Jurnal Ilmu dan Teknologi Kelautan Tropis, Vol. 4, No. 1, Hlm. 9-23, Juni 2012

POTENTIAL ROLES OF BIOTIC FACTORS IN REGULATING ZOOPLANKTON COMMUNITY DYNAMICS IN BAY SHALLOW WATER COASTAL ECOSYSTEM

Arief Rachman1 and Nurul Fitriya1 1Research Center for Oceanography Indonesian Institute of Sciences Jl. Pasir Putih I, Timur , Jakarta Utara 14430 [email protected]

ABSTRACT The dynamics in zooplankton abundance were regulated by changes in water physical-chemical parameters and interaction with biotic factors. In this research we examined the relationship between zooplankton community dynamic and important biotic factors, such as predation and food availability, in Jakarta bay. Plankton samplings were done in 10 sampling stations in Jakarta bay, from July to November 2009. Zooplankton samples were collected using horizontal towing method with NORPAC plankton net (mesh size 300 µm). Salinity, water depth, water temperature, and water transparency were measured. Phytoplankton samples were also collected with the same method as zooplankton, using Kitahara plankton net (mesh size 80 µm). Zooplankton taxas were grouped into two groups, the prey and predatory zooplankton. The results showed that there were two different patterns in zooplankton groups dynamic i.e., the single and double peak. The abundance peak in most zooplankton groups, such as copepods, cirripeds, luciferids, and tunicates, were induced by the high food availability during the phytoplankton bloom in August. The high abundance of prey zooplankton groups in August was responded by the predatory zooplankton groups, resulting in high abundance of predatory zooplankton in adjacent month. The high abundance of ctenophores and chordates (fish larvae) were suggested as the main factor for the low abundance of other zooplankton in September. Physical and chemical factors were not the regulating factors due to the stability of those factors during this research period. Thus we concluded that food availability and predator-prey interaction were the main factors which regulate zooplankton community dynamics in Jakarta bay. Keywords: predator-prey interaction, zooplankton, abundance peak, food availability, phytoplankton bloom

I. INTRODUCTION bioindicator for environmental changes and pollution, due to the high sensitivity In marine ecosystem, zooplankton of some species to any changes in water plays an important role as a link in marine quality. Variation or fluctuation in water food web, connecting the energy transfer quality might induce seasonal succession between primary producer and higher and fluctuation in the abundance and trophic level organisms, such as shrimps distribution of zooplankton in marine and fishes. Thus any change in ecosystem (Woodmanse, 1958; Hsiao et zooplankton community could affect the al., 2011). The physical and chemical community of the primary producer and parameters that usually limiting the higher trophic level organism (Horne and zooplankton abundance and distribution Goldman, 1994; Nybakken and Bertness, are dissolved oxygen, turbidity, 2005; Marques et al., 2008; Hsiao et al., temperature, current, salinity and pH. 2011). Zooplankton could also be used as Food availability, competition, predation

