The Prediction of Plankton Diversity and Abundance in Mangrove Ecosystem

The abundance of phytoplankton and zooplankton have correlation with mangrove conditions in coastal area. The mangrove degradation give negative impact for abundance and diversity phytoplankton and zooplankton. The research aimed to analysis and construct prediction model of abundance and biodiversity of phytoplankton and zooplankton in mangrove ecosystem. The research used the transect method (to determine mangrove density), filtering method (to analyze abundance of phytoplankton and zoopankton) and statistical method (to develop estimation modeling of plankton abundance). The results showed that (1) the mangrove density between 250 trees/Ha 1.250 trees/Ha (2) the phytoplankton abundance were 10.675 ind/L (in mangrove rarely) 24.290 ind/L (in mangrove high density), (3) the zooplankton abundance were 261 ind/L (in mangrove rarely) 2.204 ind/L (in mangrove high density) (4) The modelling analysis showed that (1) the phytoplankton abundance (y) = 0.0303x 22.0590x + 13004 and (2) the zooplankton abundance (y) = 0.0057x 5.39x + 1458.2, with x = mangrove density.

The phytoplankton and zooplankton need the suitable environment and habitat to support their life. The factors influenced the life of phytoplankton and zooplankton are water quality (TSS, water turbidity, pH, salinity, alkali, ammonia, nitrate, phosphate), and soil properties (Berthold et al., 2018;Menteri Negara Lingkungan Hidup, 2004;Mukherjee & Ray, 2012a;Simanjuntak, 2009). The habitats to support phytoplankton and zooplanktons to life are mangrove ecosystem and lagoon ecosystem.
The mangrove and lagoon ecosystem in Meranti Island have been characterized to support plankton to life and grow including soil and water quality (Alvarez & Garcia, 2003;George et al., 2013;Kusmana et al., 2000). But, the degradation of mangrove and lagoon ecosystem (Ardli et al., 2011) caused loss of abundance and increasing mortality of phytoplankton and zooplankton (Abdulwahab & Rabee, 2015;Khalifa et al., 2015;Pratiwi et al., 2016). The degradation of mangrove ecosystem can be seen from the density and biodiversity of mangrove ecosystem. The degradation of mangrove ecosystem can be assumed give impact for the abundance and biodiversity of plankton. This research aimed to analysis and construct prediction model of abundance and biodiversity of phytoplankton and zooplankton in mangrove ecosystem. This analysis using mangrove density as main factot to analysis abundance and biodiversity of phyto and zooplanktoon.

Research Variable
The research variables were mangrove density, the abundance of phytoplankton and zooplankton, the soil properties and the water quality. The mangrove density The method of mangrove density used transects method (Hilmi et al. 2017;Kusmana 1997). The mangrove density used equation was Di = ∑ (mangrove ha -1 ), note = Di is density of mangrove in station -i, xij is density of mangrove species -j, station i, and ni is station -i. The soil properties The soil properties method used Bored method and the laboratory analysis (Table 1). The variables of soil properties were pH, C organic, total N, Na, P, K, Ca, Mg, texture and salinity. The water quality The method of water quality used laboratory analysis. The variables of water quality were Total suspended solid, water turbidity, pH, salinity, alkali, ammonia, nitrate, and phosphate ( Table 2). The abundance of plankton To measure plankton abundance used filtering sample method followed density equation (Honggang et al., 2012;Khalifa et al., 2015;Mckinstry & Campbell, 2017;Ormanczyk et al., 2017;Pratiwi et al., 2016) = ( 20) Notes that are N: plankton dense, a: average of plankton in 1 ml of water (equal 20 water pipe), c: volume of water (ml), and L: volume of water were filtered (lt) The biodiversity of plankton The biodiversity index to analyze plankton are heterogeneity and evenness. The heterogeneity used Shannon Wiener with equation ( ′ ) = ∑ ( ) ( ) =1 , where s = number of species, pi = proportion of species density. The evenness used equation = (exp (H'))/s. (Magurran, 1996)

