Image from NASA
A mass migration that began almost 3.5 million years ago is set to resume over the coming years as the Arctic Ocean continues to warm. In a new study published in the latest issue of the journal Science, Geerat Vermeij of UC Davis and Peter Roopnarine of the California Academy of Sciences write that climate change is creating conditions in the Arctic similar to those found during the warm mid-Pliocene epoch, about 3.5 million years ago, when a number of favorable factors helped many North Pacific mollusk species invade the warming Arctic Ocean and, eventually, the North Atlantic.
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Dozens of new mollusk lineages could descend on the North Atlantic
The coastal areas of the Arctic were either permanently or seasonally ice-free at the time, and the region was characterized by high primary productivity, which facilitated the mollusks' rapid dispersal. Vermeij and Roopnarine believe these conditions may be recreated as early as 2050, or even sooner, since most climate models predict the Arctic will be completely ice-free by then. This could allow several dozen molluscan species to eventually make the move:
At least 77 molluscan lineages (35% of 219 shell-bearing, shallow-water mollusk species in the northern Bering Sea) have the potential to extend to the North Atlantic via the warmer Arctic Ocean without direct human assistance (7). Of these, 19 have Atlantic members but are separated from them by wide geographic and genetic gaps; 2 have extinct but no living North Atlantic representatives; and 56 have not yet extended beyond the Bering Sea or the Chukchi Sea just north of Bering Strait (see the figure). The remaining 142 Bering Sea lineages are distributed throughout the Arctic and subpolar North Atlantic Oceans. The number of would-be interoceanic invaders could well be much higher, because many species with northern limits in Kamchatka and the Aleutian-Commander island arc can expand northward and therefore also become candidates for trans-Arctic invasion.
Invasive species will "enrich" the North Atlantic
While invasive species are typically considered harmful to biodiversity -- with many recent studies positing that climate-induced invasions could drastically alter ecosystems -- the authors actually think these invaders will enrich the North Atlantic by adding new lineages and by hybridizing with other species. Indeed, they found little evidence in the fossil record to support the contention that invasions in marine environments led to mass extinctions over the past millenia.
The addition of large, fast-growing species will, through natural selection, force established species to adapt and could lead to the evolution of new ones. The melting of the Arctic's ice cap will likely also help increase the region's productivity, by freeing up more space for photosynthesizing phytoplankton, which could allow more populations to thrive.
Via ::ScienceDaily: Pacific Shellfish Ready To Invade Atlantic (news website)