Evaluation of riverine DIN in the nori Pyropia cultivated in coastal sea areas using nitrogen stable isotopes

Abstract

To clarify the in‰uence of nutrient supply from rivers on nori (Pyropia ), we investigated the distributions and variance of nitrogen stable isotope (d 15 N) in nori thalli in the Bisan Strait in the eastern part of the Seto Inland Sea. The d 15 N value of nori cultured in low salinity areas was 7.7±0.1. On the other hand, the d 15 N value of discolored nori collected in high salinity areas was 11.1±0.1. Using these results, the contribution ratios of riverine nitrogen to nori were estimated. The d 15 N value in nori transplanted to an estuarine zone far from the river mouth decreased to the same level as the nori originally growing until 7 days. d 15 N re‰ected the in‰uence of nitrogen supply from rivers more quickly than the change of color.

Parameter optimization of a 3D coastal model using Green's functions for modelling river plume dynamics

“…The dark shading area disappears from the model domain until the next ebb tide comes. The changing low-salinity area modelled here is qualitatively consistent with the results of field observations in this area [12], and the next paragraph gives the evaluation of the consistency. bad as compared to the previous study which modeled river plumes (e.g.…”

“…Takagi et al [12] continuously monitored salinity at a number of stations in an area of seaweed culture in Okayama prefecture, and fully explored the pulsed river plume there. High-precision modelling of the river plume is the next step required if we are to forecast the supply of nutrients and so help to manage river discharge.…”

“…Salinity was measured every 10 min from 7 th to 31 st December 2007 by instruments moored at 0.5 m from the surface at 16 stations [12] and we used salinity data at stations 4 to 9 and 11 to 13 ( locations in Figure 1c) for the optimization. Figure 2 shows an example of the observed salinity variation with tidal elevation (derived from the tide gauges) and daily mean river discharge (observed by the Ministry of Land, Infrastructure Transport and Tourism).…”