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ZOOPLANKTON ASSEMBLAGES IN SEMATAN RIVER, SEMATAN, SARAWAK Nurul Syaza Bt ZainGI QL 123 N974 2011 Bachelor of Science with Honours (Aquatic Resource Science and Management) 2011 ,.. hsat Khld.t Maklamat Akademik UNlVERSm MALAYSIA SARAWAK Zooplankton Assemblages in Sematan River, Sematan, Sarawak P,KHIDMAT MAKLUMAT AKADI!MIK 111111111 fIlii 111111111 1000235688 Nurul Syaza Bt Zainol This project is submitted in partial fulfillment ofthe requirements for the degree of Bachelor of Sciences with Honours (Aquatic Resource Science and Management) ., I, Faculty of Resource Science and Technology UNIVERSITI MALAYSIA SARAW AK 2011 , Acknowledgement Alhamdulillah. Thanks for God. I would like to express my thankfulness to my supervisor, En. Mohd Nasarudin Harith for his supports and guidance through this year until able to complete this study. I would love to thank: my parents, Zainol b. Yusoff and Habsah bt. Hamid and other family members for their financial and emotional supports. Thank you to Mr. Azlan, Mr. Nazri, Miss Nur Atiqah bt. Mohamad Yusoff and all FRST's staff that involved in Sematan River water sampling and for their helps and advices. Last but not least, I would like to express my gratitude to all Aquatic Science's lectures and class members for their advice, support, love and care. DECLARA TION I hereby declare that no portion of the work referred to in this dissertation has been submitted in support of an application for another degree of qualifications of this or any other university or institution of higher learning. Nurul Syaza Zainol (22069) Program of Aquatic Resource Science and Management Department of Aquatic Science Faculty of Resources Sciences and Technology University Malaysia Sarawak II Pusat Khidmat Mlkiumat AkJdemik UNIVERSm MALAVSIA SARAWAK Table of Contents Acnowledgement ........................................................................ ..': I Declaration ............................ ............................................... ....... II Table of Contents. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . III List of Abbreviation......................................................................... V List of Tables .......................... ... ............ .. ............ ... ...................... VI List of Figure ................................................................................ VII List of Appendices .......... ... ............... ............... ..... ................. ... ..... VIII Abstract '" ........................... ...... ... ... ................................. ... ......... 1 1.0 Introduction........................ ... .............................. ... ............ ...... 2 2.0 Literature Review.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.1 Distribution of zooplankton ..... ... ............................ ... ..... . 5 2.2 Freshwater zooplankton ............ .................. ............... ... .. . 6 2.3 Classification of Zooplankton ............................ ................ 9 2.4 Importance of Zooplankton ...... .... .......... .. .............. .... .. ... . 11 2.5 Relation between zooplankton and physico-chemical characteristic 12 2.6 Behaviors of Zooplankton ............................................... . 14 3.0 Material and Method...................... ........... ............ ... ... ... ............ 15 3.1 Sampling Site .......................................................... . ... .. 15 3.2 Field work ............................................ ... .................. . 17 3.3 Laboratory work and analysis .......................................... . 18 3.3.1 18 Zooplankton analysis .....: .................................... , 3.3 .2 Water quality analysis ............................ .. ........ .. 20 3.4 Data analysis............ ......................... .. ............. ... ...... 24 3.4.1 Species diversity of zooplankton composition.................... 24 3.4.2 Similarity analysis of zooplankton composition..... ......... ... 24 3.4.3 Statistical analysis........................................................ 25 III _. I 4.0 Result and Discussion ................................... .. ........................ .. . 26 Zooplankton assemblages ............... .......... .. ........... . .... ... . ; 26 4.1.1 Zooplankton genera occurrence. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 4.1.2 Zooplankton genera composition and abundances ......... 29 4.1 4.1.3 Comparison of individual zooplankton composition in different season .......................................... .. ...... 34 4.1.4 Zooplankton Diversity........................ ... ......... ... .... 39 4.1.5 Zooplankton Similarities...... .. .......... ... ... ...... ...... ... 41 Water Quality Parameters .......... ............................. .. ...... . 