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and disease were other factors which relatively eutrophic condition during all might also limiting the abundance and seasons, especially during rainy season. distribution of zooplankton in marine This condition should creating a relatively ecosystems (Horne and Goldman, 1994; stable pattern, with low fluctuation, in Nybakken and Bertness, 2005; Escribano both phytoplankton and zooplankton et al., 2007; Hsiao et al., 2011) abundance in shallow water tropical Research on zooplankton coastal ecosystem (Wickstead, 1976; community dynamics revealed that Raymont, 1983; Nybakken and Bertness, bottom-up control by phytoplankton was 2005). an important factor that determines the Jakarta bay locates in the north of abundance and distribution of zooplankton jakarta and it is a shallow coastal waters.. in marine ecosystem. Thus zooplankton There are 13 big and small rivers flows to maxima were usually occurred right after the Jakarta Bay which makes river the occurrence of phytoplankton maxima. outflow plays a great role in transporting Predation by zooplanktivorous fish and huge amount of sediments, nutrients and carnivorous zooplankton, such as pollutants to its ecosystem. A number of ctenophores and chaetognaths, also investigations have been done in the capable on limiting the zooplankton Jakarta Bay and shows a decline in abundance and distribution in marine plankton diversity but harmful algal ecosystem (Horne and Goldman, 1994; blooming was occured more often due to Uye et al., 2000; Escribano et al., 2007; low water quality (Hadikusumah, 2008; Reaugh et al., 2007; Sullivan et al., 2007). Muchtar, 2008; Sidabutar, 2008). Predation was known as one of the major Although research on zooplankton ecological forces that regulating the community in Jakarta bay has been done abundance, biomass and composition of several times, little or no specific attention the prey organisms in coastal ecosystem. was given to the interaction between Predator might also act as top-down zooplankton community dynamic to some control to regulate the dynamics of other important biological factors, such as zooplankton groups, thus might inducing predation and food availability. Thus in the trophic cascade phenomena to happen this research, we examined the in the ecosystem (Pace et al., 1998; relationship between the changes in Vadeboncoeur et al., 2005; Rilov, 2009). zooplankton abundance to predation and Biotic factors plays great role when food availability in Jakarta bay shallow there were no apparent fluctuation on water coastal ecosystem. water physical and chemical parameters during seasonal change. In contrast with II. METHODS temperate marine ecosystem, tropical marine shallow water ecosystem has no The research was conducted in extreme changes in both water Jakarta bay (Figure 1) which was a temperature and salinity all over the year. shallow marine tropical waters, located in Waves and currents were also played a the north of Jakarta, the capital city of great role in creating well-mixed or Indonesia. The width of Jakarta bay is 22 homogenous water columns, thus miles, with maximum depth is ± 30 m. preventing strong thermocline to form in There are 13 rivers flows to Jakarta bay. the shallow water tropical ecosystem. At Those rivers are river of Citarum, Bekasi, the same time, land run-off and river Marunda, Angke, Ciliwung, , outflow carried huge amount of nutrients Kamal, Ancol, Karang, Cakung, lencong, which enriched the ecosystem, creating a Sunter, Pesanggrahan, and Grogol.

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Samples were taken five times at 10 exactly the same method as zooplankton stations around Pluit, Bidadari Island, sampling. Sunda Kelapa, , and Muara Both zooplankton and phyto- Gembong from July to November 2009. plankton were identified and counted in Zooplankton were taken with Plankton and Primary Productivity NORPAC plankton net (mesh 300 µm) by Laboratory, Research Center for horizontal towing method at 1 m depth. Oceanography, Indonesian Institute of The net were towed at 2 knot boat speed Sciences. Zooplankton identification and in 5 minutes. Samples were preserved in enumeration were done using fraction 250 cc plastic bottle and fixated with 4% sub-sampling, taken with 2.5 ml sample borax-neutraled formaldehyde. Salinity, pipette, placed in Bogorov disc and water depth, water transparency, and observed with LEICA MZ-6 stereo water temperature were measured in each microscope. Phytoplankton were also sampling station. Water depth and counted using fraction sub-sampling with transparency were measured with secchi 1 ml stample pipette, placed in Sedgewick disc, while salinity and water temperature Rafter Counting Cell (SRCC) and were measured with SCT. Phytoplankton observed with Nikon Diaphot inverted samples were taken with Kitahara microscope. Phytoplankton cells were not plankton net (mesh 80 µm), using the identified.

Figure 1. Sampling stations in Jakarta bay during research in July to November 2009. The stations were located around Pluit, Bidadari Island, Sunda Kelapa, Tanjung Priok, and Muara Gembong.

