Journal of Scientific Research & Reports 27(2): 72-84, 2021; Article no.JSRR.67287 ISSN: 2320-0227 Diatoms Flora from a Shallow Reservoir in Ivory Coast Blé Alexis Tardy Kouassi1*, Koffi Komoé2, Marie Paulette Adon3 and Allassane Ouattara4 1UFR Biological Sciences, Peleforo Gon Coulibaly University, P. O. Box 1328, Korhogo, Côte d’Ivoire. 2Laboratory of Botany, Félix Houphouët-Boigny University, P. O. Box 1328, Korhogo, Abidjan, Côte d’Ivoire. 3Laboratory of Hydrobiology and Fishery Resources, Jean Lorougnon Guede University, P. O. Box 150, Daloa, Côte d’Ivoire. 4Laboratory of Environment and Aquatic Biology, Nangui Abrogoua University, 02 P. O. Box 801, Abidjan, Côte d’Ivoire. Authors’ contributions This work was carried out in collaboration among all authors. Authors BATK and KK designed the study, performed the fields analysis, wrote the protocol and the first draft of the manuscript. Authors MPA and AO managed the identification of Diatoms taxa. All authors read and approved the final manuscript. Article Information DOI: 10.9734/JSRR/2021/v27i230360 Editor(s): (1) Prof. Prinya Chindaprasirt, Khon Kaen University, Thailand. Reviewers: (1) Pabllo Henrique Costa dos Santos, Federal University of Pará, Brazil. (2) Camila Leão Roland, Universidade Federal Fluminense, Brazil. Complete Peer review History: http://www.sdiarticle4.com/review-history/67287 Received 17 February 2021 Accepted 14 April 2021 Original Research Article Published 22 April 2021 ABSTRACT The diatoms flora of Adzopé Reservoir in Côte d’Ivoire was investigated from January to December 2005. The species composition of the assemblage was compiled, accompanied by illustrations. Firty-one taxa were identified in the temporal survey. Five taxa (16.3%) were new for Côte d’Ivoire. Eleven common species, 9 occasional taxa and 11 rare taxa were also recorded. No spatial variations in the taxonomic composition of the populations of diatoms were found. Variations were encountered in the seasonal analysis. Variation in the dimensions of some identified taxa have been observed. The species richness of Diatoms in the Adzopé Reservoir was in relation with water current velocity. _____________________________________________________________________________________________________ *Corresponding author: E-mail: [email protected]; Kouassi et al.; JSRR, 27(2): 72-84, 2021; Article no.JSRR.67287 Keywords: Diatoms; taxonomy; reservoir; Adzopé; Ivory Coast. 1. INTRODUCTION 61.44 ha. The reservoir has a maximum depth of 7 m and a length of about 2 km. It has no Diatoms are unicellular, eukaryotic algae, best permanent inflowing streams, but there is an known for their characteristic silica-based cell overflow channel at its southern end. The wall called a frustule. They might be solitary or sources of water inputs are seasonal, usually colonial, with some diatoms remaining being direct precipitation in the form of rainfall. suspended within the aquatic habitat while other forms of diatoms are settled within the sediment, The reservoir was built in 1977 for water where they are a major food source for grazing supplementation. Two sampling stations (St1 and protozoa and animals [1]. Fast-reproducing St2) were sampled according to the longitudinal organisms, most diatoms are widespread on gradient as shown in Fig. 2. different substrates and are closely associated with a certain microbiotope. Due to their sessile 2.2 Physicochemical Parameters nature and fast growth rate [2], diatoms are very useful for studying the impact of various forms of Some physicochemical measurements were pollution such as the discharge of waste water, made in the field immediately after each sample treated sewage effluents and organic and was collected. The Conductimeter Aqualitic inorganic nutrients [3]. They may promptly CD24 was used to assess water temperature indicate adverse changes in main biotopic and conductivity. Dissolved oxygen was conditions determined by natural environmental measured with the Oxymeter Aqualitic OX24, processes and anthropogenic impact [4]. They and pH with the pHmeter Aqualitic, pH24. For are so valuable indicators of environmental nutrients (orthophosphates and nitrates), conditions because they respond directly and subsamples of 30 ml were collected and sensitively to many physical, chemical, and refrigerated for later analysis according to the biological changes in aquatic ecosystems [5-7]. standard methods AFNOR T90-23 and T90-110. Due to this, Diatoms have proven to be The water transparency (ZSD) and the the water extremely powerful tools to explore and interpret current velocity were measured in situ, using a many ecological conditions. They are also used white Secchi disk and a Lightweight Current for monitoring the environmental conditions of meter model 106 respectively. water in many countries in Europe [8]. 