Evaluation of Growth Rate of Invasive Aquatic Macrophytes and Contribution to Its Use in Organic Fertilizer Production: A Case of Eicchornia crassipes (Mart.) Solms, 1883 in the Lobé Creek (Littoral-Cameroon)

From 20 January to 20 July 2023, a study was carried out on the Lobé Creek, a waterway subject to considerable natural and man-made pressures, with a negative impact on its biodiversity and habitats. The aim was to evaluate the growth rate of invasive aquatic macrophytes and their contribution to the use of organic fertilisers: a case of Eicchornia crassipes (Mart.) Solms, 1883 in the Lobé Creek (Littoral-Cameroon) with a view to its appropriate use in agronomy. The specific objective was to examine the impact of anthropogenic actions on Lobé Creek, characterise physico-chemical environment of the study area, and evaluate the growth rate of E. crassipes and its chemical composition with a view to producing an organic biofertiliser. The results show that E. crassipes represents a considerable threat to the populations of these localities. As for the physico-chemical parameters, the temperature values vary from 24 ± 1.41˚C to 26.5 ± 1.13˚C;pH from 6.3 ± 0.1 to 7.2 ± 0.07;conductivity and dissolved oxygen vary respectively from 40.7 ± 1.83 µS/cm to 19.6 ± 3.11 µS/cm and from 7.3 ± 0.14 mg/l to 5.8 ± 1.55 mg/l. Its average growth rate varies from 0.69 feet/day to 0.63 feet/day. With regard to the nitrogen, phosphorus and potassium content of water hyacinth plants, the results show that the average total nitrogen content ranges from 6.11 ± 1.59 g/kg to 5.2 ± 2.03 g/kg;total phosphorus, from 0.52 ± 0.54 g/kg to 0.88 ± 0.38 g/kg;and potassium, from 1.43 ± 0.45 g/kg to 2.61 ± 0.89 g/kg.

Physico-Chemical and Structural Assessment of Akono Riparian Forest Watershed, Tributary of the Nyong Basin (Centre-Cameroon) at Different Stages of Degradation

Freshwater bodies are natural resources that should be exploited to the fullest, while maintaining the sustainability of ecosystems and ecosystem services which they support. Riparian forests are more important as they contain rivers which are vital sources of fresh water for local populations. However, the quality and quantity of water issued from the watershed depend on the structural state of these forests. The aim of this work was to assess the physico-chemical and structural state of the Akono gallery forest. To achieve this, fieldwork consisted of selecting six major streams of the watershed including Ndjolong, Menyeng adzap, Emomodo, Mvila, Negbe and Ossoé kobok. On each of these, two stations, one intact and one degraded, were marked by transects. The method involved measuring Hydrometric parameters (depth, length, width) of the stream and Physico-chemical parameters of water in the streams while dendrometric parameters were measured along 100 m-transects laid using the point-centred quarter method modified for water bodies to collect tree, shrub and palm variables such as trunk diameter, crown diameter and height. Macrophytes and species identification were carried out using standard botanical procedures. Results showed that, the majority of physico-chemical parameters measured differed significantly between intact and degraded stations (P Pentachletra mancrophylla, whereas on degraded sites, this index was low and characterized by the relative dominance of species Piptadeniastrum africanum. Sorensen’s index (0.56) and CFA showed that the different stands were homogeneous. We can affirm that the riparian forests of Akono watershed are towards a state of stability notwithstanding the perpetuation of anthropological actions.

Effects of Desmodium uncinatum Leaf Meal in the Diet on Lohmann Brown Hens’ Laying Performance and Eggs Quality

