Temporal variability in primary and copepod production in Sagami Bay, Japan

Seasonal variability of the red tide-forming heterotrophic dinoflagellate Noctiluca scintillans in the neritic area of Sagami Bay, Japan: its role in the nutrient-environment and aquatic ecosystem

“…At our study site, the abundance and biomass of planktonic organisms (i.e. pico-, nano-, micro-and mesozooplankton) and the concentrations of particulate carbon and nitrogen (PC and PN, respectively) were higher in spring-autumn, especially in the upper layer, whereas these were lower throughout the water column (0-50 m depth) in winter (Ara & Hiromi 2007, Ara et al 2011a, b, Okutsu et al 2012). These could enhance population growth of Noctiluca in the upper layer in spring-autumn, except during the periods of temperatures higher than ca.…”

“…water temperature, salinity and density) and Chl-a concentration at this station were previously published by Ara & Hiromi (2007, 2008, Ara et al (2011a, b) and Okutsu et al (2012), and details of observation methods can be found in these papers. Prior to sample collection, water temperature and salinity were recorded using a Memory STD (AST-1000/ P-64K, Alec Electronics, Japan), and density (σ t ) was calculated.…”

“…Primary productivity (PP) was determined by the in situ 13 C tracer method (Hama et al 1983), as described by Ara & Hiromi (2007 and Ara et al (2011b). Water samples were taken from depths corresponding to 100, 50, 25, 10, 5 and 1% photon fluxes of that just above the sea surface using a Niskin bottle.…”

“…gradual rise in COD and Chl-a concentration, decline in transparency, red tide outbreaks) have occurred, partly in the coastal waters of Sagami Bay (Yamada & Iwata 1992, Yamada 1997, Machida et al 1999, Yamada & Matsushita 2005, Miyaguchi et al 2006, Ara & Hiromi 2008, Ara et al 2011a). The neritic waters in the innermost open area of Sagami Bay, especially the upper layer around Enoshima Island, have higher phytoplankton standing crops (Chl-a) and primary production than those in any other open area in the bay (Ara & Hiromi 2007, 2008, Ara et al 2011a. The higher phytoplankton biomasses and production rates in these waters are induced by much higher nutrient concentrations due to nutrient-rich run-off from the Sakai and Hikiji Rivers (Saitou 1992, Yamada & Iwata 1992, Tanaka 1993, Yamada & Matsushita 2005, Ara & Hiromi 2007, 2008, Ara et al 2011a.…”

“…The neritic waters in the innermost open area of Sagami Bay, especially the upper layer around Enoshima Island, have higher phytoplankton standing crops (Chl-a) and primary production than those in any other open area in the bay (Ara & Hiromi 2007, 2008, Ara et al 2011a. The higher phytoplankton biomasses and production rates in these waters are induced by much higher nutrient concentrations due to nutrient-rich run-off from the Sakai and Hikiji Rivers (Saitou 1992, Yamada & Iwata 1992, Tanaka 1993, Yamada & Matsushita 2005, Ara & Hiromi 2007, 2008, Ara et al 2011a.…”