The marine green macroalgal genus Ulva (Chlorophyta) requires the presence of a combination of regulatory morphogenetic compounds released by their associated epiphytic bacteria in addition to nutritional parameters. The activity of algal growthand morphogenesispromoting factors (AGMPFs) derived from bacteria was determined in a land-based integrated multitrophic aquaculture (IMTA) system of fish and macroalgae (located at the coastal lagoon Ria de Aveiro, Portugal) using a standardised bioassay with axenic cultures of Ulva mutabilis during a snapshot study. The study thus informs aspects of various potential aquaculture− environment interactions. It was observed that both the water from the lagoon (external to the farm system) and the water from the fish pond (input for algae cultures) could completely restore the normal growth and morphology of the macroalga under axenic conditions. The results highlight the presence of a sufficient chemical cocktail of AGMPFs in this IMTA system required for growth and morphogenesis of the sea lettuce Ulva spp. In addition, the water from fish farming increased the nutrient availability (nitrate and ammonium) needed for macroalgae production at low concentrations of metal contaminants. Interestingly, the abundances of known morphogenesis-inducing bacteria (e.g. Maribacter mutabilis, Sulfitobacter spp.) were enriched in the Ulva aquaculture water compared to the water from the lagoon. We thus conclude that sustainable growth and development of Ulva spp. can benefit from multitrophic aquaculture systems and shallow-water systems, due to the naturally enriched AGMPFs and their in situ production by bacteria in intensive algal aquacultures.

中文翻译：

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综合多营养水产养殖系统中藻类生长和形态发生促进细菌因子（AGPFs）的分析，用于养殖绿海藻石莼

除了营养参数外，海洋绿色大型藻类石莼属（绿藻）还需要存在由其相关附生细菌释放的调控形态发生化合物的组合。来自细菌的藻类生长和形态发生促进因子 (AGMPFs) 的活性是在陆基多营养水产养殖 (IMTA) 鱼类和大型藻类系统（位于葡萄牙 Ria de Aveiro 沿海泻湖）中使用无菌培养的标准化生物测定法测定的Ulva mutabilis 在快照研究期间。因此，该研究为各种潜在的水产养殖-环境相互作用提供了信息。观察到来自泻湖（农场系统外部）的水和来自鱼塘的水（藻类培养的输入）都可以在无菌条件下完全恢复大型藻类的正常生长和形态。结果突出表明，海生菜石莼属的生长和形态发生所需的 IMTA 系统中存在足够的 AGMPF 化学混合物。此外，来自养鱼业的水增加了在低浓度金属污染物下大型藻类生产所需的营养物质（硝酸盐和铵）。有趣的是，与来自泻湖的水相比，石莼水产养殖水中的已知形态发生诱导细菌（例如 Maribacter mutabilis、Sulfitobacter spp.）的丰度更高。因此，我们得出结论，石莼属的可持续增长和发展。