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Journal of Ecology & Natural Resources Research Article 9 min read

Microalgal Diversity Study of Lake Basaka, Metehara, Ethiopia

Nega R*
* Corresponding author
ISSN: 2578-4994  10.23880/jenr-16000256  Received: August 13, 2021  Published: September 17, 2021
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Keywords
Algae Diversity Basaka
Abstract

Lake Basaka is characterized by a Na-HCO3-Cl type of water which is typical feature of saline water. Such saline environments may harbors unique microbial genetic resource which have wide industrial applications. This study was conducted with the objective of describing algal diversity of the lake Basaka. For algal diversity study 90 water samples were collected in October, 2015. Microscopic study of the water samples showed that phylum Chlorophyta and Diatoms were dominated the Lake during sample collection. Scenedesmus, Selenastrum, Volvox, Navicula and Nitzschia species were observed with high frequencies. Moreover, few algal species belong to Phylum Euglinophyta were observed.

Introduction

Lake Basaka is a soda (alkaline lake) having PH 9.5 and it is situated in awash basin which is located in the northern Main Ethiopian Rift valley [1]. Lake Basaka is a volcanically dammed terminal lake located at near distance to the Afar Triangle. There is a number of hot springs supplying water to this lake. The outlets of these springs are currently submerged due to the abrupt rise of lake water. As the area is situated in the upper most part of central Rift Valley region of Ethiopia, it is vulnerable to the occurrences of various tectonic and volcanic activities [2, 3].

Lake Basaka has been expanding drastically since the late 1960s [4]. The expansion of the lake is alarming and has had detrimental effect on the surrounding biological, physical, hydrological and infra-structural environment. The lake growth has affected the highway and railway structures which run along its northern shore and lake has flooded the highway, the only import-export line to the port of Djibouti, several times [5]. The growth of the Lake is a natural disaster for the surrounding ecosystems, as the expansion has created an unstable transitional zone between the wetland and nearby terrestrial ecosystem. The Metehara sugar plantation has been inundated and lost income from 161.55 ha of land [6]. The sugar plantation in Abadir suffers from salt-water encroachment and has lost more than 30 ha of farmland [5].

Microalgae are the major O2 producer and they are commercially important in the food industry and aquaculture, as a natural source of high-value products such as fatty acids, carotenoids, steroids etc [7, 8]. Microalgae uses as alternative source for fuel production [9, 10]. Microalgae have been considered as potential source of energy, food, co2-fixation (from atmosphere or industrial flue gas, hence, reduces global warming), up take nitrogen and phosphorus from waste water (consequently reduce eutrophication in aquatic ecosystems) and restoration of land (by fertilizer or soil conditioner obtained from biomass residue) [11, 12, 13].

Diversity measures are useful in lake ecosystems which harbour a large variety of algal species in general and species diversity within the genera. Detailed studies on algal diversity have been done by Aiyaz [14] Basavarajappa [15]. Most of these studies deal with the distribution of algal species in different water bodies. However the study on algal groups is lacking and the significant relationship between different groups of algae is insufficient.

The study was aimed to collect the water samples from the Basaka Lake and to identify the Microalgal species to make a record on its diversity from the sampling sites of the lake.

Material and Methods

Study area

Lake Basaka is an alkaline lake in the Oromia Region of central Ethiopia. It is located in the Great Rift Valley about 200 kilometres south east of the capital Addis Ababa in Metehara. The lake watershed area is 540km with latitude N8°41’- 9°0’, longitude of E39°43’-39°59’ and an altitude 1200 meters above sea level. The salt lake has grown significantly in the past 50 years, growing from 3 square kilometres (740 acres) in 1957 to 42.6 square kilometres (10,500 acres) in 2008. The lake is growing to the east and north east due to the local topography [16]. Due to the growth of the lake, there increasing concern that it will permanently damage the nearby Awash River, which is a major water source for nearby cotton and sugar plantations [17].

Sampling and analysis

Water samples were collected from six sampling stations of lake during October 2015. Water samples were collected in sterile 50 ml plastic bottles and 50 ml of the fresh water sample were preserved in 4% of 1ml formaldehyde solution. And also fresh water samples were collected from the lake in 100 ml bottle containing BG/BBM media. The collected samples were brought to Ethiopian biodiversity institute, microbial laboratory. Then, temporary mounts of microalgae specimen were prepared by placing a drop of the water samples onto a microscope slide and carefully lower a coverslip onto it and examined under an inverted microscope. Observing the Microalgal samples at lower magnification (X10, X40) and move sequentially up if necessary and their identification to genus or species level were made on the basis of various descriptors of Microalgae [18, 19, 20, 21] and internet resources were also used for identification.

