tailieunhanh - Lake Trout Ecosystems in a Changing Environment - Chapter 7

Những ảnh hưởng của phốt pho và nitơ hồ sản xuất (Salvelinus namaycush) cá hồi và môi trường sống Các mối quan hệ giữa các cấp các chất dinh dưỡng, đặc biệt là phốt pho (TP), trong hồ nước và hồ cá hồi Salvelinus namaycush rất phức tạp. Đây là một hệ quả của thực tế rằng phốt pho có thể ảnh hưởng đến hồ cá hồi trong hai cách đối diện nhưng tương quan với nhau. | chapter seven The effects of phosphorus and nitrogen on lake trout Salvelinus namaycush production and habitat Peter J. Dillon Environmental and Resource Studies Trent University Bev J. Clark Dorset Environmental Science Centre Ontario Ministry of the Environment Hayla E. Evans RODA Environmental Research Limited Contents Introduction Nutrient-phytoplankton-fish linkages Nutrient-biomass relationships Characterization of Ontario lake trout lakes with respect to phosphorus and nitrogen Characterization of Ontario lake trout lakes with respect to morphometry TP-morphometry-oxygen linkages Summary References Introduction The relationships between the levels of nutrients particularly phosphorus TP in lakes and lake trout Salvelinus namaycush are complex. This is a consequence of the fact that phosphorus may affect lake trout in two opposite but interrelated ways. On one hand phosphorus is the nutrient that controls algal biomass in almost all lakes in the Boreal ecozone of Canada and most lakes directly to the south in the Laurentian Great Lakes region . in almost all lakes in North America that are inhabited by lake trout Dillon and Rigler 1974 Schindler 1977 . Phytoplankton is a very important component of the 2004 by CRC Press LLC food web in all lakes and algal abundance may strongly influence the biomass and productivity of higher trophic levels including fish. On the other hand high algal biomass is associated with oxygen depletion in the hypolimnia of lakes an adverse effect on the amount of suitable habitat available to species including lake trout that prefer or require cold well-oxygenated waters is therefore expected when algal biomass is high. In this chapter we discuss the two conflicting roles that the limiting nutrient phosphorus plays in lake trout biology. Considerably less information is available with respect to the role of nitrogen but we have included as much as is available. We first review the literature with respect to relationships between .