VOL. 9, NO. 7, JULY 2014 ISSN 1990-6145

ARPN Journal of Agricultural and Biological Science ©2006-2014 Asian Research Publishing Network (ARPN). All rights reserved.

www.arpnjournals.com

246

PHYTOPLANKTON FAUNA ABUNDANCE AND DIVERSITY IN AQUACULTURE POND, JIMMA TOWN, JIMMA ZONE

SOUTH WEST ETHIOPIA

Tesfaye Koricho and Eba Alemayehu

Department of Biology, College of Natural Sciences, Jimma University, Ethiopia E-Mail: ebasimma@yahoo.com

ABSTRACT

The main objective of this study was to assess the abundance and diversity of phytoplankton communities in the aquaculture pond in Jimma University, College of Agriculture and Veterinary Medicine, Jimma Town. The study was conducted from April 1-30, 2013 by purposively selecting three experimental ponds based on their vegetation type and phytoplankton coverage. Phytoplankton samples were identified using stereo microscope. In situ physicochemical parameters were measured using portable pH and Dissolved Oxygen(DO) meter. From the total 27 collected samples, 25 phytoplanktons genera, belonging to 5 classes were identified. Among the 5 classes, Chlorophyceae (green algae) was the most dominant and abundant phytoplankton group which contributed 49%-76.6% of the total observed phytoplankton population. The overall contribution of Chlorophyceae in Pond I was about 75.7% where as in Pond II and III 59.7% and 49% respectively. Interestingly among the observed Chlorophyceae taxa the genus Pediastrum was the most dominant and abundant group in all the three Ponds followed by the genus Scenedesmus in Ponds I and II. The second most dominant and abundant phytoplankton group next to Chlorophyceae was Bacillariophyceae (Diatoms) which contributed 18.9%-40.4% of the total observed phytoplankton population. Keywords: phytoplankton, diversity, abundance, aquaculture pond. INTRODUCTION

Phytoplanktons are the autotrophic component of the plankton community. They are photosynthesizing microscopic organisms that inhabit the upper sunlit layer of almost all oceans and bodies of freshwater. They are agents for primary production, the creation of organic compounds from carbon dioxide dissolved in the water a process that sustain the aquatic food web [1]. Phytoplanktons obtain energy through the process of photosynthesis and must therefore live in the well lit surface layer on the ocean, sea, lakes or other body of water. They are responsible for much of photosynthetic activity on the Earth and hence responsible for the oxygen presents in the Earth’s atmosphere [2, 3]. They convert solar energy to chemical energy and release oxygen to the water body and the surrounding terrestrial environment through photosynthesis process. Their cumulative energy fixation in primary production is the basis of the vast majority of oceanic and also many fresh water food webs. Phytoplanktons are also indicators of the tropic status of aquatic ecosystem [4]

A large number of studies [5, 6, 7] have been made on the community structure and primary production of phytoplankton in various East African lakes including those found in Ethiopia. In Ethiopia several lakes and reservoirs are found. Most of the reservoirs have been built basically for the generation of hydroelectric power. However, very limited attention has been given to the biodiversity of plankton fauna in the lakes ,reservoirs and ponds of the country. So far very few studies reported the diversity and abundance of phytoplankton communities in Ethiopia lakes and reservoirs [5-8].

Thus this study tried to assess the diversity and abundance of phytoplankton communities in the

aquaculture ponds in Jimma University, College of Agriculture and Veterinary Medicine experimental aquaculture ponds, Jimma Southwest Ethiopia. METERIALS AND METHODS

Phytoplankton were collected from the three ponds purposively based on their vegetation type and phytoplankton coverage. A total of 27 samples were collected and immediately at the sampling site Lugol’s iodine at the ratio of 1:100mL was added to preserve the organisms. The preserved samples were taken to Jimma University Zoological Sciences laboratory for identification and enumeration of phytoplankton fauna. A drop of samples were placed on the glass slide and covered with cover slip and examined with stereo microscope. Identification to the level of genus was done based on standard keys [8, 9]. Measurement for physicochemical parameters for temperature, pH and dissolved oxygen (DO) was done in situ in the field. Finally the data was analyzed using Microsoft Excel 2007. RESULT AND DISCUSSIONS Physico-chemical features of the ponds

The highest temperature value of the Ponds was 24oC whereas the lowest value was 23.2oC. The pH varied from 6.10 to 6.71 and the dissolved oxygen also varied from 5.05 mgL-1 5.29mgL-1. There was no major difference in the physicochemical parameters in the aquaculture Ponds that were measured during the study period (Table-1).

VOL. 9, NO. 7, JULY 2014 ISSN 1990-6145

ARPN Journal of Agricultural and Biological Science ©2006-2014 Asian Research Publishing Network (ARPN). All rights reserved.

www.arpnjournals.com

247

Table-1 Some physicochemical parameters in aquaculture ponds, Jimma Town, 2013.