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Zooplankton was identified and was not as high as the first peak (Figure grouped into 15 functional groups, then 2). Although in general the predator and further grouped into 2 major groups based prey zooplankton groups have similar on its trophic level, which are predator pattern (Figure 2), all taxa in both groups and prey. The predatory group consist of have its own pattern, which sometimes Cnidaria, Ctenophora, Chaetognatha, very different from the others (Figure 5 Polychaeta, and Chordata (fish larvae), and 6). while prey group consist of Copepoda, Different patterns were occurred Cladocera, Luciferidae, Mysidae, when the absolute abundance data was Malacostraca, Ostracoda, Cirrpedia, converted into relative abundance. The Echinodermata, Mollusca, Bryozoa, and double peak pattern was still observed in Tunicata. Zooplankton identification and predatory zooplankton group, but the grouping was done using reference on pattern of prey zooplankton was changed plankton taxonomy and ecology (Davis, into single peak pattern (Figure 3). The 1955; Newell and Newell, 1963; predatory zooplankton still has first peak Wickstead, 1965; Yamaji, 1966; in August and the second peak in October, Raymont, 1983; Lenz, 2000; Nontji, with a decline in September (Figure 3). 2008). Meanwhile the prey zooplanktons The data were analyzed with only have one peak and it occurred in Pearson cross-correlation method (Bakus September (Figure 3). The pattern of prey 2007), using Biodiversity Pro free zooplankton relative abundance was ecological statistic software (McAleece et different from its absolute abundance al., 1997). To quantitatively measure the pattern (Figure 2). It was interesting to strength of top-down or bottom-up control note that even when the abundance of in the ecosystem, data analysis using prey zooplankton was declined in Trophic Control Index (TCI) September, it occupied more proportion in (Vadeboncoeur et al., 2005). the zooplankton community during adjacent month. III. RESULT AND DISCUSSION 3.1.2. The Dynamics of Zooplankton 3.1. Results Absolute Abundance in Jakarta Bay 3.1.1. General Pattern of Predator and Copepods, cladocerans, cirripeds, Prey Zooplankton Group luciferids and tunicates were dominant Abundance in Jakarta Bay groups in Jakarta bay from July to From this research it was found that November 2009 (Figure 4 and 5).. The the general pattern of predator and prey results also revealed two general patterns zooplankton group abundance were on the dynamic of zooplankton similar (Figure 2). Both groups reached its abundance, which were (1) single peak, or highest abundance, or peak, in August. single maxima; and (2) double peak, or After the first peak, the zooplankton double maxima. Those peaks occurred in abundance was declined in September, both prey and predator zooplankton, before increasing in October and might be although variation on the peak time were regarded as the second peak, although it observed in some groups (Figure 4).

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3 Prey Predator Predator Individu/m

Figure 2. The absolute abundance of prey and predator zooplankton group in Jakarta bay in July to November 2009.

(%) (%) Prey Predator Predator

Figure 3. The relative abundance of prey and predator zooplankton group in Jakarta bay during research in July to November 2009.

The prey zooplankton which tively (Figure 4). Echinodermates reached showed single peak pattern are cirripeds, it peak in July with 4,854.75 ind/m3 and cladoceran, luciferids, mysids, bryozoans, was different from other prey zooplankton echinodermates and tunicates (Figure 4). observed in this research (Figure 4). Two Predatory zooplanktons which showed predatory zooplankton groups, which have single peak pattern are ctenophores and single peak pattern, were reached its chordates (Figure 5). maxima in different month. The Cirripeds, luciferids, mysids, ctenophores reached its peak in September bryozoans, and tunicates were reached its with 341.41 ind/m3, while chordates peak in August, with abundance 17,762.63 reached its peak in August with 707.07 ind/m3, 8,177.78 ind/m3, 575.76 ind/m3, ind/m3 (Figure 5). 62.63 ind/m3, 11,742.42 ind/m3 respec-

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The prey zooplankton which ind/m3, malacostracans were 712.12 showed double maxima pattern are ind/m3, ostracods were 402.02 ind/m3, copepods, malacostracas, ostracods and molluscas were 968.69 i ind/m3, molluscas (Figure 4), while predatory cnidarians 4,289.90 ind/m3, chaetognaths zooplankton which showed such pattern were 3,280.81 ind/m3 and polychaetes are cnidarians, chaetognaths, and were 1,718.18 ind/m3. In the second peak polychaetes (Figure 5). at October, copepods abundance were All zooplankton groups with double 19,081.68 ind/m3, malacostracas were peak pattern reached its first peak in 662.69 ind/m3, ostracods were 144.24 August and the second peak in October. It ind/m3, molluscas were 317.91 ind/m3, was different with the single peak pattern cnidarians were 1,743.84 ind/m3, zooplankton group which has different chaetognaths were 1,183.77 ind/m3 and peak time (Figure 4 and 5). In August polychaetes were 390.71 ind/m3. copepods abundance were 14,430.30

Figure 4. Abundance dynamic of prey zooplankton groups in Jakarta bay during research in July to November 2009.

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Figure 5. Abundance dynamic of predatory zooplankton groups in Jakarta bay in July to November 2009.

