典型养殖湖泊大通湖软体动物的时空分布格局

研究于 2008 年 12 月至 2009 年 10 月按季度对大通湖水质及软体动物资源监测, 并通过纵向比较, 探讨了集约化养殖对大通湖水域环境及软体动物群落的影响, 以期为其渔业可持续发展提供理论依据。结果显示, 大通湖水质全年呈碱性 (8.62 0.07), 具有较高的还原性 (-88.40 9.10) mv, 属富营养水体。软体动物共计 5 科 15 种, 梨形环棱螺(Bellamya purificata)、河蚬(Corbicula fluminea)和圆顶珠蚌(Unio doug lasiae)是主要优势种。软体动物平均密度和生物量具有明显的时空差异, 时间上呈现由春夏季到秋冬季逐渐升高的趋势, 空间上整体呈现由东北向西南逐渐递减的趋势。典范对应分析表明氧化还原电位、pH、溶氧、水深、电导率和水温与大通湖软体动物时空变化的关系最显著。与 1960 年相比, 大通湖水体碱性显著增强 (7.0-7.5 vs 8.4-8.8), 电导率增加了 9 倍 (0.25-0.27 vs 2.17-2.56 mS/cm), 环境类型由氧化型转变为还原型。湖区喜好水草 (白旋螺、光亮隔扁螺、萝卜螺) 与流水生境 (德氏狭口螺、湖沼股蛤、橄榄蛏蚌) 的物种消失, 软体动物优势种群呈现由双壳类向腹足类演替的特征。生境破坏和过度捕捞是大通湖软体动物资源面临的最大威胁, 也是湖区渔业可持续发展所面临的核心问题。  

TEMPORAL AND SPATIAL DISTRIBUTIONAL PATTERNS OF MOLLUSCA IN A TYPICAL AQUACULTURAL LAKE -- DATONG LAKE

The environmental characteristics and Mollusca community in Datong Lake were investigated seasonally from December 2008 to October 2009. Potential effects of intensive aquaculture on water quality and Mollusca in Datong Lake were studied by comparing the current sampling with the historical data in 1960, to provide theoretical support for sustainable fishery of the freshwater lakes. The results showed that Datong Lake was eutrophic and the water was alkaline (8.62 0.07), with higher reducibility (-88.40 9.10 mv). Fifteen Mollusca species were recorded, belonging to 5 families. Bellamya purificata, Corbicula fluminea and Unio douglasiae were the dominant species. Both the mean density and biomass of Mollusca showed significant seasonal and temporal variations. These two parameters in-creased gradually as the sequence of Spring, Summer, Autumn and Winter. In a spatial scale, they showed a pattern of decreasing from Northeast to Southwest. CCA analysis showed that the relationship between Oxidation-reduction po-tential (ORP), pH, dissolved oxygen (DO), depth, electrical conductivity (EC) and temperature (T) and the community variance was more significant. Compared with 1960, the water quality of Datong Lake changed dramatically. The water alkalinity became much higher (7.0-7.5 vs 8.4-8.6); EC was 9 times than before (0.25-0.27 vs 2.17-2.56 mS/cm), and water type changed to reducibility from oxidizability. For Mollusca, Gyraulus albus, Segmentina nitida and Radix which preferred habitat of aquatic macrophytes, and Stenothyra divalis, Limnoperna lacustris and Solenaia oleivara which preferred lotic habitat disappeared. The dominant species of Mollusca have been changed from Lamellibranchia to Gastropoda. The results indicated that habitat destruction and overexploitation were the main factors affecting the Mollusca community in Datong Lake, and they are also the key problems for sustainable fishery in the future.