scholarly journals Dynamics of Noctiluca scintillans red tides in coastal waters of Harima-Nada, the Seto Inland Sea

2021 ◽  
Vol 30 (3) ◽  
pp. 47-55
Author(s):  
Kuninao Tada ◽  
Ren Chiba ◽  
Saho Kitatsuji ◽  
Daisuke Ishii ◽  
Tetsuo Yanagi
Keyword(s):  
Coastal Waters ◽  
Seto Inland Sea ◽  
Red Tides ◽  
Noctiluca Scintillans ◽  
The Seto Inland Sea

Population ecology of Noctiluca scintillans Macartney, a red-tide-forming dinoflagellate

1999 ◽  
Vol 50 (3) ◽  
pp. 243 ◽  
Author(s):  
Shauna Murray ◽  
Iain M. Suthers
Keyword(s):  
Nutritional Status ◽  
Population Ecology ◽  
Coastal Waters ◽  
Red Tide ◽  
Good Condition ◽  
Late Summer ◽  
Red Tides ◽  
Noctiluca Scintillans ◽  
Near Surface ◽  
Eastern Australia

The population ecology of the large heterotrophic dinoflagellate Noctiluca scintillans Macartney was examined in the coastal ocean and two estuaries in south-eastern Australia from July 1996 to June 1997. High concentrations (>100 cells L–1) occurred in spring and again in late summer, and low concentrations (<5 cells L–1) in mid summer and mid winter. Abundances were greater in coastal waters than in the estuaries during all months in which concentration exceeded 1 cell L–1. During the spring bloom, Noctiluca cells from coastal stations had small diameters (340–450 µm), a high nutritional status and a high proportion of division stages, indicative of good condition. During the late summer blooms, poor-condition cells were found in coastal waters and especially in the near-surface concentrations of red tides (>104 cells L–1), and were characterized by large diameters (400–1200 µm), cell lysis and uniformly low nutritional status; at this time, Noctiluca cells from estuaries were generally fewer, smaller and in better condition. Overall, cell concentrations were higher in coastal waters than in the estuaries, and red tides of Noctiluca probably developed along the local coast (in spring) or were advected into the area from northern regions (in late summer).

scholarly journals Long-term trends in the occurrence of red tides in the Seto Inland Sea, Japan

2014 ◽  
Vol 23 (6) ◽  
pp. 217-236 ◽  
Author(s):  
Daisuke Ishii ◽  
Tetsuo Yanagi ◽  
Satoshi Sasakura
Keyword(s):  
Seto Inland Sea ◽  
Red Tides ◽  
The Seto Inland Sea ◽  
Long Term Trends

scholarly journals Historical changes in primary production in the Seto Inland Sea, Japan, after implementing regulations to control the pollutant loads

Water Policy ◽  
2018 ◽  
Vol 20 (4) ◽  
pp. 855-870 ◽  
Author(s):  
Satoshi Nakai ◽  
Youhei Soga ◽  
Satoshi Sekito ◽  
Akira Umehara ◽  
Tetsuji Okuda ◽  
...  
Keyword(s):  
Water Pollution ◽  
Environmental Management ◽  
Primary Production ◽  
Seto Inland Sea ◽  
Load Control ◽  
Red Tides ◽  
Pollutant Load ◽  
Nutrient Loadings ◽  
Management Measures ◽  
The Seto Inland Sea

Abstract A total pollutant load control system (TPLCS) was implemented in the Seto Inland Sea in 1979 to reduce the water pollution and the frequency of red tides. We estimated primary production from 1981 to 2010 to determine the effects of reducing the nutrient loadings from the surrounding land. While primary production has decreased overall in the Seto Inland Sea in response to the TPLCS and the associated reductions in the total nitrogen (T-N) and phosphorus (T-P) loads from land since 1981, the reductions were limited to 4 of its 11 subareas. Primary production has increased in the Harima Nada but has been stable in the Bingo Nada subarea, reflecting the fact that the T-N and T-P stocks have not decreased in these subareas over the study years. The inconsistent responses of the 11 subareas suggest that the characteristics of each subarea should be considered when environmental management measures are established and implemented in the Seto Inland Sea. The controls on the nutrient loadings according to the TPLCS should be modified to permit better management of this semi-enclosed sea.

EVALUATION OF MOUNTAIN AREA AS NON-POINT SOURCE OF NITROGEN FOR SETO INLAND SEA: THE NORTHERN SHIKOKU REGION, JAPAN

2017 ◽  
Author(s):  
Shohei Morisawa ◽  
Shohei Morisawa ◽  
Yukio Komai ◽  
Yukio Komai ◽  
Takao Kunimatsu ◽  
...  
Keyword(s):  
Average Concentration ◽  
Point Sources ◽  
Seto Inland Sea ◽  
Mountain Streams ◽  
Unit Load ◽  
Mountain Areas ◽  
Mountain Area ◽  
The Seto Inland Sea ◽  
Unit Load Method ◽  
Important Position

The northern Shikoku region is located in the Western part of Japan and faces towards the Seto Inland Sea. The forest area, which is one of the non-point sources in the Seto Inland Sea watershed, occupies 75% of the land use in the watershed of the northern Shikoku region. The amount of loadings of nutrients and COD in the Seto Inland Sea has been estimated by the unit load method but actually the data has not been investigated. It is however, necessary to know the real concentration of nitrogen in mountain streams to evaluate the role which is the mountain area plays as non-point sources. Therefore, more water samples of mountain streams in the watershed need to be taken and the concentrations of nitrogen analyzed. The mountain streams in the northern Shikoku area were investigated from April, 2015 to November, 2015. The number of sampling sites was 283, in addition to the past data by Kunimatsu et al. The average concentration of nitrate nitrogen in Ehime, Kagawa, and Tokushima was 0.61mg/L, 0.78mg/L and 0.34mg/L, respectively. The environmental standard range for nitrogen in the Seto Inland Sea is from between less than 0.2mg/L and less than 1mg/L. Therefore, the average concentration of nitrogen in these regions was over category II, and those of mountain streams in Kagawa Prefecture exceeded category III. About 20% of mountain streams were more than 1mg/L. It has become clear that mountain areas occupy an important position as non-point sources for the Seto Inland Sea.

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