International Research Journal of Environment Sciences________________________________ ISSN 2319–1414Vol. 2(10), 1-6, October (2013) Int. Res. J. Environment Sci. International Science Congress Association 1 Preliminary Data on the Ichtyofaun ofDjiri River (Affluent ofright bankof Congo River)Mikia M1,2., Mady-Goma Dirat I., Tsoumou A.1,2 , Mabanza J., Vouidibio J. and Diatewa M.Laboratory of Research for Animal Biology and Ecology, ENS, University Marien Ngouabi, B.P. 69 Brazzaville, CONGO Faculty of Sciences and Techniques, University Marien Ngouabi, B.P. 69 Brazzaville, CONGO Faculty of Health Sciences , University Marien Ngouabi, B.P. 69 Brazzaville, CONGO Center of Research in Genetic Amélioration of Plants Brazzaville CONGO Available online at: www.isca.in, www.isca.me Received 22nd February 2013, revised 19th June 2013, accepted 3rd September 2013 AbstractA preliminary study of the ichtyofauna of the lower course of the Djiri River, tributary of right bank of the Congo River was undertaken during period of February 2008 to January 2009. Located at 20 kilometers in the North of Brazzaville, the Djiri River has never been the subject of an ichtyologic study. Median values of the following physicochemical parameters: temperature, pH, conductivity, dissolved oxygen, TDS, show that there is little variation during the year. Only turbidity varies considerably with minima in April (7,83 NTU) and maxima in May (33,1 NTU) and November - December (28,67 NTU). 2808 specimens of fishes, 95 species and 53 genera belonging to 23 families and 11 orders were inventoried during this study. The order of Characiformes is most representative with 30% of species, follow-on by Siluriformes (22%), Osteoglossiformes (20%), then by Perciformes and Cypriniformes (8,5% each one). The family of Mormyridae is the most diversified with 17% species, followed by Alestidae (15%) and Distichodontidae (11%). Two species dominate the collection: Synodontis nigriventris (13%) and Bryconaethiops boulengeri (11%), they are followed by Bryconaethiops microstoma (10%) and Micralestes stormsi (8%). The temporal evolution of specific diversity shows that the Shannon index is very high (superior to 2), and whatever the period of the year, that characterizes diversified populations, however a weak equitability is observed in January, March and April. KeywordsDjiri River, Ichtyofauna, specific diversity, Shannon index, equitability. Introduction The continental or littoral watery ecosystems are the most exploited, the most modified, threatened, and weakened environments. Indeed, in addition to intensive fishings which are practiced there, these ecosystems are frequently affected by other natural disturbances (dryness, stranding, anoxic crises) or anthropic (raising of barrage, pollution, reduction of the habitat). Some visible consequences of the disturbances are the modification of populations structure and the disappearance of taxa which are sensible to environment fluctuations. If the conservation of the biodiversity currently constitutes a great concern of the governments and scientific community, the protection of the aquatic environments and their components neither hold the attention of public authorities nor mobilized the international opinion as well as the protection of the large mammals, vegetable cover, the degraded ground, etc. Fishes are one of the best indicators of quality of any aquatic ecosystem and occupy a remarkable position from socioeconomic point of view. However, the rational management of the ecosystems requires first a whole knowledge of the various components of these ecosystems; unfortunately, the freshwater ecosystems in general and congolese freshwater fish biodiversity is poorly studied and some areas are still untouched and there is no proper documentation on freshwater fish resources of right bank of Pool Malebo. It’s the same situation for many Indian river Some studies were already carried out on Right Bank of the Congo Basin