43 4.2.1 Selected physico-chemicals parameters............... ... .... 43 4.3 Relationship of Environmental parameter to zooplankton assemblages 55 4.4 Correlation analysis between zooplankton diversity and 4.2 environmental parameter ............................................... . 59 5.0 Conclusion ........................................................................ . 62 6.0 References ..... . ........................ . ......................................... . 64 7.0 Appendices .......................................................................... . 69 IV .... List of Abbreviations I TEMP Temperature DO Dissolved oxygen BOD Biochemical oxygen demand pH Potential of Hydrogen TSS Total suspended solids N03-N Nitrate nitrogen NH4- N Ammonia- nitrogen pol Orthophosphate NTU Nephelometric Turbidity Units °C Degree Celsius mglL milligram per Liter L Liter - , Ii v I I I List of Tables Table Page Description 1 Classification of zooplankton based on sizes 2 Classification of zooplankton planktonic life 3 Brief description of sampling stations 18 4 Nutrient water analysis (Hach DR 2010) 21 5 Zooplankton genera occurrence in all stations 28 6 Distribution of zooplankton composition at all stations 33 7 Different zooplankton composition of dry and wet season 34 8 Zooplankton diversity 39 9 Sorensen's index (%)of zooplankton genera found in all stations 41 10 Correlation analysis (r) between zooplankton diversity and water quality variable 61 VI 1 based on 9 their 10 ,..... List of Figures Figure I' Description Page 1 (a) Malaysia 16 1 (b) Sematan area 16 1 (c) 6 Sampling site in Sematan River involved during this study Percentage (%) of zooplankton groups in Sematan River Comparison of individual zooplankton composition in dry and wet season Temperature value recorded at six sampling stations in Sematan River pH value recorded at six sampling stations in Sematan River 16 2 3 4 5 Dissolve oxygen value recorded at six sampling stations in Sematan River Biological Oxygen Demand (BODs) value recorded at six sampling stations in Sematan River 6 7 29 34 43 44 45 46 Salinity value recorded at six sampling stations in Sematan River Turbidity value recorded at six sampling stations in Sematan River 47 10 ORP value recorded at six sampling stations in Sematan River 49 11 Clorophyl a (mg/m3) value recorded at six sampling stations in Sematan River 50 12 A'm monia-nitrogen (mg/L) value r~corded at six sampling stations in Sematan River 51 13 Nitrate-nitrogen (mg/L) va)ue recorded at six sampling stations in Sematan River 52 14 Nitrite-nitrogen (mg/L) value recorded at six sampling stations in Sematan River 53 15 Nitrite-nitrogen (mg/L) value recorded at six sampling stations in Sematan River 54 8 9 VII I 48 I : List of Appendices Appendices Description Page A Abundance ofthe common zooplankton genera in Sematan River 69 B Dominant genera and amount of zooplankton 70 C Water Quality Parameters 71 VIII Zooplankton Assemblages in Sematan River, Sematan, Sarawak Nurul Syaza Bt Zainol Program of Aquatic Resource Science and Management Faculty of Resources Sciences and Technology University Malaysia Sarawak ABSTRACT A study on the zooplankton assemblages in Sematan River, Sematan, Sarawak was carried out to evaluate the species composition, species diversity, species similarity, abundance, distribution and selected water physico chemical parameters. Zooplankton and water samples were collected from six sampling stations at 7-8 August 2010 for dry season and 15-16 January 2011 for wet season. Zooplankton and water samples be analyzed using standard methods in interpreting infonnation about zooplankton assemblages and its relationship to environmental parameters. A total 900 zooplankton belonging to seven groups, four taxa and 14 genera were identified. Copepoda dominated the zooplankton population which made up of 68.44 % of total abundance. Zooplankton abundance followed the order: Copepoda > Cladocera > Mollusca > Protozoa > Ostracoda > Anostraca> Rotifera. A dominant genus identified in this study was Limnocalanus which represented 29.56% of total amount. The seasonal pattern was observed which recorded zooplankton composition was much higher during dry season (866 individuals) compared to wet season with lowest present (31 individuals). Species diversity values vary from 0.562 to 2.042 and recorded mostly in high value for each station during dry season. The Sorensen's index value falls were much larger in range between 13.33 % to 76.19 % among all stations. Water temperature of different season, turbidity, dissolve oxygen, pH and nutrients were main environmental parameters which were found to influence zooplankton composition in Sematan River. Key words: Zooplankton assemblages, environmental parameters, dry and wet seasons, Sematan River ABSTRAK Kajian