A cheap, safe and available alternative protein source to soybean is a huge priority for the developing world. This study is aimed at evaluating the effects of Desmodium uncinatum leaf meal incorporation levels in the diet on Lohmann Brown hens’ laying performances. For this purpose, 60 Lohmann Brown hens aged 33 weeks with an average weight of 1.78 kg were randomly assigned to 3 treatment groups of 20 birds each with 4 replicates. The experimental treatments consisted of DULM 0, DULM5, and DULM10 containing 0, 5 and 10 kg of D. uncinatum leaf meal (DULM) per 100 kg of feed respectively. The results reveal that except for the weights of hens, laying performances were significantly affected (p < 0.05) by DULM in the diet. Daily feed intake was lower with 10% incorporation of DULM in the diet as compared to a diet with 5% DULM which recorded the highest value for this parameter. Moreover, the highest value for the egg weight, egg mass, yolk index, albumen index and egg production were recorded with diet DULM5. On the other hand, the diet with 10% of DULM (DULM10) recorded the highest relative shell weight, feed conversion ratio and egg price. Nevertheless, the mortality rate found in this study was 0% for all treatments confirming the good quality of DULM as protein feedstuff for layer. It was concluded that incorporation levels of D. uncinatum leaves at 5% in the diet improved the laying performances of Lohmann Brown hens.

Bacteriological and Physicochemical Quality of Groundwater of Mbankomo Municipality(Center Region,Cameroon)

A study to evaluate the physico-chemical and bacteriological quality of groundwater was carried out in the commune of Mbankomo(Centre-Cameroon)at 4 wells and 4 springs during the period from March to August.The physico-chemical parameters were measured by the standard method.Indicator bacteria of fecal contamination,namely HAB(Heterotrophic Aerobic Bacteria),total and faecal coliforms(Escherichia coli),and faecal streptococci were isolated by the surface spreading technique on PCA(Plate Count Agar),Endo and BEA(Bile Esculin Azide)agar respectively,and sulphite-reducing clostridia by the incorporation method on Tryptone Sulfite Cycloserine(TSC)agar.From a physico-chemical point of view,the groundwater in Mbamkomo is characterized by an average temperature(24.24±0.24°C);it is polluted with organic matter,acid and poorly mineralized.It was noted from a bacteriological point of view that these waters have a high and varied bacterial load with an average value of 100.8 × 10^(5) CFU/100 mL for coliforms,16.3 × 10^(5) CFU/100 mL for fecal streptococci,5.6 × 10^(5) CFU/100 mL for Escherichia coli and 4.8 ×10^(²)CFU/100 mL for Clostridium perfringens.These concentrations are all higher than the WHO(World Health Organization)standards which are set at 0 CFU/100 mL for coliforms,fecal streptococci and Clostridium perfringens and indicate fecal pollution of these waters.Escherichia coli cell densities were significantly correlated with dissolved oxygen in the water(r=0.510;p<0.05).The degradation of the quality of these waters is favored by their proximity to pollution sources,poor maintenance and poor protection of the wells.These waters,without any treatment,are not recommended for human consumption according to the standards of the WHO.

Fruit Powder of Tetrapleura tetraptera in Local Feed on Some Zootechnical Performances of Juveniles of Clarias gariepinus in Concrete Tank

This study focused on the supplementation of four-sided spice fruit powder (Tetrapleura tetraptera) on some zootechnical performances of juveniles of Clarias gariepinus and was carried out from February 14 to July 20 at the Massoma Fish Farm of Bojongo Mbeidi located in the Littoral Region, Department of Wouri, Douala IV district. The farm benefits from a climate favorable to aquaculture activity. For this purpose, five (5) treatments were tested including T0+ (imported feed), T0-, T0.3, T0.4, and T0.5 respectively for the treatments with 0% supplemented food;0.3%;0.4% and 0.5% of Tetrapleura tetraptera powder. A total of 450 Clarias gariepinus fry with an initial average weight of 7 ± 1.5 g, were distributed in happas of 0.49 m2 each placed in Triplicate in a completely randomized device. Four isoprotein foods with 38% crude protein were formulated to feed these fry at 7% of their biomass per day for 15 days then to their fullness until the end of the experiment. Intermediate fishing was carried out every fortnight. 75 days later, the results recorded show that the highest average survival rate (96.44% ± 3.5%) was recorded with the subjects fed feed supplemented with 0.4% T. tetraptera powder. The average weight (120.93 ± 67.20), weight gain (113.93 ± 67.20), specific growth rate (3.64 ± 0.79% g/d) and total lengths and standard (26.43 ± 1.9 and 23.66 ± 1.76) the highest were recorded with the T0+ treatment (imported feed). The highest conditioning factor K (2.14 ± 0.15) was recorded with the treatment supplemented with 0.4% T. tetraptera. The lowest conversion ratio (1.28) was recorded with the treatment fed with imported blue crown food (T0+). Furthermore, the lowest production cost was recorded with the treatment supplemented with 0.4% T. tetraptera. It appears from this study that the juveniles of C. gariepinus better value the feed substituted with 0.4% of the powder of four sides (Tetrapleura tetraptera).

