Marine organisms comprised about 70% of the total impinged materials by weight at water intake screens in the Kapar Power Station (KPS), Malaysia. The general groupings of 'fish', 'shrimp', 'crab', 'cephalopod' and 'others' contributed 26% (87 species), 65% (29), 2% (17), 2% (3) and 5% (42) of the total number of impinged organisms, respectively. In general, higher impingement occurred during spring tide, at nighttime and in shallow water. The glass perchlet, anchovies, ponyfishes, mojarra, catfishes, hairtail, scat and young croakers were the most vulnerable fishes. Vulnerable invertebrates included cephalopods, sea urchin, rockshells and jellyfishes, but penaeid shrimps were the most susceptible in terms of both mortality and body injury. Annually, KPS is estimated to kill 8.5 x 10(6) marine organisms (42 tons) by impingement. This amount, however, is minimal compared to commercial fishery harvests. Multispecies impingement at Malaysian power plants poses the problem of finding the best mitigation options for tropical situations.
The impact of floating net cages culturing the seabass, Lates calcarifer, on planktonic processes and water chemistry in two heavily used mangrove estuaries in Malaysia was examined. Concentrations of dissolved inorganic and particulate nutrients were usually greater in cage vs. adjacent (approximately 100 m) non-cage waters, although most variability in water-column chemistry related to water depth and tides. There were few consistent differences in plankton abundance, production or respiration between cage and non-cage sites. Rates of primary production were low compared with rates of pelagic mineralization reflecting high suspended loads coupled with large inputs of organic matter from mangrove forests, fishing villages, fish cages, pig farms and other industries within the catchment. Our preliminary sampling did not reveal any large-scale eutrophication due to the cages. A crude estimate of the contribution of fish cage inputs to the estuaries shows that fish cages contribute only approximately 2% of C but greater percentages of N (32-36%) and P (83-99%) to these waters relative to phytoplankton and mangrove inputs. Isolating and detecting impacts of cage culture in such heavily used waterways--a situation typical of most mangrove estuaries in Southeast Asia--are constrained by a background of large, highly variable fluxes of organic material derived from extensive mangrove forests and other human activities.
Coralline macroalgae are globally distributed rhodopyhtes that remove carbon from their immediate environment and transform it into carbonate sediments through the senescence of their calcified tissues. In this study, the calcium carbonate (CaCO3) stocks in the tissue of Jania adhaerens and sediments in Tanjung Adang Shoal, Johor were quantified for a 13-month study period. The detailed maps of the geographical distribution based on the spatial and temporal variations of biomass and CaCO3 were also assessed. The highest amount of biomass, CaCO3 and organic carbon (OC) stocks in the tissues showed the highest in May 2018 and May 2019. The biomass values ranged from 65 to 143 g DW m-2, which contained 53-147 g CaCO3 m-2 and 3-11 g OC m-2. These findings provided insights into the biogeochemical cycling of these inputs, which can be used to estimate the overall carbon budget of the macrophyte meadow.
Marine biota, especially commercially important species, serves as a basis for human nutrition. However, millions of tons of plastic litter are produced and enter the marine environment every year, with potential adverse impacts on marine organisms. In the present study, we investigated the occurrence and characteristics of microplastic (MP) pollution in the digestive tracts of 13 species of wild nektons from 20 stations sampled in the South China Sea (SCS) and the Indian Ocean (IO), and assessed the human health risks of MPs. The detection rate of MPs ranged from 0.00% to 50.00% from the SCS, which was dramatically lower than that from the IO (10.00-80.00%). The average abundance of MP was 0.18 ± 0.06 items g wet weight-1 (ww-1) in the SCS, which was significantly lower than that in the IO with a concentration of 0.70 ± 0.16 items g ww-1. Most MPs were fibers in type, black in color, and polyester (PES) in polymer composition in both the SCS and IO. Interestingly, distinct profiles of MP pollution were found between the benthic and pelagic nektons: 1) The predominant MP composition was PES in the benthic nektons, whereas polyamide (PA) accounted for a larger part of the total MP count in the pelagic nektons within the SCS; 2) The abundance of MP in the benthic nektons (0.52 ± 0.24 items individual-1) was higher than that in the pelagic nektons (0.30 ± 0.11 items individual-1). Accordingly, the mean hazard score of MPs detected in the benthic nektons (220.66 ± 210.75) was higher than that in the pelagic nektons (49.53 ± 22.87); 3) The mean size of the MP in the pelagic nektons (0.84 ± 0.17 mm) was larger than that in the benthic nektons (0.49 ± 0.09 mm). Our findings highlight the need to further investigate the ecological impacts of MPs on wild nekton, especially commercially important species, and its potential implications for human health.
