In many long-term, intensive experimental and field studies there often arises a need to trade off taxonomic resolutionfor ecological answers. Compounding this problem is a taxonomic impediment, the lack of experiencedtaxonomists capable of processing large numbers of samples to species resolution, especially in groups such as theRotifera. This paper has two aims: (1) To investigate the level of taxonomic resolution required to determine theimpact of a disturbance, in the form of a flood event; (2) to compare the impact of different taxonomic resolutionsin assessing biodiversity. Results suggest both family and generic resolution can be used to determine the impactof a flood event and that these levels have some applicability to biodiversity studies. Relatively inexperiencedtaxonomists who can identify the common rotifers to generic level, can be relied upon to detect disturbance tocommunity structure but their data become unreliable when assessing biodiversity.