Determining the genetic diversity and source rookeries of sea turtles collected from feeding grounds can facilitate effective conservation initiatives. To ascertain the genetic composition and source rookery, we examined a partial sequence of the mitochondrial control region (CR, 796 bp) of 40 green turtles (Chelonia mydas) collected from feeding grounds around the Korean Peninsula between 2014 and 2022. We conducted genetic and mixed-stock analyses (MSA) and identified 10 CR haplotypes previously reported in Japanese populations. In the haplotype network, six, three, and one haplotype(s) grouped with the Japan, Indo-Pacific, and Central South Pacific clades, respectively. The primary rookeries of the green turtles were two distantly remote sites, Ogasawara (OGA) and Central Ryukyu Island (CRI), approximately 1,300 km apart from each other. Comparing three parameters (season, maturity, and specific feeding ground), we noted that OGA was mainly associated with summer and the Jeju Sea, whereas CRI was with fall and the East (Japan) Sea ground. The maturity did not show a distinct pattern. Our results indicate that green turtles in the feeding grounds around the Korean Peninsula originate mainly from the Japan MU and have genetic origins in the Japan, Indo-Pacific, and Central South Pacific clades. Our results provide crucial insights into rookeries and MUs, which are the focus of conservation efforts of the Republic of Korea and potential parties to collaborate for green turtle conservation.

OBJECTIVE: Plants distributed between southern Taiwan and the north of the Philippines are spread among numerous small islands in an area crossed by the powerful Kuroshio current. Oceanic currents can be effective seed-dispersal agents for coastal plant species. Moreover, the Luzon Strait is an area prone to tropical cyclones. The aim of this study is to look at the dispersal capability of an endangered coastal plant species, the Mearns fig (Ficus pedunculosa var. mearnsii), using both experimental and population genetics methods.
METHODS: Southern Taiwan, the Philippines, and the islands between Luzon and Taiwan Island.
METHODS: This study combined two types of analysis, i.e., buoyancy experiments on syconia and double digest restriction-associated DNA sequencing (ddRAD), to analyze the population genetics of the Mearns fig.
RESULTS: We first discovered that mature Mearns fig syconia could float in seawater. They have a mean float duration of 10 days to a maximum of 21 days. Germination rates varied significantly between Mearns fig seeds that had undergone different durations of flotation treatment. Population genetic analysis shows a high degree of inbreeding among various Mearns fig populations. Moreover, no isolation by distance was found between the populations and individuals.
CONCLUSIONS: From our analysis of the genetic structure of the Mearns fig populations, we can clearly highlight the effect of the Kuroshio oceanic current on the seed dispersal of this fig tree. Comprehensive analysis has shown that Mearns fig seeds are still viable before the mature syconium sinks into the seawater, and so they could use the Kuroshio Current to float to the current population locations in Taiwan.

The nutrient-scarce, warm, and high-salinity Kuroshio current has a profound impact on both the marine ecology of the northwestern Pacific Ocean and the global climate. This study aims to reveal the seasonal dynamics of picoplankton in the subtropical Kuroshio current. Our results showed that one of the picocyanobacteria, Synechococcus, mainly distributed in the surface water layer regardless of seasonal changes, and the cell abundance ranged from 104 to 105 cells mL-1. In contrast, the maximum concentration of the other picocyanobacteria, Prochlorococcus, was maintained at more than 105 cells mL-1 throughout the year. In the summer and the autumn, Prochlorococcus were mainly concentrated at the water layer near the bottom of the euphotic zone. They were evenly distributed in the euphotic zone in the spring and winter. The stirring effect caused by the monsoon determined their distribution in the water column. In addition, the results of 16S rRNA gene diversity analysis showed that the seasonal changes in the relative abundance of Synechococcus and Prochlorococcus in the surface water of each station accounted for 20 to 40% of the total reads. The clade II of Synechococcus and the High-light II of Prochlorococcus were the dominant strains in the waters all year round. Regarding other picoplankton, Proteobacteria and Actinobacteria occupied 45% and 10% of the total picoplankton in the four seasons. These data should be helpful for elucidating the impacts of global climate changes on marine ecology and biogeochemical cycles in the Western Boundary Currents in the future.

