THE RELATIONSHIP BETWEEN MACROPLASTIC AND LARGE-MICROPLASTIC ABUNDANCE IN THE NORTHERN COASTAL REGION OF WEST PENINSULAR MALAYSIA

Several locations representing recreational area, tourist spots and fish landing grounds were selected in the northern coastal region of Peninsular Malaysia for L-Microplastic (L-MP) data collection. Marine litter samples were collected during HWS and LWN tidal regime. Quadrats of 50 cm x 50 cm were used to collect sediment from surface to 5 cm depth for microplastic analyses. A comparison between macroplastic and L-MP showed a significant relationship with R2 =0.9579 where linear regression computed resulted in y = 26.388x + 0.051, where y: microplastic (kg/m3) while x: macroplastic (kg/m3) for Perlis sampling region. The linear regression obtained for Penang island is y = 0.1248x + 0.0854 with R2=0.9036. Both results showed a significant difference where computed P-values were both <0.05. Findings from Penang island region demonstrated possibility of macroplastic and L-MP abundance relating to tidal condition, where during neap tides more plastics are settled on the beach zone as opposed to during spring tides mainly because of the difference in water volume and movement dynamics. Largest marine litter composition was plastic, followed by fabric and rubber. Although recent plastics used are of biodegradable grades meaning it breaks down into smaller sizes through exposure to sun, hydrolysis and microorganism reactions over time, these L-MP might further degrade to nanoplastic in size. The smallest microparticle reportedly detected in the oceans at the present is 1.6 µm in diameter. Further breakdown of microplastics is imminent and will be difficult to detect as these nano-sized plastics enter the food chain resulting in health risks. Based on this, the UN-SDGs directly affected will be SDGs 3, 6, 12, 14 and 15. KEYWORDS: microplastic, plastic, marine litter, marine debris, health risk, biodegradable

Effect of nitrogen management and seedling raising methods on the productivity of Aus rice under tidal ecosystem of Bangladesh

The low productivity of Aus rice in the tidal ecosystem of Bangladesh is mainly due to the difficulties in nitrogen (N) management under high tidal water along with unavailability of irrigation water during the onset of rice cultivation. Our present study demonstrated how the productivity of Aus rice could be improved using appropriate seedling raising methods and N management practices. The study was laid out in split plot design consisting two factors viz., seedling raising methods (wet seed bed and dry seed bed) and N management practices (six N treatments) in three replications. Results indicated that both the seedling raising methods and N management practices had significant effect on all the yield contributing characters of transplanted Aus rice under tidal condition. Specifically, the combination of seedlings raised in wet seed bed and fertilized with urea super granule (USG) at 10 days after transplanting (DAT) i.e., N3W showed the best values for plant height (110.33cm), number of effective tillers hill-1 (14.60), days required 50% flowering (53.00 DAT), days to maturity (84.33 DAT), panicle length (23.37 cm), number of filled grain panicle-1 (88.13), 1000-grain weight (43.17 g), grain yield (4.62 tha-1), straw yield (6.07 tha-1), biological yield (10.67 tha-1), and harvest index (43.17%). However, in considering the productivity/ grain yield, besides N3W, the whole urea application at land preparation along with wet seed bed (N1W) and USG application along with dry seed bed (N3D) also produced statistically similar results (p<0.01) and thus all these three combinations may be practiced for improving productivity and ensuring horizontal expansion of Aus rice in the tidal ecosystem of Bangladesh.

Hydrodynamic Condition of Tides and Wave Diffraction in the Estuary of Jeneberang River

The coastal hydrodynamic pattern around the estuary is determined by the wave, river discharge, and the tidal condition which work simultaneously. The wave factor contributes to more dominant influence on estuaries located in the open sea. Wave coming towards the coast can generate current on the coast. The current pattern around the estuary is determined mainly by the magnitude of the angle formed between the incoming wave and the coastline. The objective of this research is to analyze the wave diffraction patterns and the length of tidal propagation towards the direction of the coast in the estuary. Investigated area is situated in the estuary of Jeneberang River. The analysis of tidal propagation and wave diffraction covers a reach of 4270 meters upstream. Data collected include bathymetric, wind, and tidal data. Furthermore, the result of this analysis can be used as an input in efforts to manage and develop the coastal area in the estuary of Jeneberang River. The length of the tidal propagation in the estuary of Jeneberang River is approximately 1220 meters upstream. Wave diffraction occurs from the north, northwest, and west direction. The highest wave diffraction came from the west direction with the value of 0.73 m and the lowest wave diffraction came from the north direction with the value of 0.04 m.

