bleached body was the only external change observed and this was more pronounced in the fingerlings. The 96-hr LC50 for fingerlings and juveniles were 275.2 and 492.0 µgL-1 respectively. The LT50 values for fingerlings were 48.10 and 7.77 hrs for concentrations 250 and 325 µgL-1 respectively; while those of juveniles were 25.54 and 5.34 hrs for 400 and 600 µgL-1 respectively. The results indicated that DDVP was 1.79 times more toxic to the fingerlings than the juveniles.Ovim istraživanjem proučavano je letalno djelovanje 2,2-diklorovinil dimetil fosfata (DDVP) za mlađ (srednja masa 7,02 ± 2,56 g) i mladunce (srednja masa 13,54 ± 1,46 g) afričkog soma Clarias gariepinus u statičnoj obnovljivoj bioanalizi. DDVP (Dichlorvos) je organofosforni pesticid. Svaki tretman letalnog djelovanja vršio se u tri ponavljanja s testnim koncentracijama otopine (mlađ: 0, 250, 275, 300, 325 µgL-1) i (mladunci: 0, 400, 450, 500, 600 µgL-1). Prikupljani su podaci o smrtnosti ribe kao i fizikalno-kemijski parametri vode (temperatura, pH, otopljeni kisik i električna provodnost, EC) te se potom primjenjivala jednosmjerna analiza varijance (ANOVA) s 5% vjerojatnosti. Korišten je Duncan Multiple Range Test (DMRT) kako bi se razdvojile razlike između srednjih vrijednosti. Srednja letalna koncentracija (LC50) i srednje vrijeme smrtnosti (LT50) određeni su probit analizom. Parametri kvalitete vode bazena nisu pokazivali značajnu razliku od kontrolnih, osim za provodljivost i pH. Ponašanje riba se očitovalo u nepravilnom i nekoordiniranom plivanju koje je bilo naglašenije kod mladunaca. Izbijeljeno tijelo je jedina uočena vanjska promjena, a bila je naglašenija kod mlađi. 96-satne vrijednosti LC50 za mlađ i mladunce iznosile su 275,2 µgL-1, odnosno 492,0 µgL-1. Vrijednosti LT50 za mlađ su bile 48,10 i 7,77 sati za koncentracije 250 µgL-1, odnosno 325 µgL-1; dok su za mladunce bile 25,54 i 5,34 sati za 400 µgL-1, odnosno 600 µgL-1. Rezultati su pokazali da je DDVP 1,79 puta više toksičan za mlađ nego za mladunce

UPOTREBA SJEMENA FERMENTIRANOG MANGA (Mangifera indica) U HRANIDBI MLAĐI TILAPIJE (Oreochromis niloticus)

This study evaluated the use of fermented mango (Mangifera indica) seed meal (FMS) to substitute yellow maize in the practical diet for Nile tilapia, Oreochromis niloticus fingerlings (4.76±0.32 g). Five iso-nitrogeneous (35% crude protein) and approximately iso-energetic (3400 ME Kcal/kg) dietsin which yellow maize was replaced by FMSat 0% (FMS0/Control diet), 25% (FMS25), 50% (FMS50), 75% (FMS75) and 100% (FMS100) levels were formulated. The fish were fed on the diets at 5% body weight for 84 days. Alkaloids were highest (2.32%) among the anti-nutritional factors analyzed in FMS, while oxalate (0.84%) was lowest. Potassium was highest (8.91 mg/g) among the minerals, while copper was lowest (0.01 mg/g). Weight gain, specific growth rate and feed conversion ratio were similar (p>0.05) in fish fed diets FMS0 and FMS50. The fish fed diet FMS0 had the highest protein efficiency ratio (1.88). Protein digestibility decreased (p0,05). Oblik hranidbe riba FMS0 imao je najveći omjer djelotvornih bjelančevina (1,88). Probavljivost bjelančevina smanjila se povećanjem dijetetskog FMS-a, dok se probavljivost ugljikohidrata povećala. Dobiveni rezultati pokazuju mogućnost zamjene žutog kukuruza sjemenom fermentiranog manga u hrandibi tilapija do 50% bez da taj oblik hranidbe utječe na rast, iskoristivost nutritivnih sastojaka i probavljivost bjelančevina prilikom hranidbe mlađi tilapije

Water quality in relation to plankton abundance and diversity in river Ogun, Abeokuta, Southwestern Nigeria

Aims: Plankton abundance and diversity are governed by certain aquatic environmental factors which collectively determine the health of the aquatic ecosystem. This study was aimed at investigating the water quality of lower Ogun River, Abeokuta, in relation to plankton abundance and diversity. Materials and Methods: The dataset consists of physicochemical and plankton data collected for 7 months within the period of December 2011 and June 2012 in four stations. Spatial correlations were determined between physicochemical parameters, plankton abundance, and diversity. Physicochemical parameters that exhibited strong correlation with plankton abundance and diversity were used in the calculation of a water quality index (WQI) for the protection of aquatic life. Results: Results showed highly significant correlations (P ≤ 0.05) between plankton abundance, diversity, and the physicochemical parameters monitored during the study period excluding alkalinity and phosphates. The Canadian Council of Ministers of the Environment WQI showed that the river water quality in all the sampled stations (A, 63; B, 63; C, 56; and D, 64) was marginal in classification. Conclusion: It was concluded that River Ogun is polluted beyond doubt. Hence, corrective measures should be put in place so as to prevent total ecological collapse

UPOTREBA SJEMENA FERMENTIRANOG MANGA (Mangifera indica) U HRANIDBI MLAĐI TILAPIJE (Oreochromis niloticus)

This study evaluated the use of fermented mango (Mangifera indica) seed meal (FMS) to substitute yellow maize in the practical diet for Nile tilapia, Oreochromis niloticus fingerlings (4.76±0.32 g). Five iso-nitrogeneous (35% crude protein) and approximately iso-energetic (3400 ME Kcal/kg) dietsin which yellow maize was replaced by FMSat 0% (FMS0/Control diet), 25% (FMS25), 50% (FMS50), 75% (FMS75) and 100% (FMS100) levels were formulated. The fish were fed on the diets at 5% body weight for 84 days. Alkaloids were highest (2.32%) among the anti-nutritional factors analyzed in FMS, while oxalate (0.84%) was lowest. Potassium was highest (8.91 mg/g) among the minerals, while copper was lowest (0.01 mg/g). Weight gain, specific growth rate and feed conversion ratio were similar (p>0.05) in fish fed diets FMS0 and FMS50. The fish fed diet FMS0 had the highest protein efficiency ratio (1.88). Protein digestibility decreased (p0,05). Oblik hranidbe riba FMS0 imao je najveći omjer djelotvornih bjelančevina (1,88). Probavljivost bjelančevina smanjila se povećanjem dijetetskog FMS-a, dok se probavljivost ugljikohidrata povećala. Dobiveni rezultati pokazuju mogućnost zamjene žutog kukuruza sjemenom fermentiranog manga u hrandibi tilapija do 50% bez da taj oblik hranidbe utječe na rast, iskoristivost nutritivnih sastojaka i probavljivost bjelančevina prilikom hranidbe mlađi tilapije