Singapore Waters Research Articles

The sharks and rays at Singapore’s fishery ports

The status of elasmobranchs in Southeast Asia has been highlighted as a serious concern, yet there are limited data to assess stocks and develop appropriate management plans. Surveys of elasmobranchs at two fishery ports in Singapore were conducted between 2017 and 2020. These fishery ports receive fresh, whole imports of seafood from the region as well as seafood caught in Singapore waters. Data were collected on 13,817 rays, 2,480 sharks, and 1,297 wedgefishes and giant guitarfishes over 102 surveys. The majority of elasmobranchs were imported from Indonesia or Malaysia, and only a few individuals (six sharks and 278 rays) were reportedly caught within Singapore waters. In Singapore, elasmobranchs are predominantly used for their meat, and wedgefish snouts are also commonly used in collagen soup. The data collected highlights potential conservation concerns, particularly surrounding the large volumes of Maculabatis gerrardi and Maculabatis macrura rays (categorized as Vulnerable and Not Assessed by the IUCN) that are imported, and the high proportions of immature individuals of Carcharhinus sorrah and Carcharhinus sealei sharks. During this study, a single Rhynchobatus cooki was discovered – the first reported sighting in over 20 years.

Athletes’ and coaches’ perspectives of performance analysis in women’s sports in Singapore

ABSTRACT To date, little consideration has been given to the context in which performance analysis (PA) is used by female athletes, in women’s sports and in an Asian context. Through the use of an online questionnaire and follow-up semi-structured interviews, the perspectives towards the use of PA and feedback by athletes and coaches in two female’s sports in Singapore (water polo: one coach and 13 athletes; netball: one coach and eight athletes) were explored. Four key themes emerged from the inductive analysis of the data: (1) learning environment in teams, (2) considerations on the use of PA to aid development and learning, (3) application of game-related learning into practice through PA and (4) organisation of PA sessions: duration and design. The results indicated female athletes from Asian cultures welcomed group discussions, viewed information around areas for development in a positive light and were receptive to longer video reviews. Coaches and analysts should acknowledge the culture of the learner or group in addition to the session format when planning and delivering PA provisions to best meet the learners’ needs.

Numerical study of tides in the Malacca Strait with a 3-D model

Malacca Strait (MS) has an important role and potential for many countries. It is a major transportation route for oil and commodities across continents. In addition, various activities such as shipping, fishing, aquaculture, oil drilling, and energy are also carried out in MS. Tides strongly affect the MS environment so that it becomes a major parameter in MS management. This paper is the first study, which presents MS tidal hydrodynamics based on a baroclinic and nonhydrostatic approach. Tidal hydrodynamics in MS and the surrounding waters were assessed using tidal forces, temperature, salinity, and density. This study analyzes the amplitude, phase, current ellipses, and semi-major axis of the tides. These variables are obtained from the simulation results of the three-dimensional numerical models of M2 tides and combined tides (M2, S2, N2, K1, and O1) with nonhydrostatic models. Then the results obtained are verified by observation data. Amplitude and phase of the tidal wave in MS originate from two directions, namely the northern part of MS (Andaman Sea) and the South China Sea (SCS). Tides from the north of MS propagate into the MS, while tides from the SCS travel to Singapore Waters (SW) and the south of MS. This causes a complex residual flow in SW and shoaling in the middle of MS. Shoaling in the middle of MS is characterized by a large amplitude and semi-major, as in B. Siapiapi. The results of this analysis show that tidal waves are dominated by semidiurnal types rather than diurnal types. The M2 current ellipse has dominantly anticlockwise rotation along the west of the MS, while along the east of MS, it has generally a clockwise rotation.

Estimation of colored dissolved organic matter using Sentinel-2 data in the coastal waters of Singapore

In coastal waters, colored dissolved organic matter (CDOM) is often present in moderate to high concentrations due to input from nearby landmasses and rivers. CDOM absorbs light sharply in the UV-blue region, causing waters to appear yellow or brown. This has a significant effect on optical and biogeochemical processes in coastal waters, as it inhibits the penetration of light within the water. It is thus important to be able to monitor CDOM levels on a regular basis. A model is presented linking Sentinel-2 reflectance data to the CDOM absorption coefficient. Such a model is useful for monitoring the CDOM absorption in coastal waters due to the frequency of Sentinel-2 passes and relatively high-spatial resolution. This model was developed and validated using concurrent field measurements of above-surface remote-sensing reflectance and the in situ CDOM absorption coefficient, from the coastal waters of Singapore. The leave-one-out cross-validation scheme was used to validate the model due to the small number of data points. The model is further tested with Sentinel-2 images of the same locations, not more than one day apart from the in situ measurements.

