Temporal and spatiall distribution and evaluation of nitrogen and phosphorus of Macrozoobenthos in Lake Nanhu,Wuhan,China

Abstract

通过对南湖大型底栖动物的时空分布研究表明,南湖中现在的优势种主要为耐污性强的种类,其季节分布:霍甫水丝蚓以5月份密度最大,8月份密度最低;刺铗长足播蚊和红裸须摇蚊的幼虫均以11月份密度最大.水平分布:霍甫水丝蚓密度依次为Ⅴ>Ⅲ>Ⅱ>Ⅰ>Ⅳ;刺铗长足摇蚊幼虫密度依次为Ⅱ>Ⅰ>Ⅲ>Ⅳ>Ⅴ.垂直分布:寡毛类和摇蚊幼虫最大分布深度为25 cm,主要集中在0-20 cm深度范围内,此深度范围内的生物量占到30 cm柱样中同类总量的99%以上.软体动物在湖心区已很难采到活体标本,但在岸壁上能采到一些腹足类.南湖寡毛类生物量鲜重为176759.35 kg,摇蚊幼虫为46810.30 kg,腹足类为899.34 kg;其所含的TN量和TP量分别为3463.61 kg和350.92 kg.研究表明,利用大型底栖动物转移或清除南湖中的N和P是一条重要途径,但与南湖目前巨大的外源性和内源性营养盐来源相比,对N、P的清除量是有限的.;The Lake Nanhu (30°29'N,114°21'E) situated in Wuhan City, Hubei Province of China, is an eutrophic shallow lake along the middle reaches of the Yangtze River, with a main surface of 550 hmZ of aquaculture.Macrozoobenthos were collected at 5 sampling sites both seasonally and randomly in the Lake Nanhu during the period of investigation from August 2005 to May 2006. With the input of massive nutritional salts and the deteriorationof the water quality, the community structure and biodiversity of macrozoobenthos had changed in the Lake Nanhu.Few species like mollusk had already been seen in the lake. Predominant species were limnodrilus hoffmeisteri,Tubifex,tubifex, Branchiwa souxrbyi, Tanypus pua.}t如nnis and Propsilocerus akamus at present. Level distributionsdensity of L.hoffmeisteri were V>Ⅲ>I<>I>N and T. punctipennis were II>I>>Q>N>V .The largestdensity of L ho ffmeisteri in May was 3802 ind. /m²,so was the least in August The largest density of T. pu><ctipen-nis in November was 730 ind. /m². The largest distributions depth was 25 cm, while 99% of Oligochaeta and Chironomid larvae lived in depth of 0-20 cm in the sediment. Wet weight biomess of Oligochaeta's was 176759. 35kg, Chironomid larvae was 46810. 30 kg, and freshwater snails was 899. 34 kg in Lake Nanhu. Macrozoobenthos canclear away 3463.61 kg TN and 350. 92 kg TP from the lake, but their efficiency is limited, compared with huge nutrition salt source of the lake.