namely: fishes of Alima and Sangha6,7, listed fishes of the national park of Odzala, fishes of lower course Alima, fishes of the Pool-Malebo10 and very recently, the ichtyofauna of Léfini11. We purport to make an inventory of fishes of the lower course of the Djiri River, in order to contribute to the study of fishes diversity of Congo basin. These fishes inventory is important for knowledge of fishes populations12. Presentation of site of study: Djiri River, just like the majority of affluents sprinkling Right Bank of the Congo River, takes its source in the South of the plate of Mbé and in the high hills which prolong the Batékés plateau13. With a length of 50 kilometers, a surface of 853 km, a flow of 850 mm/an, a deficit of flow of 960 mm, a flow of 27 l/s/km2 and a coefficient of flow of 47%. Djiri which runs in direction NW-SE, presents the next principal tributaries: Kouala-Kouala, Bamba and Souo on left bank and Bilolo and Bitatolo on Right Bank14. Our sampling was carried out in the area located between 04,18117 - 04,13095 of Southern latitude and 15,31177 - 015,32192 of Eastern longitude (figure- 1). International Research Journal of Environment Sciences______________________________________________ ISSN 2319–1414 Vol. 2(10), 1-6, October (2013) Int. Res. J. Environment Sci. International Science Congress Association 2 Figure-1 Representative Chart of the propection site (Moukolo, 1984) Material and MethodsFishes were captured during monthly fishing from February 2008 to January 2009, in the lower course of the Djiri river. They were immediately plunged in formalin 10% for fixing, then transferred in formalin 5% or alcohol 70% for conservation. Fishes species determination is based on the morphometric and meristic characters according to identification keys described by different authors15,16,17. The specific diversity of fishes populations were calculated by Shannon Weaver index (H'). H' = - pi ln pi; with pi= Ni/N Where: Ni number of specimens of each species, N total number of specimens. The equitability E is represented by the following formula18: E= max ' ' H Where: H' max = lnS, H': real diversity, H' max: maximum, diversity, S: Total number of species. Results and DiscussionIn order to characterize the biotope in which fishes live, physicochemical parameters of surface water were measured (figure- 2). Among these five parameters, only turbidity varies considerably with a minimum (8,15 NTU) in April and a maximum in December (28,09 NTU). Water of Djiri has a fairly acid pH, around 5,80 ; conductivity is 7,50 ms/cm, the value of dissolved oxygen is very low, 7,60 mg/l; turbidity is low, around 19 NTU (slightly turbid water) and the average temperature is 25,5°C. Results are so very close to those of the two authors above mentioned13,14, with light variations related to the environmental conditions. Figure-2 Monthly variation of the physicochemical parametersList of species: 2808 fishes specimens belonging to 95 species, 53 genus, 23 families and 11 orders were listed in Djiri River sampling (table- 1). The various species are classified according to evolutionary order; then, each species is presented by its scientific name followed by a vernacular name in lingala and kikongo. Spectrum of fishes species according to the orders: Figure- 3 illustrates the proportions of the various orders according to the number of species. It arises that of the 94 species listed in Djiri River, the order of Characiformes is more diversified with 28 species either 29,8%, followed by Siluriformes (21 species, 22,3%), Osteoglossiformes (19 species or 20%), Perciformes and Cypriniformes (8 species or 8,5%), Polypteriformes and Clupeiformes (3 species or 3%), finally Lepidosireniformes, Gonorhynchiformes, Synbranchiformes, and Tetraodontiformes with 1 specie each one or 1%. Figure-3 Spectrum of inventoried fishes ordersAccording results obtained in Congo Basin18, the order of Siluriformes is most representative in Congo basin with 23,5%, it