This paper analyzes CO2 flux between the atmosphere and a tropical coastal sea using the eddy covariance technique. Coastal carbon dioxide flux studies are limited, particularly in tropical regions. Data was collected from the study site in Pulau Pinang, Malaysia, since 2015. The research found that the site is a moderate CO2 sink and experiences seasonal monsoonal changes that affect its carbon-sink or carbon-source capability. The analysis showed that the coastal sea systematically shifted from being a carbon-sink at night to a weak carbon-source during the day possibly due to cause by the synergistic influence of wind speed and seawater temperature. The CO2 flux are also influenced by small-scale, unpredictable winds, limited fetch, developing waves, and high-buoyancy conditions caused by low wind speeds and an unstable surface layer. Furthermore, it exhibited a linear relationship with wind speed. In stable conditions, the flux was influenced by wind speed and drag coefficient, while in unstable conditions, it was mostly controlled by friction velocity and atmospheric stability. These findings could improve our understanding of the critical factors that drive CO2 flux at the tropical coast.
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.
In this article, the abundance of phytoplankton community structure in Malacca Straits (MS); from Port Klang to Langkawi Island are reported. The datasets include data from 25 selected sampling sites that were acquired in August 2019 on board the RV Discovery's cruise expedition. These data contain details on the density of phytoplankton (cell L-1), total number of species, volume seawater filtered (in L) and the concentration factors (ml) in MS. Data presented in this article consists of 163 species, including unidentified species from 6 phyla of phytoplankton, along with the percentage of a major community group in MS.
Laboratory radiotracer experiment was performed to study the bioaccumulation of 109Cd and 134Cs in the Malaysian common fish White seabass (Lates calcarifer). The aim of this study was to compare the biokinetics of uptake these two contrasting radionuclides by White seabass in laboratory condition scale. Experiments were designed to determine the processes controlling uptake of both radionuclides following exposure via seawater. In this study, the curve shapes of the uptake kinetic of 109Cd and 134Cs in White seabass were slightly linear and gradually increased with increasing of exposure time but were not reach equilibrium in the period of the study of 21 days. This phenomenon can be concluded that radioelement concentrations of 109Cd and 134Cs; and exposure duration of this experiment may not adequately to reach steady-state condition for uptake kinetic of those radioelements in White seabass. Furthermore, this was indicated that the uptake rate of 109Cd was 1.79 times faster than 134Cs due to some factors may probably influenced the output of this experiment such as different element accumulation strategies, physiological, behavior of radioelements, etc.
Seagrass is a valuable marine ecosystem engineer. However, seagrass population is declining worldwide. The lack of seagrass research in Malaysia raises questions about the status of seagrasses in the country. The seagrasses in Lawas, which is part of the coral-mangrove-seagrass complex, have never been studied in detail. In this study, we examine whether monthly changes of seagrass population in Lawas occurred. Data on estimates of seagrass percentage cover and water physicochemical parameters (pH, turbidity, salinity, temperature, and dissolved oxygen) were measured at 84 sampling stations established within the study area from June 2009 to May 2010. Meteorological data such as total rainfall, air temperature, and Southern Oscillation Index were also investigated. Our results showed that (i) the monthly changes of seagrass percentage cover are significant, (ii) the changes correlated significantly with turbidity measurements, and (iii) weather changes affected the seagrass populations. Our study indicates seagrass percentage increased during the El-Nino period. These results suggest that natural disturbances such as weather changes affect seagrass populations. Evaluation of land usage and measurements of other water physicochemical parameters (such as heavy metal, pesticides, and nutrients) should be considered to assess the health of seagrass ecosystem at the study area.
Temporal variations and regional distributions of dissolved nutrients and their elemental ratios in the Iranian coastal waters of the Southern Caspian Sea were investigated. The data were collected in 1996-97 (Phase I, as a background data and undisturbed ecosystem) and in 2005 (Phase II, as a disturbed ecosystem) at sampling points (from 10 to 100 m depths). In addition to the two main sampling exercises, additional sample collections were carried out during the period of 1994 to 2004 as a long-term study. This study showed that the dissolved inorganic nitrogen/dissolved inorganic phosphorus (DIN/DIP) ratios in the southern Caspian Sea vary within a very narrow range (4.47 to 5.78) within the euphotic and aphotic layers and is by one order of magnitude lower than what have been reported for several other marine ecosystems. Phytoplankton growth seems to be nitrogen limited while the levels of P and Si always remain high. Factor Analysis/Principal Component Analysis (FA/PCA) of the correlation matrix showed that the nitrogen compounds are associated with the main factor accounting for 25.7-26.2% of the total variance for both the sampling periods. During Phase I, the Chrysophyta were the major group, whereas during Phase II the proportion of Chrysophyta in the total community progressively decreased, while the other groups increased.