3.1.3. The Dynamics of Zooplankton in the community during October, with Relative Abundance in Jakarta relative abundance of 43.74% (Figure 6). Bay Cirripeds reach it peak proportion in It was interesting that the pattern November (Figure 6), with 27.30% of occurred in the zooplankton relative total zooplankton community, although it abundance (Figure 6 and 7) were different reached its lowest abundance in adjacent compared to the one occurred in its month (Figure 4). Lucifreids and tunicates absolute abundance (Figure 4 and 5). The still have its single peak pattern which relative abundance of zooplankton groups occurred at August (Figure 6), with showed its proportion occupied by those relative abundance of 11.77% and 16.90% groups in the community. It also showed respectively. Cladocerans and echino- how its dominance changed during a time dermates were also still retaining its single series research. Different from what peak which occurred in September and occurred in zooplankton absolute July respectively (Figure 6). During the abundance pattern, the pattern of zoo- peak in September, cladocerans have plankton group relative abundance was relative abundance of 19.19%. Echino- specific for each group (Figure 6 and 7). dermates relative abundance was 11.76% The double peak pattern in prey in its peak in July. Mysids highest relative zooplankton groups’ relative abundance abundance occurred in July, with 1.19% was not occurred in most of the groups. of total zooplankton abundance (Figure 6). Only ostracods still have its double peak Malacostracas highest occupation in pattern (Figure 6), with relative abundance zooplankton community occurred in of 0.58% in August and 0.33% in October. November (Figure 6), with relative Copepods occupied its highest proportion abundance of 1.38%.

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Figure 6. Relative abundance dynamic of prey zooplankton groups in Jakarta bay in July to November 2009.

Unlike prey zooplankton groups, abundance of 5.04% and 2.71%. most of predatory zooplankton groups’ Polychaetes seems to have double peak relative abundance still has the same pattern which peak happened in July and pattern as its absolute abundance (Figure 5 November (Figure 7), with relative and 7). Cnidarians still have double peak abundance of 3.34% and 1.55%. pattern in its relative abundance which Ctenophores and chordates still retain its happenned in August and October (Figure single peak pattern which occurred in 7), with relative abundance of 6.17% and September (Figure 7), with relative 4%, respectively. Chaetognaths also have abundance of 0.85% and 1.72%, double peak pattern but occurred in July respectively. and October (Figure 7), with relative

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Figure 7. Relative abundance dynamic of predatory zooplankton groups in Jakarta bay during research in July to November 2009.

3.1.4. The Dynamic of Physical- compared to other physic-chemical factors Chemical Parameters and Food (Figure 8). The highest water transparency Availability in Jakarta Bay was observed during September which Measurement of physical-chemical averaged at 3.77 m. Due to the relatively parameters shows that it was stable with stable condition of Jakarta bay water, it relatively low variation during the was assumed that physical and chemical investigation (Figure 8). The salinity in parameters measured in this research were the water of Jakarta bay was varying not the regulating factor of zooplankton between 27.9 to 34.03 and no extreme community dynamic in the ecosystem. condition was found during this research Phytoplankton bloom was observed (Figure 8). The water temperature of in August (Figure 9), with absolute Jakarta bay water was relatively high, it abundance of 5,48 x 109 cells/m3, varies between 28.3 to 30.27 oC (Figure indicating that phytoplankton as food for 8). Similar to salinity, no drastic zooplankton was very abundant in August. temperature change was observed during Phytoplankton abundance then sharply this research, especially since Jakarta bay declined in the next month (Figure 9). It was a tropical aquatic ecosystem which was interesting to notice that the has no significant difference in water phytoplankton bloom was occurred at the temperature all over the year (Nybakken same time with the peak of several and Bertness, 2005). The depth of Jakarta zooplankton groups (Figure 4, 5, 6, and7). bay was varying in each sampling Thus there seems to be a relationship stations, starting from 4m to 20m deep. between high phytoplankton abundance But the average depth of Jakarta bay water and high zooplankton abundance in this were relatively stable with slight variation research. But the second peak in some in each month, which around 6.41 to 7.68 zooplankton groups might not related to m. Water transparency showed highest the food availability, since as some groups variation between 5 sampling months, reached its peak (Figure 4, 5, 6, and 7),

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the phytoplankton abundance were very predator population stops increasing low in Jakarta bay ecosystem (Figure 9). because of many factors, such as food limitation, increasing competition and 3.2. Discussion cannibalism. Based on the result, it was found that as 3.2.1. Interaction Between Predator and the prey zooplankton abundance increase, Prey Zooplankton in Jakarta Bay the predatory zooplankton abundance also The general pattern in predator and increases (see Figure 2). This was prey zooplankton absolute abundance (see supported by a strong correlation between Figure 2) in this research was similar with prey and predator zooplankton absolute the model of predator-prey relationship in abundance (r = 0.88). When the data of ecosystem proposed by Rosenzweig- absolute abundance were converted to MacArthur (Brewer, 1994; Krebs, 2009). relative abundance, we notice that prey The Rosenzweig-MacArthur model zooplankton occupied more proportion in suggested that as the prey population zooplankton community when the increase, the predator population will predatory zooplankton relative abundance increase as well. At high predator density, was decreasing (see Figure 3).

