Local changes in copepod composition and diversity in two coastal systems of Western Europe

摘要: Abstract While long-term monitoring is essential to improve our knowledge of marine ecosystems health, it remains challenging summarise complex ecological data in order characterise and understand biodiversity trends. To compile across large numbers species, scientists policymakers mainly rely on diversity species richness indices. This task may prove complicated however, as many indices exist no individual metric undoubtedly emerges the best overall. Here, using from zooplankton surveys 1998 2014, we examined year-to-year changes copepod communities two littoral Western Europe - Arcachon Bay Gironde estuary that share similar climate, but with different local processes, especially hydrological conditions. We tested ability commonly used α β-diversity metrics, such richness, Pielou's evenness or Jaccard's index, mirror abundances detected a synchronous change both α-diversity took place circa 2005 sites. In response environmental conditions nutrients, salinity, river discharge particulate matter, opposite trends were observed, decrease an increase downstream part estuary. Although metrics allowed us well detect trends, use multivariate approaches principal component analysis provided important information how why fluctuates. Our study provides evidence programmes must be encouraged for optimising management conservation actions Marine Strategy Framework Directive more comparative studies need initiated better characterising trajectories at very fine scales which ecologists often work.