Discussion front transport. The SPM is generally

Discussion  Distribution of SPM in Pulau Bidong According to the data in this study, the distribution of SPM-concentration in Pulau Bidong are largely determined by coastal inputs.  The suspended particulate matter is higher near the coast along all transect. The increase in suspended particulate matter within the euphotic layer at the edge of the continental slope is related to slope front transport. Similarly, this relation were observed by Signoret. M et al (2006) at South of Gulf of Mexico. This significant is very obvious in this study. Northern, Southern, Eastern and Western part of Pulau Bidong shows the same trend of SPM-concentration. However, this trend is very obvious at the Notthern, Eastern and Southern side of Pulau Bidong. The lowest SPM-concentration is observed at the Eastern side of Pulau Bidong and it decrease as it is moving away from coast. The highest concentration of SPM is recorded at Southern side of Pulau Bidong. This might be because of it is near to Pulau Kapas. The SPM-concentration increases from station S1 to S2. S2 station is nearer to coastal than of S1. As it is near to coast, this increase is related to the front transport. The SPM is generally a complex mix of substances of different origins with different properties. However, in the Western side of Pulau Bidong, tends to shows a different trend. The SPM-concentration increases as it moves away from coast. This phenomena is unable to explain in this study because the study is limited to the total SPM. The SPM may be divided into particulate organic matter (POM) and particulate inorganic matter (PIM) (Hakanson. L, 2006). Total organic matter (TOM) is generally divided into POM and dissolved organic matter (DOM). Normally, POM is about 20% of TOM, but this certainly varies among and within systems according to Ostapenia 1987, 1989; Velimorov 1991; Boulion as cited in Hakanson (2006). Normally, about 4% of POM is living and the rest is dead organic matter (detritus). About 80% of TOM is generally in the dissolved phase, and of this, about 70% is conservative in the sense that it does not change due to chemical and biological reactions in the water mass. Thus, it is hard to distinguish whether the SPM-concentration is dominated in the Western part of Pulau Bidong influenced by organic or inorganic particulate matter as the analysis is carried out focussing on the SPM-concentration instead of suspended organic particulate matter (SPOM) and suspended particulate inorganic matter (SPIM). This study could improve by analysing the different properties of SPM.  Distribution of phytoplanktonA total of 63 genus in 4 phylum were obtained from the study area of which the most abundant was from phylum Bacillariophyta. The results of this study revealed that the resource of the study area consists of closely similar genus of phytoplankton, Bacteriastrum is a genus of diatoms in family Chaetocerotaceae (Guiry, M.D. & Guiry, G.M, 2017). Why? Similar observation has been made by W.Cheah et al (2013) at South China Sea. The highest density of phytoplankton is found at Southern part of Pulau Bidong. This may be because of Southern part of Pulau Bidong is nearer to Pulau Kapas. The coastal input from Pulau Kapas might increases the density of phytoplankton in Southern part of Pulau Bidong to be the highest. Coastal inputs are linked to seasonal agricultural activity or irregular events, such as heavy precipitation or major construction. It inputs often derive from extensive areas of land and are transported overland, underground, or through the atmosphere to receiving waters (S.R. Carpenter et al, 1998). It carries phosphorus and nitrogen to the water (S.R. Carpenter et al, 1998). Consequently, it causes the increase in the density of phytoplankton. There are differences in the density of phytoplankton among the sampling stations. A similar result were obtained by W. Cheah et al, (2013) which observed high density of phytoplankton near the coast. The Southern part of Pulau Bidong shows a similar distribution trend along transect. The density of the phytoplankton decreases when moving away from coastal area in South transect. The lowest density of phytoplankton is recorded at Northern part of Pulau Bidong with the range of 11.800 ± 2.532 cell/m3. Northern, Eastern and Western part of Pulau Bidong records a different pattern of phytoplankton distribution along transect. The density of phytoplankton increases as it moves away from coastal. This shows that the abundance of phytoplankton are not only limited to the coast. Some nutrients that the phytoplankton uses are as well high in the offshore areas such as nitrite as one of the main source of nitrite in the water is species excretion (A. F. Karlucci, 1970).  Vertical distribution of salinityFrom this study it was found that the average surface salinity is 33.01 ppt which is slightly higher than the value (32.6 ppt) as reported by Husain. M. L et al (1986). Variation in surface salinity of between the stations are approximately 1ppt and it ranged from a lowest at W2 with 32.60 ppt and to a highest at N1 with 33.36 ppt. The vertical salinity profile diagram shows that the salinity increases with depth. The lower salinity at W2 may be attributed from precipitation might have occurred before sampling. However, freshening of waters at the surface were not observed in any of the stations as the salinity was not lower than 32.5ppt. Overall, the sea surface salinity is higher in the shallow stations near to coastal than the stations in the open ocean.  