Copepods such as Calanus spp. typically dominate the zooplankton community, but chaetognaths, siphonophores, medusae,
appendicularians as well as meroplankton form a significant part of the zooplankton biomass throughout the year. Overall
copepod abundance has declined since the start of records in 1958. There has been a gradual change to a warmer water
zooplankton community over the last few decades. Cold-water species Calanus finmarchicus and Pseudocalanus spp. have
decreased in abundance while the warm-water copepod C. helgolandicus has increased and spread northwards, probably in
response to ocean warming. There has been a northward shift in the distribution of many other zooplankton species by more
than 10° latitude over the past fifty years. This shift is particularly marked near the northward current along the European shelf
edge. The seasonal timing of some plankton production has also altered in response to recent climate changes.
Other states in the Celtic seas
Long-term trends in copepod abundance from the CPR survey (log-mean abundance per cubic meter) aggregated for the ICES Celtic Seas ecoregion 1958–2014. Click the image to enlarge.