A Baseline Study on the Quality and Safety of Consumption of a Pest Species(Sarotherodon melanotheron)in Bataan,Philippines:Basis for Its Productive Utilization in the Fisheries Sector

The baseline study profiled Black-chin Tilapia(Sarotherodon.melanotheron),a fish farm pest species in Bataan,Philippines,in terms of yield(processing and fillet),proximate composition(moisture,ash,crude fat,and crude protein),heavy metal load(cadmium[Cd],lead[Pb],arsenic[As],and mercury[Hg]),and microbial count(aerobic plate,Escherichia coli,and Staphylococcus aureus counts).The purpose was to establish the species’safety and quality for consumption and potential utilization in the processing of higher value fishery products.A completely randomized experiment using two factors,fish size(standard and small sizes)and collection season(dry and wet seasons),was employed.The collected data were also compared against food consumption and processing standards and/or previous reports on more valuable species.The results showed that the species has a comparable yield and mineral load with the more popular farmed Nile Tilapia(Oreochromis niloticus).It has high moisture and protein compositions.It is a lean fish that can serve as a cheaper functional raw material for processed fishery products.Moreover,the results showed that the species have no As,Cd,and Pb contamination,although traces of Hg,far below the permissible limits,were detected.The Hg load varies across collection season and fish maturity suggesting its manageability.For the microbial contents,the species’aerobic plate,Escherichia coli,and Staphylococcus aureus counts were far below the standard limits,although best post-capture practices are still suggested due to the kind of microbial parameters measured.It was concluded that the Sarotherodon melanotheron infesting Bataan farm ponds can be consumed safely and has the quality of potential raw material for processed fishery products.However,further information is still needed to establish the best post-capture handling on the species.Also,more studies must be done to determine the impact of storage and processing on its stability.

Effects of Industrial Agriculture and Urbanization on Structure and Functional Organization of Macroinvertebrate of Coastal Streams in Cameroon

The impact of land use changes on watercourses is poorly documented in Cameroon. Therefore, this study examines the effects of agriculture and urbanization on water quality, the structure and functional organization of macroinvertebrates of streams in the coastal zone of Cameroon. Nine sampling stations including three per catchment area with different land occupations (agricultural, urban and forest) were selected. Benthic macroinvertebrates were sampled monthly from February to July 2018 and the physicochemical variables were measured simultaneously. The urban and agricultural streams showed highly polluted waters with high nutrient and suspended matter content, whereas the forest stream waters are moderately polluted. In addition, the hierarchical ascending classification indicated a proximity in water quality between the agricultural and forest streams for which the main physicochemical variables did not vary significantly. With regards to macroinvertebrates, the forest watercourse is characterized by the proliferation of pollution-sensitive taxa, high diversity indices and complex trophic structuring, indicating its good ecological status. In contrast the urban watercourse, heavily polluted is characterized by low diversity indices reflecting a simplification of the structure of stands dominated by the pollution-tolerant collector-gatherer stands. The majority of biological indices and functional feeding groups were not significantly different between the agricultural and forest streams, suggesting a less pronounced impact of agriculture on macroinvertebrates. Our results showed that, riparian vegetation even though constituted of perennial crops, reduces the effects of agricultural inputs on streams and promotes the establishment of diversified macroinvertebrate communities.