Two new species of Grandidierella (Amphipoda, Corophiida, Aoridea) from Singapore

Two new species of Grandidierella Coutière, 1904 from Singapore waters are described based on specimens collected during the Comprehensive Marine Biodiversity Survey (CMBS) between 2010–2015. Grandidierella pawaiensis sp. nov. differs from the rest in the genus by a combination of characters; (1) gnathopod 1 carpus proximoventral corner with apically acute process, (2) inner face of carpus of gnathopod 1 proximoventral corner with curved process, (3) proximal margin of dactylus of gnathopod 1 male with excavation, and (4) gnathopod 2 basis anterior margin crenulate. Grandidierella sungeicina sp. nov. on the other hand, is distinguishable from other related species of Grandidierella found in the tropical region by its paired mid-dorsal projections on pereonites 2 to 5, 1 ventrodistal triangular projection on pereonite 4, and gnathopod 2 ischium with 1 large trapezoid projection.

Singapore's Water Strategy: Diversified, Robust, and Sustainable

Key TakeawaysDriven mostly by industrial development, demand for water in the island city‐state of Singapore is expected to almost double by 2060.The use of reclaimed water (known as NEWater) is the most sustainable and cost‐effective way to boost Singapore's water supply for the long term.Singapore's national water agency is encouraging companies in water‐intensive industries to implement innovative solutions to improve water sustainability.

The impact of transboundary haze pollution on household utilities consumption

This paper examines the causal effects of air pollution on the household consumption of water and electricity in Singapore. Using the transboundary haze pollution caused by forest fires in Indonesia as an exogenous shock, we find that increases in haze pollutant intensity in the air significantly increase water and electricity consumption. In particular, the intra-day and inter-day analyses on hourly household water consumption are consistent with the risk avoidance and the risk mitigation behaviors during severe haze episodes. During the haze periods, households stay indoors and avoid outdoor activities to minimize exposure to health risks. When they need to engage in outdoor activities during the weekdays, they increase efforts in mitigating health risks associated with air pollution. Moreover, the analysis of social media data shows that the level of public awareness of air pollution is positively related to energy consumption by households. In addition, the effects of haze-induced utilities consumption is correlated with the duration of air pollution. While household utilities consumption quickly returns to normal after transitory pollution exposure, the effects are stronger and persistent after a longer period of air pollution; households maintain a higher level of utilities consumption for two months after a lengthy haze, suggesting a substantial spending on additional water and electricity usage due to air pollution events.

Diet and mitochondrial DNA haplotype of a sperm whale (Physeter macrocephalus) found dead off Jurong Island, Singapore.

Despite numerous studies across the large geographic range of the sperm whale (Physeter macrocephalus), little is known about the diet and mitochondrial DNA haplotypes of this strongly female philopatric species in waters off Southeast Asia. A female sperm whale found dead in Singapore waters provided the opportunity to study her diet and mitochondrial DNA haplotype. Here we report on the identification of stomach contents and mitochondrial DNA haplotype of this individual, and we include coastal hydrodynamic modelling to determine the possible geographic origin of the whale. At least 28 species of prey were eaten by this adult female whale, most of which were cephalopods. The mesopelagic squids Taonius pavo, Histioteuthis pacifica, Chiroteuthis imperator,and Ancistrocheirus lesueurii made up over 65% of the whale’s stomach contents. Plastic debris was also found in the whale’s stomach. Based on the diet, genetics, and coastal hydrodynamic modelling that suggest an easterly drift of the whale carcass over several days, the dead sperm whale in Singapore probably originated from a pod in the Southern Indian Ocean. This study provides an increase in the understanding the diet and natural history of the sperm whale in Southeast Asia. The combined analyses of stomach contents, DNA, and hydrodynamic modeling could provide a context to future studies on the sperm whale strandings, and have broader applicability for other marine mammals in the region.

The socio-ecological practice of building blue-green infrastructure in high-density cities: what does the ABC Waters Program in Singapore tell us?