Results and Discussion

Diversity of microalgae: detailed microscopic examination of water samples revealed five families consisting of 27 genera of microalgae in the order: Chlorophyceae (13 genera), Bacillariophyceae (6 genera) Cyanophyceae (5 genera), and Cryptophyceae (2 genera) Euglinophyta (1 genera) (Table 1). Chlorophyta- Actinotaenium, Ankistrodesmus, Asterococcus, Chlamydomonas, Dunaliella, Oocystis, Palmella, Pieurococcus, Scenedesmus, Schroederia, Selenastrum Tetraspora, and Volvox Bacillariophyta- Cyciotella, Gyrosigma, Navicula, Nitzschia, Syndra and Tabellaria Cyanophyta- Aphanizomenon, Aphanocapsa, Chroccocus, Microcystis, and Snowella Cryptophyta- Cryptomonas and Rhodomonas Euglinophyta- Euglena

cultured samplepreserved sample
CHLOROPHYTA
Actinotaenium-+
Ankistrodesmus-+
Asterococcus++
Chlamydomonas+-
Dunaliella-+
Oocystis++
Palmella-+
Pieurococcus-+
Scenedesmus++++
Schroederia-+
Selenastrum++++
Tetraspora-+
Volvox++++
BACILLARIOPHYTA
Cyciotella++
Gyrosigma-+
Navicula++++
Nitzschia++++
Syndra++
Tabellaria-+
CYANOPHYTA
Aphanizomenon-++
Aphanocapsa-+
Chroccocus++++
Microcystis++++
Snowella-+
CRYPTOPHYTA
Cryptomonas-+
Rhodomonas-+
EUGLINOPHYTA
Euglena+-

Table 1: ** Microalgae taxon found from Lake Beseka.

(+ present, ++ dominant, - absent) Table 1: Microalgae taxon found from Lake Beseka.

The result showed that almost all the Microalgae genera found from the microscopic observation of the preserved samples was also found from aerated samples (The composite Microalgae samples was cultured on BBM liquid medium supplied with CO2 from compressed gas cylinders (aerator)) except Chlamydomonas and Euglina. According to (http:// site.iugaza.edu.ps/elnabris/files/2014/11/3-.pdf) this may be due to some algal species can be distorted or cannot be recovered in the sample at all and also organisms may shrink (lower cell volumes) when they preserved by formalin. And also this may be because of formalin preservation can cause contraction or diflagelation [22, 23]. As represented in Table 1 the result showed that phylum Euglinophyta was present very less number in this month. Euglinophyta are usually found in environments where there is an abundance of decaying organic matter such as marshes, bogs, fens or mires essentially brown peat water systems. Due to their association with increased levels of dissolved organics, euglenoids have been used as environmental indicators of such conditions. During the present investigation on Lake Beseka maximum Microalgal diversity was shown by Chlorophyta and Diatoms. Chlorophyta are a large and important group of freshwater green algae including some of the most common species, as well as many members that are important both ecologically and scientifically [24]. Higher population of Scenedesmus, Selenastrum, Volvox, Navicula and Nitzschia species was also observed. When conditions in the upper mixed layer (nutrients and light) are favorable (as at the spring), Bacillariophyta competitive edge and rapid growth rate enables them to dominate phytoplankton communities. According to the survey on Baiyangdian Lake, Cyanophyta and Chlorophyta became dominant in the phytoplankton community, that may be caused by the increased organic matters after organic matters in industrial wastewater and domestic sewage came into the Lake Li Y [25] and resulted in the increase of varieties and number of phytoplankton, especially these species with high pollution tolerance. Generally speaking, in eutrophic lakes, Chlorophyta and Cyanophyta are the dominant species [26, 27]. From this, a conclusion can be drawn that which the group Chlorophyta is becoming the dominant species, indicating that Beseka Lake had become.

Conclusion

Generally Lake Basaka was dominated by Chlorophyta and Bacillariophyta, which are indicators of good water quality. The finding of this study provides necessary theoretical and data support for the diversity of microalgae in Basaka Lake. However, further studies are still needed on the species composition, quantity characteristics and distribution characteristics of the Microalgae species in Basaka Lake for the conservation of biodiversity.

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@article{nega2021,
  title   = {Microalgal Diversity Study of Lake Basaka, Metehara, Ethiopia},
  author  = {Nega R},
  journal = {Journal of Ecology & Natural Resources},
  year    = {2021},
  volume  = {5},
  number  = {3},
  doi     = {10.23880/jenr-16000256}
}
Nega R (2021). Microalgal Diversity Study of Lake Basaka, Metehara, Ethiopia. Journal of Ecology & Natural Resources, 5(3). https://doi.org/10.23880/jenr-16000256
TY  - JOUR
TI  - Microalgal Diversity Study of Lake Basaka, Metehara, Ethiopia
AU  - Nega R
JO  - Journal of Ecology & Natural Resources
PY  - 2021
VL  - 5
IS  - 3
DO  - 10.23880/jenr-16000256
ER  -