ke atas kehadiran zooplankton di Sungai Sematan telah dijalankan untuk merekodkan komposisi spesis, kepelhagaian spesis, persa"lPan, spesies kelimpahan dan parameter telpilih di permukaan air. Zooplankton dan sampel air diambit dari enam stesen pada 7-8 Ogos 2010 untuk 'rusim panas dan 15-16 Januari 2011 untuk musim hujan. Zooplankton dan sampel air dianalisis menggunakan kaedah piawai untuk menghasilkan maklumat berkaitan kehadiran zooplankton dan hUbungannya dengan parameter persekitaran. Sejumlah 900 zooplankton dari tujuh kumpulan, empat taxa dan 14 genera telah dikenakpasti. Copepoda menidominasi populasi zooplankton iaitu 64.88% dan jumlah kelimpahan. Jumlah zooplankton mengikut urutan: Copepoda > Cladocera > Mollusca > Protozoa > Ostracoda > Anostraca > Rotijera. Genus yang dominan adalah Limnocalanus iaitu 29.56% dari jumlah keseluruhan. Kelimpahan berdasarkan musim, komposisi zooplankton adalah lebih tinggi semasa musim panas (866 individu) berbanding dengan musim hujan (31 individu). Nitai kepelbagaian sepsis yang direkodkan adalah dari 0.562 kepada 2.042 dan merekodkan nitai yang tinggi untuk setiap stesen semasa musim panas. Suhu air berdasarkan perbezaan musim, kekeruhan, kandungan oksigen, pH dan nutrien adalah parameter persekitaran yang utama dalam mempengaruhi komposisi zooplankton di Sungai Sematan. KflkI kunci: Kehadiran zooplankton, parameter persekitaran, musim panas dan musim hujan, Sungai Sematan 1 1.0 INTRODUCTION Zooplankton are essentially non-motile organisms but drift with water current and therefore they are susceptible to pollutants in the water (Uttah et al., 2008). The physico-chemical parameters and nutrient status of water body play an important role in governing the production of zooplankton which is the natural food of many species of fishes (Basu et aI., 20 I 0). Dominance of zooplankton community and their seasonality are highly variable in different water bodies according to their nutrient status, age, morphometry and other locational factors of the water (Rajashekhar et al., 2009) . Zooplankton can be divided into few different groups such as crustacean, rotifers, coelenterates, ctenophores, annelids and mollusk (Pary,1992). Zooplankton more specifically three taxonomic groups; Phylum Rotifera; Subclass Copepoda; and Suborder Cladocera, are an integral component of freshwater ecosystems (O'Brien, 2007). In general, freshwater zooplankton are dominated by four major group such as protozoa, rotifer, and two subclasses of crustacean, the cladocerans and copepods. Crustaceans are the most abundant and the main group of zooplankton species, .. especially those in the orders of cyclopoid copepod are often Calanoid~, dominat~d Cyclopoida and Cladocera, and the in the assemblage (Schiel, ND). Cladocerans are usually most abundant in freshwater ecosystem and the common genera are Daphnia and Bosmina (Edmondson, 1982). 2 Zooplankton are important contributors in the food webs of open-water ecosystems for both marine and freshwaters. They act as important link in the transfer of energy from the primary producers to the consumers. Community structure, biomass, and production are influenced by both producers and consumers which function simultaneously (Mayer et at., 1997). Its intermediate position between phytoplankton and fish, the zooplankton can responds to changes in both food and predation (Baloch et at., 2010). Water quality; the physico-chemical and biological characteristics of water, plays an important role in plankton productivity (Yeamin et at., 2007). Biological monitoring is the use of living organisms of zooplankton in purpose to determine the presence, amounts, changes in and effects of physical, chemical, and biotic factors in the environment (Uttah et at., 2008; Baker, 1976). The important aspect in water biological monitoring is species diversity. Species diversity can determine the health status of an environment (Uttah et at., 2008; Ogbeibu and Edutie, 2002). The types and numbers of invertebrates living in the river can determined the health of the river (Uttah et at., 2008). Different types of invertebrate species will have different tolerances rate to pollution and they are also influenced by the quality of their habitat. Zooplankton play role as indicators of conditio"n of their habitats as they can respond quickly to their aquatic environmental changes (Basu et at., 2010; Thorpe and Covich, 1991 and Carriack and Schelske, 1997). The factors that influenced the growth and distribution of zooplankton are some of abiotic factors such as pH, alkalinity, temperature, carbon dioxide and nutrients which are responsible for the organic production (Yeamin et aI., 2007; Pulle and Khan, 2003). The biotic factors such as 3 food limitation, predation and competition also influence the zooplankton distribution (Ferdous