Coastal eutrophication is one of the pivotal factors driving occurrence of harmful algal blooms (HABs), whose underlying mechanism remained unclear. To better understand the nutrient regime triggering HABs and their formation process, the phytoplankton composition and its response to varying nitrogen (N) and phosphorus (P), physio-chemical parameters in water and sediment in Johor Strait in March 2019 were analyzed. Surface and sub-surface HABs were observed with the main causative species of Skeletonema, Chaetoceros and Karlodinium. The ecophysiological responses of Skeletonema to the low ambient N/P ratio such as secreting alkaline phosphatase, regulating cell morphology (volume; surface area/volume ratio) might play an important role in dominating the community. Anaerobic sediment iron-bound P release and simultaneous N removal by denitrification and anammox, shaped the stoichiometry of N and P in water column. The decrease of N/P ratio might shift the phytoplankton community into the dominance of HABs causative diatoms and dinoflagellates.
Offshore Onna Village, Okinawa Island, Japan, there is a large and densely covered coral assemblage of free-living mushroom corals (Scleractinia: Fungiidae) on a reef slope at depths from 20 m to 32 m, covering an area of approximately 350 × 40 m2. From previous research, it is known that migration distances of mushroom corals may depend on coral shapes, coral sizes, substrate, and bottom inclination. However, until now there have been no published examples of regular Fungiidae movement and behavior from typhoon-exposed coastlines, such as those in the western Pacific Ocean. Our surveys across three years offshore Onna Village show that mushroom corals always move in down-slope direction from shallow to deeper reef zones. The results indicated that mushroom corals migrated faster in autumn than in other seasons, and that oval-elongate fungiids, and particularly those with a smooth underside, migrated more quickly than species with other shapes. Surprisingly, we observed a negative relationship between the presence of typhoons and migration rates. We also observed active migration by fungiid individuals to escape situations in which they were threatened to become overgrown by Acropora corals, or when they needed to escape from burial underneath coral debris.
Glaciozyma antarctica PI12, is a psychrophilic yeast isolated from Antarctic sea. In this work, Expressed Sequence Tags (EST) from cells exposed to three different temperatures; 15 °C, 0 °C and -12 °C were generated to identify genes associated with cold adaptation. A total of 5376 clones from each library were randomly picked and sequenced. Comparative analyses from the resulting ESTs in each condition identified several groups of genes required for cold adaptation. Additionally, 319 unique transcripts that encoded uncharacterised functions were identified in the -12 °C library and are currently unique to G. antarctica. Gene expression analysis using RT-qPCR revealed two of the unknown genes to be up-regulated at -12 °C compared to 0 °C and 15 °C. These findings further contribute to the collective knowledge into G. antarctica cold adaptation and as a resource for understanding the ecological and physiological tolerance of psychrophilic microbes in general.