Blue-green infrastructure (BGI) is the network of green spaces that provides multiple water-related ecosystem services. This article explores the Active, Beautiful, Clean (ABC) Waters Program as a socio-ecological practice that builds BGI for the high-density city-state of Singapore. Launched in 2006, the ABC Waters Program aims to simultaneously improve the recreational value, physical appearance, and water quality of all waters in Singapore through 2030. Driven by the quest for water security and the pursuit of a higher quality of life, the program involves sustainable stormwater management and waterway enhancement to enrich the functions of the existing aquatic and terrestrial green spaces. The ABC Waters Program provides valuable lessons for other high-density cities to overcome land scarcity as a constraint on BGI. With a shortage of green spaces, high-density cities should strive to optimize the existing green spaces in the provision of ecosystem services and to leverage cultural ecosystem services to engage citizens and gain public support. The case study on the ABC Waters Program also reveals a research gap in the socio-ecological practice research on BGI planning and design. The fundamental question of what qualifies as BGI has yet to be answered, and it is rarely discussed to what degree urban waterways can be considered BGI.

Construction land sprawl and reclamation in the Johor River Estuary of Malaysia since 1973

The Johor River is the main source of water in Johor Bahru and Singapore as well as a vital maritime passage in the eastern Straits of Johor. However, the Johor River Estuary (JRE) has been experiencing environmental degradation due to construction land sprawl and reclamation (CLSR), which shows a combined effect of anthropogenic environmental change. In this paper, the spatial and temporal variation of CLSR in the JRE was studied based on twelve multi-temporal Landsat images (Landsat MSS, TM and OLI) obtained from 1973 to 2017. The results showed that the area of construction land increased more than 10-fold from 1973 (13.33 km2) to 2017 (135.46 km2). Each type of construction land showed an increasing tendency, and their area-weighted centroids migrated towards the mouth of the Johor River. Over the last four decades, an increased land area of 40.32 km2 contributed by reclamation was mainly distributed in the Tekong Island and the eastern Singapore Islands, which shortened the minimum distance between lands in the JRE. The largest decrease in minimum distance was 1889 m between Johor Bahru and Tekong Island. CLSR is mainly driven by human activities such as population growth, economic development and policy change. To better protect the coastal environment in the JRE, construction land expansion and reclamation activities should be planned properly by the local government.

The leakage of sewer systems and the impact on the 'black and odorous water bodies' and WWTPs in China.

China has achieved significant progress on wastewater treatment and aquatic environmental protection. However, leakage (in- and exfiltration) of sewer systems is still an issue. By using the statistical data of water and wastewater in 2016 in China, and the person loads (PLs) of water and wastewater in Singapore, the leakage fractions of hydraulic flow, organic carbon (COD), nitrogen (N) and phosphorus (P) mass loading, and in-sewer COD biological removal in the sewer systems of China (except Hong Kong, Macau and Taiwan), Shanghai, Guangzhou and Beijing were reported for the first time. The fractions of hydraulic flow infiltration (13%, Shanghai and Guangzhou) and exfiltration (39%, China) were calculated. Except Beijing, whose sewer networks are under appropriate management with small leakage fractions, the exfiltration fractions of COD (including in-sewer biological COD removal) ranged from 41% (Shanghai) to 66% (China) and averaged 55%; N ranged from 18% (Shanghai) to 48% (China) and averaged 33%; and P ranged from 23% (Shanghai and Guangzhou) to 44% (China) and averaged 30%. The exfiltrated sewage, COD, N and P not only wastes resources, but also contaminates the aquatic environment (especially groundwater) and contributes to 'black and odorous water bodies'. In- and exfiltration in the sewer network leads to low influent COD concentration, C/N ratio and high inorganic solids and inert particulate COD concentrations of many municipal wastewater treatment plants (WWTPs) causing high cost for nutrient removal, poor resource recovery, additional reactor/settler volume requirement and other operational problems. Therefore, tackling sewer leakage is of primary importance to today's environment in China. Recommendations for the inspection of sewer systems and the rehabilitation of damaged sewers as well as the development of design and operation guidelines of municipal WWTPs tailored to the specific local sewage characteristics and other conditions are proposed.

Planulation in the Scleractinian Coral Pocillopora damicornis in Singapore Waters

Planulation in the Scleractinian Coral Pocillopora damicornis in Singapore Waters

Larval development of the invasive charru mussel, Mytella strigata (Bivalvia: Mytilidae)

ABSTRACTThe South American charru mussel, Mytella strigata, was recently recorded in Singapore waters, possibly introduced into Southeast Asia through shipping. The mussels have rapidly spread across estuarine coastal mudflats. Adult mussels were collected, spawned in aquaria and larvae were successfully cultured to the juvenile stage in the laboratory. The larval morphology and development of M. strigata is described in this paper. D-shaped veligers were produced within 20 h of fertilization and were approximately 75 µm in shell length. These larvae were capable of settlement two weeks post fertilization. Given an adequate amount of food, they were able to grow up to 1 mm in shell length within 30 days. The larval shell of M. strigata possesses anterodorsal G2 hinge teeth as distinct wavy ledges, with a pitted resilial ridge clearly evident in the juvenile shell.