2.3 Sampling, Preparation, and Data Although diatoms are recognized as being the Analysis best bioindicators [9], little is known about Diatoms in adzopé reservoir in Côte d’Ivoire. This Diatoms communities were assessed both by reservoir, surrounded by urban development, is a sampling natural (stones and leaves of shallow raw potable water reservoir, influenced Nymphaea lotus) and artificial (glass fragments by a diverse variety of anthropogenic activities. and pieces of wood) substrates located at well- The aim of this study is to provide a taxonomic illuminated places. Algae were removed monthly and floristic account, and to try to understand the by scraping the substrates with razor blades. species richness of the Adzopé Reservoir Other samples were collected with 20 µm mesh diatoms. plankton net at surface level. Diatom valves were cleaned by hot nitric acid in order to remove the 2. MATERIALS AND METHODS organic material and were embedded in Naphrax resin. For qualitative analysis an Olympus BX40 2.1 Description of Study Area microscope, equipped with a Canon camera was used. Species were identified according to the The area has four seasons as shown in Fig. 1: relevant taxonomic guides [12-17]. the long dry season (December-February), the long rainy season (March-July); the short dry In average, 50 organisms were used for season (August) and the short rainy season measurements. The frequency of each species (September-November) [10]. The reservoir as present was determined according to [18]. Three shown in Fig. 2, located at 6°06’N and 3°51’E, frequency groups were distinguished according lies in an urban area of the city of Adzopé, in the to value of frequency (F) : 1) common species (F south-east of Côte d’Ivoire that belongs to the > 50%) ; 2) occasional species ( 25% < F < 50 subequatorial zone [11]. It has a surface area of %) ; 3) rare species (F < 25%).. 73 Kouassi et al.; JSRR, 27(2): 72-84, 2021; Article no.JSRR.67287 Fig. 1. Climate graph of Adzopé area Fig. 2. Localization of Adzopé reservoir with sampling sites In taxonomic part, for each taxon, the latin name based on own observations is presented in with authors name (s), a year of description and Ecology (Ecol.) section. Finally, the stations reference to the illustration (s) in the where the taxon is observed and the geographic iconographic part are given. The morphology distribution of each taxon are also given in (Morph.) in which the length and width of valves, Distribution (Distr.) section. Taxa indicated by an the number of striae or fibulae are also given. asterisk are reported for the first time in Côte The habitat in which the taxon has been d’Ivoire. The taxa are arranged following the harvested is given (planktic, epilithic, epiphytic,) classification of [19]. 74 Kouassi et al.; JSRR, 27(2): 72-84, 2021; Article no.JSRR.67287 3. RESULTS AND DISCUSSION Aulacoseira granulata var. angustissima (O.F. Müller) Simonsen, 1979 (Fig. 4). 3.1 Results Frustule indentical to Aulacoseira granulata but 3.1.1 Physicochemical parameters terminal valves with 1 or 2 spines very long, The physicochemical parameters at the two almost equal in length to the valve mantle ; sampling stations (St1 and St2) throughout the Planktic, epipelic and epilithic ; Distr.: St1 & St2, seasons are summarized in Table 1. Cosmopolitan. The reservoir water temperature fluctuated Class: Bacillariophyceae Haeckel between 23.3 ºC during the short dry season and Order: Licmophorales Round 30.13 ºC during the short rainy season. The Family: Ulnariaceae E.J.Cox conductivity exhibited a low fluctuation Genus: Ulnaria (Kutzing) Compère throughout the seasons. Its values varied from 190.44 µS.cm-1 in long dry season to 164.78 Ulnaria biceps (Kützing) Compère 2001 (Fig. µS.cm-1 during long rainy season. The lowest 5) average value of dissolved oxygen (1.99 mg.L-1) Morph.: Valve length: 150-220 µm, width: 7-9 was measured during the long dry season, then µm, 7-9 striae in 10 µm. Ecol.: Planktic, epipelic, the highest (4.37 mg.L-1) was in the long dry epiphitic ; Distr.: St2, Subcosmopolitan. season. The measured pH varied around the neutral value 7. The lowest average values of pH Ulnaria ulna (Nitzsch) Compère 2001 (Figs. 6- were obtained during short dry season. The 7) water transparency was essentially low (ZSD min Morph.: Valve length: 94-110 µm, width: 4-6 µm, = 35.69 cm, ZSD max = 80 cm), probably 12-13 striae in 10 µm. Ecol.: Planktic, epilitic, reflecting the high turbidity of the lake. The epiphitic ; Distr.: St1 & St2, Cosmopolitan. highest water transparency values were measured during the short dry season. The Order: Eunotiales Silva lowest water current velocity value (0.08 m3.S) Family: Eunotiaceae Kützing was measured during the long dry season, then Genus: Eunotia Ehrenberg the highest (0.38 m3.S) was in the long rainy season. The Reservoir is characterized by high Eunotia bilunaris (Ehrenberg) Schaarschmidt concentrations of nitrate and orthophosphates. 1880 (Fig. 8) The maximum concentration of nitrates (NO3-) and orthophosphates (PO 3-) values were 2.54 4 Morph.: Valve length: 40-45 µm, width: 3-4 µm, mg.L-1 and 1.68 mg.L-1, respectively. The 24-26 striae in 10 µm ; Ecol.: Planktic, epilithic ; minimum values of these parameters were below Distr.: St2 , Cosmopolitan.