and Muktadir, 2009; Beyst et at., 2001; Christou, 1998):'" According to Pandey (2004), a study that was conducted in river Ramjan of Bihar, India revealed that abiotic parameters such as pH, transparency, temperature, dissolved oxygen and some micronutrients are related to zooplankton abundance. The previous zooplankton studies in Sarawak have been carried out in Kuching Bay by Volin (2005), Batang Lupar by Arbe (2007) and Punang, Lawas & Limbang River by Nuratiqah (2009). However, there is still inadequate data especially the assemblages of zooplankton in Sematan River. Thus, study of zooplankton assemblages at Sematan River need to be carried out in order to find the relationship between zooplankton assemblages and their abundance to the water quality parameters. The objectives of the study are to (1) identify and quantify zooplankton community in Sematan River; (2) discuss the variations in selected water quality parameters; (3) find the relationship between zooplankton distributions with water quality parameters. 4 I Pusat Khidmat Maldumat Akadem.lk VNlVERSm MALAYSIA SARAWAK 2.0 LITERATURE REVIEW 2.1 Distribution of Zooplankton Zooplankton are microorganism that float freely in surface water column of water bodies (Shanna, 2008). They are attract to sunlight and nutrient that available and be adapted to suspension in the sea and freshwater (Battish, 1992). They move in the sunlight zone where food resources are most abundant and they also found in deep ocean water (Ferdous and Muktadir, 2009). Zooplankton distribution primarily determined by water waves and current (Sharma, 2008). They are very weak swimmers and they drift in water column of ocean, seas and fresh water bodies (Ferdous and Muktadir, 2009). Their abundance and species comp<!sition of zooplankton community are also controlled and influenced by their susceptibility to environmental stressors of physical, chemical and biological factors of the water ecosystem. Water parameters such as temperature, salinity, pH and electrical conductivity can influence the composition and population density of zooplankton (Sampaio et at., 2002). The composition of zooplankton also can be influenced by the distribution of phytoplankton and its species composition (K~jalainen et at., 1996). 5 ,...... 2.2 Freshwater Zooplankton !I The freshwater zooplankton are commonly smaller in size and only represented by fewer animal compare to marine counterparts (Davies and Otene, 2009). The freshwater zooplankton comprised of Protozoa, Rotifera, Crustacea, Cladocera, Copepoda, Ostracoda and Meroplankton organism including insect larvae (Davies and Otene, 2009; Parsons, 1980). 2.2.1 Protozoa Planktonic protozoans are classified as unicellular ciliated or flagellated organisms. Ciliates organism are many species in all size classes from <20 11m to about 2 mm. They graze bacteria, unicellular algae, filamentous cyanobacteria, other protozoa and occasionally rotifers and micro zooplankton. Flagellated organism uses the flagella for locomotion, feeding, or both. Flagellates are the principal consumers of suspended bacteria, and important grazers of the bacteria in surfaces and sediments (Finlay, 1998). Protozoa are feed on either picoplankton or nanoflagellates and small nanophytoplanktons according to their size (Ferdous and Muktadir, 2009). The relative size of the ~,rotozoan to its prey also influences their most efficient food-capturing mechanism. Where the predator to prey length ratio exceeds 10: 1, filter-feeding prevails. Where the ratio is smaller than 10: 1, raptorial feeding (seeking out and capturing relatively large, individual food particles) is more common (Finlay, 1998; Fenchel, 1986). 6 2.2.2 Rotifer " Rotifers can be classified as soft-bodied metazoans of invertebrates and they are having a very short life cycle among other type of plankton. There are only about 100 rotifer species that widely spread are planktonic organism and rotifer life cycles are influenced by temperature, food and photoperiod (Ferdous and Muktadir, 2009; Dhanapathi, 2000). Rotifers are considered to be the most diverse group of zooplankton (Baloch, 2010). Rotifer may increase into large number in rapidly under favorable environmental conditions of that area (Dhanapathi, 2000). 2.2.3 Cladoceran Cladocerans are an important group among zooplankton. They form the most valuable and nutritive group of crustaceans' for fishes in the food chain in water column (Ferdous and Muktadir, 2009). Cladocerans are mostly herbivorous in their feeding habit (Baloch, 2010) that feed on smaller zooplankton, bacterioplankton and algae (Ferdous and Muktadir, 2009; Murugan et at., 1998). They are able to response against pollutants which can react in the low concentration of contaminants in water column. 