Considered as an ecosystem with several functions, forest streams constitute an excellent environment for biodiversity conservation because they host a large fauna that provides information on the multiple events occurring over time. In order to gain a good understanding of the functioning and maintenance of ecological balance of this environment, it is, therefore, necessary to carry out regular inventories to monitor the evolution of various biological groups that inhabit these environments and characterise them. Although the monitoring of aquatic environments integrity has long been based on abiotic components, which only provide specific information, the increasingly important combination of biological approaches in most hydrobiological studies makes it possible to provide more complete information, since the physico-chemical properties of water quality associated with that of aquatic habitats can be used to assess water quality [1] . It is therefore necessary to integrate the study of biological communities in forest environments, which can be used as reference points to characterise aquatic environments. In urban areas, the development of agricultural and industrial activities contributes to the settlement of humans and exerts a real tropism on new populations [2] . However, demographic densification and agricultural intensification remain the major causes of degradation of aquatic ecosystems [3] . Indeed, contaminants from anthropogenic activities have adverse effects on the development of the biota present and overall disturbance of aquatic ecosystems is very often felt at the level of biological communities. This concern implies that adequate measures be taken to permanently monitor the quality of aquatic environments, and more specifically forest milieu, which are capable of constituting a veritable niche of precise biological information for assessing the health condition of watercourses. Thus, the monitoring of aquatic ecosystems integrity is now based on measurements relating to the biological communities in place, and in particular macroinvertebrates. These organisms, which are widely distributed in different water, are characterised by their differential pollutant sensitivity, a main characteristic used in the bioindication of aquatic ecosystems [4] [5] . This study constitutes an informative data bank that can be used as a basis for comparison for further studies and a certain reference state for knowing the diversity of benthic macroinvertebrates as bioindicators of the state of environment. The analysis of the results obtained will make it possible to highlight aquatic macroinvertebrate taxa of ecological interest or even bioindicators of the biological quality of these water bodies.

A total of 13,436 individuals were collected. 4491 individuals were obtained in Abouda watercourse, 2715 individuals in Fam watercourse, 2574 individuals in the Nkoumou watercourse and 4356 individuals in Nga watercourse. These individuals are divided into 3 phyla (Annelida, Mollusca and Arthropoda), 6 Classes (Acheta, Oligocheta, Gasteropoda, Lamellibrancha, Crustacea and Insecta), 14 orders and 80 families. Insects dominate the benthic fauna with 9498 individuals (71.03%) of the total abundance. They are followed by Crustacea with an abundance of 2923 or 21.86%. Bivalva, Gasteropoda, Oligocheta and Acheta are the least represented groups with 343 individuals or 2.56%, 367 individuals or 2.74%, 156 individuals or 1.16% and 259 individuals or 1.94% respectively.

With 13436 individuals recorded, this study is one of the most important databases of the benthic macrofauna of the forested rivers of Central South ecological region of Cameroon available to date. This survey made it possible to organise the data into 3 phyla, 6 classes, 14 orders and 80 families identified. These results are similar to those of [5] [15] who obtained a high diversity in few Mefou turbutary. This would be due to the fact that the surveyed rivers are located far from anthropogenic disturbances and are in the same ecological zone and contrast with those of [4] [11] in the Bagré dam lakes and the Volta basin in Burkina Faso which are environments disturbed by anthropogenic activities. The high taxonomic richness obtained in the different rivers and, the presence of several phyla would be due to the presence in these ecosystems of a remarkable diversity of microhabitats, essential for the development of a rich and diversified benthic fauna [16] . In addition, the class of insects predominates the benthic

fauna with an abundance of 9498 individuals (71.03%), with a remarkable representation of the EPT (Ephemeroptera, Plecoptera, Trichoptera) complex, which stands out with 26 families and contributes for 32.62% of total abundance. This quasi-dominance of insects and also the presence in all watercourses the EPT that are considered as the most sensitive to pollution by [17] , translates the fact that these environments have stable conditions and good water quality, which makes it possible to confer on these ecosystems the character of reference

environments. In this respect [18] point out that in aquatic environments, insects are very sensitive to pollution and environmental modification. Crustaceans constitute the second most important class in terms of abundance with 2923 individuals (21.75%) of all benthic organisms. The family Atyidae is the most represented and was collected synchronously with the EPT and confirms the character of the dominant family of forest streams. This observation corroborates the work of [15] and [19] who indicated a predominance of Atyidae in the few forest streams of Cameroon. This remarkable proliferation of Crustacea would be due to the good oxygenation of waters which is a criterion of good water quality. To this effect, [8] affirmed that Crustacea Decapoda thrives in well oxygenated environments and is very sensitive to the decrease in dissolved oxygen content. According to [14] , the study of an environment should not only focus on the absence or presence of a few key species, but should take into account all the species present in the community. It therefore appears that the Decapoda, Hemiptera and the EPT complex would be good biological tools for assessing the biological quality of forest aquatic environments.

