Tracing anthropogenic inputs to production in the Seto Inland Sea, Japan--a stable isotope approach.
The Seto Inland Sea (SIS) receives waste runoff from ∼24% of Japan's total population, yet it is also important in regional fisheries, recreation and commerce. During August 2006 we measured carbon and nitrogen stable isotopes of particulate organic matter (POM) and zooplankton across urban population gradients of the SIS. Results showed a consistent trend of increasing δ(15)N in POM and zooplankton from the western to eastern subsystems of the SIS, corresponding to increasing population load. Principal components analysis of environmental variables indicated high positive loadings of δ(15)N and δ(13)C with high chlorophyll-a and surface water temperatures, and negative loadings of low salinities related to inputs from large rivers and high urban development in the eastern SIS. Anthropogenic nitrogen was therefore readily integrated into the SIS food web from primary production to copepods, which are a critical food source for many commercially important fishes.
Miller
Todd W
TW
Center for Marine Environmental Studies, Ehime University, 2-5 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan. millertw@dpc.ehime-u.ac.jp
Omori
Koji
K
Hamaoka
Hideki
H
Shibata
Jun-ya
JY
Hidejiro
Onishi
O
D002244:Carbon / Q000737:chemistry*; D002247:Carbon Isotopes / Q000737:chemistry; D004784:Environmental Monitoring / Q000379:methods*; D006802:Human Activities; D007564:Japan; D009584:Nitrogen / Q000737:chemistry*; D009587:Nitrogen Isotopes / Q000737:chemistry; D014865:Waste Disposal, Fluid; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D014877:Water Pollution, Chemical
D002247:Carbon Isotopes; D009587:Nitrogen Isotopes; D014874:Water Pollutants, Chemical; D002244:Carbon; D009584:Nitrogen