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Greater amberjack (Seriola dumerili) is an important fishery resource with a circumglobal distribution from tropical to temperate waters. Here, we investigated the spawning migration and habitat utilization of S. dumerili in the East China Sea (ECS). Archival tags were attached to 22 adult fish to examine their horizontal and vertical movements and estimate the spawning ground. S. dumerili were captured and released in the coastal waters of eastern Taiwan on November of 2016 and 2017. Information from seven pop‐up satellite archival tags and seven depth–temperature recorders was recovered. Almost all of the fish stayed in the Taiwanese exclusive economic zone. Most individuals moved from released site to the southern edge of the ECS and showed behavior associated with the topographic features in winter (November to December). These phenomena may be related to foraging and be driven by oceanographic features such as the seasonal monsoon and the Kuroshio. The fish then migrated to the south offshore area of Taiwan in January and February. During their southward migration, the fish experienced a slowly elevated water temperature regime (SETR), which is one of the environmental factors that induce final oocyte maturation. In the spawning season (February to April), tagged females exhibited continuous diel vertical movements (DVMs) after experiencing the SETR. These continuous DVMs were observed over a wide geographic range from north to south in the Kuroshio off eastern Taiwan. Our study demonstrated that the putative spawning ground of S. dumerili must extend further in a north–south direction than predicted in a previous study. [ABSTRACT FROM AUTHOR]

To learn about the movement patterns of bigeye tuna in eastern Taiwan, pop-up satellite archival tags were attached on five tuna ~55 kg and prematurely detached and popped-up after 32 to 132 days-at-liberty. Two tags were physically recovered and provided fine-scale data archiving the full 47 and 132 days-at-liberty. The deepest descent recorded was 1,292 m and the coldest temperature visited 2.7°C. During daytime, the fish spent the majority of time above 400 m at temperatures from ~10 - 25°C and at nighttime; residency was largely confined to the mixed-layer from the surface to ~100 m. Vertical movements traversing through the thermocline during the daytime are based on physiological constraints and/or rapid directional changes conducive for optimal search strategies that increases the chances of prey encounters. Bigeye tuna appear to follow the diel vertical movements of prey organisms comprising the deep sound scattering layer to exploit them as a resource. [ABSTRACT FROM AUTHOR]

An ecological risk assessment was undertaken using productivity‐susceptibility analysis (PSA) to determine the relative vulnerability of 52 species caught by fisheries in the waters off eastern Taiwan. Overall, eight and 20 species were classified as having high and moderate vulnerability, respectively, and the remaining 24 species were classified as having low vulnerability. The species with the highest vulnerability scores were caught mainly by longline and gillnet fisheries, highlighting the need for improved data collection to facilitate a more detailed investigation using more quantitative methods. The data quality analysis indicated that the quality of data was classified as "moderate" for economically important species. However, many species were considered data‐limited and thus collecting high‐resolution catch and effort information and conducting biological studies, especially relating to age, growth and reproduction, are recommended to improve the reliability of outputs from data‐limited assessments such as PSA. [ABSTRACT FROM AUTHOR]

We examined the distribution and genetic variability of the greater amberjack Seriola dumerili in the East China Sea (ECS) from the mitochondrial DNA (mtDNA) control region of young-of-the-year (YOY) individuals, which may reflect the genetic characteristics of the spawning population. In the years 2016 and 2017, a total of 165 YOY S. dumerili were collected from two different locations in the ECS: the southern part of the ECS, and western Japanese coast. The spawning period was estimated using otolith daily increments from a total of 67 larvae and juveniles collected in the ECS. Results from size and age distribution indicated that S. dumerili spawned near the shelf break region in the southern ECS from January to April. Phylogenetic analysis based on mtDNA sequence data showed no significant genetic differentiation among samples collected from different locations, implying S. dumerili in the ECS is mainly composed of one population. S. dumerili around the Japanese coast may be originated from the southern ECS. [ABSTRACT FROM AUTHOR]