The mangrove density
The mangrove density in Meranti Island was dominated by Avicennia spp, Rhizophora spp, and Sonneratia spp ( Table 3). The data showed the influencing of mangrove distribution to support plankton life and grow. The presence of phytoplankton and suspended microphytobenthos in lagoon are influenced by the water column (Tsuji & Montani, 2017) the existence of mangrove ecosystem, and presence of the major species and dominant species (Hilmi, 2018;Hilmi et al., 2017;Kusmana et al., 2000Kusmana et al., , 2005Mukherjee & Ray, 2012a). The landscaping and domination species (Hilmi, 2018) of mangrove ecosystem is influenced by soil properties and water quality. The mangrove density in Meranti Island had three grade that were mangrove rare (25 -50 trees ha -1 ) (Station 2), moderate (525-650 tress ha -1 ) (station 1) and dense (900 -1300 trees ha -1 ) (station 3). But, based on Kusmana et al. (2005), Menteri Negara Lingkungan Hidup, (2004) and Ardli and Wolff (2008) note that the mangrove in Meranti Island can be categorized as mangrove rare -moderate.
Based on land cover, density of trees, abrasion, sedimentation (Sari et al., 2016;Syakti et al., 2013), abrasion and intrusion (Hilmi, 2018;Hilmi et al., 2017), the mangrove density in Meranti Island had category as the mangrove degradationn, especially station 2 (rare and high degradation). The mangrove degradation in Meranti Island could be caused by (1) Sari et al. (2016) emphasis that the degradation of mangrove ecosystem also was caused by the decreasing of total economic value from mangrove ecosystem. The degradation of mangrove ecosystem decrease supporting of spawning, feeding and nursery ground for phytoplankton and zooplankton (Cadier et al., 2016;Kruk et al., 2016;Masuda et al., 2017), loosing of the phytoplankton and zooplankton habitat's.

Soil properties
The soil texture, pH, C-organic, N-Organic, P, Ca, Mg, K, Na, and soil salinity (Ashton & Macintosh, 2002; J. G. Kairo et al., 2001; James G. Kairo et al., 2008;Macintosh et al., 2002) have function to support mangrove grow. The soil properties of mangrove ecosystem in Meranti Island were showed by Table 4. The soil properties also were used to find level of fertilize of mangrove ecosystem and classification of soil properties to support mangrove life, phytoplankton and zooplankton growth.
The soil properties in mangrove ecosystem both of (a) chemical properties were pH, C organic N total, capacity of soil cation exchange (CEC), soil fertility matter (P, Ca, Mg, K, Na), soil salinity and (b) physical properties was soil texture can be shown on Table 4. The data of soil properties showed that mangrove ecosystem in Meranti Island had soil properties that were acid -very acid, highest of C organic, N matter moderate, the soil fertility matter like as phosphate and calcium were low, magnesium, potassium, and sodium were highest. The other soil properties were capacity of soil cation exchange was moderate, and salinity was moderate. Based on data suggested that the soil properties in Meranti Island can be categorized good suitable to support mangrove grow (Ashton & Macintosh, 2002; James G. Kairo et al., 2008;Ragavan et al., 2014). Kusmana et al. (2005), Ragavan et al. (2014), Kairo et al. (2001) write that the environment suitability to support mangrove grow are salinity < 30 ppt, pH acidneutral, soil texture between clay -sandy clayloam. Kantharajan et al. (2018), Kusmana et al. (2005) and Truong, Ye, and Stive (2017) write mangrove need supporting of soil fertilizer like as C-organic, N-Organic, P, Ca, Mg, K and Na to grow. But mangrove ecosystem also could support to increase soil fertilizer by leaves, fruit, flower and stem decomposition. The supporting of mangrove ecosystem with decomposition gives positive impact for soil fertilizer. The potential of soil fertilizer in Meranti Island Regency (like as Mg, K, Na, CEC, C organic) showed moderate -high potential. The potential of soil fertilizer will influence to increase mangrove growth including for seedling, sapling and mangrove trees. The soil properties in Meranti Island Regency give the important role for nutrient cycle process in a lagoon and estuary ecosystem to support existence of plankton, zooplankton and benthos as key players of organic nutrient cycling in coastal regions. For example is Arcuatula senhousia (Takenaka et al., 2018) need supporting of C-organic, N-Organic, P, Ca, from decomposition of mangrove leaves, stem and others.

