Latitudinal Change in Benthic Foraminiferal Fauna by ITCZ Movement along the ~131°W Transect in the Equatorial Pacific Ocean

Takata, Hiroyuki,Yoo, Chan Min,Kim, Hyung Jeek,Khim, Boo-Keun Korean Ocean Research & Development Institute and 2016 OCEAN SCIENCE JOURNAL Vol.51 No.4

Modern and fossil benthic foraminifera were examined from nine surface sediments and two piston cores along the <TEX>${\sim}131^{\circ}W$</TEX> transect in the equatorial Pacific Ocean. This study was conducted to clarify the biotic response of abyssal benthic foraminifera during the last 220 ka to changes in the seasonal extent of the Intertropical Convergence Zone (ITCZ). The abundance of modern benthic foraminifera was high at stations between the equator and <TEX>$6^{\circ}N$</TEX>, whereas it was low at stations north of <TEX>$6^{\circ}N$</TEX>, which is generally consistent with the latitudinal <TEX>$CaCO_3$</TEX> distribution of surface sediments. The northward increase of Epistominella exigua from the equator to <TEX>${\sim}6^{\circ}N$</TEX> is similar to the seasonal variations in chlorophyll-a concentrations in the surface water and ITCZ position along <TEX>${\sim}131^{\circ}W$</TEX>. This species was more common at core PC5103 (<TEX>${\sim}6^{\circ}N$</TEX>) than at core PC5101 (<TEX>${\sim}2^{\circ}N$</TEX>) after ~130 ka, when the Shannon-Wiener diversity (H') between the two cores started to diverge. Hence, the presentday latitudinal difference in benthic foraminifera (E. exigua and species diversity) between <TEX>${\sim}2^{\circ}N$</TEX> and <TEX>${\sim}6^{\circ}N$</TEX> along <TEX>${\sim}131^{\circ}W$</TEX> has been generally established since ~130 ka. According to the modern relationship between the seasonality of primary production and seasonal ITCZ variations in the northern margin of the ITCZ, the latitudinal divergence of benthic foraminiferal fauna between <TEX>${\sim}2^{\circ}N$</TEX> and <TEX>${\sim}6^{\circ}N$</TEX> since ~130 ka appear to have been induced by more distinct variations in the seasonal movement of ITCZ.

Distribution of Chaetognaths (Aphragmophora: Sagittidae) in Korean Waters

Lee, Bo Ram,Kim, Hyun Woo,Park, Wongyu Korean Ocean Research & Development Institute and 2016 OCEAN SCIENCE JOURNAL Vol.51 No.3

The distribution of chaetognaths was investigated at 10 stations in the southern part of Korean waters (line S), at six stations in the eastern part of Korean waters (line E) and at 8 stations in the western part of Korean waters (line W). Ten species were present at the stations at line S and Flaccisagitta enflata and Zonosagitta bedoti were dominant among these species. Mean densities at line S ranged from <TEX>$7inds.m^{-3}$</TEX> to <TEX>$27inds.m^{-3}$</TEX>. Five chaetognath species were found at the stations at line E and Zonosagitta nagae and Parasagitta elegans were the most abundant. Mean densities ranged from 1 to <TEX>$10inds.m^{-3}$</TEX>. Four chaetognath species were present at line W and Aidanosagitta crassa and chaetognath juveniles were dominant in this line. Mean densities ranged from 21 to <TEX>$199inds.m^{-3}$</TEX>. The density of chaetognaths was highest at line W while the diversity of chaetognaths was highest at line S. Individuals of chaetognaths were divided into two groups, a group of line E and a mixed group of lines W and E. This study suggests that F. enflata is a warm water species; Z. nagae is a mixed water species; P. elegans is a cold water species; and A. crassa is a less saline water species. The mtCOI of F. enflata, which was a dominant species in the sampling area, was analyzed. F. enflata that are present in waters around Korean were genetically divided into two groups, which may be influenced by various oceanic factors.

Population structure of the Korean gizzard shad, Konosirus punctatus (Clupeiformes, Clupeidae) using multivariate morphometric analysis

Myoung, S. H.,Kim, J. K. Korean Ocean Research & Development Institute and 2016 OCEAN SCIENCE JOURNAL Vol.51 No.1

<P>The gizzard shad, Konosirus punctatus, is one of the most important fish species in Korea, China, Japan and Taiwan, and therefore the implementation of an appropriate population structure analysis is both necessary and fitting. In order to clarify the current distribution range for the two lineages of the Korean gizzard shad (Myoung and Kim 2014), we conducted a multivariate morphometric analysis by locality and lineage. We analyzed 17 morphometric and 5 meristic characters of 173 individuals, which were sampled from eight localities in the East Sea, the Yellow Sea and the Korean Strait. Unlike population genetics studies, the canonical discriminant analysis (CDA) results showed that the two morphotypes were clearly segregated by the center value '0' of CAN1, of which morphotype A occurred from the Yellow Sea to the western Korean Strait with negative values, and morphotype B occurred from the East Sea to the eastern Korean Strait with positive values even though there exists an admixture zone in the eastern Korean Strait. Further studies using more sensitive markers such as microsatellite DNA are required in order to define the true relationship between the two lineages.</P>