is followed by the order of Perciformes (18,7%), then Osteoglossiformes (16,5%), Cypriniformes (16,3%), Characiformes (14,3%) finally of Cyprinodontiformes (6,6%). In the national park of Odzala, the catfishes (Siluriformes) are the more diversified group with 22,66%. International Research Journal of Environment Sciences______________________________________________ ISSN 2319–1414 Vol. 2(10), 1-6, October (2013) Int. Res. J. Environment Sci. International Science Congress Association 3 Table-1 Details of Collected Fishes of Djiri River (Fev 2008-Jan 2009)FamiliesScientific NameVernacular names Lingala Kikongo PROTOPTERIDAE Protopterus dolloï nzombo njomo POLYPTERIDAE Polypterus ansorgi mokonga mukuwa Polypterus mokelembembe mokonga mukuwa Polypterus palmas congicus mokonga mukuwa OSTEOGLOSSIDAE Heterotis niloticus kongo ya sika kongo ya sika PANTODONTIDAE Pantodon buchholzi NOTOPTERIDAE Xenomystus nigri Peke pekoe MORMYRIDAE Cyphomyrus macrops mbese mbese Gnathonemus petersii mbese mpima Hippopotamyrus weeksii mbese mbese Marcusenius greshoffi mbese boso Marcusenius kutuensis mbese boso Marcusenius macrolepidotus angolensis mbese boso Marcusenius moorii mbese boso Marcusenius schilthuisae mbese boso Marcusenius stanleyanus mbese boso Mormyrus ovis Boulenger mbese mpima Wild Petrocephalus ballayi mbese mbese Petrocephalus christyi Boulenger mbese mbese Petrocephaus microphthalmus mbese mbese Wild Petrocephaus simus mbese mbese Petrocephalus sp mbese mbese Pollimyrus nigripinnis mbese mbese CLUPEIDAE Odaxothrissa will losera nsangui Pellonula leonensis nsangui Pellonula vorax nsangui PHRACTOLAEMIDAE Phractolaemus ansorgii mokisi mubiri CYPRINIDAE Clypeobarbus matthesi Clypeobarbus stanleyi Clypeobarbus sp nionzi Labeo lineatus monganza Labeo sp monganza Leptocypris weeksii sardine mulima Raïmas buchholzi sardine mulima Raïmas christyi sardine mulima HEPSETIDAE Hepsetus odoe muengue muengue ALESTIDAE Alestes liebrechtsii mokobe mpemo Bathyaethiops greeni Brachypetersius altus Brycinus comptus mapoyo nsangui za kuala Brycinus imberi mapoyo nsangui za kuala Brycinus macrolepidotus mapoyo ntsuele Brycinus poptae mapoyo ntsuele Bryconaethiops boulengeri mpemo Bryconaethiops microstoma mpemo Duboisialestes tumbensis Hydrocinus vittatus mbenga mbenga Micralestes acutidens Micralestes stormsi International Research Journal of Environment Sciences______________________________________________ ISSN 2319–1414 Vol. 2(10), 1-6, October (2013) Int. Res. J. Environment Sci. International Science Congress Association 4 Phenacogrammus interruptus CITHARINIDAE Citharinus gibbosus liyanga yanga Citharinus latus liyanga yanga Citharinus macrolepis liyanga yanga DISTICHODONTIDAE Distichodus altus Distichodus antonii mboto mbutu Distichodus atroventralis mpongui Distichodus lusosso lusoso Distichodus noboli Distichodus sexfasciatus Eugnathichthys macroterolepis Ichtyborus ornatus minkari nkari Mesoborus crocodilus Nannocharax schoutedeni Phago boulengeri mutitikiri CLAROTEIDAE Auchenoglanis occidentalis mboka mbuka Chrysichthys ornatus suaro Chrysichthys punctatus kamba suaro Chrysichthys thonneri kamba suaro Parauchenoglanis punctatus ke SCHILBEIDAE Parailia congica malewa malewa Pareutropius debauwi lilagwa lagwa Schilbe intermedius lilagwa lagwa Schilbe marmoratus lilagwa lagwa Schilbe mystus lilagwa nkembi CLARIIDAE Channallabes apus ngabili tondia Clarias gariepinus ngolo ngola Clarias spngolo ngola MALAPTERURIDAE Malapterurus electricus Nina tsula MOCHOKIDAE Synodontis alberti, likoko nkoko Synodontis congicus likoko nkoko Synodontis contractus likoko nkoko Synodontis flavitaeniatus likoko nkoko Synodontis nigriventris likoko nkoko Synodontis nummifer likoko nkoko Synodontis schoutedeni likoko nkoko MASTACEMBELIDAE Mastacembellus congicus mfulatse CICHLIDAE Hemichromis bimaculatus kingulu Hemichromis elongatus kingulu Hemichromis stellifer kingulu Tilapia tholloni libundu bundu Tilapia zillii libundu bundu Tylochromis lateralis libundu