MAPPING OIL SPILLS ON SEA SURFACE FROM SENTINEL 2 IMAGES USING PRINCIPAL COMPONENTS AND CATEGORICAL BOOSTING

A large oil spill in Iloilo Straight that occurred on July 3, 2020, as well as a possible deliberate, small but frequent oil spill and surfactant contamination in Manila Bay, were mapped. The method employs the Sentinel 2-1C image, which is transformed into principal components to reveal the presence of oil spills and possibly surfactants. Additionally, a gradient boosting algorithm was trained to discriminate between pixels that were contaminated with oil and those that were not. The multi-band image with three principal components with a 99% cumulative explained variance ratio highlights the occurrence of an oil spill in Iloilo Straight. Further, the classified image produced by pixel-based classification clearly distinguishes between water and oil pixels in the said area. The methodology was applied to a Sentinel 2-1C image of Manila Bay, with pixels observed/identified as oil and classified as well. The highest density of supposedly oil-contaminated pixels (large or small but frequent) was observed on the eastern side of Manila Bay (Bataan). While there were no documented oil spills concurrent to the satellite image used, historical reports on the area indicate that the likelihood of an oil spill is extremely high due to the massive amount of shipping activity. Pixels supposedly contaminated by oil spills also occur in areas near ports where oil spills could occur as a result of ship operations. Pixels with the same properties as oil contamination are also visible in areas adjacent to fishponds and aquaculture, where phytoplankton and fish contribute to surfactant contamination.

Description of a new species of queenfish, Scomberoides pelagicus from Indian seas

Aim: The study was carried out to ascertain whether morphotype of Scomberoides commersonnianus (Talang queenfish) existing along the Indian coast is a new species or not. Methodology: Talang queenfish and the morphotype were tested for their uniqueness using systematic and molecular tools. The morphometric and meristic details including otolith morphometry were analysed and compared for taxonomic divergence and Cytochrome Oxidase I and Cytochrome b gene sequences for quantifying genetic divergences. Results: The systematic analysis indicated significant morphometric differences between both. The otolith morphometry and phylogeny also confirmed the divergence between them, and qualified the morphotype as an independent species status and named Scomberoides pelagicus sp. nov. Interpretation: The new species is distinct by deep ovate body, concave dorsal head profile, anal fin origin anterior to second dorsal fin and pelvic to pectoral fin, helical arrangement of body scale and stout and less numerous gill rakers on the first gill arch. The phylogeny as on Cytochrome b and Cytochrome Oxidase 1 sequences are very distinct, with 11.2% and 2.0% divergence respectively. Their known distributional range are peninsular region of Indian coast, Malaysian region of the South China Sea and Manila Bay, Philippines.

A DISPERSIVE LONG-WAVE MODEL FOR PREDICTING COASTAL FLOODING DUE TO STORM SURGES AND SURFACE WAVES IN MANILA BAY

Manila Bay is a shallow coastal water encompassing the urban areas of Metro Manila and variouscities of sub-urban provinces in the Philippines. It is a relatively shallow semi-enclosed basinwith an average depth of 20 m whose coastal areas are crowded with residential, industrial,agricultural, and aquaculture production. Its shallow depths imply that the effect of wind stress onsea level becomes appreciable in driving storm surges even during enhanced Southwest Monsoonand the passage of moderate storms.Using a dispersive long-wave model coupled with the significant wave model of the CoastalEngineering Research Center (CERC), the occurrence of potentially devastating storm surgeflooding around Manila Bay was numerically simulated. A unique characteristic of the new modelis the inclusion of the dispersive terms in the associated momentum balance equations. Deepwater gravity waves are always dispersive and inclusion of the dispersive terms is expected toprovide more accurate modelling results.The predictive capability of the model was verified using observations during the passage ofseveral storms including Typhoon Milenyo (2006) and Typhoon Pedring (2011). The occurrenceof the anomalously high storm surge of about 2.5 metres during the passage of Typhoon Pedringfar north of the area was correctly simulated. Numerical integration of the dispersive long-wavemodel with the addition of higher order terms in the momentum balance appears to give accuratepredictions of the coastal flooding due to storm surges and waves.The hydrodynamic set-down which occurs in many coastal areas during strong typhoons can besimulated well by the model. A new empirical model for the hydrodynamic force exerted by thecombined action of storm surges, waves, and extreme currents is also presented. Initial calculationsof hydrodydynamic forces generated by an actual typhoon crossing Manila Bay are discussed.