Spatial and Temporal Variation of the Hydrological Parameters in the Wouri-Nkam Section of the Cameroon Estuary, Central African Atlantic Coast

This study aimed to provide relevant knowledge about the dynamics of the hydrological parameters in the river-estuary continuum of the Wouri-Nkam river estuary for a sustainable management program. The hydrological parameters were recorded in eleven stations spanned out on the basis of population density and human activities. Water quality parameters (Temperature, salinity, dissolved oxygen, pH, Total dissolved solutes, Redox potential and conductivity) were collected in subsurface water using a multiple parameter. Surface currents and morphometric (depth and width) parameters were recorded using a drifter, sonar depth and GPS. The field measurements took placed between 18/05/2019 to 08/09/2020 and were divided into six (06) cruises. The data were later subjected to an analysis of variance (ANOVA) and Principle Component Analysis using XLSTAT 2017 (2.7 version) software. Results obtained revealed that, the water quality parameters were spatially more stable notsignficant at (df = 9, p < 0.05) with a relatively low temperature (25.5°C - 27°C) during the wet period. The limit of the frontal zone extended to S5 (Bonalokan, 8.25 km from S1) during the snapshot of the dry period, spring phase and flood tide conditions. Inversely, during wet period, this extension reduced to S1 (Bridge) and relatively increases slightly to S3 (Bonangang) during the neap phase and ebb tides of this season. This result revealed a change in the axial gradient of about eight (08) and four (04) kilometers during the seasonal and tidal scales (lunar and diurnal periods) respectively. These changes were also accompanied by changes in the water quality signatures, that may affect the fishery distribution and compositions. However, futures studies to buttress the results of this investigation should focus on longer time series sampling methods and model developments.

Understanding Seasonal and Spatial Variation of Water Quality Parameters in Mangrove Estuary of the Nyong River Using Multivariate Analysis (Cameroon Southern Atlantic Coast)

To evaluate the actual status of water quality and conclude on the mains source of pollution in the Nyong estuary River, seasonal and spatial variation of water quality parameters was interpreted by multivariate statistical techniques (Principal Component analysis). Nine (09) environmental variables were monitored at four surface stations in the estuary for two seasonal cycles. The fieldwork was conducted from 2018 to 2019 during high tide and low tide for each survey. In situ physical parameters were measured for a total of 64 samples (32 samples for each tide). The laboratory works consisted of some physicochemical analyses and processing of these data by descriptive and multidimensional statistical analyses. Temperature, suspended particle matter, nitrate, nitrite and phosphate change significantly in the estuary with season (p < 0.05), while salinity, dissolved oxygen, pH, and ammonium do not vary significantly with season (p > 0.05). Principal Component analysis found temperature, salinity, pH, ammonium to be the most important parameters contributing to the fluctuations of surface water quality in the Nyong estuary during the dry seasons whereas suspended particle matter, nitrate, and phosphate are the most important parameters contributing to the fluctuation of surface water quality in the Nyong estuary during the rainy seasons. Based on spatial variation, the Principal Component analysis found that, suspended particle matter, nitrate and phosphate contribute to the fluctuation of surface water quality parameters upstream of the estuary while downstream salinity, pH, and ammonium contribute the most to the fluctuation of surface water quality. This study shows us the usefulness of multivariate statistical techniques used in assessing water quality data sets that would help us in understanding seasonal and spatial variations of water quality parameters to manage estuarine systems.

Antidiabetic potential of methanol extracts from leaves of Piper umbellatum L. and Persea americana Mill.

Objective: To determine inhibitory activity of methanolic leaf extract of Piper umbellatum and Persea americana(P. americana)(traditionally used in Cameroon against diabetes) on β-glucosidase, β-glucosidase, maltase-glucoamylase, aldose reductase and aldehyde reductase activities, enzymes involved in starch digestion or diabetic complications. Methods: The methanol extracts from Piper umbellatum and P. americana were prepared by maceration. To assess relative efficacy of these extracts, the determination of concentrations that were needed to inhibit 50% of enzyme activity was done, whereas, gas chromatography-mass spectrum was used to identify components from extracts that may be responsible for the activities. Results:The tested extracts strongly inhibited β-glucosidase, maltase-glucoamylase, aldose reductase and aldehyde reductase activities with IC50 ranging from(1.07 ± 0.03) to(31.77 ± 1.17) μg/mL.Among the tested extracts, P. americana was the most active against sensitive enzymes(IC50 of1.07 ± 0.03 to 15.63 ± 1.23). But, none of the extracts showed interesting inhibitory effect against β-glucosidase as their percentage inhibitions were less than 16%. From gas chromatographymass spectrum analysis, 10 and 8 compounds were identified in Piper umbellatum and P.americana extracts respectively, using NIST library 2014. Conclusions: Results of this study provide the scientific credential for a prospective usage of these plants to treat diabetes.

