Abstract Meroplankton are frequently overlooked within the zooplankton community, yet they provide an important link between benthic and pelagic ecosystems. Long-term studies of holoplankton have revealed connections between climate and community dynamics, yet such studies are rare for meroplankton. We monitored the spring meroplankton community of a sub-Arctic fjord over 11 years (March–May 2014–2024), identifying 36 taxa across six phyla. Spring abundance peaked in April, averaging 5899 ind/m2, with the highest overall yearly abundance in 2018 and followed by a 30-fold decline across all taxonomic groups in 2019. The typical spring meroplankton succession began with a dominance of cirripedes around mid-March that shifted to high abundances of spionid larvae during April. However, two periods deviated from this succession pattern: From 2016 to 2018, when ophiopluteus larvae succeeded cirripeds, and from 2019 onwards, when cirripeds dominated before almost disappearing in 2023–2024. We do not report statistically significant relationships between climate indices (North Atlantic Oscillation or Arctic Oscillation) and meroplankton abundance. Instead, our results suggest that meroplankton respond to environmental variability related to deep water advection into the fjord’s basin and bottom temperature. Abrupt changes in the meroplankton community composition and succession might have strong implications for benthic recruitment and the pelagic food web.
Mau et al. (Fri,) studied this question.