bundu ANABANTIDAE Ctenopoma nebulosum tsimpete CHANNIDAE Parachanna insignis mungusu nsinga TETRAODONTIDAE Tetraodon miurus mbulitsui Spectrum of fishes species according to the families: The figure- 4 illustrates the proportional representation of the number of species according to the various families observed. The distribution of the species according to the families indicate a clear predominance of Mormyridae (16 species 17%); they are followed by Alestidae (14 species either 15%), Distichodontidae (10 species or 10,6%), Cyprinidae (8 species or 8,5%), Mochokidae (7 species or 7,4%), Cichlidae (6 species or 6%) and finally the other families the proportions of which are lower than 6%. International Research Journal of Environment Sciences______________________________________________ ISSN 2319–1414 Vol. 2(10), 1-6, October (2013) Int. Res. J. Environment Sci. International Science Congress Association 5 Figure-4 Spectrum of the families of listed fishes Our results are very close to those of the national park of Odzala with a clear predominance of the family of Mormyridae with 22%, followed by Distichodontidae (14%) and Mochokidae (10,7%). The family of Mormyridae is more diversified with (17%) of the total of the listed species; it is followed by Alestidae (14,9%), Distichodontidae (10,7%), Cyprinidae (8,5%), and Mochokidae (7,5%). The differences observed are related to each type of biotope characteristic of each river. In Congo Basin19, the family of Cyprinidae is the most diversified with 16,3% as well as Mormyridae (16,2%); they are followed by Cichlidae (13,1%), Mochokidae (8,7%), Characidae (7,0%), Distichodontidae (6,8) and Cyprinodontidae (6,6%). Specific richness: The specific richness of twelve months study is represented by figure- 5. Figure-5 Total biological spectrum This figure 5 shows that five species dominate the river: Synodontis nigriventris (13%), Bryconaethiops boulengeri (11%), Bryconaethiops microstoma (10%). Temporal variation of Shannon index: The Shannon index shows a variation according to months as indicated in figure- 6. Figure-6 Temporal variation of the index of Shannon This Figure shows that whatever the period of the year, the Shannon index is high, because it is superior to 2.Temporal variation of equitability: The equitability shows a temporal variation (figure- 7). Figure-7 Temporal variation of the equitability The equitability is fairly weak in January, March, and April (lower than 0,7) and strong during the rest of the year (higher than 0,7). Seasonal variation of Shannon index and equitability: The seasonal variation of specific diversity and equitability are represented by figure- 8. The analysis of this figure shows that, on the one hand, whatever the season, specific diversity is high (higher than 1). On the other, the environment is equilibrated (equitability higher than 0,7). The temporal evolution of specific diversity shows that the Shannon index is very high (superior with 2), and whatever the period of the year; that characterizes very rich diversified population. The weak equitability in March, January, and April shows the presence of ecological niches of Synodontis nigriventris and, Bryconaethiops boulengeri. International Research Journal of Environment Sciences______________________________________________ ISSN 2319–1414 Vol. 2(10), 1-6, October (2013) Int. Res. J. Environment Sci. International Science Congress Association 6 Figure-8 Seasonal variation of the index of Shannon and the equitabilityConclusion Djiri River has a great socio-economic importance because of the various activities which are undertaken there (truck farming, breeding, fishing, pisciculture, hotel trade). The demographic pressure is more and more growing with the creation of new districts around Djiri, special attention must be lent to its environment to avoid overexploitation, the reduction and the exhaustion of the resources of this ecosystem. 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