Effects of Methenamine Feeding Regime on Growth Performances, Gut Microbiota, Organs Histology and Haemato-Biochemical Profile of Broiler Chickens

Microbial resistance in livestock has become a subject of great concern of public and scientific interest. This study was designed to assess the effects of methenamine feeding regime on growth performances of broilers chickens. For this purpose, 120 chicks of Cobb 500 strain, including 60 males and 60 females of 21 days old with an average weight of 639 g and 584 g respectively were used. They were randomly distributed in 60 experimental units of 2 chicks of same sex per cage until 49 days. Methenamine was incorporated in feed (TA), acidified (TEa) and non acidified (TE) water and compared to an antibiotic medicated diet as positive control (T0+) and a ration without any supplement as negative control (T0). The main results showed that, regardless of the feeding regime, methenamine significantly (p < 0.05) increased feed inteake, body weight, weight gain and decreased (p < 0.05) feed conversion ratio. Methenamine whatever the feeding regime induced a significant increase in lactic acid bacteria counts compared to coliforms and coccidies counts. Salmonella were absent throughout the trial period. Regardless of sex and feeding regime, hematological parameters were not significantly affected, with the exception of white blood cell and platelet concentration that decreased significantly (p < 0.05) in male broilers. Serum content in ASAT (Aspartate-transferase), ALAT (Alanine-transferase), creatinine, urea and LDL-cholesterol decreased significantly (p < 0.05), while HDL-cholesterol increased. Histology of organs was not affected. Feeding methenamine to broiler chickens through drinking water can be used as an alternative to antibiotic to improve growth performances.

Effects of Graded Levels of Joy Perfume Tree (<i>Pentadiplandra brazzeana</i>) Powder in Drinking Water on Growth Performance, Gut Microbiota and Haemato-Biochemical Parameters of Broiler Chickens

The restriction of antibiotic growth promoters in livestock nutrition has led to a growing interest in plant feed additives. This study was designed to assess the production performance of broiler chickens fed on graded levels of Pentadiplandra brazzeana powder in drinking water. A total of 448 day-old Cobb 500 broiler chicks were randomly assigned to seven treatment groups with 4 replicates of 16 birds each (08 males and 08 females). Pentadiplandra brazzeana root was grounded and incorporated at 1, 2, 3, 4 and 5 g/L of drinking water. Control rations consisted of diet without any supplement (T0) and antibiotic (1 g/kg) medicated diet (T0+). Throughout the experimental period (49 days) feed intake was not significantly (p > 0.05) affected by graded levels of Pentadiplandra brazzeana except for 5 g/L of water that significantly (p < 0.05) decreased feed intake. Weight gain was significantly higher (p < 0.05) with 1, 2 and 3 g/L, while feed conversion ratio was significantly lower (p < 0.05) with the same treatments compared to the control group (T0). Chickens fed on 1 g Pentadiplandra brazzeana/L recorded a higher (p < 0.05) carcass yield compared to the control ration (T0). Haematological parameters were not significantly (p > 0.05) affected irrespective of the level of incorporation of the test spice in drinking water. Serum content in urea was significantly lower (p < 0.05) with 3 g Pentadiplandra brazzeana/L compared to all other treatments. ASAT, ALAT, creatinine, total cholesterol, triglycerides, HDL and LDL-cholesterol were not significantly affected by the inclusion of Pentadiplandra brazzeana powder in drinking water. Feeding chickens with up to 4 g of Pentadiplandra brazzeana significantly increased (p < 0.05) lactic acid bacteria count. E. coli and salmonella counts significantly (p < 0.05) decreased with the spice in water as compared to the control diet. In conclusion, the administration of up to 3 g of Pentadiplandra brazzeana powder through drinking water can be used as alternative to antibiotics to improve growth performance of broiler chickens.

