Production of Daphnia zooplankton on wastewater-grown algae for sustainable conversion of waste nutrients to fish feed
Production of Daphnia zooplankton on wastewater-grown algae for sustainable conversion of waste nutrients to fish feed
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DOI：
10.1016/j.jclepro.2021.127501
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发表时间：
2021-05-24
影响因子：
11.1
通讯作者：
Higgins, Brendan T.
中科院分区：
文献类型：
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作者：
Hyman, Miriam;Wang, Qichen;Higgins, Brendan T.
本研究探讨了厌氧消化中营养物质通过藻类生物量向浮游动物的升级循环，浮游动物是一种天然的鱼类饲料。据作者所知，目前还没有发表过关于在消化物生长的藻类上生长浮游动物的可行性的研究。在这里，研究人员测试了用消化液培养的小球藻作为大型通才浮游动物水蚤的饲料的可行性。研究发现，以消化物生长的C. sorokiniana为饲料的水蚤种群增长量比以固定饲料Ankistrodesmus sp.为饲料的水蚤种群增长量高1.5 ~ 14倍。一项对sorokiniana的甾醇分析发现，其甾醇、麦角甾醇和α -亚麻酸的含量几乎是Ankistrodesmus的两倍。甾醇和α -亚麻酸通常是水蚤饮食中的限制性营养素。我们还测试了其他可能影响藻类向水蚤转移营养的因素，包括藻类饲料浓度、甾醇补充和藻类饲料中消化细菌的存在。细菌和外源胆固醇的存在对水蚤生长无显著影响。较高的饲料浓度（5mg C/L）使水蚤的生长比低饲料浓度（1.5 mg C/L）高3倍，尽管后者已被其他研究人员经常使用。结果表明，在未优化的系统中，藻类对水蚤的饲料转化率在0.19 ~ 0.31之间，碳的营养转移为25 ~ 28%，氮的营养转移为29 ~ 34%。这些值与牲畜饲料转化效率相比是有利的，但如果将水蚤喂给鱼类，则会造成额外的损失。这些结果表明，在消化藻类上培养水蚤在技术上是可行的。
This study investigates the upcycling of nutrients in anaerobic digestate via algal biomass to zooplankton which is a natural fish feed. There are no published studies, to the authors' knowledge, on the viability of growing zooplankton on digestate-grown algae. Here, the viability of digestate-grown Chlorella sorokiniana as a feed for the large-bodied generalist zooplankter, Daphnia, was tested. It was found that Daphnia fed with digestate-grown C. sorokiniana led to 1.5- to 14-fold greater Daphnia population growth than Daphnia fed with Ankistrodesmus sp., an established feed. A sterol analysis of C. sorokiniana found 4-6 mg/g of the sterol, ergosterol, and nearly double the alpha-linolenic acid content of Ankistrodesmus. Sterols and alpha-linolenic acid are often-limiting nutrients in Daphnia diets. Other factors hypothesized to influence nutrient transfer from algae to Daphnia were also tested, including algal feed concentration, sterol supplementation, and the presence of digestate bacteria in the algal feed. The presence of bacteria and exogenous cholesterol had no significant impacts on Daphnia growth. The higher feed concentration (5 mg C/L) led to 3 times higher Daphnia growth than the low feed concentration (1.5 mg C/L) even though the latter concentration has frequently been used by other researchers. Finally, it was determined that the feed conversion ratio of algae to Daphnia fell in the range of 0.19-0.31 and that trophic transfer of carbon was 25-28% while that of nitrogen was 29-34% in this un-optimized system. These values compare favorably to livestock feed conversion efficiency but additional losses will occur when Daphnia are fed to fish. These results show that cultivation of Daphnia on digestate-grown algae is technically feasible.