Increasing acidity of seawater caused by increasing anthropogenic carbon dioxide absorbed into the seawater attracted the interest of researchers due to increased concern on the deterioration of marine systems and food supply to humans. Total alkalinity (TA) is one of the important parameters in determining carbonate chemistry and is described as the capacity of the sample to neutralize acids. Over the last two decades, many analytical techniques have been developed to determine TA. This article presents a review of different analytical techniques including titration, colorimetric, spectrophotometric, and potentiometric analyses in measuring TA. Among these analytical techniques, potentiometry analysis, which utilizes electrode systems such as glass electrode and ion-selective electrode used as indicator electrodes, is the most used technique. Important features such as principle, limitations, and challenges of the involved technique are discussed in detail.
Astaxanthin, a carotenoid pigment found in several aquatic organisms, is responsible for the red colour of salmon, trout and crustaceans. In this study, astaxanthin production from freshwater microalga Chlorella sorokiniana and marine microalga Tetraselmis sp. was investigated. Cell growth and astaxanthin production were determined spectrophotometrically at 620 and 480 nm, respectively. Astaxanthin was extracted using acetone and measured subsequent to biomass removal. Aerated conditions favoured astaxanthin production in C. sorokiniana, whereas Tetraselmis sp. was best cultured under unaerated conditions. C. sorokiniana produced more astaxanthin with the highest yield reached at 7.83 mg/l in 6.0 mM in nitrate containing medium compared to Tetraselmis sp. which recorded the highest yield of only 1.96 mg/l in 1.5 mM nitrate containing medium. Production in C. sorokiniana started at the early exponential phase, indicating that astaxanthin may be a growth-associated product in this microalga. Further optimization of astaxanthin production was performed using C. sorokiniana through a 2(3) full factorial experimental design, and a yield of 8.39 mg/l was achieved. Overall, the study has shown that both microalgae are capable of producing astaxanthin. Additionally, this research has highlighted C. sorokiniana as a potential astaxanthin producer that could serve as a natural astaxanthin source in the current market.
Jeotgalibacillus campisalis SF-57(T) (=KCCM 41644(T), JCM 11810(T)) is a moderate halophilic bacterium isolated from a Korean marine saltern. In this study, we describe the high-quality draft genome of strain SF-57(T), which was assembled into 24 contigs containing 3,650,490bp with a G+C content of 41.06%. Availability of the genome sequence of J. campisalis SF-57(T) will contribute to a better understanding of the genus Jeotgalibacillus.
Climate change has been predicted to influence the marine phytoplankton community and its carbon acquisition strategy. Extracellular carbonic anhydrase (eCA) is a zinc metalloenzyme that catalyses the relatively slow interconversion between HCO3- and CO2. Early results indicated that sub-nanomolar levels of eCA at the sea surface were sufficient to enhance the oceanic uptake rate of CO2 on a global scale by 15%, an addition of 0.37 Pg C year-1. Despite its central role in the marine carbon cycle, only in recent years have new analytical techniques allowed the first quantifications of eCA and its activity in the oceans. This opens up new research areas in the field of marine biogeochemistry and climate change. Light and suitable pH conditions, as well as growth stage, are crucial factors in eCA expression. Previous studies showed that phytoplankton eCA activity and concentrations are affected by environmental stressors such as ocean acidification and UV radiation as well as changing light conditions. For this reason, eCA is suggested as a biochemical indicator in biomonitoring programmes and could be used for future response prediction studies in changing oceans. This review aims to identify the current knowledge and gaps where new research efforts should be focused to better determine the potential feedback of phytoplankton via eCA in the marine carbon cycle in changing oceans.
Tropical seawater harbors a rich diversity of microorganisms as a result of its nutrient-rich environment, constant supply of sufficient sunlight, and warm climate. In this report, we present the complexity of the microbial diversity of the surface seawater of the Georgetown coast as determined using next-generation sequencing technology.
The sustainability performance of the desalination processes has received increasing attention in recent years. In this study, the current progress and future perspective of a life cycle assessment (LCA) of desalination technology in 62 previous studies have been reviewed for the period 2004-2019. It was found that the number of LCA studies related to seawater reverse osmosis has gained popularity compared to other types of desalination technologies. The review emphasized the application of LCA to desalination by means of research objective, scope of study, life stages, and impact assessment. Although previous LCA studies were conducted to assess the environmental performance of the desalination technology, little attention was given to evaluating the impact of other sustainability aspects (i.e., economic and social). The latter part of this study discusses the challenges, feasibility, and recommendations for future LCA studies on desalination technology. The integration of the LCA approach with other approaches allows a comprehensive assessment of the sustainability performance of desalination technology. Thus, the combined approaches should be explored in future studies to gain insight into the sensitivity and uncertainty of the data to make an assessment that can be useful in policy-making.
