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Volume 45 (1989)
- Issue 6 Pages 361-
- Issue 5 Pages 289-
- Issue 4 Pages 243-
- Issue 3 Pages 167-
- Issue 2 Pages 95-
- Issue 1 Pages 1-
Volume 45, Issue 4
Displaying 1-5 of 5 articles from this issue
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Gretchen H. Bishop, Makoto Omori, Fumio Muranaka1989 Volume 45 Issue 4 Pages 243-250
Published: August 25, 1989
Released on J-STAGE: June 17, 2011
JOURNAL FREE ACCESSTemporal and spatial variations in the spawning activity of Sergia lucens were investigated in relation to some environmental conditions of Suruga Bay. The daily egg abundance varied considerably with the coefficient of variation from 81% to 269% in July. The spawning activity was most clearly affected by temperature, but the relationship to lunar period- and content of chlorophyll a were not obvious. Timing ofthe July spawning is predictable with increase of the surface temperature to 24°and strorig vertical movements of the 18°isotherm depth; it is also related to modal length of the shrimp in June. It is suggested that intrusion of cold water at 20-50 m affects reproduction of the shrimps and vertical distribution of eggs and larvae. The shrimp population seemed to relate principally to two spawning grounds, i.e. the head part and the western part of the bay. The timing of spawning is not always synchronous throughout the bay. The spawning is sporadic and the distribution of eggs is patchy. This may reflect a recent decrease in the population of the shrimp due to increased fishing pressure.View full abstractDownload PDF (1526K) -
Hideshige Toda1989 Volume 45 Issue 4 Pages 251-257
Published: August 25, 1989
Released on J-STAGE: June 17, 2011
JOURNAL FREE ACCESSSurface distributions of zooplankton were surveyed with simultaneous measurements of temperature, salinity, chlorophyll and nitrate, around the Izu Islands in July 1988. Several phytoplankton patches, which had developed in the upwelled waters, were encountered around the islands. Zooplankters collected with a 20μm mesh mainly consisted of copepods including eggs, nauplii, copepodites and adults.Paracalanus parvusdominated among the copepod females. High concentrations of all copepod stages were associated with the phytoplankton patches. The increase in reproductive activity of female copepods was considered as a possible process to form the copepod patches associated with the phytoplankton patches.View full abstractDownload PDF (1332K) -
Hiroshi Sasaki, Satoshi Nishizawa1989 Volume 45 Issue 4 Pages 258-269
Published: August 25, 1989
Released on J-STAGE: June 17, 2011
JOURNAL FREE ACCESSSinking particulate matter were obtained from twelve depths using free-drifting sediment trap arrays which were deployed in the upper 2, 000m water column of the Izu Trench, northwest Pacific Ocean. The largest flux of 146 mgC M-2day-1was observed at 150 m depth. The flux generally decreased with depth below the maximum, however, minor flux peaks occurred at 1, 000 and 1, 250 m depth (>30 mgC m-2day-1). Sinking large particles (>100μm) were composed of fecal pellets typical of crustaceans, macroscopic aggregates, and planktonic organisms and their fragments. Three major components constituted 19%, 20% and 29%, respectively, of the total carbon flux (averaged from the fluxes at five depths; 50, 100, 150, 1, 000 and 2, 000m). Among them, fecal pellet flux and large organism flux were well correlated with the total flux. The closecorrespondence between the fecal flux and the total carbon flux suggests that the latter is derived from a group of variables including other biogenic matter, among which fecal pellet is one of the leading factors controlling total flux, though the latter is only a minor covariable in quantity. Vertical flux profiles of fecal pellets and their internal constituents revealed some new inputs of feces occurring through the water column. This phenomenon implies that downward transportation of organic material is characterized by feeding and egestion activities of zooplankton, including overlapping processes of sinking and dispersion of large fecal particles and repackaging of dispersed small particles.View full abstractDownload PDF (1977K) -
Yoshio Sato1989 Volume 45 Issue 4 Pages 270-278
Published: August 25, 1989
Released on J-STAGE: June 17, 2011
JOURNAL FREE ACCESSAt the Minamichita Beach Land (Mihama-cho, Aichi, Japan), seawater is pumped up from underground and is supplied to aquaria. The underground seawater contains ca. 2 ppm of Fe (II), 0.1 ppm of Mn (II) and a little dissolved oxygen. Iron oxide is formed in the seawater when aerated. The oxidation rate of Fe (II) was measured to be 1.4×1014mol-3l3which is comparable to the lowest values in the literature. The slow rate of Fe (II) oxidation obtained here can be attributed to the presence of organically bound iron in the seawater. The distribution coefficient of cations between seawater and iron oxide phase was in the order of Cu≥Ni≥Co≥Cd≥Mn, which is consistent with that predicted from their hydrolysis constants. The adsorption affinity sequence of oxyanions was phosphate≥vanadate≥molybdate. The difference in phosphate from the prediction of the adsorption theory was attributed to the formation of ferriphosphate on the oxide surface. On the basis of these data, the limitation and usefulness in the application of the distribution coefficients to marine environments were discussed.View full abstractDownload PDF (1469K) -
Fluctuation of Transports and Sea Level in the Western Boundary Region of the Tropical Pacific OceanT. Robert Kendall1989 Volume 45 Issue 4 Pages 279-287
Published: August 25, 1989
Released on J-STAGE: June 17, 2011
JOURNAL FREE ACCESSLarge fluctuation in transport of the Equatorial Countercurrent flowing eastward from the western boundary is not the direct result of fluctuation in transport of the North Equatorial Current, but rather relates to fluctuation of sea level anomaly in the Philippine Sea.View full abstractDownload PDF (2247K)
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