The life-cycle of the sponge Ephydatia fluviatilis (L.) living on the reed Phragmites australis in an artificially regulated lake
The life-cycle of the sponge Ephydatia fluviatilis (L.) living on the reed Phragmites australis in an artificially regulated lake
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生活在人工调节湖芦苇芦苇上的海绵 Ephydatiia Fluviatilis (L.) 的生命周期
DOI：
10.1023/a:1025454506643
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发表时间：
2004
期刊：
影响因子：
2.6
通讯作者：
T. Lancioni
中科院分区：
文献类型：
--
作者：
E. Gaino;M. Rebora;C. Corallini;T. Lancioni
Piediluco湖（意大利中部）有一个不连续的芦苇带，主要由芦苇组成，芦苇支撑着海绵Ephydatia fluviatilis的生长。沿带的7个地点进行了采样，以确定这种海绵的生命周期。该湖是人工调节的，水位每天变化约52厘米。2000年6月至2001年5月每月采集标本。根据季节的不同，海绵的形态从薄的覆层（春季）到袖状的菌落（夏季）到小的复盖越冬代表。颜色也从均匀的绿色到褐色再到绿斑褐色不等。超微结构研究表明，绿色海绵中含有小球藻，而棕色海绵中没有小球藻。这些共生体是细胞内的，在同一个海绵细胞中可以发现几个共生体。从春天开始，褐色海绵的逐渐色素沉着与从环境中获得小球藻是一致的。组织学调查表明，性活动集中在4个月（5 - 8月），生长在老芦苇和年轻芦苇上的海绵都参与生殖。黄柳附体是一种雌雄同体的物种，精子和卵母细胞成熟的阶段重叠。我们的数据表明，温度（从4月到5月上升约6℃）在该湖泊中起着控制配子分化的作用。佩迪鲁科湖河蚌种群缺乏繁殖，芦苇根部附着的小海绵是主要越冬代表。幼虫的释放和它们在定居后随之而来的蜕变，加上海绵的自然破碎，可能解释了小越冬群落的起源。
Lake Piediluco (Central Italy) shows a discontinuous reed-belt mainly consisting of Phragmites australis ,t he reeds support the growth of the sponge Ephydatia fluviatilis. Seven sites located along the belt were sampled to determine the life cycle of this sponge. The lake is artificially regulated and the variation in water level is about 52 cm by day. Specimens were collected monthly from June 2000 to May 2001. According to the season, sponge morphology differs from thin encrusting laminae (in spring) to sleeve-shaped colonies (in summer) to small overwriting-wintering representatives. The colour also varies from uniformly green to brownish to greenspotted brownish. Ultrastructural investigation revealed that green sponges harbour zoochlorellae, which were not observed in the brownish colonies. These symbionts are endocellular and several may be found in the same sponge cell. The progressive pigmentation of the brownish sponges from spring onwards is coherent with the acquisition of the zoochlorellae from the environment. Histological investigation revealed that sexual activity is concentrated in a four month period (from May to August) and that sponges growing on old and young reeds are both involved in reproduction. Ephydatia fluviatilis is a gonochoristic species with overlapping phases of sperm and oocyte maturation. Our data suggest that temperature (which rises about 6 ◦ C from April to May) plays a role in controlling gamete differentiation in this lake. The population of E. fluviatilis in Lake Piediluco lacks gemmulation and the small sponges adherent to the reed rootlets are the main over-wintering representatives. The release of larvae and their ensuing metamorphosis after settlement, coupled with natural sponge fragmentation, may explain the origin of the small overwintering colonies.