Membrane technology, especially nanofiltration (NF) has great attention to provide an imperative solution for water issues. The membrane is considered to be the heart in the separation plant. Understanding the membrane characteristics could allow predicting and optimizing the membrane performance namely flux, rejection and reduced fouling. The membrane development using biomaterials and nanomaterials provides a remarkable opportunity in the water application. This review focuses on the membrane characteristics of biomaterials and nanomaterials based nanofiltration. In this review, recent researches based on biomaterials and nanomaterials loaded membrane for salt rejection have been analyzed. Membrane fouling depends on the membrane characteristics and this review defined fouling as a ubiquitous bottleneck challenge that hampers the NF blooming applications. Fouling mitigation strategies via membrane modification using biomaterial (chitosan, curcumin and vanillin) and various other nanomaterials are critically reviewed. This review also highlights the membrane cleaning and focuses on concentrates disposal methods with zero liquid discharge system for resource recovery. Finally, the conclusion and future prospects of membrane technology are discussed. From this current review, it is apparent that the biomaterial and various other nanomaterials acquire exclusive properties that facilitate membrane advancement with improved capability for water treatment. Regardless of membrane material developments, still exist considerable difficulties in membrane commercialization. Thus, additional studies related to this field are needed to produce membranes with better performance for large‒scale applications.
Various environmental samples (seawater, TSS, sediment, rainwater and fly ash) from eight different stations near Kapar coastal area were analyzed. The 210 Po activity concentrations in liquid samples (seawater and rainwater) varied between 0.34 ± 0.03 mBq L-1 to 22.44 ± 0.53 mBq L-1 . Whereas the concentrations in particulate samples (TSS, sediment and fly ash) varied between 43.79 ± 2.31 Bqkg-1 to 364.48 ± 5.43 Bqkg-1 . Results also showed the radioactivity in Kapar coastal is higher than most of Malaysian coast, reaching a factor of seven. This condition is mainly due to the operation of a coal-fired power plant nearby. This study also clarify the variability of 210 Po in environment was strongly influenced from rainfall events especially during wet seasons.
Bacillus sp. is a Gram-positive bacterium that is commonly found in seawater. In this study, the genome of marine Bacillus sp. strain G3(2015) was sequenced using MiSeq. The fosfomycin resistant gene fosB was identified upon bacterial genome annotation.
The multi-scale and nonlinear nature of the ocean dynamics dramatically affects the spreading of matter, like pollutants, marine litter, etc., of physical and chemical seawater properties, and the biological connectivity inside and among different basins. Based on the Finite-Scale Lyapunov Exponent analysis of the largest available near-surface Lagrangian data set from the Global Drifter Program, our results show that, despite the large variety of flow features, relative dispersion can ultimately be described by a few parameters common to all ocean sub-basins, at least in terms of order of magnitude. This provides valuable information to undertake Lagrangian dispersion studies by means of models and/or of observational data. Moreover, our results show that the relative dispersion rates measured at submesoscale are significantly higher than for large-scale dynamics. Auxiliary analysis of high resolution GPS-tracked drifter hourly data as well as of the drogued/undrogued status of the buoys is provided in support of our conclusions. A possible application of our study, concerning reverse drifter motion and error growth analysis, is proposed relatively to the case of the missing Malaysia Airlines MH370 aircraft.
Strength and durability are important characteristics of concrete and desired engineering properties. Exposure to aggressive environment threatens durability of concrete. Previous studies on bio-concrete using several types of bacteria, including sulphate reduction bacteria (SRB), had to increase durability of concrete have shown promising results. This study used mixtures designed according to concrete requirement for sea water condition with SRB composition of 3%, 5% and 7% respectively. The curing time were 28, 56 and 90 days respectively. The mechanical properties, namely compressive strength and water permeability, were tested using cube samples. The results showed compressive strength had higher increase than the control at 53.9 Mpa. The SRB with 3%composition had maximum water permeability. Thus, adding SRB in concrete specimens improves compressive strength and water permeability. This is particularly suitable for applications using chloride ion penetration (sea water condition) where corrosion tends to affect durability of concrete constructions.
This study describes the adaptations of diatoms, Cylindrotheca fusiformis and other marine diatoms, in a new formulated enriched medium Tris-phosphate seawater (TP-SW). The medium was designed to maintain long-term cultures of wide-range marine diatoms in laboratory that produces high biomass of cultures. The diatoms were adapted and cultivated in the medium for 15 days and the number of cells was recorded daily. It was found that the number of cells declined after two weeks indicating death phase of the cells. This indicates that the TP-SW medium has supported the growth of diatoms during the period and can be used to cultivate diatoms in vitro. Studies on the TP-SW medium must be done to obtain optimal medium that can provide not only a conducive environment for the survival of diatoms but also high biomass production.
Temporal variation of Synechococcus, its production (μ) and grazing loss (g) rates were studied for 2 years at nearshore stations, i.e. Port Dickson and Port Klang along the Straits of Malacca. Synechococcus abundance at Port Dickson (0.3-2.3 × 10(5) cell ml(-1)) was always higher than at Port Klang (0.3-7.1 × 10(4) cell ml(-1)) (p 0.25), but nutrient and light availability were important factors for their distribution. The relationship was modelled as log Synechococcus = 0.37Secchi - 0.01DIN + 4.52 where light availability (as Secchi disc depth) was a more important determinant. From a two-factorial experiment, nutrients were not significant for Synechococcus growth as in situ nutrient concentrations exceeded the threshold for saturated growth. However, light availability was important and elevated Synechococcus growth rates especially at Port Dickson (F = 5.94, p 0.30). In nearshore tropical waters, an estimated 69 % of Synechococcus production could be grazed.