| Fish community is an important part of the estuarine ecosystem, which plays a key role in ecosystem structure and function. For the reason of environment pollution, over fishing and other human activities, the fishery resources is declining in recent years, and many fish habitats got lost or destroyed, which is very important for the protection of fishery. During2010November to2011June, the fish community is studied in Chongxi wetland intertidal creeks with the fyke net in creeks. The adaptability of released fish is also studied under different habitat types. At the base of these study, the possibility of releasing fish species from intertidal creeks is discussed. The main parts include:(1) the fish community composition in Chongxi wetland creeks and the main eco-characters;(2)the characters of creeks habitat using of Chongxi wetland fishes and the relation between fish community and environment factors in use of diversity index, nMDS, Cluster, ANOSIM and other biometrical method.(3) Experimental study of fish adaptability after released in two different type pools. The process of released fish from lab or breeding base to wild habitat is discussed.(4) Introduction is made for the Salmon habitat eco-restoration in Washington Harbor in USA. Some experience can be used in Yangtze estuarine eco-restoration work is summarized.The main results include:1Fish community composition in Chongxi wetland intertidal creeks and the dominant speciesIn this study,46fish species obtained, which belong to9orders and16families. Cypriniformes has the most species with24species, and the next order is Perciformes with12species. The most dominant families is Cyprinidae and Gobiidae not only on the species contained, but also the abundance and biomass. The first five dominant species are Hemiculter bleeleri, Acanthogobius ommaturus, Pseudobrama simony, Hemiculter leucisculus and Carassius auratus.In addition, on the fish eco-type,27freshwater species,15estuarine species and2 migratory species,2seasonal estuarine-ocean species and1temporal estuarine-ocean specie were obtained in this study. Each eco-type has their own appearance time during the year. What need to notice is most estuarine species appeared in Spring or Summer with the rising temperature, and most of these species found in this study are juvenile or young fish.2The spatial temporal variation of fish community in Chongxi wetland creeksMore high diversity were found in the lower or middle creek in Chongxi wetland creeks. The diversity index goes up with the elevation in creek B but opposite in creek A. During the year, the highest diversity is found in March and April, the next is June, and the diversity is not much different between November and January. With the Bray-Curtis analysis, it is found that the scope of fish appearance is the most limited in January, and the relation between scope of fish appearance and elevation in the creeks. With the Pearson index analysis for the number of fish species, abundance and biomass with the environment factors like the dissolved Oxygen, water temperature and so on, it is found that in Chongxi wetland creeks the correlation between this factors is not significant. But temperature plays an positive effect for the fish community diversity, abundance and biomass, but DO and pH value play negative correlation to these fish community indexes.3Environment difference between two types of pools and the adaptive characters of released fishTo explore the environmental differences of the open and closed pond and their ecological effects, a continuous experiment of15days was carried out to monitor the environmental factors and the fish growth rate. Environment monitoring included temperature, dissolved oxygen, pH, water depth, total nitrogen, total phosphorus, plankton content, at the same time we measured the body length and weight of the fish and calculated the growth rate per day and the specific growth rate. The differences between the two ponds of the three above factors were not significant. Temperature and dissolved oxygen had significant diurnal variations, and the closed pond had slightly higher temperature and dissolved oxygen. The temperature differed significantly in the big tide, and dissolved oxygen differed significantly in the small tide. The density and composition of the plankton between the two ponds were significantly different. It was inferred that the amount of plankton, temperature and dissolved oxygen are the main factors affecting the growth of carp. The average growth rate of fish body length in the open pond was0.63mm/day, slightly higher than that of the closed pond,0.60mm/day. In contrast, weight growth rate in the open pond was0.018g/day, lower than the station ponds,0.03g/day. The growth rate of fish body length and weight in the two ponds had no significant differences, which meant that the open pond might be a suitable location for fish discharge.4Habitat eco-restoration for Salmon in Washingtion Harbor, USA and the valuable experience can be used in Yangtze River estuaryAs the important habitat for the fish, the estuarine salt marsh wetland gets more and more people’s attention. The design principle and technological methods for eco-habitat restoration was discussed in this paper. Take the Washington harbor as an example, an introduction was made for the landscape pattern change and the Salmon habitat damage in the harbor under historical human activities. The changes to Washington Harbor brought about by the causeway have resulted in habitat fragmentation and tidal disconnection. The causeway forms a physical barrier to the movement of plants and animals. The majority of the adverse effects seen in this area are due to the loss of hydraulic connection and wave energy. The habitat restoration design of rebuilding a bridge after removing the causeway and converts was discussed and some experience on habitat restoration was summarized for the habitat protection and restoration work of Yangtze River estuary. It is recommended that the historical data should be made good use in order to know the main reason leading to the habitat damage. The ecosystem self balanc ability should be applied in the habitat and function restoration work. Some suggestions were given on maintaining the integrity and continuity of fish habitat in the Yangtze estuary. |
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