Relationship of the Distribution of Macrobenthos with Environmental Factors in the Port of Shimizu (Orido Bay)

Journal of The School of Marine Science and Technology,Vol.4 No.3

Relationship of the Distribution of Macrobenthos with Environmental
Factors in the Port of Shimizu (Orido Bay)

Kenshi KIMURA, Rie IWATA, Youko TAKAGI and Toshihiro YAMASAWA

	Abstract

	The Port of Shimizu is a narrow body of water extending far inland,with Orido Bay that is the site of marinas and log-storage facilities at its innermost point.This means the Port of Shimizu has strong characteristics of a closed body of water.Treated water from three treatment plants and the waters of the Tomoe River and two other rivers flow into the bay.The Tomoe River has a particularly strong impact on macrobenthos in the bay,because of the 60 to 80％ load of COD, nitrogen, and phosphorus in its water. macrobenthos in the Port of Shimizu includes organic pollutant resistant species in its inner part,accurately reflecting the condition of the bay’s bottom layer environment. On the other hand many species with low resistance to organic pollution are found near the mouth of the port.The relationship of macrobenthos with the bottom deposits is represented by peaks in the numbers of species and the population at less than 0.2mg/g sulfides and at ignition loss of about 6％. This trend is similar to that seen Tokyo Inner Bay and Osaka Bay.A comparison with macrobenthos and bottom sediment data obtained in 1968suggests that the bottom layer environment in the Port of Shimizu has improved.