2.2.4 Copepod , \ Copepods zooplankton have toughest or hardest exoskeleton which can help them to swim faster compare to any other zooplankton (Ferdous and Muktadir, 2009). Their feeding habits are differing between the three orders of zooplankton copepods. Generally, Cyclopoid copepods are carnivorous that live on other zooplankton and fish 7 larvae. They also feed on algae, bacteria and detritus. The calanoid copepods are commonly omnivorous that feed on such as ciliates, rotifers, algae, bacteria and detritus. Their food intake of calanoid copepods is mostly dependent on their age, sex, season and food availability. The other group is harpacticoid copepods that are mostly benthic (Ferdous and Muktad ir, 2009). Copepod also can tolerate in harsher environmental forms due to their physical structures and versatile feeding habits (Ferdous and Muktadir, 2009). 2.2.5 Ostracod Ostracods generally are bottom dwellers of water column (Ferdous and Muktadir, 2009). They mostly live on detritus and dead phytoplankton. These organisms are act as food for fish and benthic macroipvertebrates in waterbodies (Chakrapani et al., 1969; Ferdous and Muktadir, 2009). 8 I ,--- r I 2.3 Classification of Zooplankton The classifications of zooplankton are based on their size and duration of their planktonic life. In this aspect, zooplankton can be divided into picoplankton, nanoplankton, microplankton, mesozoplankton, macroplankton and megaplankton (Table 1). Classification of zooplankton based on their stage of development can be divided into two categories; meroplankton and holoplankton. Table 1: Classification of zooplankton based on sizes (Adapted from: Callieri, 2002 as cited in Dussart, 1965) Class Example Size Nanoplankton Flagellates 2-20 /lm Microzooplankton Protozoan, rotifer 20-200/lm Macrozoop lankton Amphipod, shrimp, fish larvae 200-2000/lm Megaplankton Copepod >2000/lm 1 Microzooplankton are a diverse group of organisms that are found in all aquatic . habitats. The arthropods which include in the abundant and diverse of copepod are 66% of the total meso zooplankton species (Diebel, 1992). The change in the abundance or species composition of meso zooplankton may reflect fundamental change in the ocean environment that affecting phytoplankton (Clark, 1992). This is because meso zooplankton are the primary consumers of phytoplankton and plays important function in energy economy of the sea that forming a vital connection 9 ,... between the phytoplankton at the base of the food web to the higher consumer level of finfis h, shellfish, bird and mammals (Diebel, 1992). Zooplankton can be divided into duration of their planktonic life or their development stage as summarized in Table 2, which are Holoplankton and Meroplankton (Michael, 1990). Holoplankton will remain as plankton for their entire life, while meroplankton will a ct as planktonic organism only in larval stages of their life cycle (Harnzah, 2007). Table 2: Classification of zooplankton based on their planktonic life (Adapted from Michael, 1990) Class Example Description Holoplankton Copepod, d ino flagellated,krill, amphipods Remain plankton for their entire life cycle Meroplankton Fish larvae, sea urchins, seastars, crustaceans, worm, gastropods Act as planktonic organism only a portion of their life cycle . II 10 1 2.4 Importance of Zooplankton Zooplanktons contribute significantly to biological productivity of freshwater ecosystems (Naz, 2008). The availability of zooplankton is an important factor that determines the relative survival of juvenile fishes (Fernando, 1994). Young fishes mostly breed in area where the planktonic organisms are plenty to get sufficient food for their survival and growth, especially in pelagic area. Therefore, the occurrences and distribution of zooplankton can influence the pelagic fishery potentials fishes. Zooplankton plays significant role in aquatic ecosystems (Baloch et at., 2010) due to central position between the autotrophs (algae, phytoplankton) and other heterotrophs (fish and other carnivores). They form an important link in the food web of aquatic ecosystems (Tevlin and Burgis, 1979; Gulati, 1982). In addition, they are primary consumer of second trophic level in aquatic food web in most aquatic environments (Basu et aI., 2010; Licandro and Ibaney, 2000). Zooplankton forms the principal source of food for omnivorous and carnivorous fishes (Hossain et at., 2007; Prasad and Singh, 2003), and also support the necessary amount of protein for the rapid growth of larval carps (Basu et at., 2010; Hussain and Rahman, 2008). Zooplankton function to provide fish with nutrients seeing as fish requires proteins, fats, carbohydrates, mineral salts and water in the right quantity (Davies and Otene, 2009; Guy, 1992). Fish can modify zooplankton biomass and thus also phytoplankton concentration due to changes in the intensity of zooplankton grazing (Gulati, 1982). 