Abstract
An analysis of the time series data sets collected from the 1960s to 1990s in the Oyashio Water revealed signs of alteration in the physical, chemical and biological properties of the water column in the western subarctic North Pacific. Wintertime salinity, phosphate concentration and apparent oxygen utilization (AOU) in the subsurface increased linearly over the 30 years. At the same time, salinity and phosphate in the surface mixed layer decreased. An increase in the density gradient in the surface and subsurface suggested that the water column stratification intensified, reducing the vertical exchange of water properties during the period. The Net Community Production (NCP), estimated from the phosphate consumption from February through August, also declined. Water column Chl a was approximately halved and diatoms decreased by one order of magnitude in spring, consistent with the multi-decadal decreasing trend of NCP. Zooplankton biomass was also nearly halved during the same period. In contrast, wintertime Chl a increased by 63% and diatom abundance doubled. Developmental timing became earlier in Neocalanus flemingeri, and spring occurrence of N. plumchrus increased after the 1980s. Reduced vertical water exchange might have limited nutrient supply to the level, decreasing winter-summer NCP for these three decades. It is speculated that, in the meantime, the earlier stabilization of the surface layer might have enhanced wintertime diatom production in the Oyashio's light-limited environment. This condition could allow zooplankton to effectively utilize diatoms from earlier timing, resulting in the apparent early developmental timing and abundance increase.
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Andreev, A. G. and M. Kusakabe (2001): Interdecadal variability in dissolved oxygen in the intermediate water layer of the Western Subarctic Gyre and Kuril Basin (Okhotsk Sea). Geophys. Res. Lett., 28, 2453–2456.
Andreev, A. G. and S. Watanabe (2002): Temporal changes in dissolved oxygen of the intermediate water in the subarctic North Pacific. Geophys. Res. Lett., 29, 10.1029/ 2002GL015021.
Banse, K. and D. C. English (1999): Comparing phytoplankton seasonality in the eastern and western subarctic Pacific and the western Bering Sea. Prog. Oceanogr., 43, 235–288.
Batchelder, H. P. and T. M. Powell (2002): Physical and biological conditions and processes in the northeast Pacific Ocean. Prog. Oceanogr., 53, 105–114.
Beamish, R. J., D. J. Noakes, G. A. McFarlane, L. B. Klyashtorin, V. V. Ivanov and V. Kurashov (1999): The regime concept and natural trends in the production of Pacific salmon. Can. J. Fish. Aquat. Sci., 56, 516–526.
Boyd, P. W., D. L. Muggli, D. E. Varela, R. H. Goldblatt, R. Chretien, K. J. Orians and P. J. Harrison (1996): In vitro iron enrichment experiments in the NE subarctic Pacific. Mar. Ecol. Prog. Ser., 136, 179–193.
Brodeur, R. D. and D. M. Ware (1992): Long-term variability in zooplankton biomass in the subarctic Pacific Ocean. Fish. Oceanogr., 1, 32–38.
Brodeur, R. D., B. W. Frost, S. R. Hare, R. C. Francis and W. J. Ingraham, Jr. (1996): Interannual variations in zooplankton biomass in the Gulf of Alaska and covariation with California Current zooplankton biomass. CalCOFI Report, 37, 80–99.
Carpenter, J. H. (1965): The Chesapeake Bay Institute technique for the Winkler dissolved oxygen method. Limnol. Oceanogr., 10, 141–143.
Chavez, F. P., J. Ryan, E. Lluch-Cota and M. C. Niquen (2003): From anchovies to sardines and back: multidecadal change in the Pacific Ocean. Science, 299, 217–221.
Chiba, S. and T. Saino (2002): Interdecadal change in the upper water column environment and spring diatom community structure in the Japan Sea: an early summer hypothesis. Mar. Ecol. Prog. Ser., 231, 23–35.
Cushing, D. H. (1972): The production cycle and the numbers of marine fish. p. 213–232. In Conservation and Productivity of Natural Waters, Vol. 29, ed. by R. W. Edwards and D. J. Garrod, Symposia of the Zoological Society of London.
