单胞藻和破囊壶菌对卤虫幼体高密度短期营养强化条件和效果的探究

Optimal conditions and effects of high-density and short-term nutritional enrichment of Artemia nauplii with microalgae and Schizochytrium aggregatum

本研究以商业化生产的湛江等边金藻、三角褐指藻和破囊壶菌干粉为强化剂,探究其对高密度卤虫幼体短期营养强化的条件,并在最适条件下分别强化美国大盐湖和乌兹别克斯坦咸海两个品系的卤虫幼体,探究两种单胞藻和破囊壶菌对不同品系卤虫n-3高不饱和脂肪酸(n-3 HUFA)的强化效果。结果表明,利用湛江等边金藻,在不同强化剂量(0.05、0.1、0.15和0.2 g/L)和不同强化时间(12、18和24 h)条件下进行高密度卤虫强化(150、200和250 ind./mL),强化后卤虫存活率均在85%~90%,且随强化时间的延长和强化剂量的增加,卤虫个体体长和总生物量有所增加。考虑到育苗场对卤虫个体大小的要求和可操作性,建议卤虫幼体最佳强化密度为150~200 ind./mL,微藻强化剂量为0.1~0.2 g/L,强化时间为12~24 h。卤虫n-3 HUFA强化效果与强化剂种类和卤虫品系密切相关。对于大盐湖卤虫而言,强化三角褐指藻和湛江等边金藻强化的卤虫幼体EPA含量分别为7.39 mg/g dw和3.20 mg/g dw,与初孵卤虫EPA含量1.63 mg/g dw相比显著增加;对于咸海卤虫幼体,与初孵卤虫EPA含量14.35 mg/g dw相比,两种单胞藻强化的卤虫幼体EPA有所增加(分别为17.59 mg/g dw和17.26 mg/g dw),这与咸湖卤虫幼体中较高的EPA本底含量有关。强化两种单胞藻对两个品系卤虫的DHA含量没有显著提升作用,但破囊壶菌强化咸海卤虫幼体的DHA含量达到2.31 mg/g dw,这与破囊壶菌本身较高的DHA含量(115 mg/g dw)有关。本研究为开发单胞藻营养强化剂和高密度短期卤虫营养强化技术在水产育苗中的应用提供了数据参考。

Short-term Artemia enrichment is an efficient approach for improving the desired nutritional value of live feed Artemia nauplii.To investigate the optimal enrichment conditions,newly-hatched Artemia nauplii were enriched with commercially produced dry powder of microalgae Phaeodactylum tricornutum and Isochrysis zhanjiangensis,and fugus Schizochytrium aggregatum in this study.And the n-3 HUFA enrichment with the above products was compared with two commercially important Artemia strains from Great Salt Lake,USA(GSL)and Aral Lake,Uzbekistan.Higher Artemia survival percentages(85%-90%)were obtained when Artemia nauplii were enriched with I.zhanjiangensis under the following conditions:enrichment dose(0.05,0.1,0.15 and 0.2 g/L),enrichment duration(12,18 and 24 h)and Artemia density(150,200 and 250 ind./mL).And the individual body length and total biomass of Artemia increased with prolonged duration and increased dose.Considering the Artemia size preference and easy operation in the hatchery,the optimal enrichment parameters were proposed with Artemia nauplii density of 150-200 ind./mL,enrichment dose of 0.1-0.2 g/L,and enrichment duration of 12-24 h.Fatty acid analysis showed that fatty acid profile of the enriched Artemia was closely related to the enrichment agent and Artemia strains.For GSL Artemia,P.tricornutum and I.zhanjianggensis enrichment remarkably increased the EPA contents(7.39 and 3.20 mg/g dw,respectively)in Artemia when compared with newly-hatched Artemia nauplii(1.63 mg/g dw);whilst for Aral Lake Artemia,slight increase of EPA content could be observed between the enriched-Artemia(17.59 mg/g dw and 17.26 mg/g dw,respectively)and newly-hatched Artemia nauplii(14.35 mg/g dw),showing that the enrichment effect closely linked to the original EPA content of Artemia strains.On the other hand,the DHA content in two Artemia strains did not show remarkable improvement when enriched with microalgae,but S.aggregatum enrichment remarkably improved the DHA content of Aral Lake Artemia(2.31 mg/g dw),which should be attributed by the high DHA content of S.aggregatum(115 mg/g dw).The results of this study will support development of microalgae enrichment agent and application of Artemia nutrition enrichment in hatcheries.