In this study, we determined the concentrations of polycyclic aromatic hydrocarbons (PAHs) in road dust from Myanmar, Japan, Taiwan, and Vietnam. PAHs were detected in urban and rural areas of Myanmar at mean concentrations of 630 ng/g dry weight and 200 ng/g dry weight, respectively. PAHs were also detected in road dust from Vietnam (mean 1700 ng/g) and Taiwan (2400 ng/g). PAH diagnostic ratios suggested that fossil fuel vehicular exhaust and biomass combustion are major sources of PAHs in road dust in Myanmar. Road dust samples from Japan, Taiwan, and Vietnam had similar PAH diagnostic ratios, implying that PAH sources are similar. We assessed the human health risks posed by PAHs in road dust using carcinogenic equivalents (CEQs) and incremental lifetime cancer risk (ILCR). Mean CEQs were decreased in the order Taiwan (173 ng/g) > Vietnam (162 ng/g for Hanoi) > Myanmar (42 and 31 ng/g for Yangon and Pathein, respectively) > Japan (30 ng/g for Kumamoto). Benz[a]pyrene, fluoranthene, and benzo[b]fluoranthene, the predominant PAHs, contributed > 70% of total CEQs. High ILCR values were found for Taiwan (5.9 × 10−4 and 9.9 × 10−4 for children and adults, respectively) and Vietnam (6.5 × 10−4 and 9.2 × 10−4 for children and adults, respectively, in Hanoi), indicating that PAHs in road dust pose cancer risks to the inhabitants of Taiwan and Hanoi. To our knowledge, this is the first report to identify PAH pollution in the environment and to evaluate the human health risks of these PAHs in Myanmar. [ABSTRACT FROM AUTHOR]

To investigate the early life history of Seriola dumerili, we first validated otolith daily increments using reared fish (11-51 days after hatching). Four larval and early-juvenile S. dumerili were collected in May and July 2015 around the Penghu Islands, Taiwan (23.45-23.70 °N, 119.40-119.70 °E), by surface larval net towing, but not from drifting seaweeds. Seriola dumerili were caught at the thermal front, and the total lengths and ages ranged 7.4-42.5 mm and 18-56 days, respectively. Our results indicate that the hatching dates of S. dumerili were April to June and larvae may have been accumulated in the frontal zone before the juvenile phase. [ABSTRACT FROM AUTHOR]

The structural complexity of macrophytes that provide various microhabitats is related to local infaunal abundance and diversity. Seagrass is considered an ecosystem engineer that alters the benthic environment and enables certain distinct meiofauna to thrive in sediments. The effects of seagrass species in a mixed-species seagrass bed at Haikou, Taiwan were examined. Analysing quantitative samples obtained from patches of Thalassia hemprichii, Halodule uninervis, Halophila ovalis and adjacent unvegetated sediments inspected the community structures of meiofauna and marine nematodes. The abundance and diversity of crustaceans and nematodes were substantially higher in habitats in which seagrass grew than in those comprising unvegetated sediments. Both the compositions of higher meiofaunal taxa and nematode species were distinct between seagrass habitats and unvegetated areas. Several nematode species existed exclusively in patches of individual seagrass species, whereas no nematode specifically occurred in unvegetated areas. Regarding the trophic types of nematodes, non-selective deposit feeders were prevalent in the present study, whereas selective deposit feeders and epistrate feeders were relatively dominant in seagrass habitats. Sediments underneath various patches of seagrass species harbour dissimilar nematode communities, even with similar sediment parameters and at a small-scale distance. [ABSTRACT FROM PUBLISHER]