An OSSE Study for Deep Argo Array using the GFDL Ensemble Coupled Data Assimilation System

Chang, You-Soon,Zhang, Shaoqing,Rosati, Anthony,Vecchi, Gabriel A.,Yang, Xiaosong Korean Ocean Research & Development Institute and 2018 OCEAN SCIENCE JOURNAL Vol.53 No.2

An observing system simulation experiment (OSSE) using an ensemble coupled data assimilation system was designed to investigate the impact of deep ocean Argo profile assimilation in a biased numerical climate system. Based on the modern Argo observational array and an artificial extension to full depth, 'observations' drawn from one coupled general circulation model (CM2.0) were assimilated into another model (CM2.1). Our results showed that coupled data assimilation with simultaneous atmospheric and oceanic constraints plays a significant role in preventing deep ocean drift. However, the extension of the Argo array to full depth did not significantly improve the quality of the oceanic climate estimation within the bias magnitude in the twin experiment. Even in the 'identical' twin experiment for the deep Argo array from the same model (CM2.1) with the assimilation model, no significant changes were shown in the deep ocean, such as in the Atlantic meridional overturning circulation and the Antarctic bottom water cell. The small ensemble spread and corresponding weak constraints by the deep Argo profiles with medium spatial and temporal resolution may explain why the deep Argo profiles did not improve the deep ocean features in the assimilation system. Additional studies using different assimilation methods with improved spatial and temporal resolution of the deep Argo array are necessary in order to more thoroughly understand the impact of the deep Argo array on the assimilation system.

First Retrieval of Data regarding Spatial Distribution of Asian Dust Aerosol from the Geostationary Ocean Color Imager

Lee, Kwon Ho,Ryu, Joo Hyung,Ahn, Jae Hyun,Kim, Young Joon Korean Ocean Research & Development Institute and 2012 OCEAN SCIENCE JOURNAL Vol.47 No.4

Aerosol optical thickness (AOT) was retrieved from the Geostationary Ocean Color Imager (GOCI) on board the Communication, Ocean, and Meteorological Satellite (COMS) for the first time. AOT values were retrieved over the ocean at a spatial scale of <TEX>$0.5{\times}0.5km^2$</TEX> by using the look-up table (LUT)-based separation technique. The radiative transfer model (RTM) was used for different models of atmosphere-ocean environmental conditions, taking into account the realistic variability of scattering and absorption. Ocean surface properties affected by whitecaps and pigment content were also taken into account. The results show that the radiance observed by the GOCI amounts to only 5% of the radiation that penetrated the ocean and, consequently, 95% of the radiation is scattered in the atmosphere or reflected at the ocean surface in the visible wavelengths longer than 0.6 im. Within these wavelengths, radiance variations at the top of atmosphere (TOA) due to pigment variations are within 10%, while the radiance variation due to wind speed is considerably higher. For verification of GOCI-retrieved AOTs, comparison between GOCI and ground-based sunphotometer measurement at Gosan, Korea (<TEX>$126.10^{\circ}E$</TEX>, <TEX>$33.23^{\circ}N$</TEX>)) showed good correlation (r = 0.99). The GOCI observations obtained by using the proposed technique showed promising results for the daily monitoring of atmospheric aerosol loading as well as being useful for environmental supervisory authorities.

In-situ Measured Carbon and Nitrogen Uptake Rates of Melt Pond Algae in the Western Arctic Ocean, 2014

Song, Ho Jung,Kim, Kwanwoo,Lee, Jae Hyung,Ahn, So Hyun,Joo, Houng-Min,Jeong, Jin Young,Yang, Eun Jin,Kang, Sung-Ho,Yun, Mi Sun,Lee, Sang Heon Korean Ocean Research & Development Institute and 2018 OCEAN SCIENCE JOURNAL Vol.53 No.1

