浒苔声反射特征的实验测定

Acoustic backscattering property of Enteromorpha prolifera

以2008年夏季在中国黄海中南部海域引起绿藻暴发的主要种类浒苔(Enteromorpha prolifera)为研究对象,在消声水池内利用经过校正的、工作频率为70kHz的Simrad EY500回声探测-积分系统对其声反射特征进行测定,根据浒苔的回声积分等测定值建立了浒苔声反射强度与浒苔密度关系的定量表达式。实验结果显示,浒苔是有效声散射体,其体积反向散射强度(Sν,dB)与浒苔密度(ρ,g/m3)之间的关系为Sν=17.31gρ-95.9,与鱼类目标强度和体长关系具有类似的表述模式。结果证实渔业声学原理和现行渔业声学仪器、方法同样适用浒苔的探测,水声技术可成为下沉浒苔快速监测的有效手段。实验同时显示,浒苔的声散射特征具有其特殊的复杂性,这可能与其可通过光合作用产生气体(氧气)有关。因此,若欲利用声学方法对下沉浒苔资源进行定量评估调查,需对浒苔的生理生化特征进行同步观测研究。

Experimental measurements on the acoustic backscattering properties of Enteromorpha prolifera were conducted in an anechoic tank with a calibrated,70 kHz,Simrad EY500 echosounder;and a quantitative expression for the relationship between acoustic backscattering strength and density of Enteromorpha prolifera was established based on those relevant measurements,including echo integrals.The experiment shows that Enteromorpha prolifera is an effective sound scattering target;and that the relationship between volume backscattering strength（s ν,dB）and density of the organism（ρ,g/m 3 ）can be expressed as S ν =17.31gρ-95.9,which is in line with the target strength to length relation of fish in terms of model expression.These findings indicate that the principles of fisheries acoustics as well as the current acoustic instrumentation and methodology can also be used for Enteromorpha prolifera detection,and that hydroacoustics can be used as an available and effective technique for rapid monitoring of submerged Enteromorpha prolifera.The experiment also shows that the acoustic scattering property of Enteromorpha prolifera is characterized with special complexity,which is likely to be connected with gas（oxygen）production property of the organism during photosynthesis process.Therefore,if acoustic method is to be used for quantitative assessement of submerged Enteromorpha prolifera,the physiological and biochemical characteristics of Enteromorpha prolifera need to be observed concurrently.