武昌东湖水生维管束植物的生物量及其在渔业上的合理利用问题

STANDING CROP OF THE MACROPHYTES OF LAKE TUNG-HU,WUCHANG,WITH REFERENCE TO THE PROBLEM OF ITS RATIONAL PISCICULTURAL UTILIZATION

  • 摘要: 本文是根据1962—1964年部分调查研究资料整理而成的。文中列出了83种水生维管束植物(以下简称水生植物)的名录,比较了全湖21个采集断面、3个植物带和17个植物群丛以及长江中下游6个浅水湖泊水生植物的生物量,分析了东湖两个断面(Ⅻ和ⅪⅡ)的生物量的周年变化和湖中不同水深区的生物量变化情况。全湖面积为28.5平方公里。8月是生物量的高峰期,平均每平方米的生物量为1,068.1克(湿重)或94.8克(风干重)或82克(烘干重)或322千卡(能量)。其中,以黄丝草所占的比例为最大,其次为大茨藻、聚草、黑藻和金鱼藻。全湖水生植物的年生产量为30,440吨(湿重)或2,337吨(烘干重)或9×109千卡(能量),连同浮游植物(16×109千卡)一起,则东湖全年的原初生产量为25×109千卡,其中水生植物约占总原初生产量的36%。本文最后讨论了水生植物在湖泊渔业上的合理利用问题,提出了草食性鱼种放养量的计算公式和合理利用水生植物资源的建议。

     

    Abstract: The paper presents the results of investigations on the macrophytes of Lake Tung-Hu,Wuchang,carried out in the year 1962—1964.83 species,which constituted theaquatic vegetation,are listed.Data on biomass,based on sampling along 21 transects(involving 3 zones,17 plant-associations,and 224 sampling positions),are presented,and a comparison is made for the macrophytic biomass of 6 shallow lakes of theMiddle and the Lower Yangtze Basin.The monthly changes in biomass of 2 tran-sects (Ⅻ ⅩⅢ) have been followed up through the year.The biomass conditionsfor zones of different depth-ranges are analyzed.Lake Tung-Hu,28.5 km2 in area,had a peak average biomass of 1068.1 g (wetweight) or 94.8 g (air-day weight) or 82 g (oven-dry weight) or 322 kcal per squaremeter in August.Annual production of aquatic vegetation in the whole lake amo-unted to 30,440 metric tons in wet weight,or 2,337 t in oven-dry weight,or 9×109kcal in terms of calorific value.Potamogeton maáckianus ranked first in the pro-duction,being 38.2% of the total wet weight or 52.5% of the total air-dry weight,andit was followed by Najas major,Myriophyllum spicatum,Hydrilla verticillata and Ceratophyllum demersum in turn.In the lake,the annual primary production from aquatic macrophytes and phy-toplankton put together amounted to 25×109 kcal,of which the aquatic macrophytescontributed 36%.In passing,the authors discuss the problem of the rational utilization of this re-source in special regard to pisciculture,and a formula is proposed for calculating thestocking density of the phytophagous fish,for instance,Ctenopharyngodon:X=(B·P/K·W·S),in whichX——the number of fingerlings of the phytophagous fish to be stocked per mou (1mou=1/15 hectare)B——maximum average biomass (attained during August—October) of the macro-phytes suitable for fish consumption (in catties per mou) (1 catty=500 g)P——percentage of the macrophytic biomass intended to be consumed by the fishK——gross feed-coefficient of the phytophagous fish during the entire growing sea-son (in catties)W——expected average increase in weight per fish (in catties)S——percentage of the number of survivors (to the end of the growing season) tothe number of fingerlings stocked

     

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