Occurrence of microplastics in the sediments of Baseco Port area at Manila Bay, Philippines

Microplastic in marine sediments is nowadays considered an environmental pollutant. Seaports are particularly susceptible to microplastic pollution through series of human activities occurring in these areas. In the Philippines, research on microplastics is still limited and there is still no study determining the occurrence of microplastics in the harbour of Manila Bay, Philippines. Hence, this work conducted a preliminary investigation of microplastics in the sediments of Baseco Port area, Manila Bay. Nine stations within the study region were sampled. The types of microplastics found are fragments, foam, fiber, film, pellet, and filament with an average size measurement of 1.6±1.4 mm. Results from this study suggest that anthropogenic impacts are most likely the dominant sources of accumulation and distribution of microplastics in the sediments of Baseco port. This study provides preliminary assessment of microplastics contamination in the area that may serve as important reference for further studies.

UTILIZATION OF SENTINEL-2 IMAGERY IN THE ESTIMATION OF PLASTICS AMONG FLOATING DEBRIS ALONG THE COAST OF MANILA BAY

With the Philippines ranking as the third largest source of plastics that end up in the oceans, there is a need to further explore methodologies that will become an aid in plastic waste removal from the ocean. Manila Bay is a natural harbor in the Philippines that serves as the center of different economic activities. However, the bay is also threatened with plastic pollution due to increasing population and industrial activities. BASECO is one of the areas in Manila Bay where clean-up activities are focused as this is where trash accumulates. Sentinel-2 images are provided free of charge by the European Commission's Copernicus Programme. Satellite images from June 2019 to May 2020 were inspected, then cloud-free images were downloaded. After downloading and pre-processing, spectral data of different types of plastic such as shipping pouch, bubble wrap, styrofoam, PET bottle, sando bag and snack packaging that were measured by a spectrometer during a fieldwork by the Development of Integrated Mapping, Monitoring, and Analytical Network System for Manila Bay and Linked Environments (project MapABLE) were utilized in the selection of training data. Then, indices such as the Normalized Vegetation Index (NDVI), Floating Debris Index (FDI) and Plastic Index (PI) from previous studies were analyzed for further separation of classes used as training data. These training data served as an input to the two supervised classification methods, Naive Bayes and Mixture Tuned Matched Filtering (MTMF). Both methods were validated by reports and articles from Philippine agencies indicating the spots where trash frequently accumulates.

DEVELOPMENT OF THE MASDAN MOBILE APPLICATION AND WEB-BASED GIS INTERFACE FOR THE MONITORING AND MANAGEMENT OF THE MANILA BAY ENVIRONMENT

This paper presents the development of MASDAN, an integrated platform consisting of a mobile application and a web-GIS interface for monitoring the Manila Bay environment. The MASDAN mobile application uses citizen science and Volunteered Geographic Information (VGI) to collect data on specific environmental issues. It also serves as an information, education, and communication (IEC) tool for its users. The MASDAN Monitoring Interface is a centralized citizen report assessment tool for local authorities and environmental agencies to validate and monitor environmental reports within their area of jurisdiction. These two components create a two-way flow of information between citizens and authorities, ensuring prompt and information-driven actions to environmental issues affecting the Manila Bay and linked environments.

DEVELOPMENT OF THE IM4MANILABAY MAPABLE WEB PORTAL

Products and outputs for water quality monitoring are made available in the IM4ManilaBay MapABLE Web Portal, a web-based GIS platform that serves as a repository of processed maps for Manila Bay and linked systems. The Portal is also linked with the MASDAN mobile application that has been developed to allow the public to report different environmental issues. The web development involved the utilization of geospatial content management system, spatial database system, operating systems, programming, and style language. Services included frontend and backend development. The Web Portal serves as a repository for all outputs derived for water quality monitoring. It contains processed results, technical overview on the developed models and tools, historical data viewing and use of basic geoprocessing tools, and viewing of reported incidents from the MASDAN app. It is expected that the Web Portal will contribute significantly in the efforts of communities and environmental agencies to implement policies for sustainable development and management of Manila Bay and its watershed.