11 Zooplanktons act as an important group as most of them feed upon and incorporate the primary producers into their bodies and then make themselves available to next higher organisms in the food chain (Michael, 1968). They contribute significantly to biological productivity of freshwater ecosystem and playa major role in the energy transfer at secondary level (Naz, 2008). They are very important in the energy economy of the sea, that forming a vital connection between the phytoplankton at the base of the food web to the "higher" consumer level including finfish, shellfish, bird and mammals (Deibel, 1992). Community structure, biomass, and production are influenced by both producers and consumers which function simultaneously (Mayer et ai., 1997). The abundance of producer and consumer's composition will influenced to the level of community structure of zooplankton in water ecosystem. 2.5 Relationship between zooplankton and physico-chemical characteristic Zooplankton are highly sensitive to environmental variation and provide important indication of environmental change or disturbance as a result of their abundance, species diversity or community composition (Sharma et ai., 2008). The diversity of species, amount of biomass and abundance of zooplankton community can be used to determine health of ecosystem (Uttah et ai., 2008; Ogbeibu and Edutie, 2002). Zooplankton indicates the quality of the' water body in which they are found and as excellent indicator of the environmental condition by respond to low dissolve oxygen, high nutrient levels, toxic contaminant, poor or abundance food quality and predation (Johnson, 2000), 12 The community interactions in pelagic food webs are affected by small to large scale of physical, chemical and biological processes that are tropicaHy dynamic. The interactions are also governed by nutrient limitation, competition, predation and other ecological forces (Mayer et at., 1997). Water parameter such as temperature may give different affect to the zooplankton that depends on their metabolic rate with their respond to their temperature. Organisms like zooplankton tend to adjust temperature slowly because their metabolic rate cannot respond in drastic temperature change (Makinster et at., 2004). Some zooplankton can survive in colder weather in winter month and some can thrive in wanner temperature. Therefore, different plankton group will flourish under different temperature. Besides that, pH is important to act as indicator of the water quality in the water bodies (Jonna[agadda and Mhere, 2000). Water ecosystem that have pH range 6-9 can be threatened by increasing rate of acidic precipitation and the change in acidic levels will give risk ofa zooplankton and phytoplankton declination (Makinster et at., 2004). Suspended solid also will give influence to the water quality parameters. Too high or too low concentration of total suspended solid in water may limit the growth and may cause death of many aquatic organisms (Ntengwe, 2006). Turbidity in water column is caused by the occurrences of suspended of sa lid such as organic and inorganic matter, plankton, silt and clay in the water hodies (Ntengwe, 2006). Turbidity may cause the major effects in blockage of light and smother of organism (Y ong, 1999). Some zooplankton will suffer and risk to declination of their composition due to clogged of their feeding mechanism by suspended solid in the water. 13 Dissolved oxygen also influenced the zooplankton composition. Water is considered as "healthy" when dissolved oxygen is above SmglL (iLau, 2003). The low level of dissolve oxygen «2mg/L) would indicate poor water quality and will give the negative effect on the aquatic life organism. 2.6 Behaviors of Zooplankton Zooplankton conununity show vertical migration In the water column. They swimming actively both through up and back down again within 24 hours. The pattern of normal diel vertical migration (NDVM) occurs in nocturnal and diurnal. Nocturnal occur when zooplankton goes upward at night and diurnal occur downward during the day. While the reverse diel vertical migration (RDVM) also occurs but it pattern does not conunon. The pattern of migration occur when zooplankton go ascent through the water column during the day and descent during the night. The function for the both migration are to avoid predators by fish and reduce the risk of mortality (Lampert, 1989 in Hays et aI., 1996). Zooplankton are more varied by patchiness, diurnal vertical migration and season. Through vertical migration of both type and their presence at varying depths, the zooplankton utilized to assess energy transfer at secondary level (Johanna, 1992). Zooplankton feed on phytoplankton and transfers of plant materials into animal tissue and be the basic food for higher animals. 14