Geoscience Reference
In-Depth Information
Despite four centuries of relentless exploitation, the Atlantic still has the capacity to renew itself and inspire awe.
This scenario will have two major impacts on seabirds. There is likely to be a northerly shift in their ranges,
probably in response to shifts in the ranges of prey species. Such a shift has already been observed with north-
ern gannets. During the last century, gannets have expanded their range northward. Colonies at Cape St.
Mary's and Funk Island, for example, have grown as water temperatures have warmed up and the gannets'
prime prey, mackerel, has moved north. Rising sea level, in combination with greater storm surges and tides,
may wipe out important low-lying breeding colonies like those at Funk and Sable Islands, as well as shrinking
the great mudflats in the inner Bay of Fundy, which are critical feeding grounds for migrating shorebirds.
Changes in tidal range may also disrupt the spawning cycle of horseshoe crabs in Delaware Bay, putting it out
of phase with the red knots' migration patterns in spring.
Conditions might well improve for a number of seabird species. Low Arctic breeders like common murres
are likely to expand their breeding colonies northward, as will southern non-breeders like shearwaters, which
use the northwest Atlantic as a feeding ground during the austral winter. Winter visitors from the Arctic will
also retreat northward as the Atlantic warms. Ivory gulls now scavenge the herds of harp seals and hood seals
as they pup at the Front off southeast Labrador. With warming seas, seals will move north and the gulls with
them. Breeding conditions in the north for low and high Arctic breeders like thick-billed murres and dovekies