Rising levels of atmospheric carbon dioxide are driving ocean warming and acidification. This could cause stress resulting in decreases in nutritional quality of marine species for human consumption, if environmental changes go beyond the optimal range for harvested species. To evaluate this, we used ambient and near-future elevated temperatures and pCO2 to assess impacts on the proximate nutritional composition (moisture, ash, protein, and lipids), fatty acids and trace elements of the foot tissue of Turbo militaris, a commercially harvested marine snail from south-eastern Australia. In a fully orthogonal design, the snails were exposed to ambient seawater conditions (22 ± 0.2 °C, pH 8.13 ± 0.01-450 μatm pCO2), ocean warming (25 ± 0.05 °C), pCO2 ocean acidification (pH 7.85 ± 0.02, ∼880 μatm pCO2) or a combination of both in controlled flow-through seawater mesocosms for 38 days. Moisture, ash, protein and total lipid content of the foot tissue in the turban snails was unaffected by ocean warming or acidification. However, ocean warming caused a reduction in healthful polyunsaturated fatty acids (PUFA) relative to saturated fatty acids (SFA). Under future warming and acidification conditions, there was a significant 3-5% decrease in n-3 fatty acids, which contributed to a decrease in the n-3/n-6 fatty acid ratio. The decrease in n-3 PUFAs, particularly Eicopentanoic acid (EPA), is a major negative outcome from ocean warming, because higher n-3/n-6 ratios in seafood are desirable for human health. Furthermore, ocean warming was found to increase levels of zinc in the tissues. Calcium, iron, macroelements, microelements and the composition of toxic elements did not appear to be affected by ocean climate change. Overall, the major impact from ocean climate change on seafood quality is likely to be a decrease in healthy polyunsaturated fatty acids at higher temperatures.
To assess the effects of environmental changes on phytoplankton community structure in a mangrove ecosystem, phytoplankton distribution in Matang mangrove, Malaysia was examined. Phytoplankton and water samples, and in situ environmental parameters from three estuaries with differing levels of disturbance were examined monthly for one year. Two species, Cyclotella choctawhatcheeana and Skeletonema costatum, were dominant in the least disturbed and moderately disturbed areas, respectively. Skeletonema costatum was also the most dominant in the most disturbed area. Significant differences in phytoplankton density and biodiversity between the least and most disturbed areas were also observed. Principle component 1 (salinity, conductivity, total solids/water transparency and nitrogenous compounds) and PC2 (dissolved oxygen, pH and temperature) explained 60.4% of the total variance. This study illustrated that changes in phytoplankton community structure in Matang mangrove estuaries were significantly correlated with environmental parameters which were in turn influenced by ecosystem disturbance levels as well as seasonal changes.
Over the years, coral reefs in the South China Sea have degraded and faced severe threats from rapid development, coral bleaching, and Crown-of-Thorns Starfish (COTS) outbreak. There is limited knowledge relating to the effects of anthropogenic disturbances and natural events on the coral reefs of Pulau Layang-Layang. This study aims to assess reef cover changes by utilizing Landsat satellite images spanning from 1989 to 2022. Using the object-based image analysis method, this study classified the reef cover into three categories: coral, rock and rubble, and sand. The supervised classification had an overall accuracy of 86.41-87.38 % and Tau's coefficients of 0.80-0.81. The results showed island development and construction of artificial bird sanctuary have led to an increase in coral cover. Furthermore, it was illustrated that the impact of COTS outbreaks in 2010 and 2020 differed significantly, with the latter showing no signs of recovery. Our study underscores the importance of timely intervention to mitigate the spread of COTS. This study provides insights into the resilience and vulnerability of these ecosystems in the face of various stressors.
