放养河蟹对黑龙江东湖水库底栖动物和水生维管束植物的影响

EFFECTS OF STOCKING CHINESE MITTEN CRAB ON THE ZOOBENTHOS AND AQUATIC VASCULAR PLANT IN THE EAST LAKE RESERVOIR,HEILONGJIANG,CHINA

在面积为2700hm2的东湖水库,以散养的方式养殖河蟹。在放养密度不同的情况下,研究放养河蟹对水库中底栖动物和水生植物的影响。2001年规格为220只/kg河蟹放养量为1500kg、密度为122只/hm2时,对摇蚊幼虫和寡毛类影响显著,而对其他软体动物和水生植物无显著影响。2002年同样规格的河蟹放养量增加至3500kg、密度为285只/hm2时,对底栖动物和部分沉水植物影响显著。本文对河蟹养殖容量作了讨论,认为东湖水库散养河蟹的放养量不应超过1500kg。

Chinese mitten crab was stocked in the East Lake Reservoir with area of 2700 hm^2. The zoobenthos and aquatic plants were measured before and after stocking crab,and the effects of the crab on the zoobenthos and aquatic plants were studied by the way of ANOVA. The Chinese mitten crab carrying capacity of reservoirs and lakes depends on the biomass of different zoobenthos and macrophytes. The study also analyses the crab food selection of different natural diets in East Lake Reservoir. In 2001,with stocking amount of crab of 1500kg,the mitten crab(220ind.kg~ -1)had noticeable effects on chironomus and oligotricha,and little effect on other mollusca and aquatic plant,at the stocking density of 122ind.hm~ -2. In 2002,with stocking amount of crab of 3500kg,the mitten crab of same size(220ind.kg~ -1)had significant effects on zoobenthos and some submersed macrophyte, at the stocking density of 285ind.hm~ -2. The ideal stocking amount is that,after stocking crabs,the structure and function of aquatic ecosystem still can be maintained,the food resources of the crab were not damaged seriously,particularly the zoobenthos and submersed macrophyte. Therefore,the carrying capacity,in large lakes and reservoirs,is defined as the maximal standing biomass of the crab in the case that the growth of aquatic vegetation and zoobenthos were not significantly affected by the crab. The authors think that the stocking amount of crab of East Lake Reservoir should not be beyond 1500kg. The research of crab carrying capacity in East Lake Reservoir gives an exploration sample of other waste shallow water area in high frigid zone.