The effects of two free-floating plants (Eichhornia crassipes and Pistia stratiotes) on the burrow morphology and water quality characteristics of pond loach (Misgurnus anguillicaudatus) habitat

Loach exhibit conspicuous drilling behaviors in the mud of shallow waters,yet their burrow morphology and the factors affecting this behavior have received little attention.We characterized the burrow morphology and water quality of the pond loach Misgurnus anguillicaudatus in three scenarios:in tanks without plants,tanks with the free-floating plant water hyacinth Eichhornia crassipes,and tanks with water lettuce Pistia stratiotes.Water hyacinth effectively removed water TN,COD,NO3-N and NH4-N,and water lettuce removed water TP and NH4-N.Water hyacinth and water lettuce markedly reduced water turbidity and DO,increased TOC and EC.Water hyacinth purified water more effectively than water lettuce,providing a suitable habitat for loach feeding,living and burrowing.The burrow structures were V-shaped,Y-shaped,inverted L-shaped,or complicated dendritic networks composed of multiple V shapes.The hyacinth treatment was characterized by the greatest burrow volume,length,depth,and structural complexity,but the opening size was reduced by dense root mat coverage.Burrows in the water lettuce treatment were characterized by intermediate volume,length,branches and sinuosity,but they had the largest opening and pit size.The control treatment had a flat bottom with the smallest,shortest burrows.This study indicates that free-floating plants improve habitat suitability and change burrow morphology and may be used to improve loach breeding methods。

不同收获策略对养殖长吻鮠网箱大薸生物量的影响

为了降低网箱养殖长吻鮠对水体的污染,探究环保型生态网箱,在网箱内种植了漂浮植物大薸。为探讨合理的收获策略,比较了几种不同收获方式对大薸生物量的影响。在收获频率分别为5 d、10 d、15 d和20 d,收获面积分别为20%、40%、60%和80%的条件下,以收获频率为5 d,收获面积为20%,收获的生物量最多,60d共收获大薸13655.2 g。不同收获方式对大薸的氮和磷含量以及干湿重均无显著性影响。移除氮和磷量最多的是收获频率5 d,收获面积20%的收获策略,60 d共收获氮和磷量分别为28.13 g和5.50 g,移除氮和磷量分别为26.62 g和5.06 g。移除氮和磷量最少的是收获频率10 d,收获面积80%的收获策略,60 d共收获氮和磷量分别为8.88 g和1.80 g,移除氮和磷量分别为7.37 g和1.37 g。收获频率5 d,收获面积20%的收获策略的氮和磷的移除量是收获频率10 d,收获面积80%的收获策略的3.61倍和3.69倍。

水生植物大薸对不同类型的克隆片段化响应的基因型差异

克隆植物的相连分株因干扰而经常发生片段化,这种克隆片段化会影响克隆植物的生长。然而,不同类型的克隆片段化是否对克隆植物的生长产生不同的效应,以及这种效应是否存在基因型间的差异目前尚不清楚。我们将源自广东、广西、湖北、江苏、四川和云南6省的匍匐茎植物——大薸(Pistia stratiotes)的分株进行4种不同类型的克隆片段化处理,即所有后代分株保持与其亲体分株的连接(对照)或切断初级(1°)、次级(2°)或三级(3°)后代分株与其亲体分株的连接。我们发现显著的生长差异,表明从这6个省采集的分株具有不同的基因型。与对照相比,切断1°、2°或3°分株与亲体分株的连接对整个克隆的生物量无显著影响,且切断1°分株与亲体分株的连接显著提高了亲体分株的生物量。然而,除了切断2°分株与亲体分株的连接显著降低了广西基因型亲体分株的生物量之外,切断2°或3°分株与亲体分株的连接并不影响其它基因型亲体分株的生物量。切断1°、2°或3°分株与亲体分株的连接对所有基因型的1°或3°分株的生物量和数量均无显著影响。然而,切断1°分株与亲体分株的连接显著降低了广东和云南基因型2°分株的生物量,但对其它4个基因型2°分株的生物量却无显著影响。因此,不同类型的克隆片段化对克隆植物的亲体分株和后代分株可产生不同的效应,并且这种效应存在基因型的差异。