Effect of <i>Zingiber officinale</i>and <i>Allium sativum</i>Powders as Natural Feed Additives Promoting Growth, Feed Utilization and Whole-Body Composition in <i>Clarias gariepinus</i>Fry

Nutrition is the main factor determining the potential of farmed fish to exhibit their growth capacity as a function of the protein content and certain additives contained in their diet. Thus, the present study was conducted to assess dietary supplementation effects of ginger and garlic as feed additives on growth, feed utilization and whole-body composition in Clarias gariepinus fry. Following a 24 h fasting, 525 fry weighing 1.2 ± 0.01 g were randomly divided in triplicate into five treatments of 105 fish each and fed for 56 days. In treatment T0, fry was fed with control basal diet, in treatments T1 and T2, fry was fed with basal diet containing 1% and 2% ginger, while in treatments T3 and T4, fry was fed on basal diet supplemented with 1% and 2% garlic. Fish were fed at the rate of 10% of their body weight and every 14 days, intermediate fish sampling was done during which fry per treatment was counted, measurements taken on a representative sample and the feeding rate adjusted. Main water parameters were recorded daily before feeding. After the feeding trial, fish fed 1% (T3) garlic had the best growth performance in term of final weight (33.01 ± 2.99 g), weight gain (WG) (31.81 ± 0.99 g), specific growth rate (SGR) (5.86 ± 0.16%/d) and feed conversion ratio (FCR) (1.25 ± 0.11) which was significantly different from other treatments, particularly T0 which had the lowest growth performances (final weight (17.02 ± 0.27 g), WG (15.81 ± 0.28 g), SGR (4.73 ± 0.03%/d) and FCR (2.03 ± 0.01)). Similar trend to growth parameters was found with whole-body composition (moisture, crude protein, crude lipid, ash, and energy) and nutrient retention. In conclusion, C. gariepinus fry fed 1% dietary inclusion level of garlic has had better growth, feed utilization and body composition, which has been more attributed to its physiological and pharmacological properties than its nutritional effects.

Diversity and Structure of the Prokaryotic Communities Indigenous to Two Volcanic Lakes: Nyos and Monoun in Cameroon

This study explores the diversity and structure of prokaryotic communities (Archaea and Bacteria) of 2 tropical volcanic lakes (Nyos and Monoun) in Cameroon, using 16SrRNA sequences. Metagenomics analysis of sequences showed that most OTUs (Operational Taxonomic Units) were associated with 26 phyla (23 for Bacteria and 3 for Archaea) in Nyos and 36 phyla (33 for Bacteria and 3 for Archaea) in Monoun. In both lakes, Proteobacteria for Bacteria and Crenarchaea for Archaea were predominant and present at all depths but in different proportions. Bacterial community compositions were generally dominated by members of Proteobacteria, Firmicutes, Actinobacteria, Chloroflexi and Bacteroidetes covering about 98% of the sequences. Crenarchaea, Thaumarchaea and Euryarchaea were the three main phyla of Archaea common to both lakes. The amount of virus and total bacteria was determined by flow cytometry technic and the evaluated ratio ranged from 0.2 to 1.2 at Nyos and from 0.6 to 2.6 at Monoun. For both lakes, the correlation was very significant between viruses and total bacteria. The depth-dependent variability is discussed with chemical and physical environmental parameters. These could significantly influence virus-mediated bacterial lysis and abundance and vertical stratification of the prokaryotic community.

Effect of Tide on Temporal and Spatial Distribution of Some Physical and Chemicals Parameters in the Shallow Estuary of the Kienke River (Kribi Deep Sea Port Area, South Cameroon Coast)

The aim of this study was to highlight the effect of tide on the variation of the physicochemical parameter in the Kienké estuary. Six (06) environmental variables were monitored at nine (09) stations with the time step of one hour from 7 am to 7 pm on 4th August 2019. The hovmuller analysis showed that salinity, conductivity, total dissolved solids, and pH values increased during the flood phase and decreased during the ebb phase while oxygen concentration decreased during the flood and increased during the ebb phase. The stratification parameter has shown that the influx of seawater during high tide shifts the Kienké estuary from a well-mixed to a partially mixed environment.

