Short-term variation in copepod community and physical environment in the waters adjacent to the Kuroshio Current

Environmental characteristics of spawning and nursery grounds of Japanese sardine and mackerels in the Kuroshio and Kuroshio Extension area

“…Additionally, coastal/inner bay species such as P. parvus influence (Shimode, Toda, & Kikuchi, 2006). Coastal copepod community was reported to expand offshore in the eastern Kuroshio area as Kuroshio axis leave shore (Sogawa et al, 2017). From these results, it can be inferred that the copepods outflow from the coast and inner bay along with the Kuroshio variation and its surrounding flow succeed increasing its population in the high productivity area (the bottom-up effect).…”

“…Low copepod diversity is reported for the coastal/shelf‐water community and during periods of high primary production in Sagami Bay, where variety of water masses and currents (Kuroshio current, coastal current, Oyashio water, and river waters) influence (Shimode, Toda, & Kikuchi, ). Coastal copepod community was reported to expand offshore in the eastern Kuroshio area as Kuroshio axis leave shore (Sogawa et al., ). From these results, it can be inferred that the copepods outflow from the coast and inner bay along with the Kuroshio variation and its surrounding flow succeed increasing its population in the high productivity area (the bottom‐up effect).…”

“…Copepods are of great ecological importance, as they comprise one of the most abundant zooplanktonic groups and play various roles in the food web as herbivorous, omnivores/detritivores, and carnivore (Mauchline, Blaxter, Southward, & Tyler, 1998;Ohtsuka & Nishida, 1997;Sano, Maki, Nishibe, Nagata, & Nishida, 2013). The importance of two coastal/shelf-water species of copepods, Calanus sinicus and Paracalanus parvus s.l., as prey for small pelagic fish around the Kuroshio area off the coast of Japan, has been established (Hirai, Hidaka, Nagai, & Ichikawa, 2017;Mitsuzawa, Miyamoto, & Ueda, 2017;Nakata & Hidaka, 2003;Sogawa et al, 2017;Uye, 2000). Copepods are also known to prey on ichthyoplankton (Bailey & Yen, 1983;Lillelund & Lasker, 1971;Turner, Tester, & Hettler, 1985), and competition between copepods and fish larvae for food organisms has been pointed out (Ambler & Frost, 1974;Turner, Tester, & Conley, 1984;Yen, 1985).…”

Spatial variations in zooplankton community structure along the Japanese coastline in the Japan Sea: influence of the coastal current

“…Zooplankton communities have been treated as water mass indicators in other areas (Russell, 1935). Rapid changes in zooplankton community in response to oceanic currents have been identified in areas such as the Kuroshio coast and Mediterranean (Sogawa et al, 2017;Raybaud et al, 2008), but in our study site, the zooplankton community was temporally stable, as indicated by the lower values 25 of Year in RD1 (Table 2). In addition, the dominance of the herbivorous O. atlantica in Toyama Bay suggests its food web structure differs from the other areas, which are dominated by the carnivorous C. affinis (Ohtsuka and Nishida, 1997); the effect of bottom topography on the path of the CBTWC creates a heterogenic ecosystem along the Japanese coast in the Japan Sea.…”

“…The importance of ocean currents to zooplankton community structure has also been demonstrated in coastal areas facing the open ocean, such as the Kuroshio off Japan (Sogawa et al, 2017), and on the Pacific and Atlantic 35 coasts of North America (Mackas et al, 1991;Keister et al, 2011;Pepin et al, 2011;Pepin et al, 2015). In our study, the response of zooplankton to temperature was focused after VIF selection, but the horizontal advection of zooplankton by the CBTWC is also relevant; the importance of the original zooplankton community structure has been demonstrated in a study of Ocean Sci.…”