Water quality
The data of water quality in Meranti Island Regency (Table 5) showed the performs of lagoon ecosystem to support phytoplankton and zooplankton life. Abdulwahab and Rabee (2015) and Hilmi, Sari, and Setijanto (2019) write that the main variables of water quality have high correlation with plankton are water temperature, pH, EC, turbidity, TDS, DO, BOD5, total hardness, Ca +2 , Mg +2 , chloride, nitrate and reactive phosphate. Bagheri, Turkoglu, and Abedini (2014) writes that the potential of water quality in Ye-ihrmak Rivers to support phytoplankton are temporal surface temperature had variation between 8.80 and 28.6°C with the annual average temperature was 18.1±7.07 °C. Salinity variations, varied between 7.33 and 12.7 psu, the annual average surface salinity in 2003 was 11.3±0.63 psu.
The data on Table 5 also showed that the water qualities of estuary and lagoon ecosystems in Meranti Island Regency were influenced by mangrove density. The mangrove ecosystem decreasing of water turbidity (from 140 NTU to 25 NTU) and total solid suspended (from 512 mg/l to 244 mg/lt), increasing of pH for aquatic ecosystem (from pH 5,73 (acid) to 7,25 (alkaline). The potential of water salinity in Meranti Island Regency had good suitability to support life of zooplankton and phytoplankton. The other properties of water quality were the decreasing of alkalinities (the mangrove rare to mangrove dense), but mangrove didn't give impact for the potential of nitrate and phosphate.
The Phosphate and nitrogen are essential of an organic matter to support growth and life stage of phytoplankton. The high potential of nutrient matter in aquatic ecosystem will increase the plankton density. MENLH (2004) write the standard value of phosphate is 0.015 mg/l or 0.465 μg A/l, nitrate is 0.008 mg/l or 0.112 μg A/l (0.49-1.07 μg A/l or 0.007-0.015) and the standard of Ammonia is not more than 0.42 ppm -0.3 mg/l or 4.20 μg A/l. The other properties of water quality are pH and dissolve oxygen. The potential pH to support plankton, fish and aquatic organism in brackish water is 5 -9 (Menteri Negara Lingkungan Hidup, 2004). The potential of dissolve oxygen is 2 -10 ppm or less than 2 ppm (Simanjuntak, 2009). Basicaly the nutrient matter in aquatic ecosystem to support plankton growth correlated with water drainage and the potential of water pollution (Simanjuntak, 2009). George et al., (2013) also writes that the mangrove ecosystem as mixing of fresh water with marine water has temperature variation between 22-33.2 o C, pH between 7.8 to 8.3, dissolved oxygen has the range of 0.1 mg L -1 -12.3 mg L -1 , salinity between 1.2-31.5 ppt, and ammoniacal nitrogen between 0.001 -0.744 mg L -1 . According Yan et al., (2012) write that salinity (S), pH, chemical oxygen demand (COD), and nitrite (NO2 -N) were importantly environmental factors influencing the distribution of phytoplankton community. Li et al. (2012) also emphasize that excess nitrogen (N) and phosphorus (P) being primarily responsible for fueling primary production and excessive organic matter accumulation.
The decomposition and remineralization of mangrove detritus is important in nutrient dynamics (Roy et al., 2012) which will increase the water fertilization in mangrove ecosystem. Decomposition and remineralization supply detritus and nutrient through leaching and break down of leaf litter into the adjacent estuary and thus regulates the productivity (Roy et al., 2012). Mukherjee & Ray, (2012b) write that cycling of carbon and nutrients in forest ecosystems shows the forward litter decomposition process. Highly productive mangrove ecosystems (approx. productivity 2500 mg C m −2 day −1 ) shows mangrove ecosystem as source of nutrients. Litter fall is one of the driving forces and the main energy source in this system. Mangrove litter undergoes first degradation and then decomposition into dissolved inorganic nutrients, which are important for growth of phytoplankton. Berthold et al., (2018) also write that pphosphorus supports primary production in the water column and can elevate phytoplankton and macrophyte growth.

