Publication Date:
2022-05-25
Description:
Author Posting. © The Author(s), 2015. This is the author's version of the work. It is posted here by permission of Elsevier for personal use, not for redistribution. The definitive version was published in Deep Sea Research Part I: Oceanographic Research Papers 104 (2015): 159-172, doi:10.1016/j.dsr.2015.06.009.
Description:
Little is known about how larvae disperse in deep ocean currents despite how
critical estimates of population connectivity are for ecology, evolution and
conservation. Estimates of connectivity can provide important insights about the
mechanisms that shape patterns of genetic variation. Strong population genetic
divergence above and below about 3000m has been documented for multiple
protobranch bivalves in the western North Atlantic. One possible explanation for
this congruent divergence is that the Deep Western Boundary Current (DWBC),
which flows southwestward along the slope in this region, entrains larvae and
impedes dispersal between the upper/middle slope and the lower slope or abyss. We
used Lagrangian particle trajectories based on an eddy-resolving ocean general
circulation model (specifically FLAME - Family of Linked Atlantic Model Experiments)
to estimate the nature and scale of dispersal of passive larvae released near the sea
floor at 4 depths across the continental slope (1500, 2000, 2500 and 3200 m) in the
western North Atlantic and to test the potential role of the DWBC in explaining patterns
of genetic variation on the continental margin. Passive particles released into the
model DWBC followed highly complex trajectories that led to both onshore and
offshore transport. Transport averaged about 1 km d-1 with dispersal kernels
skewed strongly right indicating that some larvae dispersed much greater distances.
Offshore transport was more likely than onshore and, despite a prevailing
southwestward flow, some particles drifted north and east. Dispersal trajectories
and estimates of population connectivity suggested that the DWBC is unlikely to
prevent dispersal among depths, in part because of strong cross-slope forces induced by interactions between the DWBC and the deeper flows of the Gulf Stream.
The strong genetic divergence we find in this region of the Northwest Atlantic is
therefore likely driven by larval behaviors and/or mortality that limit dispersal, or
local selective processes (both pre and post-settlement) that limit recruitment of
immigrants from some depths.
Description:
ASB was
supported by Grant No. OCE-0926656 to WHOI by the U.S. National Science
Foundation and RJE was supported by NSF Grants OCE0726382 and OCE1130541.
Keywords:
Dispersal
;
Population connectivity
;
Circulation model
;
North Atlantic
;
Protobranch bivalve
;
Deep-sea
Repository Name:
Woods Hole Open Access Server
Type:
Preprint
Format:
application/pdf
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