tailieunhanh - ECOTOXICOLOGY: A Comprehensive Treatment - Chapter 29

Trong revery amnesiac nó cũng dễ dàng bỏ qua các dịch vụ hệ sinh thái cung cấp cho nhân loại. Họ làm giàu cho đất và tạo ra không khí chúng ta hít thở. Nếu không có những tiện nghi này, nhiệm kỳ còn lại của loài người sẽ khó chịu và ngắn gọn. (E. O. Wilson 1999) Các hệ sinh thái đại diện cho mức độ cao nhất và cuối cùng của tổ chức sinh học mà chúng tôi sẽ xem xét trong điều trị của chúng ta về sinh thái chất độc. Đó là thích hợp mà chúng tôi. | PartV Ecosystem Ecotoxicology In amnesiac revery it is also easy to overlook the services that ecosystems provide humanity. They enrich the soil and create the very air we breathe. Without these amenities the remaining tenure of the human race would be nasty and brief. . Wilson 1999 Ecosystems represent the highest and final level of biological organization that we will consider in our treatment of ecotoxicology. It is appropriate that we conclude with a discussion of ecosystems which have been considered by some ecologists to be the fundamental units of nature Tansley 1935 . The critical defining feature of ecosystems that is unique from other levels of biological organization we have considered is the inclusion of abiotic variables. Ecosystem ecotoxicology is necessarily a multidisciplinary science and the ecosystem processes that respond to contaminants go beyond those of populations and communities. Because these processes are often scale dependent Carpenter and Turner 1998 effects of contaminants on ecosystem function also vary across spatiotemporal scales. Ecosystem ecologists have made tremendous progress developing biogeochemical models of nutrient dynamics and these models can be readily adapted to predict contaminant movement within and between ecosystems. Quantifying effects of contaminants on ecosystem processes and demonstrating causal relationships between stressors and responses is challenging. As a consequence ecosystem responses are not routinely measured in ecological risk assessments. However characterization of ecological integrity based exclusively on structural measurements has provided a somewhat incomplete picture of how ecosystems respond to anthropogenic perturbations Gessner and Chauvet 2002 . Furthermore the unprecedented rate of species extinction occurring at a global scale Wilson 1999 requires that ecologists and ecotoxicologists develop a better appreciation of the relationship between community patterns and ecosystem processes. .