Phytoplankton communities have long been used as water quality indicators within environmental policies. This has fostered the development of national and international phytoplankton monitoring programs, but these networks are subject to sources of uncertainty due to laboratory issues. Nevertheless, studies regarding the interference associated with these aspects are not well-documented. Hence, a long time series (2003–2015) from the Basque continental shelf (southeastern Bay of Biscay) was analyzed to evaluate the uncertainty given by laboratory strategies when studying phytoplankton variability. Variability in phytoplankton communities was explained not only by environmental conditions but also by changes in fixatives (glutaraldehyde and acidic Lugol's solution) and laboratory staff. Based on Bray-Curtis distances, phytoplankton assemblages were found to be significantly dissimilar according to the effect of changes in the specialist handling the sample and the employed fixative. The pair-wise permutational multivariate analysis of variance (PERMANOVA) showed significant differences between the two fixatives utilized and also between the three taxonomists involved. Thus, laboratory-related effects should be considered in the study of phytoplankton time series.

浮游植物群落长期以来一直被用作环境政策中的水质指标。这促进了国家和国际浮游植物监测计划的发展，但是由于实验室问题，这些网络容易受到不确定性的影响。然而，关于与这些方面相关的干扰的研究尚未得到充分记录。因此，在研究浮游植物变异性时，对巴斯克大陆架（比斯开东南湾）的一个较长时间序列（2003-2015年）进行了分析，以评估实验室策略给出的不确定性。浮游植物群落的变化不仅可以通过环境条件来解释，还可以通过固定剂（戊二醛和酸性卢戈尔溶液）和实验室人员的变化来解释。根据Bray-Curtis距离，根据处理样品和所用固定剂的专业人员变化的影响，发现浮游植物的组合明显不同。配对的方差多变量方差分析（PERMANOVA）显示，所使用的两种固定剂之间以及所涉及的三个分类学家之间都存在显着差异。因此，在浮游植物时间序列的研究中应考虑实验室相关的影响。