Spatio-Temporal Variation of Dinoflagellates of the Genera Ceratium (Schrank 1793) and Protoperidinium (Bergh 1881) in Relationship with Some Abiotic Variables in the Atlantic Coast of Kribi (South Region—Cameroon)

A study to list Dinoflagellates species belonging to the genera Ceratium and Protoperidinium and some abiotic factors associated with them was carried out in the Kribi coast from February 2020 to February 2021 following a monthly sampling frequency. For the inventory, 60 L of water including 20 L on the surface, 20 L in the trophogen layer and 20 L in the tropholytic layer were filtered through a sieve of 20 μm and the retentate obtained was fixed whith lugol for identification and counting operations using an Olympus microscope. The morphotypes of the taxa were filmed using an Omax Toupvix eye camera. Physico-chemical results showed very good water oxygenation (89.35%), low Suspended Solid concentration (6.36 ± 4.71 mg/L), basic pH (8.53 ± 0.4 U.C), average salinity of 15.87 ± 3.1 g/L and conductivity around 26.73 ± 4.96 mS/cm. The average water temperature hovered around 29.51°C ± 1.28°C. The average values of nitrates and orthophosphates showed a progressive enrichment of the waters of the studied section with nitrate (1.52 ± 0.87 mg/L) and orthophosphate (1.84 ± 3.98 mg/L). This work allowed to identify 17 species of the genera Ceratium and 22 of Protoperidinium. The genera Protoperidinium was the most diverse while it was the taxa belonging to the genera Ceratium that had the highest densities. Ceratium furca was the only spatially and seasonally regular species with occurrence frequencies of 75.31% and 79.16% respectively. According to similar studies, 06 species reconized harmful were inventoried during this study. These are Ceratium furca, Ceratium fusus, Ceratium tripos, Protoperidinium divergens, Protoperidinium steinii, Protoperidinium crassipes. Temperature and oxygen are the abiotic factors that showed more affinities with the taxa inventoried in view of the significant correlations obtained. With a view to preventing blooms on the Cameroonian Atlantic coast, regular monitoring of the harmful species identified is desirable.

Effects of Replacing Maize with Dioscarea bulbifera Flour on Growth Performance of Broiler Chickens

The present study was designed to evaluate Dioscarea bulbifera flour as potential feed ingredient in broilers diets. For this purpose, 256-day-old Cobb 500 broiler chicks, were divided into 4 groups replicated 4 times in a completely randomized design. A control ration (R0) containing maize as the main energy source was compared to three other rations in which 50%, 75% and 100% maize were substituted with Dioscarea bulbifera flour. The main results showed that, the increasing rate of Dioscarea bulbifera flour had no significant (p > 0.05) effect on the digestibility of feed components. Feed intake was higher with 50% and 75% Dioscarea bulbifera flour inclusion levels. As compared to the control ration, a significant (p < 0.05) drop in live weight and weight gain was recorded with 50% substitution while feed conversion ratio increased significantly with increasing level of Dioscarea bulbifera flour in the ration. Dioscarea bulbifera flour induced a linear and significant (p < 0.05) increase in the relative weight of the gizzard, liver and production cost. It was concluded that, substituting 50% maize with Dioscarea bulbifera flour could be a sustainable solution to palliate the growing inflation of maize as animal feed ingredient. However, the incorporation level of Dioscarea bulbifera as feed ingredient in substitution of maize must not exceed 50% at the risk of depreciating growth performance of broilers.