This is probably due to the fact that the shallow stations were closer to the coast and subjected to sediment runoff that influences the salinity. However this study is contradict with what W. Cheah et al (2013) proposed. Halocline layers were also observed at most of the stations and is more significant at stations in North transect and South part of Pulau Bidong. Vertical distribution of temperatureFrom the temperature-depth profiles, the surface layer for Northern, Eastern and Southern part of Pulau Bidong shows well-mixed layer characteristics until approximately 10m of depth. For Western transect, the well-mixed layer characteristics can also be noticed but with only 4m in depth. The thermocline is exist at east coast of peninsular Malaysia before and after Northeast monsoon season but in deeper part before Northeast monsoon as compared to Southwest monsoon (Saadon. M.N et al, n.d). From this study, thermocline is very obvious. This is not new as it has been reported Akhir, M. F. M & Chuen, Y. J (2011).  Relationship between temperature and salinity profile diagram to find water mass characteristics.During winter season, Australian continent tends to be warmer causing the rising of air creating a low pressure system and the Asian continent is colder that causing descends of air and creating high pressure system. Northeast wind along the east coast of Peninsular Malaysia and in Gulf of Thailand generated by this differences in pressure system together with Coriolis effect are called Northeast monsoon (Saadon M. N at al, n.d). The reciprocal is true in the Asian continent during summer. The formation of different pressure system over Australian and Asian continents are enhanced due to this relationship. The Southwest wind prevails over the Gulf of Thailand and Peninsular Malaysia as a result from the high and low atmospheric pressure system of Australian and Asian continent respectively. Two transitional (in April and October) periods between the two monsoon seasons are distinguishable that tends to last for about four to seven weeks according to Nasir and Marghany (1996) as cited in Saadon, M. N et al (n.d). The Northeast monsoon season brings heavy rain at the east coast of Peninsular Malaysia and minimum precipitation is observed during the Southwest monsoon, especially in July and August according to Camerlengo et al. (1996b) as cited by Saadon, M. N et al (n.d). The overcast skies lowers the ability of the penetration of solar radiation to the atmosphere causes major reduction of evaporation and insolation at the east coast of Peninsular Malaysia during Northeast monsoon especially in November and December. Highest insolation value had recorded at the east coast of Peninsular Malaysia in February and March (Saadon, M. N et al, n.d). The Northeast monsoon wind is stronger than the Southwest monsoon wind (Taira et al, 1996). During Northeast monsoon, the overcast skies reduces the solar insolation and the sea surface temperature reduces. However, the sea surface temperature increases, as the sky clears up, during the Southwest monsoon. The intrusion of water mass from Karimata Straits to South China Sea occurs during Southwest monsoon and the water during this month are usually less saline and high in temperature (Akhir, M. F. M & Chuen, Y. J, 2011). However, in this study, the overall water tends to be high saline and high in temperature. This might be due to high evaporation. Generally, the water generated at equator are high in temperature. Mixed layer water of high temperature in this study not only because of that the current flow from south brings warmer water to this region, but because of high solar heating and weak wind are two other reasons for the characteristics of water mass according to Yanagi et al, 2000 as cited by Akhir, M. F. M & Chuen, Y. J, (2011). Although the sampling provided limited data, the observation can still be made. This study can be improved by obtaining meteorological data to know the precipitation rate of the month of sampling.  Surface distribution of chlorophyll.The distributions of chlorophyll concentrations in the South-Western coastal waters of Pulau Bidong is presented in Figure 6. Measured chlorophyll data in different stations were analysed. Physical structure of water column and variations of seawater properties such as temperature at the time of observations showed a strong thermal stratification (Figure 4). The vertical structure of temperature in the study area is shows a significant seasonal thermocline between 10–20 m depths. Based on measurements, water temperature at the sea surface varied in a range of 3–4 ?C. In that time, salinity values were varied between 32.67 – 33.36 ppt. In the time of measurement, the thermocline was located between 10-20 m depths and temperature at the lower level of thermocline was about 28 ?C. In the study area, chlorophyll-a concentrations changed with the aspects that affect phytoplankton growth. Some of those factors were amount of sunlight, nutrient concentrations near the coastline and amount of mixing. The chlorophyll concentrations were higher near the coast than other stations.  