Although the areal coverage of melt pond in the Arctic Ocean has recently increased, very few biological researches have been conducted. The objectives in this study were to ascertain the uptake rates of carbon and nitrogen in various melt ponds and to understand the major controlling factors for the rates. We obtained 22 melt pond samples at ice camp 1 (<TEX>$146.17^{\circ}W$</TEX>, <TEX>$77.38^{\circ}N$</TEX>) and 11 melt pond samples at ice camp 2 (<TEX>$169.79^{\circ}W$</TEX>, <TEX>$76.52^{\circ}N$</TEX>). The major nutrient concentrations varied largely among melt ponds at the ice camps 1 and 2. The chl-a concentrations averaged from the melt ponds at camps 1 and 2 were <TEX>$0.02-0.56mg\;chl-a\;m^{-3}$</TEX> (<TEX>$0.12{\pm}0.12mg\;chl-a\;m^{-3}$</TEX>) and <TEX>$0.08-0.30mg\;chl-a\;m^{-3}$</TEX> (<TEX>$0.16{\pm}0.08mg\;chl-a\;m^{-3}$</TEX>), respectively. The hourly carbon uptake rates at camps 1 and 2 were <TEX>$0.001-0.080mg\;C\;m^{-3}\;h^{-1}$</TEX> (<TEX>$0.025{\pm}0.024mg\;C\;m^{-3}\;h^{-1}$</TEX>) and <TEX>$0.022-0.210mg\;C\;m^{-3}\;h^{-1}$</TEX> (<TEX>$0.077{\pm}0.006mg\;C\;m^{-3}\;h^{-1}$</TEX>), respectively. In comparison, the nitrogen uptake rates at camps 1 and 2 were <TEX>$0.001-0.030mg\;N\;m^{-3}\;h^{-1}$</TEX> (<TEX>$0.011{\pm}0.010mg\;N\;m^{-3}\;h^{-1}$</TEX>) and <TEX>$0.002-0.022mg\;N\;m^{-3}\;h^{-1}$</TEX> (<TEX>$0.010{\pm}0.006mg\;N\;m^{-3}\;h^{-1}$</TEX>), respectively. The values obtained in this study are significantly lower than those reported previously. A large portion of algal biomass trapped in the new forming surface ice in melt ponds appears to be one of the main potential reasons for the lower chl-a concentration and subsequently lower carbon and nitrogen uptake rates revealed in this study. A long-term monitoring program on melt ponds is needed to understand the response of the Arctic marine ecosystem to ongoing environmental changes.

Characterization of Deep-sea Macrofauna in the Korean Exploration Claim Area in the Clarion-Clipperton Fracture Zone, Northeastern Pacific Ocean

Yu, Ok Hwan,Lee, Hyung-Gon,Kim, Dongsung,Wi, Jin Hee,Kim, Kyeong Hong,Yoo, Chan Min Korean Ocean Research & Development Institute and 2018 OCEAN SCIENCE JOURNAL Vol.53 No.2

Macrofauna in the Clarion-Clipperton Fracture Zone remain poorly understood, due both to gross undersampling and to the fact that most species collected from the area are new to science. Evaluation of the diversity and species distribution of the benthic fauna in this area is critical to predicting and managing the impacts of manganese nodule mining. In this study, we investigated the distribution of macrofauna to understand the natural variability in the macrobenthic community and, by extension, to establish a baseline for environmental risk assessment. Samples were collected from the KR5 block of the Korea Contract Area, within the abyssal area of the Clarion-Clipperton Fracture Zone in the northeastern Pacific Ocean, by the RV Onnuri from 2012-2014. A total of 36 core samples were examined in the survey, from which we identified 183 macrobenthic species in 25 faunal groups with a mean density of <TEX>$257ind/m^2$</TEX>. Not taking into account meio-faunal groups such as nematodes and harpacticoid copepods, the highest percentage of individuals was represented by Arthropoda. The dominant species (> 1% of total density) were the tanaids Typhlotanais sp.1, and Akanthophoreus spp. and Stenotanais sp., the isopod Macrostylis sp.1, and the polychaetes Cirratulidae spp. and Levinsenia uncinata. The abundances of the two dominant species, the tanaid Typhlotanais sp1. and isopod Macrostylis sp.1., were positively correlated with total organic carbon (TOC). There were no differences in macrofaunal density and community structure between preserved areas (PRA), the potential benthic impacted site (BIS), and other areas near the BIS. In general, higher diversity was associated with homogeneous environmental conditions, with high nodule coverage (> 50%) and TOC.

Modeling the changes in the concentration of aromatic hydrocarbons from an oil-coated gravel column

Jung, J. H.,Kang, H. J.,Kim, M.,Yim, U. H.,An, J. G.,Shim, W. J.,Kwon, J. H. Korean Ocean Research & Development Institute and 2015 OCEAN SCIENCE JOURNAL Vol.50 No.4

Antioxidative-related Genes Expression Following Perfluorooctane Sulfonate (PFOS) Exposure in the Intertidal Mud Crab, Macrophthalmus japonicus

Park, Kiyun,Nikapitiya, Chamilani,Kwak, Tae-Soo,Kwak, Ihn-Sil Korean Ocean Research & Development Institute and 2015 OCEAN SCIENCE JOURNAL Vol.50 No.3

Effect of Dikes on the Distribution and Characteristics of Phragmites australis in Temperate Intertidal Wetlands located in the South Sea of Korea

Lee, Jiyoung,An, Soonmo Korean Ocean Research & Development Institute and 2015 OCEAN SCIENCE JOURNAL Vol.50 No.1