Inventory and Distribution of Benthic Macroinvertebrates, Indicators of Water Quality in Four Forested Watercourses in Centre Region of Cameroon

The inventory of benthic macroinvertebrate species was carried out in some streams of the Mefou catchment area, from August 2021 to August 2022, in order to determine the biological groups that make up the population and characterise these environments. The dataset acquired during this study made it possible to update the existing database and contribute to the knowledge of the biological groups associated in these environments, and to provide additional information on the existing ones in relation to bioindication. Overall 80 families were identified and, on the basis of frequencies of occurrence greater than 75%, 22 families were retained as potential biological indicators. The remarkable diversity of insects and the low abundance of Diptera reflect the low degradation of environments and the good quality of water. The high diversity indices obtained reflect the maintenance of the favourable ecological conditions that favours the development of a balanced and, integrated biological community capable of adapting to changes.

Physico-Chemical and Biological Characteristics of the Nklobisson Artificial Lake in Yaounde, Cameroon

The deterioration of water quality in lakes constitutes an environmental problem faced by humanity. The Nkolbisson artificial lake which is located downstream of the Abiergue and Mintotomo streams in Yaounde is under the influence of various forms of pollution, mostly resulting from human activities. There is proliferation of algae on the lake surface that consumes the available oxygen in the lake. The main objective of the current study is to evaluate the different forms of pollutants in the lake, in order to propose efficient solutions for a suitable management strategy, basing on the physico-chemical and biological analysis. The lake retains an average of 2535.49 tons/year of suspended solids in the rainy season and 1438.05 tons/year in the dry season. The range of dissolved oxygen (5.2 - 3.8 mg/l);pH (7.8 - 6.8);temperature (23.9°C - 23.1°C);electrical conductivity (266.1 - 87.3 μS/cm);turbidity (22.3 - 10 UNT);suspended solid (240 - 40 mg/l);BOD (55 - 8 mg/l);COD (76 - 87.3 mg/l). Biologically, faecal coliforms fluctuates between (42 × 102 - 425 × 103 FCU/100 ml), faecal streptococci (8 × 103 - 158 × 103 FCU/100 ml) and total Coliform (15 × 103 - 78 × 106 FCU/100 ml) evidence that, the studied lake is highly polluted. Consequently the lake retains an average of 2888.7 tons/year of suspended matter.

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.

An Appraisal of Water Availability, Infrastructures for Faecal Disposal and the Potential of Spread of Infectious Diseases in the Traveling Agencies and Motor Parks in the City of Yaounde (Cameroon)

The number of interurban and urban-rural travelers in the city of Yaounde has recently exceeded one hundred thousand per year, yet surprisingly few studies have assessed travelers’ behavior, illness, and risk factors in a sanitary risks setting. Particularly scarce are surveys of data spanning travel, return, and follow-up of the same cohort in traveling agencies and parks. This study examines behavior and illness among travelers moving from Yaounde to other urban and rural areas of Cameroon and beyond. Patterns of behavior connected to a type of travel and illness are characterized in this study so as to identify risks factors and provide background data for pre-travel advice in our traveling agencies. Assessing the susceptibility that imported cases could pose to the national response to infectious diseases depends both on public health, health services and infrastructures. The six agencies assessed: Nvan, Mokolo, Tongolo, Biyem Assi, Mimbowman and Etoudi reveal that the sanitary infrastructures for faecal and urinary disposal are not sufficient and more so, some agencies do not keep enough cleanliness, let alone provide adequate hand washing material as prescribed by national and international concerns to combat the global health challenges. This could be an impediment to travellers going out or inside of the city, and could be a preponderant mechanism for the spread of infectious disease as presented by the infectious diseases isolated and identified in the health districts around the travelling agencies.

Spatiotemporal Distribution of Cladocera and Rotifer of the Mangrove Waters of Mouanko (Coastal Cameroon): Influence of Some Abiotic Variables

The Mouanko mangrove is subjected to major anthropogenic activities such as agriculture, fishing and deforestation, hence information on Cladocerans and Rotifers amongst other aquatic organisms in order to monitor and manage this ecosystem is vital. The aim of this work is to study the physicochemical parameters of the environment that influence the diversity and spatiotemporal distribution of Cladocerans and Rotifers in the mangrove waters of Mouanko. This study was carried out from November 2019 to October 2020 at 8 sampling stations. Both biological and physico-chemical sampling and analyses were done following standard recommendations. The results of the phyico-chemical analyses revealed that the waters of the Mouanko mangroves were slightly basic (7.64 ± 0.71 UC), moderately oxygenated (69.56% ± 14.29%) with low levels of nutrients [ NO -2 (0. 06 ± 0.05 mg/L), NH+4 (0.39 ± 0.3 mg/L) and PO3-4 (up to 0.12 mg/L)] and high values of electrical conductivity (up to 6531.04 μS/cm), salinity (up to 3.71‰). 15 species of Cladocerans and 30 species of Rotifers were identified accounting for a total abundance of 612 ind/L. The species richness was higher in freshwater influenced zones (40 taxa) compared to marinewater influenced zones (17 taxa). Among these species, the Cladocera, Penilia avirostris was the most abundant in marinewater influenced zones (84 ind/L) while the Rotifer, Keratella tecta was the most abundant in freshwater influenced zones (64 ind/L). Shannon-Weaver’s diversity and Pielou’s equitability indices indicated that freshwater influenced zones host a diverse community with a tendency towards equi-partition of species while marinewater influenced zones revealed the opposite. The low levels of organic pollution indicator variables recorded and the high diversity of the freshwater influenced zones population studied attested to the low level of anthropization in this environment. High salinity and electrical conductivity values influence the distribution of these organisms.

