Variability and composition of mysid assemblages in a northwest Iberian estuary: Insights from a 10-year data series

Long-term temporal studies have been used to assess the effects of climate change on mysid populations and their complex ecological interplay within heterogeneous ecosystems. This study is the first to investigate the mysid community in the Mondego estuary, western Portugal, for a decade, from 2003 to 2012. Monthly data collected from five stations along the estuary was used to investigate variations in mysid assemblage composition, patterns, phenology, and the interactions with environmental variables. Thirteen taxa were found in the assemblages. The community was dominated by Mesopodopsis slabberi, which was found in great numbers in the upper estuarine region. Praunus flexuosus and Schistomysis spiritus dominated the assemblages in the middle estuary, while Gastrossacus spinifer and Heteromysis formosa were very abundant at the mouth of the estuary. Overall, mysids were mostly present during autumn periods, when local environmental factors such as water temperature and chlorophyll-a concentrations influenced assemblage abundances. The high productivity of the system played a pivotal role in fostering greater species abundance. However, lower abundances were detected during warmer years, further evidencing changes in these key species’ communities under future climatic scenarios of increasing water temperatures.