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Coolia are marine benthic dinoflagellates which are globally distributed and potentially toxic. This study provides the first investigation of species diversity and toxicity assessment of Coolia in Hong Kong waters. Fifty-one strains of four Coolia species, including C . malayensis , C . canariensis , C . tropicalis , and C . palmyrensis , were isolated from twelve sub-tidal habitats, and identified phylogenetically using 28S rDNA sequences. Exposure experiments (48-hour) demonstrated that the algal lysates extracted from the four Coolia species exhibited different toxic effects on the lethality and abnormality of two invertebrate larvae, i.e., brine shrimp Artemia franciscana and sea urchin Heliocidaris crassispina . Heliocidaris crassispina was more sensitive to the toxic effects of Coolia species than A . franciscana . Toxicity tests from both larvae revealed that C . malayensis was generally more toxic, and caused higher mortality rates when compared with the other three species. The emerging threat of harmful benthic dinoflagellates to marine environments and sensitive biota is discussed. [ABSTRACT FROM AUTHOR]

Abstract: Environmental fate of fish farm wastes (FFW) released from an open-sea-cage farm at Kat O, Hong Kong was examined by measuring carbon and nitrogen stable isotope (SI) ratios in selected benthic organisms collected along a 2000m transect from the farm. Our results showed that FFW significantly influenced the energy utilization profile of consumers near the fish farm. Although nitrogen enrichment effect on δ15N was anticipated in biota near the farm, the predicted patterns did not consistently occur in all feeding guilds. Two species of suspension-feeders, which relied on naturally δ15N-depleted sources, were δ15N-enriched near the fish farm. In contrast, both species of benthic grazer and deposit-feeder, which relied on naturally δ15N-enriched algal sources, were δ15N-depleted under the influence of FFW. The SI signatures of biota can, therefore, serve as feasible biomarkers for FFW discharges only when the trophic structure of the receiving environment is fully elucidated. [Copyright &y& Elsevier]

Benthic dinoflagellates produce a diverse range of phycotoxins, which are responsible for intoxication events in marine fauna. This study assessed the hemolysis associated toxicities of six species of benthic dinoflagellates from the genera Coolia , Fukuyoa , Amphidinium and Prorocentrum. Results demonstrated that Amphidinium carterae , Coolia tropicalis and Fukuyoa ruetzleri were the three most toxic species, while Prorocentrum cf. lima did not have significant hemolytic effect. Grouper samples (Cephalopholis boenak) were more tolerant to the hemolytic algae than the blackhead seabream (Acanthopagrus schlegelii), with decreased heart rate and blood flow being observed in medaka larvae after exposure to toxic algal extracts. LC-MS/MS analysis detected a gambierone analogue called 44-methylgambierone produced by the C. tropicalis isolate. This analogue was also detected in the F. ruetzleri isolate. This study provided new information on the hemolysis associated toxicities of local toxic benthic dinoflagellates, which contributes to better understanding of their emerging threats to marine fauna and reef systems in Hong Kong. • Rapid screening of hemolysis associated toxicity of benthic dinoflagellates in marine fish. • Species of Coolia , Fukuyoa and Amphidinium could induce hemolysis in marine fish. • Cephalopholis boenak was more tolerant to toxic algae than Acanthopagrus schlegelii. • Hemolytic algae can cause lethality, decreasing heart rate and blood flow in marine medaka. • 44-Methylgambierone was detected in Coolia tropicalis and Fukuyoa ruetzleri. [ABSTRACT FROM AUTHOR]

Long-term effects of environmental factors on phytoplankton community in Deep Bay, Hong Kong, were investigated from 1994 to 2016. Phytoplankton community experienced three important shifts: small flagellates and Chroomonas spp. dominated from 1994 to 2006. Heavy blooms of diatoms Skeletonema costatum and Thalassiosira spp. occurred and became the dominant species between 2007 and 2009. Phytoplankton community was dominated by small flagellates and Chroomonas spp. from 2010 to 2015, and their abundance was much higher than earlier periods. Abundance of Chroomonas spp. decreased sharply in 2016, and Thalassiosira spp. became the dominant species. Phytoplankton community changed from consisting mainly of small flagellates and Chroomonas spp. to more diatoms, changing from ~90% to ~45% for other species abundance and from <10% to ~55% for diatoms. Nitrite, 5-day biochemical oxygen demand, salinity, suspended solids and turbidity were more influential on phytoplankton variation (23.65% explained by all the variables). [ABSTRACT FROM AUTHOR]

Organic UV filters are common ingredients of personal care products (PCPs), but little is known about their distribution in and potential impacts to the marine environment. This study reports the occurrence and risk assessment of twelve widely used organic UV filters in surface water collected in eight cities in four countries (China, the United States, Japan, and Thailand) and the North American Arctic. The number of compounds detected, Hong Kong (12), Tokyo (9), Bangkok (9), New York (8), Los Angeles (8), Arctic (6), Shantou (5) and Chaozhou (5), generally increased with population density. Median concentrations of all detectable UV filters were <250 ng/L. The presence of these compounds in the Arctic is likely due to a combination of inadequate wastewater treatment and long-range oceanic transport. Principal component analysis (PCA) and two-way analysis of variance (ANOVA) were conducted to explore spatiotemporal patterns and difference in organic UV filter levels in Hong Kong. In general, spatial patterns varied with sampling month and all compounds showed higher concentrations in the wet season except benzophenone-4 (BP-4). Probabilistic risk assessment showed that 4-methylbenzylidene camphor (4-MBC) posed greater risk to algae, while benzophenone-3 (BP-3) and ethylhexyl methoxycinnamate (EHMC) were more likely to pose a risk to fishes and also posed high risk of bleaching in hard corals in aquatic recreational areas in Hong Kong. This study is the first to report the occurrence of organic UV filters in the Arctic and provides a wider assessment of their potential negative impacts in the marine environment. [ABSTRACT FROM AUTHOR]

