Biological Structure and Seasonality in the Japan/East Sea (original) (raw)
Related papers
Seasonal and inter-annual dynamics of mesoplankton in the northwestern Japan Sea
Progress in Oceanography, 2004
Based upon four decades of observations in the northwestern part of the Japan Sea, the seasonal and inter-annual variations of zooplankton abundance and species composition in the epipelagic layer are considered. Seasonal characteristics of the zooplankton community are described in detail for five domains that occur within this part of the Japan Sea. Inter-decadal variation was not significant, but inter-annual variation was considerable and generally opposite to water temperature changes in the upper layer. Exceptional years such as 1996 were noted when a maximum abundance of zooplankton in summer occurred along with a slowing of the seasonal pattern of succession.
Review of recent findings on the water masses and circulation in the East Sea (Sea of Japan
Journal of Oceanography, 2008
Recent findings on water masses, biogeochemical tracers, deep currents and basin-scale circulation in the East/Japan Sea, and numerical modeling of its circulation are reviewed. Warming continues up to 2007 despite an episode of bottom water formation in the winter of 2000–2001. Water masses have definitely changed since the 1970s and further changes are expected due to the continuation of warming. Accumulation of current data in deep waters of the East/Japan Sea reveals that the circulation in the East/Japan Sea is primarily cyclonic with sub-basin scale cyclonic and anticyclonic cells in the Ulleung Basin (Tsushima Basin). Our understanding of the circulation of intermediate water masses has been deepened through high-resolution numerical studies, and the implementation of data assimilation has had initial success. However, the East/Japan Sea is unique in terms of the fine vertical structures of physical and biogeochemical properties of cold water mass measured at the highest precision and their rapid change with the global warming, so that full understanding of the structures and their change requires in-depth process studies with continuous monitoring programs.
Oceanography of the East Sea (Japan Sea)
2016
The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. Cover Image: The image shows a distribution of chlorophyll a concentration over the East Sea derived from Geostationary Ocean Color Imager (GOCI) observations taken in September, 2011. It reveals various ocean surface features such as fronts, plumes, filaments and eddies. Natural color composite is shown on the land. GOCI, the first ocean color instrument operated on geostationary orbit, is collecting ocean color radiometry data since July, 2010. GOCI has an unprecedented capability to provide eight images a day with a 500 m resolution for the North East Asian seas around Korean peninsula.
Progress in Oceanography, 2003
Seasonal and interannual change in mesozooplankton community structure in the offshore Tsushima Current area of the Japan/East Sea was studied in relation to climatic events and temporal variability of the upper water column environment from 1991 to 1999. We observed a clear seasonal succession in zooplankton community structure from a cold-water copepod-dominated community in winter and spring to a gelatinous, carnivorous and warm-water copepoddominated community in summer and autumn. The mean abundance (inds. m Ϫ3 ) of the spring community was 3-4fold higher than that of the other season. The spring community structure varied considerably between years: the community characterized by the summer-autumn type zooplankton assemblage appeared in 1991-1993 and 1998, while the community characterized by high abundance of cold-water copepods appeared in the mid 1990s. Time series profiles of water density and nutrients showed the thickness of the surface warm Tsushima Current and the cold subsurface water increased and decreased, respectively, limiting nutrient supply to the surface water in 1992 and 1998. These results suggest that a thick, warm surface layer might reduce the reproductive success and survival ratio of the coldwater copepods both directly and indirectly, by hindering their upward migration to the surface where food is available, and by limiting phytoplankton growth due to nutrient depletion, respectively. A Monsoon Index (MOI) showed weaker winter wind stress in 1992 and 1998, which might have attenuated formation of the cold subsurface layer in the northern Japan/East Sea and been responsible for surface warming of the study area. Since 1992 and 1998 were El Niño years, this study revealed that ENSO related climatic variability on an interannual time scale considerably influenced the lower trophic level ecosystem in the Japan/East Sea.
Circulation and currents in the southwestern East/Japan Sea: Overview and review
Progress in Oceanography, 2004
A review is made of circulation and currents in the southwestern East/Japan Sea (the Ulleung Basin), and the Korea/ Tsushima Strait which is a unique conduit for surface inflow into the Ulleung Basin. The review particularly concentrates on describing some preliminary results from recent extensive measurements made after 1996. Mean flow patterns are different in the upstream and downstream regions of the Korea/Tsushima Strait. A high velocity core occurs in the mid-section in the upstream region, and splits into two cores hugging the coasts of Korea and Japan, the downstream region, after passing around Tsushima Island located in the middle of the strait. Four-year mean transport into the East/Japan Sea through the Korea/Tsushima Strait based on submarine cable data calibrated by direct observations is 2.4 Sv (1 Sv = 10 6 m 3 s À1 ). A wide range of variability occurs for the subtidal transport variation from subinertial (2-10 days) to interannual scales. While the subinertial variability is shown to arise from the atmospheric pressure disturbances, the longer period variation has been poorly understood.