In near coast stations, intrusion of nutrients runoff from sediments into the surface layers occurs. This process enhance the chlorophyll concentration as it can stimulate phytoplankton growth. On the other hand, due to the study area are subjected to few main river influences, the chlorophyll concentration in this study can also be influenced by these river inflow. The maximum concentration of chlorophyll were found at S1. The concentration of measured chlorophyll in S1 and N1 were higher than the concentration measured in W1 and E1.  In total, the concentrations of chlorophyll in South transect and were larger than recorded values in North, East and West transects. The distribution of chlorophyll-a indicated gentle decrease with increasing distance between coastal in the area. Based on measurements at Pulau Bidong water, the amount of the chlorophyll concentrations varied from 0.0084 to 0.642 mg m?3. The concentration of chlorophyll sharply decreases as it moves away from coastal and reaches 0.084mg/m-3. Thus, it is clear that the concentration of chlorophyll in the study area are restricted to near coast area.  Relationship between SDD and SPM   In Pulau Bidong, the Secchi disk depth mainly lies between 12.9m to 22.6m and suspended particulate matter lies between 0.492mg/L to 0.692mg/L. The changes in the concentration of suspended particulate matter in marine water are generally smaller (Postma, 1961).This statement is proved in this experiment as the ranges of suspended particulate matter is between 0.492mg/L to 0.692mg/L. The negative correlation straight line in figure 6 is derived from equation (1) and equation (4). If only measurements at one fixed point during a tidal period are considered, there is again a straight line correlation between the value of disc visibility and suspended matter. This line, however, does not pass through the origin. This may be explained by assuming the presence of a certain amount of finely divided suspended matter which remains in suspension at slack tide and to which increasing quantities of coarser materials are added by increasing current velocities.  The figure shows that the secchi disk depth decreases as the concentration of suspended particulate matter increases. The visibility changes reflects the variations in the concentration of suspended particulate matter (Postma, 1961). The slope of the regression line gives R2 is 0.87 which indicates that the given change in SPM would indicates a strong change in SDD (Postma, 1961). SPM could be influenced by many variables among and within systems (Hakanson, 2006). Increase in SPM decreases the secchi depth. This is because of the SDD is a measure of water clarity. The secchi disk depth increases with water clarity and the greater the potential for photosynthetic production. The importance of this study is that it can be used to define photic zone to estimate productivity area. The photic zone has a maximum depth of 200 m. However, it depends on the light absorption properties of water. The correlation between SDD and SPM is highly significant.  Distribution of nutrients In this study, generally, the distribution of phosphate in Pulau Bidong is mainly influenced by coastal. The concentration of phosphate decreases as it moves away from coastal area. The reason for this might be because of nutrients concentration near the coastline. This data is expected because ocean receives inputs of phosphorus from coastal through weathering such as aerosol fluxes (P. N. Froelich et al, 1982). Similarly, the pattern in this study has also been observed by W.Cheah (2013) in Kuching which observed higher phosphate near coast. However, coastal runoff is not the only possible factors of phosphorus inputs in ocean. The concentration of ammonia is as well high at the Southern part of Pulau Bidong. The concentration of ammonia in Pulau Bidong is mainly dominated by coastal runoff. The Southern part of Pulau Bidong tends to have highest concentration of phosphate and ammonia. This is because it is near to two coastal which are Pulau Bidong and Pulau Kapas. Pulau Kapas is located in the south of Pulau Bidong. The coastal runoff of this two islands increases the concentration of ammonia and phosphate in Southern part of Pulau Bidong. However, coastal runoff is not the only source of ammonia, phosphorus and nitrite in the ocean. There are many biological and chemical processes that contributes to nutrients in the ocean water. Low temperature weathering input will contribute to increase in phosphate concentration in the ocean water. Phosphate could enter the ocean via low temperature reaction between seawater and seafloor basalt (P. N. Froelich et al, 1982). The phosphorus in the sediment releases as the process occurs and increase the concentration of phosphate in the water column. In the ocean, it appears that, in certain micro-environments, decomposition of particulate matter releases ammonia with its subsequent oxidation to nitrite. The amounts of these nutrients and the rate at which they are produced are dependent upon the nature of the materials undergoing decomposition and the associated bacteria. In some other areas of the sea, where phytoplankton standing stock is high and nitrate is non-limiting, excretion by these organisms is a major source of nitrite (A. F. Karlucci, 1970). Thus, the concentration of nitrite is higher in the offshore areas than the near coastal stations.  