Duce, R. A. and N. W. Tindale (1991): Atmospheric transport of iron and its deposition in the ocean. Limnol. Oceanogr., 36, 1715–1726.
Emerson, S., S. Mecking and J. Abell (2001): The biological pump in the subtropical North Pacific: nutrient sources, Redfield ratios, and recent changes. Global Biogeochem. Cycles, 15, 535–554.
Freeland, H., K. Denman, C. S. Wong, F. Whitney and R. Jacques (1997): Evidence of change in the winter mixed layer in the Northeast Pacific. Deep-Sea Res., 44, 2117–2129.
Gifford, D. J. (1993): Protozoa in the diets of Neocalanus spp. in the oceanic subarctic Pacific Ocean. Prog. Oceanogr., 32, 161–177.
Hanawa, K. (1995): Southward penetration of the Oyashio water system and the wintertime condition of midlatitude westerlies over the North Pacific. Bull. Hokkaido Natl. Fish. Res. Inst., 59, 103–120.
Hare, S. R. and N. Mantua (2000): Empirical evidence for North Pacific regime shifts in 1977 and 1989. Prog. Oceanogr., 47, 103–145.
Harrison, P. J., P. W. Boyd, D. E. Varela, S. Takeda, A. Shiomoto and T. Odate (1999): Comparison of factors controlling phytoplankton productivity in the NE and NW subarctic Pacific gyres. Prog. Oceanogr., 43, 205–234.
Honda, M. C., K. Imai, Y. Nojiri, F. Hoshi, T. Sugawara and M. Kusakabe (2002): The biological pump in the northwestern North Pacific based on flux and major components of particulate matter obtained by sediment-trap experiments (1997-2000). Deep-Sea Res., 49, 5595–5625.
Japan Meteorological Agency (1995-2000): Data report of oceanographic observations, 85–90 (CD-ROMs).
Karl, D. M., R. R. Bidigare and R. M. Letelier (2001): Longterm changes in plankton community structure and productivity in the North Pacific Subtropical Gyre: the domain shift hypothesis. Deep-Sea Res., 48, 1449–1470.
Kasai, H. (2000): Seasonal change of nutrients and primary production in the Oyashio region. Bull. Plankton Soc. Japan, 47, 116–118.
Kawai, H. (1972): Hydrography of the Kuroshio extension. p. 235–352. In Kuroshio: Physical Aspects of the Japan Current, ed. by H. Stonmel and K. Yoshida, University of Washington Press, Seattle.
Kawasaki, T. (1989): Long-term variability in the pelagic fish populations. p. 47–60. In Long-Term Variability of Pelagic Fish Populations and Their Environment, ed. by T. Kawasaki, S. Tanaka, Y. Toba and A. Taniguchi, Pergamon Press, Sendai, Japan.
Kim, K., K. R. Kim, D. H. Min, Y. Volkov, J. H. Yoon and M. Takematsu (2001): Warming and structural changes in the East (Japan) Sea: a clue to future changes in global oceans? Geophys. Res. Lett., 28, 3293–3296.
Kim, K. R., G. Kim and K. Kim (2002): A sudden bottom-water formation during the severe winter 2000–2001: the case of the East/Japan Sea. Geophys. Res. Lett., 29, 10.1029/ 2001GL014498.
Kobari, T. and T. Ikeda (2000): Life cycle of Neocalanus species in the Oyashio region. Bull. Plankton Soc. Japan, 47, 129–135 (in Japanese with English abstract).
Kobari, T. and T. Ikeda (2001): Ontogenetic vertical migration and life cycle of Neocalanus plumchrus (Crustacea: Copepoda) in the Oyashio region, with notes on regional variations in body sizes. J. Plankton Res., 23, 287–302.
Kobari, T., A. Shinada and A. Tsuda (2003): Functional roles of interzonal migrating mesozooplankton in the western subarctic Pacific. Prog. Oceanogr. (in press).
