镜湖夏秋季节裂足臂尾轮虫卵率变化及影响因素

Factors affecting egg-ratio of Brachionus diversicornis in Lake Jinghu during summer and autumn

调查了安徽省芜湖市镜湖中裂足臂尾轮虫的卵率,分析了卵率与种群密度、食物资源、潜在捕食者和竞争者、水温、水体透明度、溶氧、pH以及氨氮浓度等之间的关系。结果表明,大湖区中,裂足臂尾轮虫的卵率在0.095-1.073间变动,均值为0.293;卵率与种群密度和透明度呈显著的负相关(r值分别为-0.346和-0.329),与总叶绿素a含量和直径小于25μm的藻类叶绿素a含量均呈显著的正相关(r值分别为0.457和0.417);异尾轮虫密度对裂足臂尾轮虫卵率的影响具有明显的时滞效应(r=0.382);在晶囊轮虫密度高峰期,其密度是影响卵率的最主要因素(R2=0.5074)。小湖区中,裂足臂尾轮虫的卵率在0.0471-0.5455间变动,均值为0.194;卵率只与总叶绿素a含量呈显著的正相关(r=0.356)。研究结果提示影响裂足臂尾轮虫卵率的因素具有时空异质性。

The egg ratio of Brachionus diversicornis during summer and autumn in Lake Jinghu,Wuhu City,Anhui Province,was investigated,and the relationships between the egg ratio and its population density,food resource,potential predators and competitors,water temperature,transparency,dissolved oxygen,pH value as well as the N-NH＋4 concentration in water column were also analyzed.The results showed that in the big region of the lake,the egg ratio of B.diversicornis ranged from 0.095 to 1.073,with an average of 0.293,and was negatively correlated with both the rotifer population density and water transparency（r was-0.346 and-0.329,respectively）,but positively correlated with both the total Chl-a content and the Chl-a content in water filtered through 25 μm net（r was 0.457 and 0.417,respectively）.An obvious time-lag effect of Trichocerca density on the egg ratio of B.diversicornis was observed.Asplanchna density was a main factor affecting the egg ratio of B.diversicornis during the end of June and the beginning of September（R2=0.5074）.In the small region of the lake,the egg ratio of B.diversicornis ranged from 0.0471 to 0.5455,with an average of 0.194,and was positively correlated with only the total Chl-a content（r = 0.356）.All the results stated above indicated that the factors affecting the egg ratio of B.diversicornis have spatial and temporal heterogeneity.