东海原甲藻(Prorocentrum donghaiense)和链状亚历山大藻(Alexandrium catenella)对模拟食物链物质传递的影响

The effects of Prorocentrum donghaiense and Alexandrium catenella on the material transfer in a simulated marine food chain

研究了东海原甲藻的基本营养组成,并就赤潮密度下的东海原甲藻(Prorocentrum donghaiense)和链状亚历山大藻(Alexandrium catenella)在单一和混合情况下对赤潮藻→卤虫模拟食物链物质传递的影响进行了探讨。结果表明:与其它饵料微藻相比,东海原甲藻必需氨基酸中的苯丙氨酸、赖氨酸和组氨酸含量明显偏低。东海原甲藻单独投喂时,卤虫对其的总物质转化效率随着藻密度的增加呈现先逐渐增加再逐渐降低的趋势。而当不同密度的东海原甲藻分别与一种硅藻小新月菱形藻(Nitzschia closterium)混合投喂时,随东海原甲藻密度的增加,卤虫选择性地增加对东海原甲藻的摄食,而降低对小新月菱形藻的摄食,并且其总物质转化效率逐渐降低。暴露于链状亚历山大藻藻液,卤虫体重减轻,且在其体内未检测到叶绿素a,表明卤虫未摄食该藻。当链状亚历山大藻藻细胞重悬液和去藻过滤液分别与小新月菱形藻或东海原甲藻混合时,卤虫对后两株藻的摄食量和总物质转化效率均有所降低。因此,在大规模赤潮发生时,东海原甲藻和链状亚历山大藻可能分别对浮游动物的营养和存活带来不利影响,并影响物质沿食物链的传递。

The biochemical composition （C, N elements, fat, carbohydrate, ash and amino acids） of Prorocentrum donghaiense was analyzed and the effects of P. donghaiense and Alexandrium catenella on the transport of materials through a simulated marine food chain （algae-Artemia salina ） were investigated. The results showed that the content of phenylalanine, histidine and lysine in P. donghaiense was obviously lower than in other dietary microalgae. Fed with P. donghaiense solely, the gross conversion efficiencies （GCEs） of A. salina increased gradually when the algal densities were lower than 4 × 10^4 cells/mL, and decreased gradually at higher densities. When fed with the mixture of P. donghaiense and the diatom Nitzschia closterium, A. salina preferred grazing on P. donghaiense to N. closterium, and the GCEs of A. salina decreased with the increasing density of P. donghaiense. When exposed to A. catenella at the densities of 10 -- 10^3cells/ mL, A. salina lost weight with no Chlorophyll a detected in their guts, which indicated that A. salina didnt ingest the algal ceils. When the re-suspended ceils and cell-free medium of A. cateneUa were mixed with N. closterium or P. donghaiense respectively, the grazing and GCEs of A. salina were all diminished. Consequently, based on the results from this simple food chain model, we propose that the large-scale blooms of P. donghaiense and A. catenella in the East China Sea could adversely affect zooplankton due to insufficient food or nutrition, and therefore impact the materials transfer efficiency through the food chain.