Numerical Modeling of Tidal Current Patterns Using 3-Dimensional MOHID in Balikpapan Bay, Indonesia

HighlightsThe results of the model and observation showed the similarity of the amplitude and phase formedAt the highest tide was in the position above the Sea Mean level and the current velocity was lower than when heading to the tideThere was a difference in the direction of the current when heading towards high tideStratification of the water column in both seasons tended to be classified in well-mixed watersAbstractBalikpapan Bay is significant as a link between the cities within and outside of East Kalimantan by becoming the primary path used for local transportation and distribution of produced goods. The various anthropogenic activities increased liquid wastes and debris, which flowed through channels and rivers along the bay. This study aimed to determine tidal current patterns in Balikpapan Bay and its influence on salinity and temperature distributions. This study applied a baroclinic three-dimensional (3D) hydrodynamic model, employing wind, tides, and density variations, resulting from the differences of temperature and salinity, as the model input. To simulate the tidal current flow, we applied MOHID Water Modeling System, which the tidal current patterns depicted current directions and speeds at the different tidal conditions. During the displacement toward the high tidal condition, the water mass moves northwestward entering the river body, while at the displacement toward the low tidal condition, the water mass moves southeastward, which flows toward the coast and without the bay. The current speed varies at certain tidal conditions. At the highest tidal condition, the surface elevation ranged 1.3 - 1.5 m above mean sea level; the current rate is lower compared to the displacement toward high tidal condition, which ranged from 0.01 - 0.15 m/s. At the lowest tidal condition, the surface elevation reached 1 - 1.2 m below mean sea level, and the weaker flow velocity took place (less than 0.15 m/s). The results also showed that the water mass temperature tends to be higher in the inner part of Balikpapan Bay, the Balikpapan Bay waters profile that is increasingly shallow towards the bay head also causes this area to tend to have a higher temperature. Also, areas located on the inside of the bay tend to get more freshwater input from rivers, so this area has lower salinity while the area located at the mouth of the bay tends to be of higher salinity because it gets a lot of mass input of seawater from the Makassar Strait.

Numerical Simulation of Ocean Wave Using High-Order Spectral Modeling Techniques: Its Influence on Transport Sediment in Benoa Bay, Bali, Indonesia

Benoa Bay is threatened by sedimentation issue within the bay. It impairs the water mass circulation, influencing scour, mixing, and turbulence as well as sediment transport processes. This study focuses on the wave characteristic and its relation to sediment transport within Benoa Bay. Spectral wave modeling techniques were employed. The equation was discretized based on the condition of winds, tidal, and currents. Total sediment transported was calculated according to the wave model result. Total suspended sediment (TSS) model was simulated which the simulation considers bed load and suspended load transport. Significant wave height (Hs) ranged 0-0.48 m and 0-0.44 m during high tidal condition and low tidal condition respectively. Wave undulation propagates toward the West and Northwest within Bay. The wave period (Ts) ranged 2-6.5 second. Total sediment transport ranged 2828.16 - 86235.66 m3/year. TSS concentration ranged 1-100 mg/L and 1-155 mg/L during high tidal condition and low tidal condition respectively. Those conditions indicate that the sedimentation has been extremely occurred within the bay. The areas around Benoa peninsula, Benoa harbor, and Serangan Island are heavily polluted by suspended sediment. Bottom sediment is stirred by hydraulic jump off wave propagation. The first wave crest induces scour, which its train carries the stirred sediment entering the bay. If ongoing, this condition will exacerbate the existing ecosystem. Benoa Bay development has a big role evoking the level of TSS and turbidity. The more the sedimentation occurs, the more the ecological problem takes place.

Tidal Current Influence on Distributing Submarine Groundwater Discharge (SGD) Area in the North Lombok Waters, Indonesia [Pengaruh Arus Pasang Surut dalam Distribusi Keluaran Air Tanah Lepas Pantai (KALP) di Perairan Lombok Utara, Indonesia]

