Eggers胃含物法测定赤鼻棱鳀的摄食与生态转换效率

Food consumption,growth and ecological conversion efficiency of Thryssa kammalensis,determined by eggers model in laboratory

应用 Eggers现场胃含物法 ,以卤虫幼体为饵料和在室内流水条件下 ,研究了渤海主要上层鱼类赤鼻棱的摄食和生态转换效率等生态能量学特征。结果表明 :( 1 )赤鼻棱体重与空消化道重量的定量关系可用指数函数 W=1 .1 2 64e5.86 4· ESW加以定量描述 ,其瞬时全消化道内含物量可用公式 St=1 0 0× [SW-( ln W- 0 .1 1 90 ) /5 .8640 ]/W计算得到 ;( 2 )全消化道内含物随时间的变化趋势为 St=1 .7837e- 0 .2 136 t,瞬时排空率为 Rt=0 .2 1 36g WW/( 1 0 0 g· d) ;( 3)按 Eggers公式可求得日摄食量为 Cd=1 2 .32± 8.47g WW/( 1 0 0 g· d)或 32 .88± 1 9.5 9k J/( 1 0 0 g· d) ;( 4 )从赤鼻棱的平均日生长量实测值 ( Gd=0 .64g WW/( 1 0 0 g·d)或 2 .73k J/( 1 0 0 g· d) ) ,可求得其生态转换效率 Eg=5 .2 0 % WW或 8.30 % k J。

Rednose anchovy, Thryssa kammalensis (Bleeker), is a small\|size marine pelagic fish species, feeding mainly on zooplankton. Due to the decline of traditional economic fish resources, the fish species has become an important fishery resources in the offshore area in the middle and north part of Yellow Sea in recent years. Studies on its ecological energetics could provide basic data for quantifying dynamic process of food web and establishing corresponding nutrition dynamic model for the started research project\| “GLOBEC” on the East Sea and Yellow Sea. Simulated test in laboratory by taking individual fish as study object is the main method of getting fish energetics parameters at present. This method has the advantages of simplicity, less cost, and easiness of controlling experiment conditions. Due to the significant differences in the environment conditions between laboratory and nature, however, the determined parameters are generally difficult to reflect the actual situation in nature. In situ stomach content method is another important kind of methods of getting the ecological energetics parameters of fish. As obtaining the basic data is mainly by means of investigating on the spot, the parameters determined by the methods are relatively close to nature conditions. Among those methods, both Eggers and Elliott\|Persson models have been proved to be comparatively more successful. But so far, because time and quantitative sampling in situ is much difficult, there was little data determined by this method. Although both of the above\|mentioned models have coordinative veracity, Eggers model is more maneuverable due to its simplified sampling process. The ecological energetic parameters of including food consumption, growth, and ecological conversion efficiency were determined in laboratory by using Eggers stomach content method. The results indicated that: Relationship between the body weight and corresponding empty stomach weight could be described as W =1 1264 e 5.864·ESW , and instantaneous food content in stomach could be calculated by the following formula S t=100×[SW -(ln W -0 1190)/5 8640]/ W . Relationship between instantaneous food content in stomach and corresponding time could be described as S t =1 7837 e - 0.2136 t ,and instantaneous gastric evacuation rate could be represented as R t =0 2136 gWW/(100g·d). Food consumption could be calculated, according to Eggers' formula, C d =12 32±8 47 gWW/(100g·d)or 32 88±19 59 kJ/(100g·h). Based the determined value of growth( G d = 0 64 gWW/(100g·d) or 2 73kJ /(100g·d)), ecological conversion efficiency could be obtained by the formula E g =5 20% WW or 8 30% kJ.