The marine dinophyte Alexandrium tamiyavanichii is a toxigenic species that produces a group of neurotoxins that is responsible for paralytic shellfish poisoning in humans. Early detection of the species is essential for efficient monitoring. Harmful microalgal monitoring systems have evolved over the years with the advent of environmental DNA (eDNA)-based species detection techniques. In this study, eDNA samples were collected from a large-scale sampling covering the southern South China Sea. The sensitivity and specificity of metabarcoding of the V4 and V9 18S ribosomal DNA barcodes by high-throughput sequencing (HTS) were compared to the species-specific real-time qPCR targeting the A. tamiyavanichii ITS2 region. Environmental samples were screened for A. tamiyavanichii by qPCR (n = 43) and analyzed with metabarcoding (n = 30). Our results revealed a high occupancy profile across samples for both methods; 88% by qPCR, and 80-83% by HTS. When comparing the consistency between the two approaches, only two samples out of 30 were discordant. The V4 and V9 molecular units detected in each sample were positively correlated with the qPCR ITS2 gene copies (V4, rs = 0.67, p
Anadara granosa or blood cockles have been reported to be a candidate for biomonitoring agents due to their sedimentary nature and their nutrient uptake mechanisms. Yet, this bivalve is still regarded as a delicacy in Asian cuisine. Malaysia is the largest exporter of this sea product that contaminated cockles may also be experienced by the importing countries. However, the bioaccumulation of microplastics in A. granosa cultivated in Malaysia has not been extensively studied. It is crucial to comprehend the risk posed to humans by consuming A. granosa in their diet. Therefore, the purpose of this research is to investigate the levels of microplastic accumulation in A. granosa from major exporters in Peninsular Malaysia, to evaluate the associated risk of microplastics on the species, and to estimate daily human consumption of microplastics through the consumption of A. granosa. The abundance of microplastics was quantified through the use of a stereo microscope, and the polymer type was determined using FTIR and micro-FTIR. Findings from this investigation revealed that all samples of A. granosa were contaminated with microplastics, with the highest levels of accumulation found in bivalves collected from the west coast (0.26 ± 0.15 particles/g) of Peninsular Malaysia. Fragment and fiber microplastics, measuring between 0.05 and 0.1 mm in size, were found to be the most prevalent in A. granosa, with blue being the dominant identified colour and rayon being the most common polymer type. Microplastic risk assessment due to the presence of polyacrylate, polycarbonate (PC), and polymethyl methacrylate (PMMA) resulted in a high risk of contamination for A. granosa. It was further determined that the current estimated dietary intake (EDI) suggests that consumers of A. granosa uptake approximately 21.8-93.5 particles/person/year of microplastics. This study highlights that A. granosa accumulates microplastics, which could potentially result in bioaccumulation and biomagnification in humans through consumption.
The study examines the influence of temperature and pH on the leaching of six heavy metals (HMs) species: aluminum (Al), zinc (Zn), chromium (Cr), copper (Cu), lead (Pb) and arsenic (As) from transparent polyethylene pellets into seawater. The idea is to understand the potential influence of intensifying global warming and ocean acidification towards microplastic toxicity in the ocean. HMs leaching was obvious by 24th hours, with most HMs concentration decreased in water by 120th and 240th hours except Al. Nevertheless, we report that temperature and pH do not influence the overall HMs leaching from PE pellets with statistical analysis showing no significance (p
Small pelagic fisheries in the Java Sea (JS) contributes to about 26.6% of the total marine fisheries resources, where their spatial-temporal variation is controlled by seasonal oceanographic changes. This study aims to investigate a relationship between seasonal reversal circulation and number of light-fishing vessels (VBD) dispersion that capture small pelagic fishes, using multi-datasets from a regional ocean circulation model, satellite-derived datasets, and pelagic fish landing datasets between 2010 and 2020. The model demonstrates that main axis of eastward (westward) monsoon current that brings warmer and fresher (cooler and saltier) water, confines much closer along the northern Java (southern Kalimantan) during the northwest (southeast) monsoon period. These changes are followed unprecedentedly by southward (northward) shift of VBD and high abundance of euryhaline (stenohaline) fish species. This new evidence implies that reversal monsoon current and surface component of Makassar Throughflow play a significant role on delineating potential small pelagic fishing ground and fish productions.