Physical parameter Pond I Pond II Pond III

Temperature(oC) 23.5 24.0 23.2 pH 6.10 6.58 6.71 Dissolved oxygen (mgL-1) 54.29 50.05 54.21

The rates of biological and chemical processes

depend on water temperature. Aquatic organisms from microbes to fish require certain temperature ranges for optimal development. If temperatures are outside optimal range for a prolonged period of time, organisms get stressed and may die [6]. In the present study the temperature of the ponds ranges from 23.2-24.0oc which indicates that the ponds are suitable for the production phytoplankton in agreement with similar results [9].

In the studied ponds the pH level was an important parameter to be measured since its level can correlate with phytoplankton population size. The favorable range of pH at any daybreak, are most suitable [10] the present study which ranged between 6.1-6.71, similar with other findings from Boye Pond [11].

Dissolved oxygen (DO) measures the amount of free oxygen available in water; hence sufficient DO is essential for good water quality. The amount of DO in the water is directly related to the population size and community. Therefore, DO levels are indicators of a water

body ability to support aquatic life [6]. According to the [12] DO>5mgL-1 is considered to be favorable for the growth of most aquatic organisms. In the present study the range of DO in the aquaculture Ponds was between 50.05 mgL-1 - 54.29 mgL-1. Phytoplankton abundance and composition

In the present study 25 genera which belong to 5 classes of phytoplankton were identified during the study period (Table-2). Detailed taxonomic study in Lake Kuriftu [13] and in Koka Reservoir [5] reported 25 and 24 phytoplnkton genera respectively. In the current study in Pond I we identified four (4) classes of phytoplankton namely; chlorophyceae (green-algae) with 9 genera, Bacillariophyceae (Diatoms) with 4 genera, Euglenophyceace (Euglenoid flagellate) with 2 genera and Cyanophyceae (Blue-green algae) with 2 genera. In pond II two classes of phytoplankton were identified. They are chlorophyceae (green-algae) with 4 genera and Bacillariophyceae (Diatom) with 2 genera. Similarly in Pond III five classes of phytoplankton were identified. These are Chlorophyceae (green algae) with 6 genera, Bacillariophyceae (diatom) with 5 genera, Euglenophyceae (Euglenoid Flagellate) with 3 genera, Rhodophyceae (red-algae) with 1 genus and Cyanophyceae (Blue-green algae) with 4 genera (Table-2). The highest abundance of chlorophyceae in the Ponds might be due to high dissolved oxygen content. Chlorophyceae (green algae) preferred water with higher concentration of dissolved oxygen.

Table-2. List of identified phytoplankton genera from aquaculture ponds, Jimma Town, 2013.

Genus name Phytoplankton class

Pond I Pond II Pond III

Chlorophyceae (Green-algae)

Pediastum Scenedesmus Stichococcus

Enteromorpha Ankistrodesums Prasiola

Eudorina Dictyosphaerium

Pediastrum Scenedesmus Stichococcus Mesotaenium

Pediastrum Ankistrodesmus

Prasiola Eudorina

Dictyosphaerium Enteromorpha

Bicillariophceae (Diatoms)

Navicula Synedra

Tabellaria Fragilaria

Navicula Tabellaria

Navicula Tabellaria Diatoma

Fragilaria Surirella

Euglenophyceae (Euglenoid flagellate)

Phacus Trachelomanas None

Phacus Euglena

Batrachospermum Rhodophyceae

(Red algae) None None Porphyridium Surirella

Cyanophyceae (Blue-green algae)

Anabaena Oscillatoria

Oscillatoria Anabaena

Gloeotrichia Microcystis

Chlorophyceae (green algae) was the most

dominant and abundant phytoplankton group which contributed 49%-76.6% of the total observed phytoplankton community. In Pond I the total

VOL. 9, NO. 7, JULY 2014 ISSN 1990-6145

ARPN Journal of Agricultural and Biological Science ©2006-2014 Asian Research Publishing Network (ARPN). All rights reserved.

www.arpnjournals.com

248

contribution of chlorophyceae was about 75.7%, in Pond II and III 59.7% and 49% respectively. Interestingly among the observed Chlorophyceae the genus Pediastrum was the most dominant and abundant group which was recorded in appreciable number in all the three Ponds. The second most dominant and abundant chlorophyceae genus was Scenedesmus in Pond-I and Pond-II. The second most dominant and abundant phytoplankton group was Bacillariophyceae (diatoms) which contributed 18.9%-40.4% of the total observed phytoplankton population.

Among the Bacillariophyceae (diatoms), Navicula genus was dominant in all the three Ponds, which accounted for 17.4%, 38.9% and 23.2% in Pond-I, II and III respectively followed by Rhodophyceae (red-algae) which contributed 19.6% of the total phytoplankton abundance. Rhodophyceae were only sampled from Pond-III with two genera. The least abundant groups were Euglenophyceae and cyanophyceae which contributed only 3.7%-4.6% and 0.7%-3.2% respectively. These two classes were sampled from Pond-I and Pond-III (Table-3).

