tailieunhanh - Restoration of Aquatic Systems - Chapter 13 (end)

Tại Hoa Kỳ ngày hôm nay, mặc dù hình ảnh bản thân rằng chúng tôi là tất cả các nhà môi trường, có rất ít bằng chứng cho thấy quan điểm lạc quan của chúng ta về chính mình là thực tế. Lịch sử môi trường của đất nước này là hỗn hợp, với thời gian không quan tâm đến cực cho môi trường tự nhiên ngắt quãng bởi những tiến bộ vững chắc trong việc bảo vệ môi trường. Lịch sử gần đây của mối quan tâm của chúng tôi là không khuyến khích. Theo báo cáo của các. | chapter 13 Conclusions Introduction In the United States today despite the self-image that we are all environmentalists there is little evidence that our optimistic view of ourselves is realistic. The environmental history of this country is mixed with periods of extreme disregard for the natural environment punctuated by solid advances in environmental protection. Recent history of our concern is not encouraging. According to a report by the widely respected Pew Oceans Commission America s Living Oceans 2003 there are some problems regarding our aquatic systems that are not being addressed Coastal development and associated sprawl destroy and endanger coastal wetlands and estuaries that serve as nurseries for many valuable fishery species. More than 20 000 acres of these sensitive habitats disappear each year. Paved surfaces have created expressways for oil grease and toxic pollutants into coastal waters. Every eight months nearly 11 million gallons of oil run off our streets and driveways into our waters the equivalent of the Exxon Valdez oil spill. More than 60 percent of our coastal rivers and bays are moderately to severely degraded by nutrient runoff. This runoff creates harmful algal blooms and leads to the degradation or loss of seagrass and kelp beds as well as coral reefs that are important spawning and nursery grounds for fish. Each summer nutrient pollution creates a dead zone the size of Massachusetts in the Gulf of Mexico. These types of problems occur in almost every coastal state and the trends are not favorable. If current practices continue nitrogen inputs to . coastal waters in 2030 may be as much as 30 percent higher than at present and more than twice what they were in 1960. Many ecologically and commercially crucial fish species including ground fish and salmon populations along the Atlantic and Pacific Coasts face over fishing and numerous other threats. Thirty percent of the fish populations that have been assessed are over fished or