Human emissions of carbon dioxide are causing irreversible changes in our oceans and impacting marine phytoplankton, including a group of small green algae known as picochlorophytes. Picochlorophytes grown in natural phytoplankton communities under future predicted levels of carbon dioxide have been demonstrated to thrive, along with redistribution of the cellular metabolome that enhances growth rate and photosynthesis. Here, using next-generation sequencing technology, we measured levels of transcripts in a picochlorophyte Chlorella, isolated from the sub-Antarctic and acclimated under high and current ambient CO2 levels, to better understand the molecular mechanisms involved with its ability to acclimate to elevated CO2. Compared to other phytoplankton taxa that induce broad transcriptomic responses involving multiple parts of their cellular metabolism, the changes observed in Chlorella focused on activating gene regulation involved in different sets of pathways such as light harvesting complex binding proteins, amino acid synthesis and RNA modification, while carbon metabolism was largely unaffected. Triggering a specific set of genes could be a unique strategy of small green phytoplankton under high CO2 in polar oceans.
Red tide caused severe impacts on marine fisheries, ecology, economy and human life safety. The formation mechanism of the red tide is rather complicated; thus, red tide prediction and forecasting have long been a research hotspot around the globe. This study collected ocean monitoring data before and after the occurrence of red tides in Xiamen sea area from 2009 to 2017. The Pearson correlation coefficient method was used to obtain the associated factors of red tide occurrence, including water temperature, saturated dissolved oxygen, dissolved oxygen, chlorophyll-aand potential of hydrogen. Then, we built a short-time red tide prediction model based on the combination of multiple feature factors. chlorophyll-a, dissolved oxygen, saturated dissolved oxygen, potential of hydrogen, water temperature, salinity, turbidity, wind speed, wind direction and Air pressure were used as the input variables, building a short-time prediction model based on the combination of multiple feature factors to forecast red tide in the next 6 h by using the monitoring data. The accuracy of different forecast models with different feature combinations was compared. Results show that the distinguishing factors which have the most significant influence on red tide prediction in Xiamen are chlorophyll-a, dissolved oxygen, saturated dissolved oxygen, potential of hydrogen, and water temperature. the convergence speed of the Gated Recurrence Unit (GRU) prediction model based on the main feature factor proposed in this paper was faster and obtained the expected result, and the accuracy rates of the buoys are above 92%. The research shows the feasibility to use GRU network model to predict the occurrence of red tide with multi-feature factors as input parameters. the paper provides an effective method for the red tide early warning in Xiamen sea area.
Seaweed has garnered increasing interest due to its capacity to mitigate climate change by curbing carbon emissions from agriculture, as well as its potential to serve as a supplement or alternative for dietary, livestock feed, or fuel source production. Moreover, seaweed is regarded as one of the earliest plant forms to have evolved on Earth. Owing to the extensive body of literature available and the uncertainty surrounding the future trajectory of seaweed research under evolving climate conditions, this review scrutinizes the structure, dynamics, and progression of the literature pertaining to seaweed and climate change. This analysis is grounded in the Web of Science Core Collection database, augmented by CiteSpace software. Furthermore, we discuss the productivity and influence of individual researchers, research organizations, countries, and scientific journals. To date, there have been 8047 articles published globally (after a series of filters and exclusions), with a notable upswing in publication frequency since 2018. The USA, China, and Australia are among the leading countries contributing to this research area. Our findings reveal that current research on seaweed and climate change encompasses 13 distinct research clusters, including "marine heatwave", "temperate estuary", "ocean acidification", and "macroalgal bloom". The most frequently cited keywords are "climate change", "biomass", "community", and "photosynthesis". The seaweed species most commonly referenced in relation to climate change include Gracilaria sp., Sargassum sp., Ecklonia maxima, and Macrocystis pyrifera. These results provide valuable guidance for shaping the direction of specialized topics concerning marine biodiversity under shifting climate conditions. We propose that seaweed production may be compromised during prolonged episodes of reduced water availability, emphasizing the need to formulate strategies to guarantee its continued viability. This article offers fresh perspectives on the analysis of seaweed research in the context of impending climate change.
