The impact of 150 years of anthropogenic pollution on the shallow marine ostracode fauna, Osaka Bay, Japan

Coastal bays adjacent to metropolitan areas are commonly polluted heavily, and the direct and indirect results of pollution (e.g., heavy metal pollution, eutrophication, and hypoxia) seriously influence metazoan benthos. Historical metazoan trends, however, remain poorly documented and understood. Using the ostracode record of the past 150 years (210Pb and 137Cs age information), we show that anthropogenic impacts during industrialization seriously influenced the benthic metazoan ecosystem in a bay adjacent to a metropolis (Osaka Bay, Japan). Ostracode absolute abundance decreased by 90% from ca. A.D. 1910-1920 to ca. A.D. 1960-1970 as a result of Japan's rapid industrial development, coinciding with a rapid increase in concentration of various pollutants and the Osaka City population. The ostracode abundance has not recovered despite environmental legislation enforced after ca. A.D. 1960-1970.