Abstract: The present study investigated the composition profiles and levels of polybrominated diphenyl ethers (PBDEs) and five PBDE alternatives in the blubber of two species of marine mammals, Indo-Pacific humpback dolphins (Sousa chinensis) and finless porpoises (Neophocaena phocaenoides) from the South China Sea. Despite the fact that PBDEs were the most predominant brominated flame retardants in the samples analyzed, decabromodiphenyl ethane (DBDPE), 1,2-bis (2,4,6-tribromophenoxy) ethane (BTBPE), bis- (2-ethylhexyl) -tetrabromophthalate (TBPH), 2-ethylhexyl 2,3,4,5-tetrabromobenzoate (TBB) and Dechlorane Plus (DP) were all detected in both cetacean species. In addition, significantly increasing temporal shifting trends of Deca-BDE to DBDPE, Octa-BDE to BTBPE, and Deca-BDE to DP were observed in porpoise samples between 2003 and 2012 and dolphin samples between 2003 and 2011. These patterns may be attributed to the replacement of PBDEs by alternative halogenated flame retardants (HFRs) and the increasing usage of these alternatives following the restriction/voluntary withdrawal of the production and use of PBDE commercial mixtures. Our findings suggest that the study region may be a source of contamination by PBDE alternative flame retardants due to the high detection frequencies and levels of these compounds in marine mammals. [Copyright &y& Elsevier]

Abstract We take low resolution Muller matrix images of microalgae using a Mueller matrix microscope based on time sequential polarization measurements and obtain a characteristic average Mueller matrix (AMM) which can be evaluated for each cell from the average values of the polarization component images. Using the 136 first and second order terms of the characteristic Mueller matrix elements and linear discriminant analysis (LDA), we can obtain a characteristic polarization parameter for each type of algae and use it to stain and identify these specific cells in a mixed sample containing three strains microalgae with an accuracy higher than 84%. The results demonstrate that AMM can be used for the high-throughput detection of marine microalgae. [ABSTRACT FROM AUTHOR]

• Temperature affected the growth and toxicity of Coolia malayensis. • Growth and abundance were optimized at 24°C. • Higher F v /F m and total phaeo-pigments values were observed in log phase at 28°C. • Toxicity of C. malayensis coincided with high water temperature. • C. malayensis produced more lipophilic algal toxins at a high temperature. Coolia malayensis is one of the commonly found benthic dinoflagellates in Hong Kong which can produce biotoxins and threaten the early life stages of marine invertebrates. Seawater temperature has been recognized as one of the primary environmental factors that affect the formation of harmful algal blooms. The present study evaluated the responses of C. malayensis , including growth, toxicity and toxin content (putative analogues of okadaic acid and azaspiracids), after exposure to a range of seven different temperatures (i.e. , 16°C, 18°C, 20°C, 22°C, 24°C, 26°C, and 28°C). The highest algal density and specific growth rate were recorded at 24°C. Significantly higher F v /F m (maximum quantum yield of PSII) and total phaeo-pigment values were observed in the exponential growth phase at 28°C. The toxicity of the algal extract, which was assessed by the lethality rate of Artemia larvae, increased with temperature. The highest toxin content was detected at the second highest temperature treatment, i.e. , 26°C. Overall, temperature had significant effects on the physiological activities and toxicity of C. malayensis. This study has raised attention to the potentially increasing risks posed by toxic benthic dinoflagellates during heat waves in coastal waters. Image, graphical abstract [ABSTRACT FROM AUTHOR]

• We examined biomagnification potential of TPT in marine food webs in Hong Kong. • We detected high levels of TPT and its degradants in tissues of two marine mammals. • TPT or total-PTs in marine organisms increased significantly with trophic level. • The results confirmed the trophic magnification of TPT and its degradants (DPT). The occurrence of triphenyltin (TPT) compounds, a highly toxic antifouling biocide, has been documented in marine environments and organisms all over the world. While some studies showed that marine mammals can be used as sentinel organisms to evaluate the pollution status of emerging contaminants in the environment because of their long lifespans and high trophic levels, information regarding the contamination status of TPT in marine mammal species has been limited over the past decade. More importantly, the primary bioaccumulation pathway of TPT in these long-lived apex predators and the corresponding marine food web is still uncertain. Therefore, this study aimed to evaluate the contamination statuses of TPT in two marine mammal species, namely the finless porpoise and the Indo-Pacific humpback dolphin, and assess the trophic magnification potential of TPT along the food webs of these two species, using stable isotope analysis, and chemical analysis with gas chromatography-mass spectrometry. The results showed that TPT is the predominant residue in majority of the analyzed individuals of two marine mammals, with concentrations ranging from 426.2 to 3476.6 ng/g wet weight in their muscle tissues. Our results also demonstrated an exponential increase in the concentration of TPT along the marine food web, indicating that trophic magnification occurs in the respective food webs of the two marine mammals. The range of trophic magnification factors of TPT in the food webs of finless porpoise and Indo-Pacific humpback dolphin was 2.51–3.47 and 2.45–3.39, respectively. These results suggest that high trophic organisms may be more vulnerable to the exposure of TPT-contaminated environments due to the high trophic magnification potential, and thus ecological risk of these compounds ought to be assessed with the consideration of their bioaccumulation potentials in these marine mammals. [ABSTRACT FROM AUTHOR]