A sclerochronology defined 600-year baseline of marine dynamics in the North Sea

Arctica islandica is a long-lived marine bivalve mollusc that inhabits
the continental shelf seas of the North Atlantic Ocean at subpolar
and temperate latitudes. Growth increments formed within A. islandica
shells can be analysed to form annually resolved and absolutely
dated sclerochronologies that are considered the marine counterpart to
dendrochronologies. Here, we present an updated A. islandica chronology
from the Fladen Ground (North Sea) that spans between CE 1410
and 2021. The A. islandica chronology significantly (p < 0.05) covaries
with observational local sea surface productivity, subsurface seawater
temperature and sea surface salinity. These analyses highlight the potential
sensitivity of the chronology to the variability in the regional seawater
temperature and salinity, and atmospheric circulation patterns (wind stress
and the summer North Atlantic Oscillation). The connection between the
atmospheric circulation patterns and A. islandica shell growth is likely due
to fluctuations in the strength of the Atlantic inflows into the North Sea and
local mixing. This highlights the significant potential in using A. islandica
records to provide long-term baselines of North Sea marine dynamics.
These baselines are critical for understanding the impact future changes
in regional oceanic and atmospheric variability may have on North Sea
ecosystems and fisheries.