Temporal synchrony among juvenile marine fishes and potential climate and environmental drivers in the Bay of Biscay.

• We analysed the temporal dynamics of 12 juvenile marine fishes in the Bay of Biscay. • Time-series of annual fish abundance were derived from beam trawl survey data. • Dynamic factor analysis detected synchronous changes in abundance among species. • Interspecific synchrony was explained by climate and environmental factors. • Potential drivers were sea bottom temperature and the East Atlantic Pattern. The existence of synchronous fluctuations among sympatric species is an important property of a community, potentially reducing temporal stability of ecosystem services. Yet, community synchrony and its potential drivers have rarely been studied in marine ecosystems. Here, we analyzed a 14-year time-series (2007–2020) of fish abundance data collected by a scientific beam trawl survey in the Bay of Biscay, a temperate marine ecosystem located in the North-east Atlantic. We used dynamic factor analysis to reveal common trends in abundance among juvenile demersal marine fishes, and to identify potential environmental drivers. Our results revealed synchronous changes in juvenile fish abundance among the 12 marine species examined in the study. This strong temporal coherence was likely related to the influence of climate and environmental factors, notably sea bottom temperature and the East Atlantic Pattern. We also found some support for alternative drivers of early-life fish dynamics, namely the North Atlantic Oscillation and sea surface chlorophyll-a concentration, the later suggesting bottom-up trophic control. In the context of ongoing environmental changes, our findings raise questions about the future stability of the demersal marine fish community in the Bay of Biscay. [ABSTRACT FROM AUTHOR]