The present study investigated the drag increase on aquaculture nets due to biofouling of the colonial hydroid Ectopleura larynx. It had two main parts： firstly the growth characteristics of E. larynx were investigat...The present study investigated the drag increase on aquaculture nets due to biofouling of the colonial hydroid Ectopleura larynx. It had two main parts： firstly the growth characteristics of E. larynx were investigated by use of field tests at a Norwegian aquaculture site; secondly the hydrodynamic drag on the fouled twines was studied in a towing tank by using fabricated models of net twines with artificial hydroid fouling. In the field tests, the growth of the hydroids was first measured after three weeks of immersion and then again after six weeks. During this interval, the density of hydroids and the thickness of the hydroid stem were almost constant（1.4 hydroids/mm and 0.29 mm, respectively）, while the average length of the hydroids increased from 6.4 to 11.2 mm. The hydroid length followed a Rayleigh distribution, while the thickness was normal（Gaussian） distributed. Replicas of twines with three different levels of hydroid growth were made（1.5 hydroids/mm twine, hydroid length 9 mm, 16 mm and 20 mm）, and the drag on these twines was measured at different towing velocities（0.1 to 1.4 m/s） and with different twine configurations. For the twine with the shortest hydroids（9 mm）, the drag was from 1.5 times（Re=4000） to 2.2 times（Re=1000） the drag on a clean twine. For the longest hydroids（21 mm）, the drag was 2 times and 3.8 times, respectively.展开更多
研究了Cd(Ⅱ)、Cu(Ⅱ)、Zn(Ⅱ)、Pd(Ⅱ)4种重金属离子对内刺盘管虫Hydroides ezoensis担轮幼虫的急性毒性影响。结果表明:Cd(Ⅱ)、Cu(Ⅱ)、Zn(Ⅱ)、Pb(Ⅱ)对内刺盘管虫担轮幼虫的24 h LC50分别为1042.32、85.901、1161.45、8109.6μg/L,...研究了Cd(Ⅱ)、Cu(Ⅱ)、Zn(Ⅱ)、Pd(Ⅱ)4种重金属离子对内刺盘管虫Hydroides ezoensis担轮幼虫的急性毒性影响。结果表明:Cd(Ⅱ)、Cu(Ⅱ)、Zn(Ⅱ)、Pb(Ⅱ)对内刺盘管虫担轮幼虫的24 h LC50分别为1042.32、85.901、1161.45、8109.6μg/L,48 h LC50分别为554.625、52.602、503.5、4623.81μg/L。展开更多
基金fanatically supported by the Norwegian Research Council through the project Hydroids on aquaculture constructions in Norway(190463/S40)the CREATE Centre for Aquaculture Technology
文摘The present study investigated the drag increase on aquaculture nets due to biofouling of the colonial hydroid Ectopleura larynx. It had two main parts： firstly the growth characteristics of E. larynx were investigated by use of field tests at a Norwegian aquaculture site; secondly the hydrodynamic drag on the fouled twines was studied in a towing tank by using fabricated models of net twines with artificial hydroid fouling. In the field tests, the growth of the hydroids was first measured after three weeks of immersion and then again after six weeks. During this interval, the density of hydroids and the thickness of the hydroid stem were almost constant（1.4 hydroids/mm and 0.29 mm, respectively）, while the average length of the hydroids increased from 6.4 to 11.2 mm. The hydroid length followed a Rayleigh distribution, while the thickness was normal（Gaussian） distributed. Replicas of twines with three different levels of hydroid growth were made（1.5 hydroids/mm twine, hydroid length 9 mm, 16 mm and 20 mm）, and the drag on these twines was measured at different towing velocities（0.1 to 1.4 m/s） and with different twine configurations. For the twine with the shortest hydroids（9 mm）, the drag was from 1.5 times（Re=4000） to 2.2 times（Re=1000） the drag on a clean twine. For the longest hydroids（21 mm）, the drag was 2 times and 3.8 times, respectively.
文摘研究了Cd(Ⅱ)、Cu(Ⅱ)、Zn(Ⅱ)、Pd(Ⅱ)4种重金属离子对内刺盘管虫Hydroides ezoensis担轮幼虫的急性毒性影响。结果表明:Cd(Ⅱ)、Cu(Ⅱ)、Zn(Ⅱ)、Pb(Ⅱ)对内刺盘管虫担轮幼虫的24 h LC50分别为1042.32、85.901、1161.45、8109.6μg/L,48 h LC50分别为554.625、52.602、503.5、4623.81μg/L。
