MEPS 502:39-51 (2014)  -  DOI: https://doi.org/10.3354/meps10717

Onshore transport of plankton by internal tides and upwelling-relaxation events

Alan L. Shanks1,*, Steven G. Morgan2, Jamie MacMahan3, Ad J. H. M. Reniers4, Marley Jarvis1, Jenna Brown3, Atsushi Fujimura4, Chris Griesemer

1Oregon Institute of Marine Biology, University of Oregon, PO Box 5389, Charleston, Oregon 97420, USA
2Bodega Marine Laboratory, University of California Davis, 2099 Westside Dr., Bodega Bay, California 94923-0247, USA
3Department of Oceanography, Graduate School of Engineering and Applied Sciences, Naval Postgraduate School, Monterey, California 93943, USA
4Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, Florida 33149, USA
*Corresponding author:

ABSTRACT: Identifying biophysical mechanisms of larval transport is essential to understanding the delivery of larvae to adult habitats. In addition, harmful algal blooms (HABs) can be transported onshore from populations that form offshore. In summer 2011, we measured sea surface and bottom temperatures and daily phytoplankton abundance and intertidal cyprid (barnacle post larvae) settlement at Carmel River State Beach, California, USA. Using time-series analysis, we compared the abundance of Pseudo-nitzschia spp. and daily cyprid settlement to physical forcing mechanisms (e.g. internal tides and upwelling-relaxation events) that could generate onshore delivery. Minimum bottom water temperature was significantly cross-correlated with the spring-neap tidal cycle; minimum temperatures occurred between neap and spring tides, and maximum temperatures were recorded around neap tides. When the temperature data were transformed to remove the relationship between tides and temperature, we found significantly higher maximum sea surface temperatures during upwelling-relaxation events. We observed 4 pulses in Pseudo-nitzschia spp. abundance. Pseudo-nitzschia spp. chains were longest at the start of pulses and then decreased, suggesting that they had been transported to shore from a more productive site offshore, likely the upwelling front. Pulses occurred during periods of maximum sea surface temperature associated with upwelling-relaxation events. In contrast, cyprid settlement was significantly cross-correlated with the spring-neap tidal cycle, with settlement peaks occurring during fortnightly periods of cold bottom temperatures; onshore transport of cyprids appears to have been due to the internal tides.


KEY WORDS: Internal waves · Recruitment · Harmful algal bloom · HAB · Pseudo-nitzschia · Cyprid · Settlement


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Cite this article as: Shanks AL, Morgan SG, Macmahan J, Reniers AJHM and others (2014) Onshore transport of plankton by internal tides and upwelling-relaxation events. Mar Ecol Prog Ser 502:39-51. https://doi.org/10.3354/meps10717

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