Farming Features of African Bonytongue Fish Heterotis niloticus in Cameroon, Central Africa

The characterization of African bonytongue Heterotis niloticus fish farming was conducted in the Bi-modal agro-ecological zone of Cameroon from January to May 2021, Thirty-two fish farmers were interviewed and SPSS 6.2 Version was used to analyse the data. The results showed that the majority of fish farmers (81%) are men above 51 years, all of whom are Christians with more than fifty percent of them married. About 43% of them have university level education, and more than 6% of them considered the farming of Heterotis niloticus as their main income-earning activity. The main objective of Heterotis niloticus farming is sales (50%) and the uses (56%) of waged labour. A majority of the farmers produced reared African bonytongue in a polyculture system and 65% of them raised Heterotis niloticus in derivation ponds.

Influence of Anthropogenic Pollution on the Abundance Dynamics of Some Freshwater Invertebrates in the Coastal Area of Cameroon

The abundance dynamic of some freshwater invertebrates in relation with the abiotic factors of the medium was studied from March 2013 to March 2014 on the main streams of the Wouri and Sanaga basins. Individuals of Copepoda, Atyidae, Chironomidae and Physidae were collected, identified and counted. Samplings were carried out monthly;meanwhile measurements of the environmental variables were taken. Results of the physico-chemical analyses revealed that water of the Sanaga basin is globally well oxygenated (77% - 92%) and faintly mineralized (14 - 107 μS/cm), excepted in the stations receiving house-hold pollutants. Inversely, in the Wouri basin, waters are hypoxic with high content of organic matters (27.79 ± 9.43 mg/L). During rainy season (June-September), there is a dilution-dispersion of the organic matter due to stormwaters. Concerning biological analyses, the families of Physidae and Chironomidae were more abundant in urban stations than in stations situated in suburban area, especially during low water level period, showing that they are well adapted to anthropogenic and organic pollutions. The hypoxic conditions of urban waterways do not favor the proliferation of sensitive taxa such as Atyidae and Copepoda. These taxa preferred well oxygenated waters with rapid flow, and are more abundant during rainy season in stations located in suburban area or which are less subjected to anthropogenic disturbances.

Zooplankton Dynamics of the Kienke Estuary (Kribi, South Region of Cameroon): Importance of Physico-Chemical Parameters

All Cameroonian estuarine systems, like the Kienke estuarine system (urban area of the port city of Kribi), are considered, as everywhere in the world, as unstable and vulnerable coastal ecosystems insofar as they are influenced by anthropogenic activities (port facilities, industrial facilities), without forgetting climate change. The present work was initiated in order to assess the influence of the seasonal evolution of physico-chemical parameters on the dynamics of zooplankton in the estuarine system of the Kienke. A study to assess the influence of seasonal evolution of some physico-chemical parameters on Zooplankton population dynamics was conducted from June 2016 to August 2017 in the Kienke estuarine system (Kribi, South Cameroon Region). Samples were collected in five (05) sampling points at the lower stream, at the confluence and then at 100 meters from the bank at sea following a monthly frequency. The Kienke estuary was characterized by spatio-temporal variations of physico-chemical parameters. These parameters are high temperature, relatively high electrical conductivity and salinity, and a relatively basic hydrogen potential (pH). Nutrients (ammonia nitrogen, nitrates and orthophosphates) were relatively low in the Kienke estuary. The organic pollution index (OPI) indicated moderate to high water pollution. At the surface and at depth, during the long dry season (December to February), Zooplankton densities were very low in the Kienke estuarine system. But rather high during the main rainy season (August to October). The results show that 105 species of Zooplankton belonging to 46 families grouped into four orders were identified. At the surface, 52 species of Zooplankton belonging to 23 families and 4 orders were identified, while at depth, 53 species of Zooplankton belonging to 23 families were also identified. The most abundant group was the Copepods represented by the following species: Tropocyclops confinis Kiefer, 1930;Mesocyclops sp. Sars, 1914;Macrocyclops sp. Claus, 1893;Thermocyclops sp. Kiefer, 1929;Parvocalaus elegans Adronov, 1972 and Clausocalanus sp. Giesbrecht, 1888. Overall, there was a predominance of microcrustaceans (Cladocera and Copepoda) over rotifers. The results obtained in this work will be of capital importance for the elaboration of sustainable management policies for the estuary of the city of Kribi.