Dept

Transparen Depth & Transparency Transparency & Depth

Figure 8. Water depth, temperature, and salinity in Jakarta bay during research in July to November 2009.

Figure 9. Phytoplankton density in Jakarta bay during research in July to November 2009.

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A very strong negative correlation zooplankton population during October, between predator and prey relative was not clear. The low density of abundance were observed in this research phytoplankton in September to November (r = -1). It suggested that when the should limit the abundance of prey predatory stress from predatory zooplankton (see Figure 9), yet the second zooplankton was lowered, the prey peak in its abundance was occurred in zooplankton could increase its population October (see Figure 2 and 3). It might also thus occupy more space in zooplankton was not related to the physical and community. It was interesting to note that chemical parameters in Jakarta bay, due to the first peak in prey and predatory the stability of those factors during this zooplankton was occurred at the same research periods (Figure 8). time as the phytoplankton bloom Result from TCI analysis showed an phenomena (see Figure 2, 3, and 9). The interesting pattern which suggest that the prey zooplankton, which was strength of bottom-up control was high phytoplankton grazer, seems response to (low TCI) during July to August (Figure the high density of phytoplankton in 10). The increasing TCI value during August by increasing its own population (r September to October was the indication = 0.8). As the prey zooplankton that the bottom-up control was gradually population increasing, the predatory replaced by top-down control (Figure 10). zooplankton, which feed on prey Higher TCI value in September to October zooplankton, will also increase. The indicating a stronger top-down control in decline in prey zooplankton abundance in zooplankton community. Although the September might was related to the strength of top-down control was not very decline in phytoplankton abundance and high (Figure 10), we suggest that it the result of predatory pressure inflicted capable of causing a variation in by predatory zooplankton. zooplankton community dynamics, Unfortunately the reason of the especially in prey zooplankton groups. second increase in both prey and predator

Figure 10. Dynamics of trophic control index (TCI) value in Jakarta bay during July to November 2009.

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3.2.2.Variability in Abundance Pattern polychaetes. In this research we did found of Zooplankton Groups’ in that cladocerans were negatively Jakarta Bay Related to Predator- correlated with those three predatory Prey Interaction zooplanktons; and (2) lowered compe- From the result now it assumed that tition pressure, as the competitor the food availability was important factor zooplankton abundance, such as copepods which regulating the abundance of and cirripeds, were declined in September predator and prey zooplankton in Jakarta (Figure 4). The decline in most prey bay. Observation on each zooplankton zooplankton group most likely related to groups revealed that there are two specific the predation pressure by some predator patterns in its abundance dynamic, the zooplankton group (Figure 4). single peak and double peak (see Figure 4, It was interesting to note that the 5, 6, and 7). These two distinct patterns abundance of three predator zooplankton were similar to two type of population group, the cnidarians, chatognathes and growth curve proposed by Aldo Leopold, polychaetes, were also decline in which were irruptive and cyclic type September. Meanwhile the abundance of (Brewer, 1994). Single peak pattern in ctenophores and chordates (fish larvae) some zooplankton abundance dynamic were very high in adjacent month (Figure most likely showing an irruptive type 5). Based on this data, we assumed that population growth, while the double peak ctenophores might be the main predator pattern showing cyclic type population for the most of zooplankton in Jakarta growth (see Figure 4 and 5). bay. The high abundance of ctenophores Variability in zooplankton groups’ and chordates might be the cause of the abundance pattern was most likely related low abundance or the decline in most of to the different response in food zooplankton group’s abundance, including availability and predatory stress. In most the other predatory zooplankton during prey zooplankton groups, the first peak September 2009 (see Figure 4 and 5). was highly related to the phytoplankton Data of their relative abundance in bloom which occurred in August. zooplankton community also support this Copepods, cirripeds, luciferids, mysids, assumption (see Figure 6 and 7). malacostracans, osctracods, molluscs, Ctenophores and chordates were occupied tunicates, and bryozoans were prey more proportion in zooplankton zooplankton groups which reach the peak community in Jakarta bay during at August. Cladocerans, which also known September (see Figure 7). as phytoplankton grazer (Raymont, 1983), Ctenophores and chordates might didn’t reach its peak at the same time at feed on most zooplankton groups, phytoplankton bloom phenomena. including the other predatory zooplankton, Cladocerans reach its peak when other thus reducing their abundance during high prey zooplankton abundance was abundance of those two predator declining in September (see Figure 4). It zooplankton group. We found that was interesting to note that cladocerans ctenophores were negatively correlated peak was happened during the high with nearly all prey zooplankton taxa, abundance of its predator, the ctenophores except the cladocerans. It also negatively and chordates (see Figure 5). We suggest correlated with all predatory zooplankton that it might happen as the combination taxa, except the chordates. Meanwhile of: (1) lowered predatory pressure from chordates were negatively correlated with other predatory zooplankton, such as two prey zooplankton group, the cnidarians, chaetognathes and echinodermates and mysids. Ctenophores