SPATIO-TEMPORAL MAPPING AND ANALYSIS OF MANGROVE EXTENTS AROUND MANILA BAY USING LANDSAT SATELLITE IMAGERY AND MANGROVE VEGETATION INDEX (MVI)

Mangroves are considered one of the most undervalued ecosystems in the world. It provides shelter to a wide range of species and protection from natural hazards to coastal communities. The Philippines, being a country with long coastlines, benefits greatly from mangroves. Historically, it had 400,000–500,000 hectares of mangroves forest in 1920, which declined to 120,000 hectares in 1994 due to rapid industrialization, particularly the conversion of these forests into aquaculture such as fishponds Mangrove forest in the Philippines saw a rapid decline between 1920 and 1994 due to aquaculture conversion and land reclamation Mangrove Vegetation Index (MVI), an established mangrove detection algorithm, was applied on Landsat satellite images of Manila Bay to map the extent of the mangrove forest from 1990 to 2020. Thirteen time-series maps were produced. Area computation showed that the coastline of Bulacan had the most mangroves, while the coastline of Metro Manila had the least throughout the years.

MAPPING COLOURED DISSOLVED ORGANIC MATTER IN MANILA BAY USING SENTINEL-3 AND WASI

Manila Bay is one of the most significant bodies of water in the Philippines; it has abundant natural resources that have been the source of livelihood and center of socio-economic development for centuries. However, Manila Bay is affected by multiple environmental problems and challenges. These include increased organic and nutrient loading from untreated domestic, industrial, and agricultural wastes and deterioration of marine habitats threatened by anthropogenic activities. Regular water quality monitoring is ideal in these situations, however, sampling by traditional field methods would not be enough to assess the spatial and temporal variation of water quality in Manila Bay. Gathering field data for the whole bay can also be very challenging due to its extent and logistic constraints. Remote sensing fills the need for a frequent full view of Manila Bay’s water quality. This study makes use of existing bio-optical models to estimate colored dissolved organic matter (CDOM) in Manila Bay. CDOM is the mixture of organic molecules from decayed higher plants, algae, and bacteria, and is the colored portion of the total dissolved organic matter. Sentinel-3 images with concurrent field sampling on 19 July 2021 was used to calibrate and validate the bio-optical models implemented in WASI. The parameterization output showed an R2 = 0.579 and RMSE of 1.274 m−1 from lab-measured CDOM fluorescence converted to absorption. The same parameter set was used on a different image with a concurrent water quality survey on 19 May 2021 and resulted to an R2 of 0.72 with the spectrofluorometer yellow substance concentrations.

Spirobranchus bakau sp. nov. from Singapore: yet another species of S. kraussii-complex (Polychaeta: Serpulidae)

The intertidal serpulid polychaete Spirobranchus kraussii was originally described from South Africa and has since been reported in numerous sub (tropical) localities around the world. Recently, however, S. kraussii was uncovered as a complex of morphologically similar and geographically restricted species, raising the need to revise S. cf. kraussii populations. We formally describe S. cf. kraussii from Singapore mangroves as Spirobranchus bakau sp. nov. based on morphological and molecular data. Despite their morphological similarities, Maximum Likelihood and Bayesian Inference analyses of 18S and Cyt b DNA sequence data confirm that S. bakau sp. nov. is genetically distinct from S. kraussii and other known species in the complex. Both analyses recovered S. bakau sp. nov. as part of a strongly supported clade (96% bootstrap, 1 posterior probability), comprising S. sinuspersicus, S. kraussii and S. cf. kraussii from Australia and Hawaii. Additionally, paratypes of S. kraussii var. manilensis, described from Manila Bay in the Philippines, were examined and elevated to the full species S. manilensis. Finally, we tested the hypothesis that fertilisation and embryonic development of S. bakau sp. nov. can occur under the wide range of salinities (19.6–30.9 psu) and temperatures (25–31°C) reported in the Johor Strait. Fertilisation success of ≥70% was achieved across a temperature range of 25–32°C and a salinity range of 20–32 psu. Embryonic development, however, had a narrower salinity tolerance range of 27–32 psu. Clarifying the taxonomic status of S. cf. kraussii populations reported from localities elsewhere in Singapore and Southeast Asia will be useful in establishing the geographical distribution of S. bakau sp. nov. and other members of the S. kraussii-complex.