【摘要】 白鲑(Stenodus nelma)作为鲑科濒危珍贵经济鱼种，其种群恢复依赖于人工孵化鱼卵及向自然水域投放鱼苗，然而鱼卵遭受真菌及类真菌生物侵染构成重大威胁。针对水产养殖中引发白鲑胚胎死亡的鱼卵样本展开分析，在其卵周隙内观察到菌丝体存在。该研究目的为分离鉴定导致白鲑鱼卵及胚胎病变的真菌种类。采用鱼卵真菌学培养基接种法，先后于7℃和25℃条件下培养后，测试分离菌株在3℃环境中的生长特性，并通过形态学特征与rDNA的ITS区域分子测序进行菌种鉴定。结果表明：Dactylaria dimorphospora(Helotiales,Leotiomycetes,Ascomycota)以高达90%的检出率和95.0%～99.5%的相对丰度占据绝对优势，该真菌此前未被记载为鱼卵或成鱼的病原体，同时分离获得Phoma herbarum(Diaporthales,Sordariomycetes,Ascomycota),其检出率不超过20%,相对丰度低于4.5%,该菌系鲑科鱼类鳔霉病的已知病原。鱼卵内浅色有隔菌丝的检出、D.dimorphospora在染病鱼卵培养基中的优势地位以及该菌株在3～7℃低温条件下的良好生长特性，共同证实其在白鲑鱼卵及胚胎病变过程中的关键致病作用。更多还原

【Abstract】 The nelma(Stenodus nelma) is a valuable endangered commercial species of the salmon family. The restoration of its population includes the incubation of eggs and the release of fingerlinks into natural reservoirs. However, one of the serious threats is the infection of eggs with fungi and fungi-like organisms. Caviar(eggs) were studied that used in fisheries. Mycelium was found in the perivitellin space of the caviar and the death of nelma embryos was observed. The aim of the work was to isolate and identify fungi that cause damage to eggs and nelma embryos. To isolate the fungi, mycological media was plated by eggs, followed by incubation at temperatures of 7 ℃ and 25 ℃ and subsequent testing of growth of isolates at 3 ℃. Identification of fungal isolates was carried out on the basis of morphological and cultural characteristics and molecular sequencing of ITS rDNA regions. The absolute dominance of the ascomycete Dactylaria dimorphospora(Helotiales, Leotiomycetes, Ascomycota) with a frequency of occurrence up to 90% and a relative abundance of 95.0-99.5% was revealed. The fungus was not known to be the causative agent of caviar or adult fish. Together with D. dimorphospora the pycnidial fungus Phoma herbarum(Diaporthales, Sordariomycetes, Ascomycota), with a frequency of up to 20% and a relative abundance of up to 4.5%, was isolated. It was previously registered as the causative agent of mycosis of the swim bladder of salmon fish. The presence of light-colored septic mycelium in eggs, the dominance of D. dimorphospora in plates of infected caviar on nutrient media, and the good growth of isolates of this fungus at low temperatures of 3～7 ℃ indicate its key role in the defeat of nelma caviar and embryos.更多还原