Determining the role of anthropogenic nutrients in supporting fisheries off the Mediterranean coast of Egypt: an approach using stable isotopes

随着1965年阿斯旺高坝的关闭和尼罗河流域每年发生的洪水的消除，埃及海岸外的地中海渔业崩溃了。从20世纪80年代中期开始，S的上岸渔业开始戏剧性地恢复，现在已经达到远高于大坝前渔业的水平。提出了三个主要假设来解释埃及海岸二次生产量的明显增加：用农业排水和污水中的氮和磷的人为来源取代尼罗河洪水的营养物质；用东地中海水域大规模循环的变化取代尼罗河的营养物质；产量的明显增加实际上是捕鱼活动的扩大以及数据收集和统计的改进。首席调查员将追踪来自替代氮源的稳定氮同位素，以及大型尼罗河三角洲泻湖和埃及大陆架近岸水域渔业上岸的颗粒状有机物、鱼和对虾的形成。来源包括从土地排水、污水、尼罗河水和地中海大陆架水中提取的氮。过去一个世纪无机氮的历史变化将在三角洲泻湖和近岸陆架的沉积物岩心中进行研究。进展报告将以日志形式定期张贴在为中学和中学公立学校儿童创建的网站上。对罗德岛州当地学校的课堂访问将强调将纳拉甘西特湾的污水、化肥和工厂对人类的影响与埃及的情况进行比较。在埃及国家海洋和渔业研究所同事的协助下，这些信息将被翻译成阿拉伯语，并在《环境与发展月刊》等颇受欢迎的阿拉伯语期刊和访问量大的网站(如《伊斯兰在线》)上发表。该项目的资金由国际科学和工程办公室和生物海洋学方案提供。

Following closure of the Aswan High Dam in 1965 and the elimination of annual flooding of the Nile basin, the Mediterranean Sea fishery off the Egyptian Coast collapsed. Beginning in the mid-1980's, landings began a dramatic recovery and have now reached levels well above those of the pre-dam fishery. Three major hypotheses have been advanced to explain the apparent increase in secondary production on the Egyptian Coast: replacement of the Nile flood nutrients by anthropogenic sources of nitrogen and phosphorous from agricultural drainage and sewage; replacement of Nile nutrients by a change in the large scale circulation of the Eastern Mediterranean waters; and that the apparent increase in production is actually an expansion of fishing effort and improved data collection and statistics. The principal investigator will track stable nitrogen isotopes from alternate nitrogen sources to the formation of particulate organic matter, fish, and prawns in the large Nile delta lagoons and in fisheries landings from the nearshore Egyptian Shelf waters. Sources include nitrogen derived from land drainage, sewage, Nile water, and Mediterranean Shelf water. Historical changes in inorganic nitrogen over the past century will be examined in sediment cores from delta lagoons and from the near shore shelf. Progress reports will be posted regularly in log form on a website created for middle and secondary public school children. Classroom visits to local Rhode Island schools will emphasize comparing human impacts from sewage, fertilizers, and factories in Narragansett Bay to those in Egypt. With the assistance of colleagues in the National Institute of Oceanography and Fisheries, Egypt, information will be translated into Arabic and published in popular Arabic journals such as Environment & Development Monthly and on heavily visited websites such as Islam Online. Funding for this project is provided by the Office of International Science and Engineering and by the Biological Oceanography Program.