We establish a new interstitial polyclad species, Theama japonica sp. nov., based on specimens collected from coarse-sandy habitats in three Japanese main islands (Hokkaido, Honshu, and Shikoku) along the coasts of the Pacific Ocean and the Sea of Japan. Theama japonica is characterized by i) two pairs of cerebral eyespots and four to six precerebral eyespots; ii) eosinophilic secretion glands distributed in the distal half of the inner ventral part of the prostatic vesicle; iii) a conical penis papilla, bent up dorsally, with a sclerotized inner wall; iv) the prostatic sheath with an inner angular fold on the dorso-distal side; and v) the external cilia longer dorsally than ventrally. Partial sequences of the cytochrome c oxidase subunit I (COI) gene from 20 specimens collected at eight localities along Japanese coasts represented 19 haplotypes. The uncorrected p-distances among these COI haplotypes fell within intraspecific variations observed in other polyclads. A network analysis based on these COI haplotypes suggested a geographically non-cohesive genetic structure of the species, possibly indicating the species\' high dispersibility. Molecular phylogenetic analyses based on a concatenated dataset of 18S and 28S rDNA sequences showed T. japonica formed a clade with other Theama species. The resulting tree also indicates that our new species is more closely related to Theama sp. from Colombia than species from Panama and Croatia.

Rates of seawater acidification and rise of partial pressure of CO2 (pCO2) at ocean margins are highly uncertain. In this study, nine years of time-series data sampled during 2010-2018 along Kuroshio Current near the East China Sea (ECS) were investigated. We found trends of surface seawater pCO2 at 3.70 ± 0.57 μatm year-1 and pH at -0.0033 ± 0.0009 unityear-1, both of which were significantly greater than those reported from other oceanic time series. Mechanistic analysis showed that seawater warming caused rapid rates of pCO2 increase and acidification under sustained DIC increase. The faster pCO2 growth relative to the atmosphere resulted in the CO2 uptake through the air-sea exchange declining by ~50 % (~-0.8 to -0.4 mol C m-2 year-1) over the study period. Our results imply that rapidly warming boundary currents could potentially present an elevated pCO2 trend, leading to a gradual reduction and eventual loss of oceanic CO2 uptake under climate change.

During this research, the average surface temperature, salinity, dissolved oxygen, and pH were 24.65 ± 1.53 (°C), 34.21 ± 0.07 (PSU), 6.85 ± 0.18 (mg/L), and 8.36 ± 0.03, respectively. Based on these environmental parameters, stations were arranged into three groups. Group A represents stations located around Keelung Island with the relative highest average dissolved oxygen, lowest average temperature, and pH values. Instead, the lowest average dissolved oxygen and highest average temperature, salinity, and pH values were recorded at the offshore stations. Keelung Island area was charged by cold water masses, which were driven by the Northeast monsoon, and stations in group C were affected by the Kuroshio Current. Kueishan Island area was mainly affected by mixed water masses resulting from the Kuroshio intrusion and monsoon-derived cold water. In this study, a total of 108 copepod species were identified, with an average abundance of 774.24 ± 289.42 (inds. m-3). Most species belong to the orders Calanoida and Poecilostomatoida, with an average relative abundance (RA) of 62.96% and 30.56%, respectively. Calanoid copepodites were the most dominant group, with a RA of 28.06%. This was followed by Paracalanus aculeatus, with a RA of 18.44%. The RA of Clausocalanus furcatus and Canthocalanus pauper was 4.80% and 3.59%, respectively. The dominant species P. aculeatus, C. pauper, Paracalanus parvus, and Temora turbinata were positively correlated with dissolved oxygen and negatively correlated with temperature in the surface waters. pH showed a negative correlation with P. parvus and T. turbinata, while the temperature was negatively correlated with these two dominant species. Indicator species were selected by an indicator value higher than 50%. Temora turbinata, Calanopia elliptica, C. pauper, Euchaeta concinna, Temora discaudata, Acartia pacifica, Macrosetella gracilis, Corycaeus speciosus, and P. parvus were considered as monsoonal cold water indicator species in Group A. Indicator copepod species for the Kuroshio Current were Farranula concinna, Copilia mirabilis, Candacia aethiopica, Corycaeus agilis, Farranula gibbula and Acrocalanus monachus in the study area. Paracandacia truncata, Oncaea clevei, P. aculeatus, and Centropages furcatus were considered suitable indicators for mixed water masses.

A recent study demonstrated the possibility of satellite-based detection of surface blooms of the heterotrophic dinoflagellate, red Noctiluca scintillans (RNS). The study further documented RNS bloom patterns in the East China Sea (ECS) between 2000 and 2017. Here, complemented by more recent satellite observations between 2018 and 2020, the 21-year bloom record shows that while bloom distributions vary in different years and annual cumulative bloom footprint shows an increasing trend, the 21-year cumulative bloom footprint is bounded by major ocean fronts such as the Kuroshio Front. Of all observations, 2020 is a critical year to \"complete\" the footprint as extra discharge from the 2020 Yangtze River flood event, combined with ocean currents, transports the bloom to the most northeast location of the footprint although the riverine influence reaches at least 128°E, well beyond the RNS footprint.