Resource-Constrained Scheduling for Maritime Traffic Management

We address the problem of mitigating congestion and preventing hotspots in busy water areas such as Singapore Straits and port waters. Increasing maritime traffic coupled with narrow waterways makes vessel schedule coordination for just-in-time arrival critical for navigational safety. Our contributions are: 1) We formulate the maritime traffic management problem based on the real case study of Singapore waters; 2) We model the problem as a variant of the resource-constrained project scheduling problem (RCPSP), and formulate mixed-integer and constraint programming (MIP/CP) formulations; 3) To improve the scalability, we develop a combinatorial Benders (CB) approach that is significantly more effective than standard MIP and CP formulations. We also develop symmetry breaking constraints and optimality cuts that further enhance the CB approach's effectiveness; 4) We develop a realistic maritime traffic simulator using electronic navigation charts of Singapore Straits. Our scheduling approach on synthetic problems and a real 55-day AIS dataset results in significant reduction of the traffic density while incurring minimal delays.

The demosponge Pseudoceratina purpurea as a new source of fibrous chitin

Among marine demosponges (Porifera: Demospongiae), only representatives of the order Verongiida have been recognized to synthetize both biologically active substances as well as scaffolds-like fibrous skeletons made of structural aminopolysaccharide chitin. The unique 3D architecture of such scaffolds open perspectives for their applications in waste treatment, biomimetics and tissue engineering. Here, we focus special attention to the demosponge Pseudoceratina purpurea collected in the coastal waters of Singapore. For the first time the detailed description of the isolation of chitin from the skeleton of this sponge and its identification using diverse bioanalytical tools were carried out. Calcofluor white staining, FTIR analysis, electrospray ionization mass spectrometry (ESI-MS), SEM, and fluorescence microscopy as well as a chitinase digestion assay were applied in order to confirm with strong evidence the finding of alpha-chitin in the skeleton of P. purpurea. We suggest that the discovery of chitin within representatives of Pseudoceratinidae family is a perspective step in evaluation of these verongiid sponges as novel renewable sources for both chitin and biologically active metabolites, which are of prospective use for marine oriented biomedicine and pharmacology, respectively.

Resting Stage of PlanktonDiversity from SingaporeCoastal Water: Implications for Harmful Algae Blooms and Coastal Management.

Resting strategies of planktonic organisms are important for the ecological processes of coastal waters and their impacts should be taken into consideration in management of water bodies used by multiple industries. We combined different approaches to evaluate the importance of resting stages in Singapore coastal waters. We used molecular approaches to improve the knowledge on Singapore biodiversity, we sampled and extracted cysts from sediments to evaluate the density of resting stages in Johor Strait, and we compared systematically information on Singapore planktonic biodiversity to existing published information on resting stages from these reported organisms. This is the first study evaluating the importance of resting stages in Singapore waters. Above 120 species reported in Singapore are known to produce resting stages though no previous work has ever been done to evaluate the importance of these strategies in these waters. The results from the resting stage survey confirmed 0.66 to 5.34 cyst g-1 dry weight sediment were present in the Johor Strait suggesting that cysts may be flushed by tidal currents into and out of the strait regularly. This also suggest that the blooms occurring in Singapore are likely due to secondary growth of Harmful Algae Bloom species in the water rather than from direct germination of cysts from sediment. Finally, we discuss the importance of these resting eggs for three main national industries in Singapore (shipping, marine aquaculture and provision of drinking water through seawater desalination). We argue that this study will serve as a baseline for some of the future management of Singapore waters.

