The aim of this study was to provide a first-hand water quality assessment of the River Nyong estuary, Southern Atlantic coast of Cameroon. Environmental variables and phytoplankton communities were monitored at four surface stations in the estuary for 2 season cycles from 2014 to 2015. A total of 208 species of phytoplankton, belonging to five (5) groups of microalgae, were identified. The ShannonWeaver diversity index showed a qualitative seasonal difference in composition of the phytoplankton community. Dissolved nutrients (nitrogen and phosphorus) values showed seasonal fluctuations throughout the sampling period. A ratio appeared high (42.78) in the rainy season and low (5.89) in the dry season, two values corresponding to the change in specific richness (high and low respectively during the major rainy season and the small dry season). The Water Quality Index (WQI) showed that water quality fluctuates from good to bad, in conjunction with biological indicators (Shannon-Weaver, Abundance and Specific richness).
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, sus-
The present work aimed to understand the physicochemical and phytoplanktonic structure of the Kienke estuary water in the urban area of Kribi town in relation to human activities and fluvial or oceanic influences. Field investigations and laboratory work were devoted to the sampling and measurement of some physicochemical and biological parameters, specific treatments and classical statistics (descriptive, multidimensional) of variables. Estuary water is characterised by an instability and spatiotemporal variations in its physicochemical parameters. The most sensitive parameters are as follows: a temperature ranging between 22.6°C and 31°C under the influence of atmospheric variations, electrical conductivity and salinity that are relatively high (0.22 < C. E < 49.70 mS cm-1; avg =16.56 mS cm-1; 0 < Sal < 29.32 PSU; avg = 11.51 PSU), and a pH that is overall acidic to basic (6 < pH < 8.86; avg = 7.75 ± 0.82). The nutrients variation (ammonium, nitrite, nitrate and orthophosphate) is very low in space and time, with a longitudinal distribution controlled by tidal flows, river flows and the biological pump. For the 64 samples collected, 167 phytoplankton taxa were identified. The most abundant (36.36%) were Chrysophyta Division, followed by Chlorophyta. Species richness is marked by brackish water taxa. According to this structure and the combination of both gradients, mineratilisation and organic matter enrichment is of a physicochemical typology, and the biotypology is hydrotypologically dependent.
Ernst Haeckel described four new chirodropid species in 1880. Chirodropus gorilla was seen only on a few occasions along the Western coasts of Africa, while Chirodropus palmatus (from St. Helena Island) was never recorded again. Type specimens of both species are lost, leading some scientists to doubt the validity of C. palmatus. New specimens assignable to C. gorilla from European and South African Museum collections shed light on the identification of both species. Among the C. gorilla samples, small mature individuals with more pedalial branches than in the larger specimens were discovered. Further observations on living specimens of the smaller chirodropid from Cameroon suggested that they must be C. palmatus because there were only two chirodropid species described from West African waters; comparison with Haeckelʼs descriptions and drawings confirmed the identification. Additionally, our data showed that Chirodropus palmatus must be classified into the family Chiropsalmidae and accommodated in its own genus, Chimaerus gen. nov. We also revised definitions of the families Chirodropidae and Chiropsalmidae and re-described both species.
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