Baseline for the Northeast Atlantic (58 – 70° N) intertidal Mytilus
species complex ( Mytilus spp .)
Abstract
Aim: During the last decades mussels have shown a poleward
shift in the distribution along the Atlantic coast conceivably driven by
elevated sea-surface temperatures. We aimed to determine the baseline
for the Northeast Atlantic (58 – 70° N) Mytilus species complex,
and to compare the present distribution to surveys conducted 60 years
ago. Location: Northeast Atlantic Methodology:
Baseline was obtained by investigating a total of 509 stations in the
intertidal zone, in four regions comprising the environmental gradient
from head of fjord to coast, and distributed over the latitudinal
gradient from 58 – 70° N. Results: The baseline shows a range
in continuous abundance of mussels from 12 to 36 %, patchy abundance
from 26 to 57 % and no or very limited mussel abundance from 26 to 46
% between the four regions. The presence of mussels in the southeast
and west region was compared to previous surveys conducted 60 years ago.
The data points to similar past and present presence of mussels in both
regions, yet past major mussel fields in the inner section of region
Southeast was not detected in this study. Main conclusions: The
baseline of Mytilus spp. in the Northeast Atlantic (58 – 70° N)
is now available for future reference. The baseline, compared to surveys
conducted 60 years ago, points to awareness of the population situated
in the southeast section of the investigated region. Continued
monitoring and modelling are needed to clarify drivers of temporal and
spatial variation in the mussel populations along the Northeastern
Atlantic coast.