| Freshwater fungi depend on aquatic environment throughout or part of their life cycle.These fungi constitute a rich biological diversity in aquatic habitats.Freshwater fungi play an important role in nutrient material cycling,ecosystem dynamics and aquatic ecology.They soften and decompose the lignocellulosic decaying plant substrate in water and release nutrients which can provide ready food for water-inhabiting invertebrates.In this thesis,we detail out the systematics and diversity of sexual morph and asexual morphs of Ascomycetes which are the largest of fungal groups encountered in freshwaters.A wide variety of fungi appear in freshwater environment.In 2011,Blackwell estimated about 5 million species of world fungi,through macro gene technology,and predicted that there are about 3000 species of aquatic fungi.Most of the so far described are terrestrial fungi and by the end of 2013,there were only about 800 species of aquatic fungi reported in literature.In this study,we combined baiting and random sampling methods to isolate and investigate the aquatic diversity in Binchuan county Jizu Mountain and Yongping county Baotai Mountain of Dali Prefecture.Besides we analyzed the relationship between altitude and matrix and freshwater fungi diversity and community structure.The results are presented as follows:1.During the investigation of aquatic fungi in Jizu Mountain,62 genera and 126 species of fungi were identified and the relevance ratio of them are Sporidesmiella hyalosperma(12.50%),Veronaea botryosa(9.58%),Sporidesmium macrurum(6.67%),Acrodontiella fallopiae(4.58%),Dactylaria biguttulata(4.58%),and Verticilium tenuissimum(3.33%).2.During the investigation of aquatic fungi in Baotai Mountain,40 genera and 56 species were identified,the higher relevance ratio of them are Sporidesmiella hyalosperma(19.17%),Aquanectria mengla(7.50%),Aqualignicola hyalina(6.67%)and Dactylaria biguttulata(2.50%).3.The Shannon-Wiener index of Jizu Mountain is: 4.19,the Shannon-Wiener index of Baotai Mountain is: 3.08,the similarity index of the Simpson community(S')was 0.20,0 <S'< 1.Therefore,the aquatic fungi diversity of Jizu Mountain is more than Baotai Mountain,and community difference between the two mountains remains large.4.The altitude of sampling points in Jizu Mountain were: 1890 meters,2260 meters,2310 meters,2440 meters and the diversity index(H ')were: 3.42,3.58,3.09,3.28 respectively.The altitude of Baotai Mountain sampling points were 1687 meters,2025 meters,2213 meters and 2450 meters and the diversity index(H ')were: 2.22,2.57,2.50,2.29 respectively.The results showed that there was no significant relationship between altitudes and freshwater fungal diversity.5.The diversity index of submerged wood,Dendrocalamus giganteus and Salix matsudana of aquatic fungi in Jizu Mountain were 4.11,2.85,2.72.The community similarity index of decaying wood and Dendrocalamus giganteus,decaying wood and Salix matsudana,Dendrocalamus giganteus and Salix matsudana of Jizu Mountain were 0.14,0.06,0.14.The diversity index of them in Baotai Mountain were 3.25,1.82,2.10.Those of Baotai Mountain were 0.20,0.17,0.06.We find that the aquatic fungi diversity on common decaying wood is higher than which on Dendrocalamus giganteus and Salixmatsudana.And the community similarity of the aquatic fungi on three substrates is low.6.In this work,latest molecular phylogenetic tree of Helminthosporium is established and the morphological characteristics and molecular data of the new species of Helminthosporium submersum introduced.7.This thesis presents detailed descriptions and illustrations of 26 species of aquatic fungi.The aim is to show the diversity of freshwater fungi in Jizu Mountain and Baotai Mountain and to lay foundation for development of use of freshwater fungal resources. |
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