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.

Bacteriological and Physico-Chemical Characterisation of Liquid Wastes: The Case of the University Hospital Centre (UHC) of Yaoundé-Cameroon

The untreated effluents generated by hospital activities contribute to the dissemination of pathogenic germs and multi-resistant bacteria, thus presenting a great potential danger for health and the environment. The objective of this study was to evaluate the microbiological and physico-chemical quality of the effluents of the Yaoundé University Hospital Centre and their impact on the environment. It was a prospective and analytical study on three sites where hospital effluents from the intensive care unit (Station A), the upstream of the wastewater treatment plant (Station B), and the gynaecology, surgery and hospitalisation departments (Station C) were sampled. Samples were collected in sterile glass bottles for bacteriological analyses and polyethylene bottles for physico-chemical analyses. The bacteriological parameters measured showed that the density of the bacterial species sought was very high at Station B with a predominance of the species Escherichia coli (57.36%). At Station A, total coliforms were very abundant (50.12%) and at Station C, the genus Pseudomonas was predominant (14.69%). Bacteria of the genus Streptococcus were represented by three species, namely: Streptococcus agalactiae, Streptococcus faecalis, and Streptococcus pneumoniae. The Pseudomonas genus was also represented by 3 species, namely Pseudomonas aeruginosa, Pseudomonas maltophilia and Pseudomonas putida. The physico-chemical parameters showed that apart from temperature and conductivity, which were in compliance with the standards, the other had values higher than these standards. This study shows that untreated hospital effluent contains most of the bacteria involved in community, nosocomial infections and would be a potential source of risk to the surrounding population.

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.

An Ecological Assessment of the Pollution Status of the Danube River Basin in the Galati Region—Romania

Physico-chemical parameters and bio-contamination assessment through protozoan cysts and helminths eggs were carried out from the period of June to September 2010 in order to appreciate the pollution of the Danube River Basin in Romania. It recorded a higher tenor in Magnesium ion (60 mg/L) with respect to the calcium ion (20 mg/L). Other ions identified at substantial proportions were iron (1.459 mg/L), manganese (6.583 mg/L), phenol (12.780 mg/L) and Aluminium (0.0441 mg/L). Twenty one ciliated protozoa were identified in our analysis of water in the Danube River. Prominent was the presence of Caenomorpha medusula and Metopus ovatus which are indicators of polysaprobity. Resistant forms of enteropathogenic protozoa were present in our samples. These are Cryptosporidium sp (65 oocysts/l in August), Entamoeba histolytica (22 cysts/L in September), Giardia sp with 30 cysts/L in August. The helminths identified were Ascaris lumbricoides, Clornochis sinensis, Diphyllobothium latum, Enterobius vermicularis, Heterophrys heterophrys, larva of strongiloides stercoralis and Taenia sp. There is a low impact of natural depollution mechanisms which can functionally reduce the impending effect of the communicable diseases that are being transmitted by humans who constantly explore this aquatic medium during their leisure or economic activities.

Spatiotemporal Variation of Benthic Macroinvertebrates in Some Tropical Forest Streams of the Nyong Catchment (Cameroon)

With the aim of assessing the benthic macroinvertebrates’ diversity, a study was carried out in some tropical forest streams of the Nyong River catchment in Cameroon from February 2019 to February 2020. A total of 167 samples were carried out from 13 stations during 13 months. Some environmental variables were measured. These parameters varied more or less from station to station but significantly at the temporal level. In this study, 13,690 benthic macroinvertebrates belonging to 4 phyla, 7 classes, 16 orders and 93 families were collected. The benthic macroinvertebrates were more abundant and more diversified in the stations whose waters are well oxygenated and present a moderate current compared to the stations with a very weak current. The diversity varied significantly from 1.33 ± 0.14 bits/ind to 2.00 ± 0.35 bits/ind and the high values were found in stations with multiple substrates and well-oxygenated waters. Temporally, the diversity varied significantly from 1.10 ± 0.16 bits/ind in NM sampling station in February 2020 to 1.87 ± 0.1 bits/ind in the OB sampling station in September. In addition, the settlement was more abundant during the short dry season, more precisely during the month of August (1471 individuals) but richer during the long dry season during the month of February (54 families). The distribution of the abundances of the benthic fauna in the different stations made it possible to identify five typological groups using the rarefaction curves, the ascending hierarchical classification and the principal component analyses. Each of these five groups is characterized by a specific taxonomic richness, composition and abundance.