Microbes, or microorganisms, have been the foundation of the biosphere for over 3 billion years and have played an essential role in shaping our planet. The available knowledge on the topic of microbes associated with climate change has the potential to reshape upcoming research trends globally. As climate change impacts the ocean or marine ecosystem, the responses of these "unseen life" will heavily influence the achievement of a sustainable evolutionary environment. The present study aims to identify microbial-related research under changing climate within the marine environment through the mapping of visualized graphs of the available literature. We used scientometric methods to retrieve documents from the Web of Science platform in the Core Collection (WOSCC) database, analyzing a total of 2767 documents based on scientometric indicators. Our findings show that this research area is growing exponentially, with the most influential keywords being "microbial diversity," "bacteria," and "ocean acidification," and the most cited being "microorganism" and "diversity." The identification of influential clusters in the field of marine science provides insight into the hot spots and frontiers of research in this area. Prominent clusters include "coral microbiome," "hypoxic zone," "novel Thermoplasmatota clade," "marine dinoflagellate bloom," and "human health." Analyzing emerging trends and transformative changes in this field can inform the creation of special issues or research topics in selected journals, thus increasing visibility and engagement among the scientific community.
The Strait of Malacca is well-known as an important trade route with high marine biodiversity. Among the organisms residing in the strait are the reef-building hard corals. Studies have shown that climate change and other anthropogenic stressors have induced severe degradation of coral reefs through the disruption of coral productivity and metabolisms. Moreover, in-depth investigations of causal inference of coral degradation and its correlations with potential coral-affecting physicochemical factors within the strait are limited. Hence, this study presents the analyses of the latest bi-decadal time-series trend from 1995 to 2016 of the live hard coral coverage (or live coral cover) and six coral-affecting physicochemical factors (significant wave height, sea surface salinity, particulate inorganic carbon, particulate organic carbon, turbidity, and sea surface temperature) using remote sensing and reanalysis datasets. Their potential correlations were interpreted by implementing meta- and statistical analyses of past coral surveys and remote sensing data. This study revealed the overall persistent bi-decadal decline in live hard coral coverage within the Strait of Malacca and the complex correlations among the factors that correspond to the spatial stratification of the marine environment. Among the six physicochemical factors, sea surface temperature, turbidity, and sea surface salinity were determined to be the most influential parameters on live coral cover distribution within the strait.
To mitigate adverse effects of ocean warming on coral reef degradation, resource managers increasingly explore management and regulation of local stressors to strengthen coral resilience and recovery. Comprehensive assessments and monitoring efforts offer a holistic understanding of reef dynamic ecosystems. In this study, we documented the distribution of benthic foraminiferal assemblages surrounding Pulau Redang, Malaysia, and assessed their potential for monitoring coral reef health using the Foraminifera in Reef Assessment and Monitoring (FoRAM) Index. Undeveloped (R1-R3) and developed (R4-R6) reef sites revealed distinct differences in reef conditions. Foraminiferal distribution showed Amphistegina lessonii (14-34%) as the dominant species, followed by Calcarina hispida (21%) and Calcarina mayori (19%). The Q-mode cluster analysis classified the distribution of foraminiferal assemblages in Pulau Redang into four sub-groups based on the reef ecological conditions. Group A1 and A2, represent the foraminiferal assemblage on the undeveloped west side of the island where live coral cover was >30%. Meanwhile, Group B1 and B2 represent the assemblage found in developed coastal regions with low live coral cover (≤20%). Additionally, the CCA results revealed a substantial influence of substrate type on the distribution of benthic foraminifera in the reef environments of Pulau Redang. FoRAM index consistently yielded high values across the study area despite varying coral reef conditions, probably due to the prevalence of Calcarina mayori in mesotrophic reefs (R4-R6), potentially distorting FoRAM values and providing a misleading indicator of reef conditions. The Modified Foram Index (MFI), calculated by excluding calcarinids, classified R3, R4, and R6 as less conducive for reef growth, aligning better with observed reef conditions. We recommend calibrating the FoRAM Index, particularly in mesotrophic reefs where calcarinids dominate foraminiferal assemblages, to enhance its precision and reliability for coral reef health monitoring and assessment within the region.