Distribution of metals in Pulau BidongContamination of heavy metal in marine environment has become a global issue. Normally, heavy metal contaminant in sediment is by they are transported from the urban areas, industrial effluents, boating activities, agricultural runoff, sewage treatment plant and mining activities as reported by Kamaruzzaman, Y et al (2011).  Heavy metal are toxic, non-degradable properties and accumulative behaviour which can affect the environment (Ong et al, 2015). Sediment have become an important indicator to determine pollution in seawater (Wang et al, 2014). Sources of heavy metal in Pulau Bidong are coming from Terengganu River and Merang River (closest to the island) (Ghazali et al, 2015). Anthropogenic sources such as boating are one of the major input of Zn in the ocean. Pb is often introduced to the ocean by anthropogenic sources such as paints and natural sources such as weathering (Mahdzir A., et. al, 2015). Due to the high human activities such as tourisms, high in littering can be lead increasing concentration of cadmium. Boating also can be lead on increasing of concentration of Cd. This is because the boat have coated by anti-fouling paints. Cadmium basically uses as anti-fouling paint for ship and boat. Cu concentration in the sediment may increase due to corrosion of ship’s hull and anti-fouling paints (Bazzi, 2014). Generally, Western side of Pulau Bidong tends to have highest concentration of all four metals observed because it is facing mainland. Based on this study, the IGEO calculated for all metal elements is less than 1.0(Table 1). Therefore, it can be said that the heavy metals in the surface sediment of Pulau Bidong is unpolluted to moderately polluted (Table 2).  Surface current direction in Pulau Bidong. In August, surface current is dominated by Southwest monsoon (Akhir, M. F. M & Chuen, Y. J, 2011). The wind blows across the ocean and moves its waters as a result of its frictional drag on the surface. The drifter in each transect drifted approximately 45° to the right of its direction. This phenomenon can be explained by Ekman transport. Ocean surface current are effluent by many different forces. At very large scales, many currents are associated with a dynamical balance between a pressure force and the Coriolis force called geostrophic current. Ageostrophic current are the current that been balanced by differnet forces and the most common of ageostrophic current is the wind-driven Ekman drift (NOAA & AOML, 2011). The frictional coupling between moving air and ocean surface would only push the water to the same direction of wind if the Earth did not rotates. However, the Earth rotates and the rotation of Earth causes the surface water in the motion to deflect approximately 45° to the right in the Northern Hemisphere called Coriolis Effect. Except at the equator, where the Coriolis Effect is zero, each layer of water put into motion by the layer above shifts direction because of the Earth’s rotation. The highest speed recorded was 0.1659 m/s with average of 0.142m/s. Southwest monsoon are generally less strong than Northeast monsoon (Akhir, M. F. M & Chuen, Y. J, 2011).  Coral Diversity in Pulau Bidong  Relationship between coral vertebrates and coral speciesIn this study, Pomacentridae is the most abundant fish in both transect. This is probably because due to the fish did not swim away from the observer. The most commonly observed fish family was Damselfish (Pomancentridae), with a density of 1.475 ind/m-2. Wrasses (Labridae) and Butterfly fish (Chaetodontidae) also shared a relatively high density of 0.29 ind/m-2 and 0.23ind/m-2 respectively. Similarly, a study conducted by Department of Marine Parks (2004) at Pulau Redang found that the most abundant fish was Pomancentridae. The diversity and abundance of reef fish communities are mainly related to coral reef substratum (Komyakova,V et al, 2013). Need to continue Relationship between coral invertebrates and coral species Particle size distribution Most of the samples were composed of sandy in the range of sandy gravel to slightly gravelly sand. It appeared that the most of the sediment in various stations at Southern part of Pulau Bidong tends to be coarser with quite high percentage of gravel. This might be because of the accumulation of larger grains as they roll toward the land area due to the effect of current (Yaacob.  R et al, 1986). Skewness is a dimensionless measure. Positive values of skewness indicates sediments that are dominated with finer grades and negative values of skewness indicates the dominance of coarser grades (Yaacob.  R et al, 1986). In this study, most of the sediment collected are positively skewed. This means that the sediments is Pulau Bidong are mostly dominated by finer grades of sediments than coarser. The highest skewness value in this study is +0.286 and least skewed is -0.289. Stations S1, S2 and W2 are negatively skewed. This means that the sediments here are dominated by coarser grains. Coarser grains sediments indicates that it is a high energy area which dominated by strong current action (Dyer, 1979). The sediments have kurtosis between 0.750 and 1.628. Thus it is obvious that this area appeared to be characterized by sorting processes. 


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