Sammendrag
: In central Norway, populations of the green sea urchin
Strongylocentrotus droe-
bachiensis
are collapsing, but the factors controlling its population density have not yet been
elucidated. Through field sampling, we identified several sea urchin predators and investigated
their predation rates on recently settled
S. droebachiensis
in laboratory experiments. Tethering
experiments in kelp forest and on barren ground study sites in the area where sea urchin popula-
tions are collapsing confirmed predation by some of the predators tested in laboratory experi-
ments. The edible crab
Cancer pagurus
was the most efficient sea urchin predator, and it was
more abundant at kelp forest sites than on barren grounds. Stocks of
C. pagurus
have increased
dramatically in central Norway since the 1990s, and predation by
C. pagurus
may contribute to
the decline in sea urchin densities, allowing kelp recovery and conferring resilience of the new
kelp forest state.
Vis fullstendig beskrivelse