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首页> 外文期刊>Journal of Experimental Marine Biology and Ecology >Trophic modification of food quality by heterotrophic protists: species-specific effects on copepod egg production and egg hatching
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Trophic modification of food quality by heterotrophic protists: species-specific effects on copepod egg production and egg hatching

机译：异养生物对食物质量的营养修饰：对co足类卵的生产和孵化的种特异性影响

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Recent literature suggests that heterotrophic protists could improve the biochemical constituents of poor quality algae for subsequent use by higher trophic levels, a phenomenon dubbed "trophic upgrading". We conducted experiments to test trophic upgrading effects on the omnivorous calanoid copepod Acartia tonsa. Two heterotrophic protists, Oxyrrhis marina and Gymnodinium dominans, were grown on three algal species of different nutritional qualities: Dunaliella tertiolecta, Isochrysis galbana and Rhodomonas salina. In parallel incubations, the copepods were fed the heterotrophic protists or the algae that the protists grew on. We measured the ingestion rate, egg production rate and egg hatching success of the copepods in each treatment. Comparison of the egg production efficiency (EPE; egg carbon production/carbon ingestion x 100%) between parallel diet treatments allowed us to calculate the trophic upgrading index (TUI; ratio of EPE-heterotrophic protist to EPE-alga). The copepods ingested similar amount, or 20-30% more algae than heterotrophic protists. Daily rations ranged 50-122% of body C per day. Copepods feeding on O. marina that grew on D. tertiolecta had higher egg production rate and egg hatching success than copepods feeding on D. tertiolecta directly, and the resultant TUI between the two treatments was 19.7. Similarly, the copepod egg production was improved by G. dominans that grew on D. tertiolecta and the resultant TUI was 23.3. TUI was near 1 between I. galbana treatment and the parallel heterotrophic protist treatments, indicating no or little trophic upgrading effects on the copepod's egg production. However, egg hatching success was significantly lower with G. dominans growing on I. galbana. O. marina that grew on R. salina induced a lower EPE relative to the alga itself, yielding a TUI of less than 1. Biochemical data showed that the heterotrophic protists contained eicosapentanoic acid (EPA) and docosahexanoic acid (DHA) even when they fed on alga that lacked these essential fatty acids, which may explain some of the observed trophic upgrading effects and species-specific differences in our experiments. However, our data also suggested that dietary EPA and DHA could not be the sole factors regulating the copepod's reproductive output, and that egg production and egg hatching appeared to have different nutritional requirements and respond differently to the copepod's diets.
机译：最近的文献表明，异养生物可以通过提高营养水平来改善劣质藻类的生化成分，以供后续使用，这种现象被称为“营养升级”。我们进行了实验，以测试对杂食性类an足co足类car螨的营养升级作用。两种异养原生生物，Oxyrrhis marina和Gymnodinium dominans，生长在三种营养品质不同的藻类上：杜氏杜氏藻，等鞭金藻和盐红假单胞菌。在平行孵化中，co足类被喂食了异养原生生物或原生生物生长的藻类。我们测量了每种处理中co足类的摄食率，产卵率和孵化成功率。比较平行饮食处理之间的产蛋效率（EPE；蛋碳产量/碳摄入量×100％），可以计算营养升级指数（TUI； EPE异养性原生质子与EPE-藻类的比率）。 pe足类的摄食量比异养原生生物多出20-30％。每天的定量摄入量占人体C的50-122％。以叔畸形D为食的O足类的pe足类的产卵率和孵化成功率比直接以叔on形feeding为食的co足类高，两次处理之间的总TUI为19.7。同样，co足类的卵的生长也可以通过生长在三叶线虫上的G. dominans来提高，而TUI为23.3。 T. galbana处理和平行异养原生质体处理之间的TUI接近1，表明对co足类卵的产卵没有或几乎没有营养升级作用。但是，随着在银杏上生长G. dominans的卵孵化成功率显着降低。相对于藻类，在盐沼上生长的O. marina诱导的EPE较低，TUI小于1。生化数据显示，即使他们进食，异养生物也含有二十碳五烯酸（EPA）和二十二碳六烯酸（DHA）。缺乏这些必需脂肪酸的藻类，这可以解释我们实验中观察到的某些营养升级效果和物种特异性差异。但是，我们的数据还表明，饮食中的EPA和DHA可能不是调节the足类动物繁殖产量的唯一因素，并且卵的生产和孵化卵似乎具有不同的营养需求，并且对the足类动物的饮食有不同的反应。

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