Abstract

Highly advective upwelling systems along the western margins of continents are widely believed to transport larvae far offshore in surface currents resulting in larval wastage, limited recruitment, and increased population connectivity. However, suites of larval behaviors effectively mediate interspecific differences in the extent of cross-shelf migrations between nearshore adult habitats and offshore larval habitats. Interspecific differences in behavior determining whether larvae complete development in estuaries or migrate to the continental shelf are evident in large estuaries, but they sometimes may be disrupted by turbulent tidal flow or the absence of a low-salinity cue in shallow, low-flow estuaries, which are widespread in upwelling systems. Larvae of most species on the continental shelf complete development in the coastal boundary layer of reduced flow, whereas other species migrate to the mid- or outer shelf depending on how much time is spent in surface currents. These migrations are maintained across latitudinal differences in the strength and persistence of upwelling, in upwelling jets at headlands, over upwelling-relaxation cycles, and among years of varying upwelling intensity. Incorporating larval behaviors into numerical models demonstrates that larvae recruit closer to home and in higher numbers than when larvae disperse passively or remain in surface currents.

Highlights

  • Eastern boundary upwelling systems have been studied intensively, because they are one of the most productive marine ecosystems producing ∼20% of the fish catch from less than 1% of the global ocean [1]

  • Larval transport may be affected by differences in the strength of prevailing winds, which are highly dynamic in space and time

  • The extent of larval transport is largely determined by the vertical distributions of larvae in flow [11, 12]

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Summary

Introduction

Eastern boundary upwelling systems have been studied intensively, because they are one of the most productive marine ecosystems producing ∼20% of the fish catch from less than 1% of the global ocean [1]. Surveys of the vertical distributions of progressively later larval stages over diel and tidal cycles coupled with concurrent profiles of current velocity and water column structure indicate how vertical swimming behavior may mediate crossshore distributions. Complementary approaches, such as numerical oceanographic models, are needed to determine. I briefly review similarities and differences in the characteristics of the three upwelling systems where larval surveys of nearshore benthic species have been conducted: CCS, HCS, and ICS With this background, I briefly characterize circulation in each upwelling system before reviewing the evidence for the behavioral mediation of larval transport by nearshore benthic species. I conclude by highlighting future directions for investigating larval transport in upwelling systems in an era of climate change

Behavioral Mediation of Larval Transport
California Current System
Behavioral Mediation of Larval Transport on the Shelf
30 Surface
Humboldt Current System
Iberia Current System
Larval Behavior Mediates Transport in Upwelling Regimes Worldwide
Findings
Future Directions
Full Text
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