Kubo, N. (1994): The zooplankton standing crops in the sea south of Hokkaido.J. Meteorolog., 45, 201–212.
Levitus, S. (1982): Climatological atlas of the world ocean. p. 1–173. In NOAA Professional Paper, Vol. 13, ed. by US Department of Commerce, National Oceanic and Atmospheric Administration, Rockville,
MD. Levitus, S. and T. P. Boyer (1994): World Ocean Atlas 1994. NOAA Atlas NESDIS, 4.
Mackas, D. L., H. Sefton, C. B. Miller and A. Raich (1993): Vertical habitat partitioning by large Calanoid copepods in the oceanic subarctic Pacific during spring. Prog. Oceanogr., 32, 259–294.
Mackas, D. L., R. Goldblatt and A. G. Lewis (1998): Interdecadal variation in developmental timing of Neocalanus plumchrus populations at Ocean Station P in the subarctic North Pacific. Can. J. Fish. Aquat. Sci., 55, 1878–1893.
Mackas, D. L., R. E. Thomson and M. Galbraith (2001): Changes in the zooplankton community of the British Columbia continental margin, 1985-1999, and their covariation with oceanographic conditions. Can. J. Fish. Aquat. Sci., 58, 685–702.
Mantua, N. J., S. R. Hare, Y. Zang, J. M. Wallace and R. C. Francis (1997): A Pacific interdecadal climate oscillation with impacts on salmon production. Bull. American Meteor. Soc., 78, 1069–1079.
McFarlane, G. A. and R. J. Beamish (1992): Climatic influence Multi-Decadal Scale Ecosystem Change in the Oyashio 161 linking copepod production with strong year-classes in Sablefish, Anoplopoma fimbria. Can. J. Fish. Aquat. Sci., 49, 743–753.
Miller, A. J. and N. Schneider (2000): Interdecadal climate regime dynamics in the North Pacific Ocean: theories, observations and ecosystem impacts. Prog. Oceanogr., 47, 355–379.
Miller, A. J., D. R. Cayan, T. P. Barnett, N. E. Graham and J. M. Oberhuber (1994): The 1976-77 climate shift of the Pacific Ocean. Oceanography, 7, 21–26.
Miller, A. J., F. Chai, S. Chiba, J. R. Moisan and D. J. Neilson (2004): Decadal-scale climate and ecosystem interactions in the North Pacific Ocean. J. Oceanogr., 60, this issue, 163–188.
Miller, C. B., B. W. Frost, H. P. Batchelder, M. J. Clemons and R. E. Conway (1984): Life histories of large grazing copepods in a subarctic ocean gyre: Neocalanus plumchrus, Neocalanus cristatus, and Eucalanus bungii in the northeast Pacific. Prog. Oceanogr., 13, 201–243.
Miller, C. B., J. Fulton and B. W. Frost (1992): Size variation of Neocalanus plumchrus and Neocalanus flemingeri in a 20-yr sample series from the Gulf of Alaska. Can. J. Fish. Aquat. Sci., 49, 389–399.
Minobe, S. (1997): A 50-70 year climatic oscillation over the North Pacific and North America. Geophys. Res. Lett., 24, 683–686.
Murata, A., Y. Kumamoto, C. Saito, H. Kawakami, I. Asanuma, M. Kusakabe and H. Y. Inoue (2002): Impact of a spring phytoplankton bloom on the CO2 system in the mixed layer of the northwestern North Pacific. Deep-Sea Res., 49, 5531–5555.
Murphy, J. and J. P. Riley (1961): Modified single solution method for the determination of phosphate in natural water. Anal. Chem. Acta, 27, 31–36.
Nishioka, J., S. Takeda, I. Kudo, D. Tsumine, T. Yoshimura, K. Kuma and A. Tsuda (2003): Size-fractionated iron distributions and iron-limitation processes in the subarctic NW Pacific. Geophys. Res. Lett., 30, 10.1029/2002GL016853.
