Recent changes in ichthyoplanktonic assemblages of the eastern English Channel

Abstract

Fish assemblages vary through time in both abundance and diversity, often due to changes in climate. The potential consequences of these changes on the larval phase need to be considered. In the Eastern English Channel, fish larvae of 30 taxa, from surveys conducted during spring in the nineties and in 2017 with bongo nets, were used to investigate seasonal and interannual changes in larval assemblages with different statistical tests and multivariate analyses (Outlying Mean Index, Principal Coordinate Analysis and variance partitioning). The major change observed was significant lower abundances in 2017 (in April and May) compared to the nineties. Most of the dominant taxa were two to three-fold less abundant in 2017 than the 1990s. We suggest that the reduced larval abundances in 2017 could be a consequence of lower adult abundances in the area from a switch from a colder to a warmer phase of the Atlantic Multidecadal Oscillation.