| Abstrakt: |
A three‐dimensional, primitive‐equation, ocean circulation model coupled with a Lagrangian particle‐tracking algorithm is used to investigate the dispersal and settlement of planktonic larvae released from discrete hydrothermal habitats on the East Pacific Rise segment at 9–10°N. Model outputs show that mean circulation is anticyclonic around the ridge segment, which consists of a northward flow along the western flank and a southward flow along the eastern flank. Those flank jets are dispersal expressways for the along‐ridge larval transport and strongly affect its overall direction and spatial‐temporal variations. It is evident from model results that the transform faults bounding the ridge segment and off axis topography (the Lamont Seamount Chain) act as topographic barriers to larval dispersal in the along‐ridge direction. Furthermore, the presence of an overlapping spreading center and an adjacent local topographic high impedes the southward along‐ridge larval transport. The model results suggest that larval recolonization within ridge‐crest habitats is enhanced by the anticyclonic circulation around the ridge segment, and the overall recolonization rate is higher for larvae having a short precompetency period and an altitude above the bottom sufficient to avoid influence by the near‐bottom currents Surprisingly, for larvae having a long precompetency period (>10 days), the prolonged travel time allowed some of those larvae to return to their natal vent clusters, which results in an unexpected increase in connectivity among natal and neighboring sites. Overall, model‐based predictions of connectivity are highly sensitive to the larval precompetency period and vertical position in the water column. Plain Language Summary: In this study, we use state‐of‐the‐art computer simulations to investigate how ocean currents transport larvae of animals living in hydrothermal vent fields on the crest of the East Pacific Rise ridge located at over 2,000 m below the surface of the Northeast Pacific. Our study provides an in‐depth look into how currents, seafloor topography, and physiological traits of larvae influence the biological connectivity among different habitats on a segment of the East Pacific Rise. Our simulations suggest that ocean currents form a clockwise circulation around the ridge segment, which consists of a northward flow along the western flank and a southward flow along the eastern flank. Those flows, which we call flank jets, are expressways for larval transport along the ridge and largely control the overall direction of that transport. Our simulations also suggest that large faults at the ends of the ridge segments disrupt the movement of larvae along the ridge and reduce their chance of reaching habitats located on adjacent segments. On the other hand, the presence of the clockwise circulation enhances larval connectivity among habitats within the same segment, especially for larvae that mature quickly and spend their lifetime at higher altitudes above the seafloor. Key Points: Anticyclonically sheared flank jets strongly affect the patterns of larval dispersal at the EPR 9–10°N segmentThe effect of larval precompetency period on connectivity depends on the spacing of vent fields and advection in flank jetsTransform faults and other topographic features on or near the ridge segment act as barriers to the along‐ridge larval dispersal [ABSTRACT FROM AUTHOR] |
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