From a temporal side, the taxonomic composition did not vary significantly from one season to another, despite the variations observed here and there. However, the Short dry season recorded the highest value for the family scarcity index and diversity index. This would be due to the low quantities of water and current observed at this season, thus favouring a better collection of organisms in the different microhabitats. This observation is in contrast with the conclusions of [15] who observed a high diversity during the rainy months. Indeed, the rainy seasons constitute periods of instability of the environment during which, most of benthic invertebrates are carried away by the strong currents. [20] strongly affirms in this respect that, in aquatic environments, floods create conditions of instability of the bottoms and provoke the drifting of populations. The observation of the colonisation of watercourses shows that Abouda and Nga recorded highest specific richness, and the values of diversity indices remain high. These high values of diversity indices would be the result of the perfect integrity of these hydrosystems. These observations are in agreement with [12] [21] [22] [23] who affirm that a diversity index is higher when the environmental conditions favour the installation and maintenance of a balanced, integrated biological community capable of adapting to changes. The resemblance dendrogram remains of interest for our bioindication-oriented study. Its analysis reveals that the use of the family as a taxonomic level makes it possible to discriminate between watercourses on the basis of their similarity. This taxonomic level is widely used in the calculation of the biological quality index of watercourses at the European level [22] and [23] . This study, which is one of the first concerning the inventory of benthic macroinvertebrates in four Cameroonian forest streams, the observations of the groups present in the samples coupled with their frequency of occurrence make it possible to identify macroinvertebrate taxa that can be described as pollution-sensitive. Indeed, these taxa are from the four watercourses with frequencies of occurrence greater than 75%. They are, among others, Ephemeroptera (Ephemerellidae, Beatidae, Ephemeridae), Plecoptera (Perlidae and Perlodidae), Trchoptera (Hydropsychydae, Phylopothamidae, polycentropodiidae, and Brachyentridae), Coleoptera (Gyrinidae, Hydrobiidae and Chrysomelidae), Hemiptera (Pleidae and Naucoridae), Diptera (Chironomidae), Odonata (Platycnemididae, Calopterygidae and Coenagrionidae), Crustacea (Atyidae and Potamonidae), Eulamellibrancha (Sphaeridae) and Gasteropoda (Planorbidae). The other families with a frequency of less than 50% can be considered as pollution-resistant and could be of interest for the bioindication of these hydrosystems.

The benthic communities of macroinvertebrates in the four watercourses selected for this study remain largely dominated by insects with 71.044% of all the organisms sampled. These insects are very diversified with 7 orders, Ephemeroptera being the most diversified. Quantitative observation of the orders indicates a predominance of Decapoda (21.75%), Ephemeroptera (16.67%), Hemiptera (14.92%), Trichoptera (13.47%), Coleoptera (11.13%), Odonata (10.32%) and Plecoptera (4.6%). On a family basis, Atyidae are highly represented with a relative abundance of 18.2%. The high presence of EPT and the low abundance of Diptera reflects the low anthropic-nature of the different catchment areas and the good quality of their waters. The analysis of the frequencies of occurrence of families in different watercourses has made it possible to highlight macroinvertebrate taxa that could be potential bioindicators of these forest hydro systems. These bioindicators will undoubtedly constitute a solid base on which future investigations will be based and will allow the development of biological indices well adapted to the Cameroonian environment.

The authors thank the authorities of the Research Centre for Water and Climate Change of Institute of Geological and Mining Research and those of the Laboratory of Hydrobiology and Environment (LHE) of the Faculty of Sciences of the University of YaoundéI for the material made available to us as well as all the students who assisted us during the sampling campaigns

The authors declare that there is no conflict of interest about the publication of this document.

Biram à Ngon, E.B., Chinche, S.B., Ndjama, J., Dzavi, J., Nyame Mbia, D.L., Nwaha, M., Gwos Nhiomock, S.R., Mboye, B.R., Tchaouapi, I.L., Tchouta, U., Ngalamou, C. and Foto Menbohan, S. (2024) Inventory and Distribution of Benthic Macroinvertebrates, Indicators of Water Quality in Four Forested Watercourses in Centre Region of Cameroon. Open Journal of Ecology, 14, 381-394. https://doi.org/10.4236/oje.2024.144023