Maritime Traffic Probabilistic Forecasting Based on Vessels’ Waterway Patterns and Motion Behaviors

Maritime traffic prediction is critical for ocean transportation safety management. In this paper, we propose a novel knowledge assisted methodology for maritime traffic forecasting based on a vessel’s waterway pattern and motion behavior. The vessel’s waterway pattern is extracted through a proposed lattice-based DBSCAN algorithm that significantly reduces the problem scale, and its motion behavior is quantitatively modeled for the first time using kernel density estimation. The proposed methodology facilitates the knowledge extraction, storage, and retrieval, allowing for seamless knowledge transfer to support maritime traffic forecasting. By incorporating both the vessel’s waterway pattern and motion behavior knowledge, our solution suggests a set of probable coordinates with the corresponding probability as the forecasting output. The proposed forecasting algorithm is capable of accurately predicting maritime traffic 5, 30, and 60 min ahead, while its computation can be efficiently completed in milliseconds for single vessel prediction. Owing to such a high computational efficiency, an extensive predictive analysis of hundreds of vessels has been reported for the first time in this paper. A web-based prototype platform is implemented for Singapore waters to demonstrate the solution’s feasibility in a real-world maritime operation system. The proposed approaches can be generalized for other marine waters around the world.

Understanding the behavioral influences behind Singapore's water management strategies

This paper aims to uncover the key behavioral influences behind two of Singapore's most successful water management strategies: (1) their high public acceptance rate of reclaimed water (marketed as ‘NEWater’), and (2) the adoption of targeted domestic water conservation behaviors. We used the Theory of Planned Behavior framework to construct a household survey that was mailed to a national sample (n = 218) obtained from the Singapore Department of Statistics. Our descriptive and path analysis results indicate that 74% of Singaporeans generally approve of NEWater, and that a positive attitude toward this municipal water technology was the most significant variable in predicting respondents' level of approval. In terms of water conservation, the most widely adopted behaviors were fixing water leaks promptly (80.8%) and monitoring water bills (80.3%). We discuss how knowledge of these key behavioral influencers can make behavior change campaigns more effective both in Singapore and other countries.

The bottom water exchange between the Singapore Strait and the West Johor Strait

As a part of the border between Singapore and Malaysia, the West Johor Strait (WJS) suffered newly from harmful algal blooms. There is no previous study showing the source of the nutrients in the WJS. This paper is investigating the possible water exchange between the water in the WJS and the bottom water in Singapore Strait.This paper adopts a two-level nesting atmosphere-ocean coupled models to downscale the global atmosphere-ocean model into the Singapore coastal water, keeping the large-scale and long-term ocean and climate circulation signals and the advantages of the high-resolution. Based on the high-resolution ocean circulation fields, a Lagrangian particle tracking model is used to trace the Singapore Strait's bottom water movement and the water mixing in the WJS.The results showed that the numerical models well resolved the Singapore coastal water regional circulation. There is a small but significant bottom water (1.25%) transport from the Singapore Strait to the WJS, which occurs from the southwest coastline of Singapore. The bottom water in the Singapore Strait prefers to enter the WJS during the spring tide and the flood period, and stay in Johor Strait for 6.4 days. The spring tide is the first-order factor for the water vertical mixing in the WJS, the wind is also very important for the vertical mixing especially in neap tide condition. An overall very important factor is the light perturbation. With the strongest vertical mixing of nutrients and bottom sediments due to the spring tide, the latter ones may inhibit the light penetration during the spring tide and reduce the algal bloom. The light penetration otherwise is greater during the neap tide, when the winds are the most important factor and hence favor the algal bloom. With the strongest wind in February and the longest permanence time in June and the sufficient nutrient supply in February and June, the most serious algal blooms may happen in February and June in the WJS.

Risk Avoidance and Environmental Hazard: Effects of the Transboundary Haze Pollution in Singapore

This paper examines the causal effects of air pollution on the household consumption of water and electricity in Singapore. Using the transboundary haze pollution caused by forest fires in Indonesia as an exogenous shock, we find that increases in haze pollutant intensity in the air significantly increase water and electricity consumption. In particular, the intra-day and inter-day analyses on hourly household water consumption are consistent with the risk avoidance and the risk mitigation behaviors during severe haze episodes. During the haze periods, households stay indoors and avoid outdoor activities to minimize exposure to health risks. When they need to engage in outdoor activities during the weekdays, they increase efforts in mitigating health risks associated with air pollution. Moreover, the analysis of social media data shows that the level of public awareness of air pollution is positively related to energy consumption by households. In addition, the effects of haze-induced utilities consumption are correlated with the duration of air pollution. While household utilities consumption quickly returns to normal after transitory pollution exposure, the effects are stronger and persistent after a longer period of air pollution; households maintain a higher level of utilities consumption for two months after a lengthy haze, suggesting substantial spending on additional water and electricity usage due to air pollution events.