Tintinnids Communities And Their Mixing In Different Water Masses

In this dissertation, surface tintinnids distribution of the East China Sea, a transect from the East China Sea to the Chukchi Sea, transects from coastal waters of China to the tropical western Pacific, and the Pearl River Estuary were studied. The purposes of this study were to find out the factors influencing the expansion of different tintinnids biogeographical types, the characteristics of different tintinnids communities, and the adaptation abilities of different tintinnids to the environment variation.In the East China Sea, most tintinnid genera belonging to neritic, warm water and cosmopolitan biogeographical types. According to the difference in their expansion ability, neritic and warm water types could be divided into core genera and pioneer genera. In the case of neritic type, core and pioneer neritic genera stayed together in spring and summer while pioneer neritic genera expanded a lot out to the oceanic water in autumn. In the case of warm water type, the pioneer genera always expanded a lot out to the coast in all three seasons. In spring and summer, the pioneer genera of neritic and warm water types did not meet. However, in autumn, the core genera of neritic and warm water types collided. The factor influencing the distribution of neritic type was water depth while salinity was the factor influencing the distribution of warm water type.Boreal, cosmopolitan, neritic and warm water biogeographical types occurred along the transect from the East China Sea to the Chukchi Sea. According to the presence of boreal and warm water types, three tintinnid communities(the East China Sea neritic community, the Japan Sea warm water community, and the boreal community) were identified along the transect. The boreal community extended from the Chukchi Sea to the waters north of the Sōya Strait. Abundance peaks occurred at stations in the crossroads of two branches of the Alaska Current and Oyashio Current, and decreased both northward and southward. The abundance was <10 ind. L-1 at most stations in Arctic region. The dominant genera(Acanthostomella, Codonellopsis, Parafavella, and Ptychocylis) accounted for 79.07±29.67%(n=49) of the abundance in the boreal community. The abundance of the four dominant genera covaried with strongly significant positive correlations. Tintinnids in 22–26 μm and 38–42 μm LOD size-classes were dominant and contributed 67.35% and 15.13%, respectively, to the total abundance in the boreal community. The distribution and abundance of tintinnids in the study area suggest that the Sōya Strait might be a geographical barrier for tintinnids expansion.Most tintinnids belong to cosmopolitan, neritic and warm water biogeographical types along the three transects from coastal waters of China to the tropical western Pacific. Neritic tintinnids were dominant both in number of species and abundance at coastal stations in transects L and M. At oceanic stations, cosmopolitan and warm water tintinnids were dominant at both number of species and abundance. Neritic community and warm water community were divided according to whether warm water tintinnids occurred. Tintinnid community in transect W was a warm water community, both species richness(12-40 species) and diversity index(2.03-4.76) were high. Species richness and diversity index were low in neritic communities in transects L and M. Species richness was < 10 species at each station, diversity index was < 2 at most stations in neritic communities. Species richness was > 10 species at each station, diversity index was > 2.5 at most stations in warm water communities in transects L and M. Both species richness and diversity index had a slight decrease at the southmost stations in the three transects. Species in 22-26 μm LOD size-class was the highest contributor in warm water communities, accounted for 27.82%, 30.76% and 38.56% of the total abundance in transects W, L and M, respectively. The characteristics of warm water communites in the three transects were high species richness, low abundance, high diversity index and evenness index.In the Pearl River estuary(South China Sea), tintinnid species richness was higher and more hyaline tintinnid species were identified in rainy than in dry season. The tintinnid species distribution was greatly linked to salinity, leading to their assignment to 3 types(oligohaline, mesohaline and polyhaline species) according to the salinity associated to their occurrence. Tintinnopsis mayeri was an oligohaline species and could expanded to much higher salinity region in rainy season. The mesohaline species, which were mainly found in middle salinity, were T. amoyensis, T. fimbriata, T. nana, T. tentaculata, T. tubulosa, Tintinnopsis sp. and Leprotintinnus nordqvisti. They present in both cruises. The distribution change of polyhaline species was obvious in rainy and dry seasons: Amphorellopsis acuta, T. plagiostoma and T. tubulosoides occurred at both cruises, but T. schott, T. tocantinensis and Wangiella dicollaria disappeared in rainy season. Three communities(low salinity; brackish water and coastal communities) could be identified at both cruises. One additional community(mixed community) was distinguished in the rainy season only. The dominant LOD size-classes varied within communities.From comparing the tintinnid data in different regions in this dissertation, it can be seen that species richness increased with the decrease of latitude, and had a slight decrease at the southmost stations. Species richness increased along with the salinity increase in the Pearl River estuary. Tintinnid abundance was low at tropical and Arctic oceans, but was high at temperate oceans. Tintinnid diversity index increased with the decrease of latitude, and it was much lower in the estuary area than that in the oceanic area with the same latitude. Tintinnids in 22–26 μm LOD size-classe was dominant in both boreal and warm water communities.