| This paper first comprehensively summarized the wetland fishes' master list and their mainly ecological characters and filled up the blank of study on the estuary wetland fish in China, based on 104 surveys about wetland fishes (below -6m) from Sep., 2004 to Sep., 2007 and relatively historical data in the Yangtze estuary (N30°30'～32°00'; E121°00'～122°30'). The intertidal fishes were normally collected by tide stow net, while subtidal fishes collected by deep-water stow net, eel net, macro-plankton net, Agassiz trawl and so on. In total, there were 231 fish samples collected. The paper includes four parts, the first is summery on wetland environment, fish master list and its ecology characters; the second is study on the spatial and temporal changes of community structure of the intertidal and subtidal fishes used some biostatistics methods; the third is the research to species composition of fish eggs and larvae; the forth is the effect on wetland fishes from the traditional fishing eel activity. The main conclusions follow:1. Characters offish community and flora in the Yangtze estuary(1) Based on the different sample methods, we collected 123 fish species belongs to 1 glasse, 18 orders, 46 families and 98 genera in the Yangtze estuary. Among them, Elops saurus and Sardinella sindensis are 2 new recored fishes species which were found in the middle north branch (June, 2006) and esturine mouth (September, 2006). 80 fish species were found in the south brach, while 57 and 70 species in the north branch and esturine mouth, respectively. In conclusion, fish flora in the Yangtze estuary is transitional type between fresh river water and adjacent marine fish flora.(2) The intertidal fishes were collected 93 species belongs to 15 orders and 33 families, occupied about 75% by the total collected fishes. It indicated the intertidal flat was a kind of very important habitant for fishes in estuary area.(3) We also collected 42 subtidal fish species belongs to 21 families in the estuarine mouth. The number of fishes those occasionally entering estuary wetland is the highest (17 species), then those resident and seasonally entering estuary wetland followed (both 10 species), while the fresh water and diadromous fishes are the lowest (both 1 species). Similarly, small fishes or juvenile fishes of larger size are dominant in the subtidal water area in estuarine mouth. (4) From the fish ecological groups, there are 6 groups in the Yangtze estuary wetland, fresh water fish (66 species), resident species (35 species), seasonally entering estuary wetland species (26 species), anadromous species (6 species), catadromous species (3 species), and ocassionlly entering estuary wetland species (70 species). In them, 8 fish species have 2 kind of ecological groups. Two-thirds of fishes are highly depend on the estuary, because the fishes spend their largely or all life history in estuary wetland waters.2. Characters of intertidal and undertidal fish community(1) Small fishes or juvenile fishes of larger sizes are dominant in the intertidal flat and a little fishes spawn in this area, it means that only minority of adult or spawning fishes occur in the intertidal water areas. The k-dominance curves of individuals suggested the fish community had a certain extent disturbed by long over-fishing and other anthropic activities. This paper richly approve that intertidal flat is nursey field in the Yangtze estuary.(2) Two community types were obviously divided in the intertidal fishes by CLUSTER and nMDS analyze methods, namely fresh water and brackish water fish communities. In seasonal changes, fish community structure in spring largely differ that of summer or autumn, but that of summer is relatively less differ from autumn. Temperature and salinity are two main factors affected the spatial and temporal changes of intertidal fish community. Temperature mainly affects the temporal change, because the spearman r of tempertuare are 0.023 and 0.13 in freshwater and brackish water, respectively; which higher than 0.022 and 0.1 of sanlinity. Salinity mainly affects the spatial change of fish community structure, because the salt endurance of different ecological groups of fishes decides them live in different waters in the estuary.We also studied the diel, semi-lunar and seasonal changes of fish abundances in Chong-xi intertidal flat. The results showed that the abundance in night tides is significant higher than day tides (P<0.05), but contrary to autumn and winter (P<0.05). These differences mainly caused by different tidal height. In a semi-lunar cycle, the fish species and abundances in spring tides both higher than that in neap tides (Mest, P>0.05) . From the seasonal change, many fishes occur in the intertidal flat seasonally, such as Carassius auratus, Parabramis pekinensis, Pelteobagrus nitidus, Synechogobius ommaturus, while the abundances and body-size distribution in different water depth have some extent differences in favor of juvenile fishes' growth and deceasing inter or intra food competition.(3) There was no significant difference of fish abundance between 2 sations in the subtidal fish community in the estuarine mouth (ANOSIM, P=0.68), but exite some extent difference in the temporal structure. The greater contribution on the fish community were 17 fish species, such as Anguilla japonica, Coilia ectenes, Harpodon nehereus and Collichthys lucidus, ans so on.3. Characters of ichthyoplankton community(1) Based on the data at 6 surveys in the South and North branch waters, it showed that the total number of species of eggs and larvae was 36. Eggs were not collected in fresh waters and only collected in S9 station at estuary mouth in 6 surveys. There is not clearly disciplinary in distribution of larvae.(2) The dominant species vary much in each survey, this reflect that the community structure of ichthyoplankton is complicated. The the abundance of larvae and juveniles has some extent declined in nearly 20 years. In fresh water, the dominant species are Pseudorasbora and Salangidae; while those are Coilia mystus, Anchoviella, Priacanthus macracanthus. We both collected the Coilia mystus larvae in early Sep., 1990 and latterly Sep., 2006, while the abundance of former was about 10 times than the latter. The average abundance of Hemisalanx prognathus was 0.8 ind./net, which was obviously lower than 14.5 ind./net in April-May, 1986.4. Effect on the fish community of eel fishing activity in the Yangtze estuary The traditional fishing eel activity one hand damage the population of Japaneseeel; on the other hand, heavily destroy the resources of other wetland fishes, such as Coilia ectenes, Coilia mystus, Odontamblyopus rubicundus, and Collichthys lucidus. The total catch of Coilia ectenes juveniles was above 45 and 96.6 tons in Mar., 2006 and from Jan. to Mar., 2007, respectively, which above 31 and 29 tons of Coilia mystus. Hence, the heavily decreasing population of Coilia ectenes and other fish resources were mainly affected by the fishing activity.
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