Ichthyofaunistic biogeography of the Japan (East) Sea
Aim The aim of the present study is the distribution analysis of species richness of ichthyofauna at the east and west coasts of the Japan Sea for the purpose of identification of natural biogeographic boundaries, subsequent faunistic zoning and comparison between faunistic and bioclimatic (bio-oceanographic) zoning patterns. Location Japan Sea (Korean–East Sea). Methods All statistical procedures are based on well-tried and widely accepted numerical methodology and the statistica program package. For identifying the statistically meaningful (non-random) maxima and minima in species richness, arithmetical differences in the number of species at i th and i + 1st latitudes are calculated, also trend residuals obtained by smoothing the moving average by three points and residuals in polynomial trends are analysed. Subsequent clustering of species lists for separate biogeographical units marked by local maxima and minima in species richness permits to identify the extent of mutual correspondence between the units and to make an outline for faunistic zoning. Similarity degree of faunistic lists was estimated in terms of Czekanowski–Sörensen coefficient. Results Quantitative analysis of latitudinal distribution of species richness (1130 species) of the Japan Sea ichthyofauna is indicative of the position of the following 10 local maxima and minima: at 35, 40, 43, 47, 49 and 51 ° N on the west coast and at 36, 39, 43 and 46 ° N on the east coast. In most cases local minima of the polynomial trend residuals are coincident with southern boundaries of faunistic units while local maxima with northern boundaries. Separated analysis of qualitative composition of ichthyofauna of the west and east coasts of the Japan Sea discloses 11 areas of the greatest faunistic similarity. Main conclusions The latitudinal variations in the species richness near both sea coasts represent an alternation between relatively flattened smooth portions (each 1 unit long) and sufficiently steep jumps between them. Regular interchange between local minima and maxima of species richness is accountable to spatial non-uniformity of hydrological structure resulting from alternation of variously directed and differently heated (warm and cold) circulations of waters and frontal zones. It is notable that faunistic zoning does not initially require any exact knowledge of biotic taxonomic composition and may be produced only from the variation pattern of the species richness under study. The suggested faunistic zoning scheme distinguishes the following provinces: South Korea, East Korea, South Primorie, North Primorie, Northern Japan Sea, Middle Honshu, Uetsu, Tsugaru, Soya and West Sakhalin. The comparison between faunistic units and distribution of temperature parameters and currents permits identification of subarctic, cold–temperate, mild–temperate and warm–temperate bioclimatic zones existing in the Japan Sea.
2014
1. We seek to understand the physics of the mesoscale circulation in the Japan/East Sea, focusing our efforts on the southwestern region where the variability is especially energetic. 2. We seek to understand the processes governing spatio-temporal variability in the Japan/East Sea, spanning time-scales from hours to years, and length scales from submesoscale to basin scale. Understanding this physics has broad application to other ocean basins and marginal seas.
Water masses and decadal variability in the East Sea (Sea of Japan)
Progress in Oceanography, 2004
Water masses in the East Sea are newly defined based upon vertical structure and analysis of CTD data collected in 1993-1999 during Circulation Research of the East Asian Marginal Seas (CREAMS). A distinct salinity minimum layer was found at 1500 m for the first time in the East Sea, which divides the East Sea Central Water (ESCW) above the minimum layer and the East Sea Deep Water (ESDW) below the minimum layer. ESCW is characterized by a tight temperature-salinity relationship in the temperature range of 0.6-0.12°C, occupying 400-1500 m. It is also high in dissolved oxygen, which has been increasing since 1969, unlike the decrease in the ESDW and East Sea Bottom Water (ESBW). In the eastern Japan Basin a new water with high salinity in the temperature range of 1-5°C was found in the upper layer and named the High Salinity Intermediate Water (HSIW). The origin of the East Sea Intermediate Water (ESIW), whose characteristics were found near the Korea Strait in the southwestern part of the East Sea in 1981 [Kim, K., & Chung, J. Y. (1984) On the salinity-minimum and dissolved oxygen-maximum layer in the East Sea (Sea of Japan), In T. Ichiye (Ed.), Ocean Hydrodynamics of the Japan and East China Seas (pp. 55-65). Amsterdam: Elsevier Science Publishers], is traced by its low salinity and high dissolved oxygen in the western Japan Basin. CTD data collected in winters of 1995-1999 confirmed that the HSIW and ESIW are formed locally in the Eastern and Western Japan Basin. CREAMS CTD data reveal that overall structure and characteristics of water masses in the East Sea are as complicated as those of the open oceans, where minute variations of salinity in deep waters are carefully magnified to the limit of CTD resolution. Since the 1960s water mass characteristics in the East Sea have changed, as bottom water formation has stopped or slowed down and production of the ESCW has increased recently.