Thursday, 23 June 2011


Kamaruddin, I.S., A.S. Mustafa Kamal, A. Christianus, and S.K. Daud, (2010). Distribution of macrobenthos community in the Pengkalan Gawi – Pulau Dula Section of Kenyir Lake, Terengganu, Malaysia. International Conference on Environment (ICENV 2010). Universiti Sains Malaysia. 


1Kamaruddin, I.S., 1*A.S. Mustafa Kamal, 1A. Christianus and 2S.K. Daud

1Department of Aquaculture, Faculty of Agriculture, Universiti Putra Malaysia, 43400, Serdang, Selangor
2Department of Biology, Faculty of Science, Universiti Putra Malaysia, 43400, Serdang, Selangor
*Corresponding author: E-mail:


The study was conducted to determine the distribution of macrobenthos community in the Pengkalan Gawi – Pulau Dula section of Tasik Kenyir, Terengganu. Four sampling stations located at Pulau Dula (station A), Sungai Ikan (station B), Pulau Pupi (station C) and Sungai Lawit (station D) were established. Macrobenthos samples were collected monthly for 11 months (from March 2008 to January 2009) using Wildco Eckman grab (surface area of 225 cm2) and were sieved using a 500 μm Endecotts steel sieve. Samples were counted and identified to lowest taxonomic level. A total of 18,688.89 organisms/m2 were recorded throughout the sampling period. The macrobenthos community were classified as chironomids (insects), gastropods (snails) and annelids (worms). This study area was dominated by chironomids contributing 58.4% of the total macrobenthic populations followed by gastropods (30.8%) and annelids (10.8%). The highest (p>0.05) macrobenthos density was recorded in station B totalling to 5,933.33 organisms/m2, followed by station C with 5,711.11 organisms/m2; station A (4,489.89 organisms/m2) and lowest (p>0.05) in station D (2,555.56 organisms/m2). Among the macrobenthos, chironomids were found dominating in Sungai Ikan, Pulau Pupi and Sungai Lawit, whereas, in Pulau Dula, gastropods dominated. Meanwhile, amongst the stations with insect as the dominant macrobenthos, station B had the highest (p>0.05) density. However, no significant difference (p<0.05) in terms of the total density of annelids amongst the stations was observed. The result of this study will provide important baseline information for future monitoring and sustainable management of the lake.

Keywords: Macrobenthos, Chironomids, Gastropods, Annelids, Tasik Kenyir.

Benthos is an important part of the food chain, especially for fish. Having the position as “middlemen” in the aquatic food chain as they feed on algae and bacteria and other organic matter that enters the water, they play a critical role in the natural flow of energy and nutrients. [16] defined benthic macroinvertebrates as organisms that lived at the bottom of substrates in freshwater habitats for at least in one phase of their life cycle. These organisms may be divided into two major groups which are macrobenthos and microbenthos [9] Macrobenthos can be classified as those specimens retained by a mesh size between 200 μm and 500 μm [10].
The study of macrobenthos community is important because it involves important components of the tropic chain, knowledge of its volume in monitoring programs, and ecological surveys [15]. [2] described the macrobenthos as the most suitable organisms as indicator in the water quality assessments. Benthic macroinvertebrates community structure has been largely used in monitoring studies on pollution in lake ecosystems, with the aim of identifying and quantifying ecological alternatives [16]. Macrobenthos are also important sources of food for many species of fish particularly the benthophagic ones [1]. Indirectly, their population is an indicator of the quality of water within which fishes live, and more directly as food for fishes [12].  
Being a reservoir, Tasik Kenyir is also inhabited by macrobenthos that play important roles to the lake ecosystems. To make sure the benefits of these macrobenthos continues, it is necessary to ensure sustainable managements and conservation programmes are seriously taken into consideration in managing the lake. Scientific management and conservation of lakes is overwhelmingly important in the milieu of predicted freshwater shortages in this new century, especially with the lowest per capita freshwater availability in the Asia-Pacific region [5]. However, these managements and conservation programmes needs baseline information on it macrobenthos resources. As such, this study was conducted to provide some data on macrobenthos community composition in one of the lake section named Pengkalan Gawi – Pulau Dula section of Tasik Kenyir, Terengganu, Malaysia.  

Tasik Kenyir is the biggest man-made lake in Malaysia (about 260 km2) and it lies at 4° 41’ north and longitude 102° 40’ east in the state of Terengganu, Malaysia. This man-made lake was initially impounded in 1986 to generate hydroelectric power, receiving water inputs from two main rivers – the Terengganu and Terengan Rivers [3]. Tasik Kenyir is a home for numerous species of freshwater fishes and known as paradise for anglers and eco-tourist.
The study was conducted in Pengkalan Gawi- Pulau Dula one of the lake section. This section is located from the main jetty (Pengkalan Gawi) to the south and to Pulau Dula (Dula Island) and has an area of about 30 km2. This section of the lake serves as the main entrance to the Tasik Kenyir and where many activities for ecotourism are undertaken. For these reasons disturbance and minor destruction to the ecosystems natural state is possible if not properly managed. Hence, this section of the lake was chosen for this study. Four sampling stations have been set up between this section designated as station A (Pulau Dula), station B (Sungai Ikan), station C (Pulau Pupi) and station D (Sungai Lawit).
Sample collection was conducted for 11 months, between March 2008 to January 2009. Macrobenthos samples were taken using ekman grab (Wildco) covering a surface area of 225 cm2. Macrobenthos samples were kept in a polyethylene bottles and were preserved with 10% formalin solutions for laboratory analysis. In the laboratory, macrobenthos were sieved using a 500 μm steel sieve (Endecotts). Macrobenthos were identified and counted using Leica EZ4 dissecting microscope (16X to 40X magnification). All data gathered were analysed using one-way analysis of variance (ANOVA) to determine the significant differences (p<0.05) among stations.