Long-term variation of nitrate in the East Sea was monitored in order to investigate impact of Three Gorges Dam (TGD) in the Changjiang River\'s upstream, China and Nakdong River\'s estuary dam, Korea. Tracing source of nitrate was another objective in this study. For this study, nutrient data were collected for 20 years from 1999 to 2018 in the East Sea, and divided into 4 sections, and evaluated whether a significant difference exists among the averages of nitrate concentrations. The concentrations of nitrate were affected by the major rivers (the Nakdong and the Taehwa Rivers) and Tsushima Warm Current (TWC) which diverged from the Kuroshio Current passing through East China Sea (ECS). Our results also indicated that long-term nitrate concentrations decreased and its reasons. First, the construction of TGD in the upstream of the Changjiang River may have resulted in the decrease of the nitrate supply in the river and ECS which is carried by TWC, toward the East Sea. Second, decrease in the nitrate flux of the Nakdong River\'s estuary due to the construction of the estuary dam and sewer treatment plant could also be a factor for the nitrate decrease in the East Sea. Therefore, anthropogenic activities from the Nakdong River and Changjiang River had a long-term effect on the East Sea\'s nitrate concentrations. The amount of nitrate runoff reduced by the anthropogenic activities influenced the nitrate levels over a long period by the flow of currents in the East Sea.

The 240Pu/239Pu atom ratios were determined by inductively coupled plasma mass spectrometry for seawater samples from the Okinawa Trough in the western North Pacific Ocean margin to identify their Pu sources and to elucidate the temporal variability in atom ratios in the water columns in the western North Pacific Ocean and its marginal seas. The 239Pu, 240Pu and 239+240Pu water column inventories were 12.2 ± 0.5, 10.5 ± 0.5 and 22.7 ± 0.7 Bq m-2, respectively. The observed 240Pu/239Pu ratios were clearly greater than the mean global fallout ratio of ∼0.18 with a mean value of 0.236 ± 0.014. The observed greater atom ratios confirmed the presence of close-in fallout Pu from nuclear testing at the Pacific Proving Grounds (PPG). The relative percentage of the PPG-derived Pu to global fallout Pu was estimated as 41 ± 10%. The 239+240Pu water column inventory originating from the PPG close-in fallout was also calculated as 9.2 ± 0.4 Bq m-2. The temporal variability in the mean 240Pu/239Pu atom ratios in the water columns in the western North Pacific Ocean and its marginal seas was obtained through comparison of the present study values and the previously reported values, and it had no significant temporal variation with a mean value of 0.237 ± 0.004 during the observation period of 1984-2015. The 239Pu and 240Pu derived from the two different sources of global fallout and the close-in fallout at the PPG were homogenized in the water masses in the studied areas.

Shih-Chong Chen, Ching-Rong Chang, and Yu-San Han (2018) The spawning migration of the Japanese eel, Anguilla japonica, along the western Mariana Ridge is considered one of the longest animal migrations. To establish an appropriate conservation policy for this species, a complete life cycle study is required, but the migratory routes of anguillid eels remain poorly documented. Anguilla japonica, A. marmorata, and A. bicolor pacifica are three common eel species in Taiwan. The present study used pop-up archival transmitting tags to track their movements during the oceanic phase of their migration. Twenty silver eels (farmed and wild) were tagged and released near the Gueishan and Liuchiu Islands. All three species in the Gueishan Island group were entrained in the Kuroshio Current, and pop-up tag data showed that, after 23 days, the farthest distance travelled was approximately 1,500 km, to the southern waters of Yakushima, Japan. In comparison, eels released near Liuchiu Island moved in the opposite direction, which suggests that they were influenced by the recirculation in the southwestern waters of Taiwan. The migration speed of eels was estimated to be between 12.9 km/d and 65.2 km/d. Several eels exhibited diel vertical migration behavior, moving into deeper water during the daytime and ascending into shallower waters at night. The farmed eels exhibited similar patterns of diel vertical migration to wild eels. The results of this study suggest that eels from Taiwan travel through the Kuroshio Current during their early migration, irrespective of species and source. Of importance, farmed eels appeared to behave similar to wild ones following artificial release. This information provides important rationale for releasing cultivated eels for resource enrichment programs.