Table-3. Phytoplankton composition and abundance in Aquaculture ponds, Jimma Town, 2013.

Total number of individual (N) Abundance percentage (%) Phytoplankton group Pond I Pond II Pond III Pond I Pond II Pond III

Chlorophyceae Pediastrum ** Scenedesmus

Ankistrodesmus Enteromorpha Mesotaenium

Prasiola Eudorina

Stichococcos Dictyosphaerium

2182 102 111

6 0 45 15 15 12

1108 24 0 0 4 0 0 4 0

1166

0 152 11 0 7 3 0 9

66.2 3.1 3.4 0.2 0

1.4 0.5 0.5 0.4

58.0

1.3 0 0

0.2 0 0

0.2 0

42.4

0 5.5 0.4 0

0.3 0.1 0

0.3

Bacillariophyceae Navicula* Synedra

Tabellaria Fragilaria Diatoma

564 21 12 13 0

746 0 27 0 0

636

0 14 7 8

17.1 0.7 0.6 0.4 0

39.0

0 1.4 0 0

23.1

0 0.5 0.3 0.3

Euglenophyceae Phacus

Trachelomonas Euglena

Batrachospermum

147

4 0 0

0 0 0 0

75 0

19 9

4.5 0.1 0 0

0 0 0 0

0

2.8 0

0.7

Rhodophyceae Porphyridium

Surirella

0 0

0 0

541 6

0 0

0 0

19.7 0.2

Cyanophyceae Anabaena

Nostoc Oscillatoria Microcystis Gloeotrichia

15 3 6 0 0

0 0 0 0 0

18 0

54 8 9

0.5 0.1 0.2 0 0

0 0 0 0 0

0.7 0

2.0 0.3 0.3

Total 3297 1913 2752 100% 100% 100%

0=not present *=abundant **=most abundant

VOL. 9, NO. 7, JULY 2014 ISSN 1990-6145

ARPN Journal of Agricultural and Biological Science ©2006-2014 Asian Research Publishing Network (ARPN). All rights reserved.

www.arpnjournals.com

249

CONCLUSIONS The studied aquaculture Pond supports moderate

levels of phytoplankton that constituted largely by Chlorophyceae (green algae). This clearly shows preference of green algae to higher concentration of dissolved Oxygen. Good water quality, relative high water temperature, dissolved oxygen and high primary productions make aquatic organisms including microscopic plants suitable for culture based aquaculture. REFERENCES [1] Ghosal R. and S.M. Wray. 2011. The effects of

turbulence on phytoplankton. Aerospace Technological Enterprise.

[2] NASA, 2009. Satellite detects red glow to map global ocean plant health. http://www.nasa.gov/topics/earth/features/modis_fluorescence.html.

[3] NASA. 2005. Satellite sees ocean plants increase, coasts greening. http://www.nasa.gov/centers/goddard/news/topstory/chlorophyll.html.

[4] Roach J. 2004. Source of half earth’s oxygen gets little credit. National Geographic News. http://news.nationalgeographic.com/news/2004/06/0607_040607_phytoplankton.html.

[5] Tesfay H. 2007. Spatio-Temporal Variations of the Biomass and Primary Production of Phytoplankton in Koka Reservoir, MSc thesis Addis Ababa University, Ethiopia. p. 85.

[6] Desta. H. Y. and Mengistou S. 2009. Water quality parameters and Macroinvertebrates index of biotic integrity of the Jimma wetlands, southwestern Ethiopia. J. Wet. Ecol. 3: 77-93.

[7] Ebisa N. 2010. Water quality and phytoplankton dynamics in Gefersa Reservoir, Ethiopia. M.Sc. Thesis, Addis Ababa University, Ethiopia.

 

[8] Sirage A. 2006. Water quality and Phytoplankton Dynamics in Legedadi Reservoir. M.Sc Thesis Addis Ababa University, Addis Ababa, Ethiopia. p. 109.

[9] Van Vuuren, S.J., J. Taylor, A. Gerber and C. van Ginkel. 2006. Easy Identification of the Most Common Fresh Water Algae: A Guide for Identification of Microscopic Algae in South African Freshwater. North-West University, Vanderbijlpark, South Africa. pp. 111-193.

[10] Perry R. 2003. A Guide to the Marine Plankton of Southern California. 3rd Edn, UCLA Marine Science Center, Los Angeles, California. pp. 3-22.

[11] Wacho M. 1999. Determination of eutrophication factors in Boye Pond, Ethiopia. M.Sc. Thesis, Addis Ababa University, Ethiopia.

[12] Boyd C.E. and C.S. Turker. 1998. Pond Water Quality

Management. Kluwer Academic Publishers, Boston, MA., USA.

[13] FAO. 2008. Aquaculture systems and practices: A selected review. Fishery and Aquaculture Department, FAO, Rome, Italy.

[14] Vaccari D.A., P.F. Strom and J.E. Alleman. 2005. Environmental Biology for Engineers and Scientists. John Wiley and Sons, New York, USA. ISBN: 9780471722397. p. 960.