The French beam trawl and the ORE beam trawl are common research sampling gears for deep-sea biodiversity. The French beam trawl is equipped with a tickler chain and a pair of iron sides. The ORE beam trawl has a larger mouth area than the French beam trawl and has no tickler chain. With a tickler chain, the French beam trawl appears to yield more benthic catches, whilst the ORE beam trawl may be able to collect more bathypelagic species, due to its larger mouth area. In the present study, the assemblages of decapod crustaceans in Taiwan deep waters collected with the French type and the ORE type beam trawls were compared at depths of 250, 500, and 1200 meters. With multivariate analysis, the species abundance of the catches collected by both methods appeared similar, but the catches in the French beam trawl had higher taxonomic distinctness and yielded more benthic species (especially Brachyura) at depths of 250 m and 500 m when compared to the ORE beam trawl. There were no differences in abundance of pelagic species between the two trawls, suggesting that the degree of net avoidance by species in both trawls was similar. The sizes of the dominant catches were similar in both trawls, indicating that the mesh escapement was similar in both the French beam trawl and the ORE beam trawl. During operations, the French beam trawl appears to be more robust to work on rougher terrains (e.g., with lots of sunken wood and mud). In the present study, we revealed that both French beam trawl and ORE beam trawl generally show a similar performance in collecting deep-sea decapod crustaceans, except that the French beam trawl may yield a greater diversity of benthic species at the 250 and 500 m levels. Further research is needed to compare the performance of the two trawls for catching other groups of deep-sea benthic animals (e.g., molluscs and fishes), which is essential for gear consideration in quantitative community studies. [ABSTRACT FROM AUTHOR]

The sampling efficiency of two types of beam trawl towed at different velocities was compared when sampling deep-sea demersal fish and decapod crustaceans. The trawls were a Sigsbee-Agassiz type of 2 m span, and an Oregon type of 3 m span. The different hauls caught by the Oregon type beam trawl of 3 m span towed at 1.5 knot (3m 1.5 kt), the Oregon type towed at 0.8 knot (3m 0.8 kt) and the Sigsbee-Agassiz type towed at 1.5 knot (2m 1.5 kt) were compared by analysis of variance (ANOVA), the Tukey test, cluster analysis based on Morisita-Horn index, and correspondence analysis. The minimum viable sample size was determined by a randomization test. For demersal fish, the type of gear used had more influenced on the samples obtained than the towing velocity. For decapod crustaceans, no significant difference was detected between different trawls towed at different velocities. The common idea that if these types of trawl are towed at 1 knot or more, they cannot efficiently sample epifauna, but demersal fish can be well sampled, should be abandoned. The samples of demersal fish caught by 3m 1.5 kt revealed the greatest consistency and lowest variation than the others. We recommend using an Oregon type beam trawl of 3 m span towed at 1.5 knot as an ordinary deep-sea sampling device. Only a single successful haul or a sample size of 52 individuals was sufficient for estimating demersal fish diversity, but at least two successful hauls or a sample size of 54 individuals were needed for decapod crustaceans. If possible, seven successful hauls or a sample size of 189 individuals of decapod crustaceans are recommended for community study. [ABSTRACT FROM AUTHOR]

This study investigated the spatial variation in the components of a microbial food web (viruses, picoplankton, nanoflagellates, and ciliates) in different hydrographic environments in the Taiwan Strait during winter. Water temperature and salinity varied spatially, with lower temperatures (15.3–22.8 °C) and salinities (32.2–33.4 psu) in the northern part of the Taiwan Strait, largely affected by runoff from the coast of China. Concentrations of nutrients and Chl a were significantly higher in the northern part than that in the southern part of the study area. Synechococcus spp., nanoflagellate, and ciliate abundance also varied significantly, with the northern strait having higher abundances of these communities. In contrast, a higher abundance of bacteria was found in the southern part of the Taiwan Strait. The results of this study, which describes two different ecosystems in the Taiwan Strait, suggest that during winter, a "viral loop" might play an important role in controlling bacterial production in the southern part of the Taiwan Strait, while nanofalgellate grazing of picophytoplankton may contribute mainly to the flux of energy in the northern part. [ABSTRACT FROM AUTHOR]