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and chordates were known to feed on prey zooplankton groups. Thus we could crustacean zooplankton, such as copepods, conclude that biotic factors, such as food cladocerans, malacostracans, and availability combined with the predatory luciferids (Wickstead, 1965; Roohi et al., pressure, were the main factors which 2006). regulated the dynamic of zooplankton Thus, we suggest that ctenophores abundance in Jakarta bay. might be the main predator, as well as the top predator in the zooplankton Acknowledgement community of Jakarta bay. Even with very This research was conducted with low abundance, the ctenophores seem to the competitive research grants from be able to drive the dynamics of prey and DIKTI in 2009. We would express our other predatory zooplankton groups (see sincere gratitude to Mrs. Hikmah Thoha, Figure 4, 5, 6, and 7). High TCI value in M.Sc., as lead scientist in Planktonology October (see Figure 10) was coincided Laboratory at Research Center for with peak in some zooplankton groups Oceanography, for the very helpful and very low abundance of ctenophores in discussion on our research theme. We also adjacent month (see Figure 4 and 5). This express our gratitude to Mrs. Elly might indicate that the low abundance of Asniariati and Mrs. Sugestiningsih, our ctenophores resulting in higher abundance laboratory technicians whom helped us to of both prey and predatory zooplanktons, enumerating zooplankton individuals and this happened due to lower predation phytoplankton cells in our samples. pressure from ctenophores in adjacent month. Thus we suggest that ctenophores REFERENCES might be the keystone species in zooplankton community of Jakarta bay Bakus, G. J. 2007. Quantitative analysis of during our research. Unfortunately we marine biological communities: cannot confirm this assumption since field biology and environment. John further intensive experimental experiment Wiley & Sons, Inc. USA. 102- was needed to determine the role of 106pp. ctenophores as keystone predator in Brewer, R. 1994. The science of ecology Jakarta bay ecosystem. 2nd ed. Saunders College Predation by predator zooplankton Publishing. USA. 188-198pp. might act as ecological force that prevents Davis, C. C. 1955. The marine and the dominance of one prey zooplankton freshwater plankton. Michigan State group. The predatory zooplankton might University Press. USA. 426p. act as top-down control, which regulate Escribano, R., P. Hidalgo, H. Gonzalez, R. the dynamics of prey zooplankton groups. Giesecke, R. R. Bugueno, and K. Predation might also promote the Manriquez. 2007. Seasonal and coexistence balance between all inter-annual variation of meso- zooplankton groups in Jakarta bay shallow zooplankton in the coastal upwelling water coastal ecosystem. The role of food zone off central-southern Chile. availability (either phytoplankton or prey Prog. Oceanography, 75:470-485. zooplankton) as the regulator of Hadikusumah. 2008. Perubahan massa air zooplankton abundance, were also di Teluk Jakarta sebagai indikasi regarded as ecological force that inducing perubahan iklim. In: Ruyitno (ed.). the peak of some zooplankton groups. Kajian perubahan ekologis Teluk Food availability might act as bottom-up Jakarta. LIPI Press. Indonesia. control, which regulate the dynamics of

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