大型浅水湖泊太湖霍甫水丝蚓次级生产力的研究

作为湖泊底栖动物优势种类的霍甫水丝蚓在长江中下游湖泊分布广泛,在湖泊生态系统的能流和物流中占有十分重要的地位。为了了解霍甫水丝蚓在大型浅水湖泊中的种群动态规律、生活史和周年生产量等的状况,于2005年1~12月对太湖霍甫水丝蚓进行周年的研究,以期为了解太湖这一优势种类的生产力状况及合理利用这一资源提供理论依据。研究发现,2005年太湖霍甫水丝蚓年均密度和生物量分别为3 274ind./m~2(0~13 800ind./m~2)和4.70g/m2(0~29.15g/m~2),一般均在冬季达到高峰,空间分布上霍甫水丝蚓密度和生物量呈现出明显的差异性,在太湖北部梅梁湾和竺山湾及西部河口湖区分布较高,而在其它区域的现存量均较低。根据体长频数分布的周年变化特征,推测太湖霍甫水丝蚓约为一年三代,繁殖可能发生在3、7和11月份期间。2005年太湖霍甫水丝蚓年生产量为480.21g·m~(-2)·yr-1,P/B为14.17,与同类研究报道相比属于较高水平。分析表明太湖霍甫水丝蚓的高世代数导致其高P/B系数,而高周年生产量与其所处的营养水平相对较高有关,这对于太湖渔产潜力具有显著意义。

A STUDY ON SECONDARY PRODUCTION OF LIMNODRILUS HOFFMEISTERI CLAPAR(E)DE IN A LARGE SHALLOW LAKE,LAKE TAIHU

Limnodrilus hoffmeisteri Claparède, a dominant species of zoobenthos, is widely distributed in shallow lakes of the middle and lower basin of the Yangtze River, and it plays an important role in the energy flow and biogeochemistry cycling of the lake ecosystem. To understand population dynamics, life history and production of L.hoffmesteri in the large shallow lake, field investigation were conducted in Lake Taihu during January to December, 2015. The annual average density and biomass of this worm were 3 273.75 ind./m² (0-13 800 ind./m²) and 4.70 g/m² (0-29.15 g/m²), respectively, all of which peaked in winter. The highest population density and biomass of L.hoffmeisteri were found in Meiliang Bay, Zhushan Bay and western river-mouth, while the other place of the lake had very lower worm density. According to the annual dynamics of the frequency distributions of body length, the species had three generations one year and reproduced in March,July and November. The annual P/B ratio was 14.17, which was due to high generations one year. The corresponding annual production of the animal calculated by size-frequency method was 480.21 g·m^-2·yr^-1 in wet weight, and was highest in studies reported, which is significant for potential fishery capacity in Lake Taihu.