Scottish Association for Marine Science, Oban PA37 1QA, United Kingdom.
Scottish Association for Marine Science, Oban PA37 1QA, United Kingdom.
Harmful Algae. 2023 Nov;129:102512. doi: 10.1016/j.hal.2023.102512. Epub 2023 Sep 15.
The effects of nutrient effluents from fish cage aquaculture are an important eutrophication concern. It has been proposed that marine fish farm derived nutrients have the potential to increase phytoplankton abundance and lead to intensification of Harmful Algal Blooms (HABs), and that these blooms may negatively impact both the finfish and the shellfish industry. This study addressed this hypothesis using farmed salmon biomass in Scottish marine waters (as a proxy for nutrient load added to the water column as a consequence of fish farming) cell abundance of HAB taxa that most frequently impact shellfish farms and human health in the region (Dinophysis spp., Alexandrium spp. and Pseudo-nitzschia spp.), and cell abundance of one phytoplankton species of particular concern to the salmon farming industry (Karenia mikimotoi). Data from a 15-year weekly HAB monitoring programme and parallel national monitoring data relating to salmon farm stocking biomass were summarised in 5 km per 5 km aggregation boxes. Linear regression models were used to assess (i) inter-annual variation in cell abundance and total annual farmed salmon biomass; (ii) intra-annual (monthly) variation in harmful phytoplankton cell abundance and salmon biomass; (iii) a further analysis included seasonal effects within the intra-annual analysis. Farmed salmon biomass alone had a non-significant effect on cell abundance of any of the studied phytoplankton taxa. In contrast, a significant effect on cell abundance was found when using location, month or season as the predictive variable. Despite the non-significant impact of fish biomass on phytoplankton counts, the relationship varied seasonally, with a different response of Dinophysis spp. indicating a taxa specific interaction. A possible explanation for the lack of a significant relationship between farmed salmon and harmful phytoplankton cell abundance is that aquaculture farms are generally located in hydrodynamically energetic locations where recurrent flushing likely allows efficient dilution of nutrients. Overall, the analyses suggest that current levels of salmon farming activities do not markedly impact the abundance of routinely monitored biotoxin producing or fish killing phytoplankton taxa in Scottish waters.
鱼类养殖的营养废水的影响是一个重要的富营养化问题。有人提出，来自海洋养殖场的营养物质有可能增加浮游植物的丰度，并导致有害藻类大量繁殖（HAB）加剧，而这些藻类大量繁殖可能会对鱼类和贝类养殖业产生负面影响。本研究使用苏格兰海洋水域的养殖三文鱼生物量（作为因鱼类养殖而向水柱中添加的营养负荷的代表）、该地区最常影响贝类养殖场和人类健康的 HAB 分类群的细胞丰度（双鞭甲藻属、亚历山大藻属和拟菱形藻属）、以及对三文鱼养殖业特别关注的一种浮游植物物种的细胞丰度（夜光藻），来验证这一假设。对 15 年每周 HAB 监测计划的数据以及与三文鱼养殖场放养生物量有关的国家平行监测数据进行了 5 公里乘 5 公里的聚合盒汇总。线性回归模型用于评估：（i）细胞丰度和三文鱼总年度养殖生物量的年度间变化；（ii）有害浮游植物细胞丰度和三文鱼生物量的年内（每月）变化；（iii）在年内分析中包括季节性效应的进一步分析。单独的养殖三文鱼生物量对任何研究的浮游植物分类群的细胞丰度都没有显著影响。相比之下，当使用位置、月份或季节作为预测变量时，发现对细胞丰度有显著影响。尽管鱼类生物量对浮游植物计数的影响不显著，但这种关系具有季节性变化，双鞭甲藻属的反应不同，表明存在特定分类群的相互作用。养殖三文鱼和有害浮游植物细胞丰度之间缺乏显著关系的一个可能解释是，水产养殖农场通常位于水动力活跃的位置，那里反复的冲刷可能允许有效地稀释营养物质。总的来说，分析表明，目前的三文鱼养殖活动水平不会显著影响苏格兰水域中常规监测的生物毒素产生或鱼类致死性浮游植物分类群的丰度。
