Studies On The Communities Structure And Potential Fishery Production Capacity Of Periphyton In Daoguanhe Reservoir

Daoguanhe Rerservoir is a typical hill type reservoir in Wuhan, China. Its area for fish culture is commonly 467ha.Periphytic algae and periphytic protozoan including species, the content of chl.a and primary productivity et al, were studied from April 2000 to January 2001. Discussion was also given to the variations of the temporal and spatial distribution of the periphyton groups in Daoguanhe Reservoir, and the relationships among transparence of Secchi disk (SD), water temperature and depth of water. The results obtained were as follows:1. Thirty-five genuses of periphytic algae were observed, which Seneara, Stauroneis and Mougeotia were dominant populations. Sixty species of protozoan were observed, which Amoeba proteus, Actinophrys so, Litonotus fasciola were dominant populations.2. There were obvious differences in the temporal distributions of periphytic algae biomass and their spatial distributions. The biomass of each station descended gradually from upstream region to downstream region, where the biomass of 1/2SD was usually the largest. The biomass was the largest in Autumn, lower in Summer, and the least in Winter.3. There were no obvious differences in the horizontal distributions among each periphytic algae genuses.4. To some extent, there were some differences in the vertical distributionsIn the year, 30 genuses were found at 0.5m water depth, 35 in 1/2SD, 34 in 1SD, 21 in 2SD, 19 in 3SD. In addition, the proportion of the Bacillariophyta increased along with the increasing of the water depths.5. The general tendence of the horizontal distributions of periphytic protozoan was that the number of species at station II was the most, where 37 species were found. And 33 in station I , 13 in stationIII.6. The vertical distributions of periphytic protozoan basically accorded with those of periphytic algae.7. The general tendency of the Shannon-Weaver indexes were:H I < H II < H III; H sp > H au > H su > H wi.(sp.-spring, au.-autumn, su.-summer, wi.-winter).8. The Shannon-Weaver indices and the biomass of periphytic algae varied with the changes of environmental factors.9. The mean biomass of periphytic algae was 0.2783 mg cm" , the primary productivity of periphytic algae was 1.35g O2 d-1 m-2.10.The annual mean content of chl.a was 1.39 g cm-2. The mean content of chl.a were 0.57 g cm-2 in Spring, 2.16 g cm-2 in Summer, 2.28 g cm-2 in Autumn, and 0.55 g cm-2 in Winter. The mean contents descended gradually from upstream region to downstream region.11. The water quality state was evaluated with Shannon-Weaver index and some indicators of periphyton, and results showed that the nutrient type of Daoguanhe Rerservoir was mesotrophic type, and it had a tendency to develop to the eutrophic type.12.The potential fishery productive capacity of scrape-feeding fish in Daoguanhe Reservoir was estimated to be 14.5 t.