不同磷条件对安氏伪镖水蚤的生长及摄食的影响

EFFECT OF PHOSPHORUS CONDITION ON GROWTH AND INGESTION IN PSEUDODIAPTOMUS ANNANDALEI

实验研究了海洋浮游动物桡足类安氏伪镖水蚤(Pseudodiaptomus annandalei)在分别喂食高磷和低磷扁藻(Platymonas subcordiformis)时的个体生长发育和摄食的情况。低磷扁藻(C/P=197或375,摩尔比)喂食安氏伪镖水蚤,安氏伪镖水蚤生长速率分别为g=(0.0437±0.0030)/d和g=(0.0339±0.0049)/d,高磷扁藻(C/P=78,摩尔比),安氏伪镖水蚤的生长速率为g=(0.1040±0.0395)/d。另外,从无节幼体到桡足幼体的发育所需的时间延长了1.5—2倍。就蚤体磷含量而言,在高磷条件下,个体的磷含量为干重的0.30%—0.33%,处于低磷喂养条件下的个体磷含量仅为0.08%—0.28%。结合生长速率和蚤体磷含量分析表明二者呈显著相关的线性关系。最后,在低磷条件下,无节幼体、桡足幼体和成体三个生长阶段的安氏伪镖水蚤个体的摄食率分别为150—370、695—703、648—733 cells/(ind?h),明显低于高磷条件下的790、720、728 cells/(ind?h)。据此得到结论:在磷限制条件下培养的饵料藻导致其营养价值发生了变化(C/P和C/N比值),对安氏伪镖水蚤的生长发育以及摄食率产生了显著负面影响,表明海洋桡足类安氏伪镖水蚤亦受到磷的限制。

The growth,development and ingestion of the Pseudodiaptomus annandalei were investigated by using Platymonas subcordiformis with different phosphorus contents as food.The growth rates of Pseudodiaptomus annan-dalei were（0.0437±0.0030）/d and（0.0339±0.0049）/d when using Platymonas subcordiformis with low P content（C/P=197 or 375 in molar） as food.The growth rate was（0.1040±0.0395）/d when using Platymonas subcordiformis with high P content（C/P=78 in molar） as food.Furthermore,the period of naupliar stage under low P condition was pro-longed by 1.5-2 times compared to those under the P-sufficiency condition.The P content was 0.30%-0.33% of dry weight in the animals under P-sufficiency condition,while it decreased to 0.08%-0.28% in the low P condition.There was a close linear significant correlation between the growth rates and P contents in the copepodite.The ingestion rates of nauplius,copepodites and adults decreased significantly in low P condition compared with those under P-sufficiency,which changed from790,720 and 728 cells/（ind？h） in the P-sufficiency condition to 150-370,695-703 and 648-733 cells/（ind？h） in the low P condition,respectively.It was concluded that the nutritional quality（C/P and C/N ratio） of algae was degraded in low P condition,which led to the significant impairment on the growth and ingestion of the Pseudodiaptomus annandalei.Therefore,the P-limitation in marine copepods was verified.