Noto, M. and I. Yasuda (1999): Population decline of the Japanese sardine, Sardinops melanostictus, in relation to sea surface temperature in the Kuroshio Extension. Can. J. Fish. Aquat. Sci., 56, 973–983.
Noto, M. and I. Yasuda (2002): Empirical biomass model for the Japanese sardine with sea surface temperature in the Kuroshio Extension. Fish. Oceanogr., 12, 1–9.
Obata, A., J. Ishizaka and M. Endoh (1996): Global verification of critical depth theory for phytoplankton bloom with climatological in situ temperature and satellite ocean color data. J. Geophys. Res., 101, 20657–20667.
Obayashi, Y., E. Tanoue, K. Suzuki, N. Handa, Y. Nojiri and C. S. Wong (2001): Spatial and temporal variabilities of phytoplankton community structure in the northern North Pacific as determined by phytoplankton pigments. Deep-Sea Res., 48, 439–469.
Odate, K. (1994): Zooplankton biomass and its long-term variation in the western North Pacific Ocean. Bull. Tohoku Regional Fish. Res. Lab., 56, 115–173.
Odate, T. (1996): Abundance and size composition of the summer phytoplankton communities in the Western North Pacific Ocean, the Bering Sea, and the Gulf of Alaska. J. Oceanogr., 52, 335–351.
Ono, T., T. Midorikawa, W. Watanabe, K. Tadokoro and T. Saino (2001): Temporal increases of phosphate and apparent oxygen utilization in the subsurface waters of western subarctic Pacific from 1968 to 1998. Geophys. Res. Lett., 28, 3285–3288.
Ono, T., K. Tadokoro, T. Midorikawa, J. Nishioka and T. Saino (2002): Multi-decadal decrease of net community production in western subarctic North Pacific. Geophys. Res. Lett., 29, 10.1029/2001GLO14332.
Polovina, J. J., G. T. Mitchum and G. T. Evans (1995): Decadal and basin-scale variation in mixed layer depth and the impact on biological production in the central and North Pacific, 1960-88. Deep-Sea Res., 42, 1701–1716.
Redfield, A. C., B. H. Ketchum and F. A. Richards (1963): The influence of organisms on the composition of seawater. p. 26–77. In The Sea, ed. by M. H. Hill, Wiley-Interscience, New York.
Roemmich, D. (1992): Ocean warming and sea level rise along the Southwest U.S. Coast. Science, 257, 373–375.
Roemmich, D. and J. McGowan (1995): Climatic warming and the decline of zooplankton in the California Current. Science, 267, 1324–1326.
Saito, H., A. Tsuda and H. Kasai (2002): Nutrient and plankton dynamics in the Oyashio region of the western subarctic Pacific Ocean. Deep-Sea Res. 49, 5463–5486.
Sasaoka, K., S. Saiho, I. Asanuma, K. Imai, M. Honda, Y. Nojiri and T. Saino (2002): Temporal and spatial variability of chlorophyll-a in the western subarctic Pacific determined from satellite and ship observations from 1997 to 1999. Deep-Sea Res., 49, 5557–5576.
Sekine, Y. (1999): On variation in the subarctic circulation in the North Pacific. Prog. Oceanogr., 43, 193–203.
Shiomoto, A. (2000): Chlorophyll-a and primary production during spring in the oceanic region of the Oyashio Water, the north-western Pacific. J. Mar. Biol. Ass. U.K., 80, 343–354.
Shiomoto, A. and S. Hashimoto (2000): Comparison of east and west chlorophyll tia standing stock and oceanic habitat along the Transition Domain of the North Pacific. J. Plankton Res., 22, 1–14.
Sugimoto, T. and K. Tadokoro (1997): Interannual-interdecadal variations in zooplankton biomass, chlorophyll concentration and physical environment in the subarctic Pacific and Bering Sea. Fish. Oceanogr., 6, 74–93.
Sugimoto, T. and K. Tadokoro (1998): Interdecadal variations of plankton biomass and physical environment in the North Pacific. Fish. Oceanogr., 7, 289–299.