Submarine Groundwater Discharge (SGD) has been found in the North Lombok Island. This phenomenon is strongly related to the watershed from Rinjani Mountain permeated in the form of underwater seepages. The largest seepage was observed in Krakas Beach. The emergence of these seepages may affect water quality and nutrient pollution in the surrounding by which the distribution is mainly induced by the tidal current regime. This study aimed to determine the influence of tidal current on low-temperature groundwater distribution and to analyze the environmental issues resulted from this phenomenon. Flow model and statistical analysis were employed to determine the transport pattern of SGD. The tidal current moved southwestward during the high tidal condition ranging from 0-0.15 cm/s. While tidal current flowed northeastward during the low tidal condition ranging from 0-0.3 cm/s. The temperature fluctuation follows the changes of surface elevation around SGD in which the correlation value between those two parameters reached 63 percent. This proves that the cold-water transportation depends on the fluctuation of tidal current (tidal pumping), resulting in the imbalanced ecosystem, especially during the high tidal condition when a greater water mass transport takes place.AbstrakKeluaran Air Tanah Lepas Pantai (KALP) telah ditemukan di utara Pulau Lombok. Fenomena ini sangat dipengaruhi oleh daerah aliran air Gunung Rinjani yang meresap dalam bentuk rembesan bawah air. Rembesan terbesar diketahui berada di Pantai Krakas. Kemunculan rembesan ini mungkin berdampak pada kualitas perairan dan polusi nutrien di sekitarnya yang mana distribusinya sangat dipicu oleh pengaruh arus pasang surut. Tujuan dari penelitian ini adalah untuk mengetahui pengaruh dari arus pasang surut terhadap distribusi air dingin dan menganalisis masalah lingkungan akibat dari kondisi tersebut. Arus pasang surut bergerak menuju barat daya saat kondisi pasang berkisar antara 0-0,15 cm/s, sedangkan arus pasang surut bergerak menuju timur laut pada kondisi surut berkisar antara 0-0,32 cm/s. Fluktuasi suhu mengikuti perubahan elevasi muka air di lokasi KALP dimana nilai korelasi dari kedua parameter tersebut mencapai 63 persen. Hal ini membuktikan bahwa transpor air dingin bergantung pada fluktuasi arus pasang surut, menyebabkan ketidakseimbangan ekosistem, khususnya pada kondisi pasang ketika mekanisme transpor masa air yang lebih besar sedang berlangsung.

OFFSHORE FLOATING MARINE FISH CAGE AQUACULTURE DEVELOPMENT PLANNING EVALUATION BASED ON HYDRO-OCEANOGRAPHY CONDITIONS IN SABANG BAY, WEH ISLAND

Sabang coastal bay becomes the area of significance where the development centered in the semi-enclosed area. Sabang Bay is well-known as the center of marine economy (Aquaculture, Harbor, and marine tourism). Recently, there is a planning initiated by Ministry of Marine Affairs and Fisheries (MMAF) to install the floating fish cage aquaculture (KJA) in the offshore area of Sabang Bay which the planning becomes a controversy between local people, local government, and researchers as well. This study aims to evaluate and discuss the impacts that will be happened if KJA is applied. Field surveys on hydro-oceanography aspects were done measuring currents, tides, waves, winds, bathymetry, water quality, as well as tourism condition. Based on those hydro-oceanography conditions, Sabang Bay categorized into calm water area where the sea current is weak (ranging from 0-0.12 m/s), whilst the high values of pH, salinity, and temperature are identified within the bay during low tidal condition. If KJA is installed within the bay, automatically it will pollute the water due to the accumulation of remaining fish feeder wastes. Moreover, within the bay, there are several attractive marine tourisms such as diving sites, the conservation area of Sophie Rickmers shipwreck site, and hot bubble (fumaroles hydrothermal vent). The presence of KJA will possibly disrupt marine tourism activities so that the implementation of KJA needs to be considered the impacts before installation.

Modeling Tidal Current on Banten Bay During Transitional Monsoons

Hydrodynamical condition of Java sea as a part of Indian-Pacific throughflow system which is influenced by monsoon will affect the condition of Banten bay such tidal current. Bordered by Java sea makes Banten bay preoccupied with fisheries and shipping activities, so the information of current pattern e.g. tidal current is very necessary. This study aims to simulate the tidal current pattern using flow model fm as a numerical approach. Two-dimensional hydrodynamic model was employed to perform the simulation of tidal current. Model was validated by using current and tidal observation data which was taken on September 2015 and April 2016. The result shows that the current moved southwestern toward the land during high neap and high spring tidal conditions which ranged 0 – 0.142 m/s at the first transitional monsoon and 0-0.153 m/s at second transitional monsoon. During low spring tidal condition for both transitional monsoon, the current flowed northwestward on west side and northeastward on east side within the bay which ranged 0 – 0.137 m/s and 0 – 0.127 m/s respectively. The hydrodynamic conditions of Banten Bay are severe different between 2 transitional seasons, especially for the current speed and direction. It induces a different transport mechanism, resulting the unstable accretion and abrasion along Banten Bay coast.