A total of 18,688.89 individuals/m2 macrobenthos were recorded during the study period between March 2008 to January 2009 in the Pengkalan Gawi – Pulau Dula section of Tasik Kenyir. The macrobenthos community in this section were categorized into three main groups: insects (chironomids), annelids (worms) and gastropods (snails). Overall, the highest (p<0.05) macrobenthos abundance were contributed by insects with mean total density of 10,911.11 organisms/m², comprising 58.4% of the total macrobenthos populations. This was followed by gastropods and annelids contributing mean total density of 5,755.55 individuals/m2 (30.8%) and 2,022.23 individuals/m2 (10.8%), respectively (Figure 1). 
Among the four stations, Sungai Ikan was found to contain the highest (p<0.05) macrobenthos density of 5,933.33 individuals/m2, followed by Pulau Pupi (5,711.11 individuals/m2), Pulau Dula (4,489.89 individuals/m2) and Sungai Lawit (2,555.56 individuals/m2) (Figure 2). In Sungai Ikan, Pulau Pupi and Sungai Lawit, insect (chironomids) dominated the macrobenthos community (Figure 3). Highest (p<0.05) chironomid abundance was recorded in Sungai Ikan with mean total density of 404.04±63.39 individuals/m2 (Table 1).
The abundance of this chironomid in this station might be due to the fact that this station is located the river (lotic system) (Ikan River). According to [7], 90% of the species from class Ephemeroptera (chironomid) prefer lotic habitats during the period of larval development and that the larvae simultaneously need a large amount of oxygen dissolved in water. However, the abundance of chironomids in the other two stations, Pulau Pupi and Sungai Lawit, may be attributed to the muddy condition of the bottom sediments. According to [8] chironomids larvae from the genera Chironomus, Procladius and Tanypus were found only in soft mud bottom sediments. These chironomids are widespread organisms of the mud substrates of eutrophic waters, consequently species of these genera formed 90 to 98% of all the organisms inhabiting the muddy sediments [6].
Meanwhile, in Pulau Dula gastropods dominated. The presence of gastropods community in Pulau Dula (228.28±39.59 individuals/m2) was significantly higher (p<0.05) compared to Sungai Ikan (74.75±18.35 individuals/m2) and Sungai Lawit (62.63±11.94 individuals/m2) (Table 1). The dominance of gastropods in this section of the lake was most probably due to the relatively high calcium content in the sediments [12]. According to [13] calcium is important for the development of shells in molluscs (gastropods). In this case, Pulau Dula might contain high concentration of calcium. However, calcium content of the sediments for this study was not measured.
Annelids community in all sampling station were recorded with the least (p<0.05) proportion compared to other groups of macrobenthos (Table 1). The abundance of annelids has been associated with muddy substratum rich in organic matter [14]. Since Tasik Kenyir is classified as a mesotrophic lake, a type of lake which contains low organic matter and nutrient contents [17], hence annelids may have difficulty in dominating the macrobenthic community.

The most abundant macrobenthos community in this study was chironomids (insects) and this was followed by gastropods (snails) and annelids (worms). The highest number of macrobenthos individuals at stations was recorded in Sungai Ikan (Station B) followed by Pulau Pupi (Station C), Pulau Dula (Station A) and Sungai Lawit (Station D). From the data obtained, we could suggest that the Pengkalan Gawi – Pulau Dula section of Tasik Kenyir contains various pattern of distribution in macrobenthos community, as such sustainable managements and conservation activities should be stressed out in managing the lake so that the constancy of the community continues.  

We are very thankful to Encik Junaidi Jaafar and Encik Eduardo D. Peralta for their assistance during the sample collection. We would like to thank Assoc. Prof. Dr. Sharr Azni Harmin as head of the department for giving his full support on this study. We also express our gratitude to the Malaysian Ministry of Science and Technology (MOSTI) for funding the research.


 Figure 1: Percentage composition of macrobenthos community in the Pengkalan Gawi – Pulau Dula section of Tasik Kenyir during the sampling period form March 2008 to January 2009.

Figure 2: Total number of individual macrobenthos at each station in the Pengkalan Gawi–Pulau Dula section of Tasik Kenyir during the sampling period form March 2008 to January 2009.

Figure 3: Percentage composition of macrobenthos based on stations in the Pengkalan Gawi – Pulau Dula section of Tasik Kenyir during the sampling period form March 2008 to January 2009.

Table 1: Table showing the mean macrobenthos individual based on stations during the sampling period from March 2008 until January 2009 at the Pengkalan Gawi – Pulau Dula section of Tasik Kenyir, Terengganu (same letter are no significant different).



Mean (organism/m2)
± S.E
Chironomids (insects)
Pulau Dula (A)

Sungai Ikan (B)

Pulau Pupi (C)

Sungai Lawit (D)

Annelids (worms)
Pulau Dula (A)

Sungai Ikan (B)

Pulau Pupi (C)

Sungai Lawit (D)

Gastropods (snails)
Pulau Dula (A)

Sungai Ikan (B)

Pulau Pupi (C)

Sungai Lawit (D)

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