The abundance and diversity of phytoplankton
The abundance and diversity of phytoplankton in Meranti Island Regency were shown on Table 6. A lagoon and Estuary in Meranti Island Regency are the important ecosystem to support ecological processes and has functionally linked terrestrial, freshwater, and marine ecosystems (Yamamoto et al., 2018), including as aquatic organism habitat. The phytoplankton is an aquatic organism which has ability to do photosintetic activity as the plant organism with size between 2 -200 µm (Effendi et al., 2016;Su et al., 2015). Phytoplankton has the main contributor to spatial increases in total cell abundance in mesohaline water as a result of the lake's hydrographic characteristics and water quality (Tsuji & Montani, 2017). Phytoplankton as great importance role to drive the transportation activity of surface organic carbon in the coastal, lagoon and mangrove ecosystem are either consumed by detrital feeders or deposited and stored in the sediment (Yilmaz et al., 2018). The potential of phytoplankton in Meranti Island Regency (Table 6) can be shown as the abundance, number of taxa, biodiversity index, dissimilarity index and domination index. The species compositions and community structures of halophytic plants, gastropods, and brachyurans in lagoon have the important role to reach sustainability of lagoon ecosystem (Henmi et al., 2017). The data on Table 5 explained that potential of phytoplankton in mangrove ecosystem were dominated by 1) Cyanophyceae that is Trichodesmium spp (2) Onyema (2007) find in a Polluted Estuarine Creek in Lagos, Nigeria has 48 taxa from 26 genera and 3 classes namely Bacillariophyceae (37 taxa), Cyanophyceae (10 taxa), and Shizomycetes (1 taxon). And Soylu & Gönülol, (2003) write 47 taxa was found in the plankton of the River Yeilırmak Based on data's showed that the station 2 had lowest relatively of number of taxa, pytoplanton dense and a heteronegnity. The station 2 representative of mangrove rare showed the low of mangrove dense give negative impact for the potential of phytoplanton (Kruk et al., 2016;Su et al., 2015), because the mangrove density will support the potential of nutrient matter especially phospate and nitrate were essential nutrient matter for phytoplankton to grow up (Berthold et al., 2018;Su et al., 2015). The primary factors controlling coastal phytoplankton distribution and growth are surface temperature, turbidity, river nutrient loads, and benthic and pelagic consumers (Su et al., 2015).
The data also showed that the number taxa of phytoplankton between 14 -18 taxa's with density between 10,672-24,290 indi/L, heterogeneity index between 1.75 -2.14 and evenness index between 0.66 -0.75. Gharib et al., (2011) observe 203 phytoplankton species which are influenced by marine environments, biotic and abiotic environmental factors give important effects for phytoplankton succession and abundance. Yan et al., (2012) note that in Xiaoqing River estuary has abundance of phytoplankton range from 0.6×104 to 213.30 ×104 cells.m -3 with species dominant are Skeletonema costatum, Tribonema affine, and Chlorella sp. Gharib et al., (2011) also noted that south-eastern Mediterranean Sea, Egypt is dominated by Bacillariophyta (61 genera, 120 species), Pyrrophyta (22 genera, 52 species) and in the freshwater ecosystem is dominated by Cyanophyta, Chlorophyta and Euglenophyta. In Southern Kyushu is dominated by Batillaria multiformis and B. Attramentaria (Yamamoto et al., 2018). Kruk et al., (2016) also note that the dominant taxa are Cyanoprokaryota, Bacillariophyta and Chlorophyta is lower than mangrove ecosystem in Meranti Island Regency. But, potential of phytoplankton taxa dominant in Meranti Island Regency is lower than Mahakam Delta which has 48 taxa phytoplankton belonging to Bacillariophyceae (35), Dinophyceae (6), Chlorophyceae (4), and Cyanophyceae (3). Tsuji & Montani, (2017) reported that the dominant suspended microphytobenthostaxa (Cocconeis spp. and Melosira varians) were mainly distributed in oligo-and mesohaline water, with peaks in mesohaline bottom water. In contrast, the dominant phytoplankton taxa (Skeletonema spp., Heterocapsa triquetra, and Prorocentrum spp.) were abundant at different salinity levels.
Basically, the abundance and diversity phytoplankton also can be used as the indicator of the density status of mangrove. The abundance and diversity of phytoplankton in station 2 (indicated as mangrove rare) lower than station 1 (moderate dense of mangrove) and station 3 (mangrove dense). This data showed that the mangrove density gave positive impact for the abundance and diversity of phytoplankton. The mangrove density will increase the abundance, the potential taxa and the density of phytoplankton.
The data also showed that the potential of phytoplankton in Meranti Island Regency had high relatively dense. The high density, abundance and number of taxa of phytoplankton in Meranti Island Regency indicated good condition of aquatic ecosystem in Meranti Island Regency. The water quality has positive correlation with potential of phytoplankton (George et al., 2013;Masuda et al., 2017;Su et al., 2015). The aquatic ecosystem in Meranti Island Regency had good water quality to aid growth of phytoplankton.

The abundance and diversity of zooplankton
Zooplankton is a type of plankton which has characteristic as animal using the coastal, lagoon and Estuary area as suitable habitat of zooplankton including copepoda as a micro crustcea dominanted in the brackish ecosystem, sea or ocean (Kitamura et al., 2017;Mckinstry & Campbell, 2017;Ormanczyk et al., 2017). Zooplankton also has the important role of aquatic ecosystems and Estuaries areas (Honggang et al., 2012). The abundance and diversity of zooplankton bot of the number, domination index, heterogeneity index and evenness index of zooplankton in Meranti Island Regency were shown on Table 7.
3.6. The model prediction of potential zooplankton and phytoplankton The model prediction of potential zooplankton and phytoplankton used correlation between mangrove density as independent variable (X) with the potential of phytoplankton ( Figure 2) and zooplankton ( Figure 3) as dependent variable (Y). The model prediction of phytoplankton was the abundance of phytoplankton, y = 0.0303x 2 -22.059x + 13004 (polynomial equation) and y = 11.637x + 8955.1 (linier equation). The model of zooplankton was the abundance of zooplankton, y = 0.0057x 2 -5.3921x + 1458.2 (polynomial equation) and y = 2.2235x -450.38 (linier equation).

Mangrove ecosystem in Meranti Island
Regency has categorized rare -moderate have influence for abundance and diversity of phytoplankton and zooplankton. The number taxa of phytoplankton between 14 -18 taxa's, density between 910,600 -10,846,000 ind sample -1 , heterogenity index between 1.75 -2.14 and evennes index between 0.66 -0.75. The total taxa of zooplankton between 3 -7, the density between 2610 -22040 ind/sample, with heterogenity between 0.86 -1.61, evennes between 0.79 -0.83. The grade of mangrove density gives the different potential of zooplankton and phytoplankton.