Sverdrup, H. U. (1953): On conditions for the vernal blooming of phytoplankton. J. Cons. Int. Explor. Mer., 18, 287–295.
Tadokoro, K., S. Chiba, T. Ono, T. Midorikawa and T. Saino (2003): Interannual variation of Neocalanus copepods biomass in the Oyashio water, western subarctic North Pacific. Fish. Oceanogr. (submitted).
Takahashi, T., S. C. Sutherland, C. Sweeney, A. Poisson, N. Metzl, B. Tilbrook, N. Bates, R. Wanninkhof, R. A. Feely, C. Sabine, J. Olafsson and Y. Nojiri (2002): Global sea-air CO2 flux based on climatological surface ocean pCO2, and seasonal biological and temperature effects. Deep-Sea Res., 49, 1601–1622.
Taniguchi, A. (1999): Differences in the structure of the lower trophic levels of pelagic ecosystems in the eastern and western subarctic Pacific. Prog. Oceanogr., 43, 289–315.
Tomosada, A. and K. Odate (1995): Long-term variability in zooplankton biomass and environment. Umi to Sora, 71, 1–7 (in Japanese with English abstract).
Treguer, P. and P. Pondaven (2000): Silica control of carbon dioxide. Nature, 406, 358–359.
Trenberth, K. E. (1990): Recent observed interdecadal climate changes in the Northern Hemisphere. Bull. American Meteor. Soc., 71, 988–993.
Trenberth, K. E. and J. W. Hurrell (1994): Decadal atmosphereocean variations in the Pacific. Climate Dynamics, 9, 303–319.
Trenberth, K. E. and J. W. Hurrell (1995): Decadal couples atmosphere-ocean variations in the North Pacific Ocean. p. 15–21. In Climate Change and Northern Fish Populations, Vol. 121, ed. by R. J. Beamish, Canadian Special Publication of Fisheries and Aquatic Sciences.
Tsuda, A., H. Saito and H. Kasai (2001): Life history strategies of subarctic copepods Neocalanus flemingeri and N. plumchrus, especially concerning lipid accumulation patterns. Plankton Biol. Ecol., 48, 52–58.
Tsuda, A., S. Takeda, H. Saito, J. Nishioka, Y. Nojiri, I. Kudo, H. Kiyosawa, A. Shiomoto, K. Imai, T. Ono, A. Shimamoto, D. Tsumune, T. Aono, A. Hinuma, M. Kinugasa, K. Suzuki, Y. Sohrin, Y. Noiri, H. Tani, Y. Deguchi, N. Tsurushima, H. Ogawa, K. Fukami, K. Kuma and T. Saino (2003): A mesoscale iron enrichment in the western subarctic Pacific induces a large Centric diatom bloom. Science, 300, 958–961.
Watanabe, Y. W., T. Ono, T. Shimamoto, T. Sugimoto, M. Wakita and S. Watanabe (2001): Probability of a reduction in the formation rate of the subsurface water in the North Pacific during the 1980s and 1990s. Geophys. Res. Lett., 28, 3289–3292.
Whitney, F. A. and H. J. Freeland (1999): Variability in upperocean water properties in the NE Pacific Ocean. Deep-Sea Res., 46, 2351–2370.
Yamada, K., J. Ishizaka, S. Yoo, H. Kim and S. Chiba (2003): Seasonal and interannual variability of sea surface Chlorophyll a concentration in the Japan (East) Sea. Prog. Oceanogr. (submitted).
Yentsch, C. S. and D. W. Menzel (1963): A method for the determination of phytoplankton chlorophyll and phaeophytin by fluorescence. Deep-Sea Res., 10, 221–231.
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Chiba, S., Ono, T., Tadokoro, K. et al. Increased Stratification and Decreased Lower Trophic Level Productivity in the Oyashio Region of the North Pacific: A 30-Year Retrospective Study. Journal of Oceanography 60, 149–162 (2004). https://doi.org/10.1023/B:JOCE.0000038324.14054.cf
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DOI: https://doi.org/10.1023/B:JOCE.0000038324.14054.cf