MEPS 529:1-16 (2015)  -  DOI: https://doi.org/10.3354/meps11272

FEATURE ARTICLE
Deep-water seed populations for red tide blooms in the Gulf of Mexico

Linda G. Waters1,2,*, Thomas G. Wolcott1, Dan Kamykowski1, Geoff Sinclair1,3

1North Carolina State University, Raleigh, NC 27695, USA
2Present address: Instituto Oceanografico, University of São Paulo, SP 05508-120, Brazil
3Present address: US Environmental Protection Agency, Crystal City, VA 22202, USA
*Corresponding author:

ABSTRACT: Populations of the toxic dinoflagellate Karenia brevis that remain near the benthos in deep shelf water in the Gulf of Mexico could be the source for toxic bloom occurrences near shore. A biophysical dynamic simulation model and migrating drifters were used to assess whether such ‘seed populations’ could persist in nature. The vertical migration responses of plankton to an exclusively benthic nutrient source and light limitation would result in near-benthic behavioral trapping of a slowly growing population in conditions found on the West Florida Shelf (WFS). The model indicated that for a 50 m deep bottom, a 2-m-thick layer of ≥2 µmol NO3/NO2 fluxing from the benthos was the minimum needed to permit growth for dark-adapted K. brevis in an oligotrophic water column. Growth rates depended more on the duration of exposure to nutrients than on concentration; a 1-m-thick nutrient layer sustained minimum growth levels independently of the nutrient distribution at depths ≤40 m. Field experiments using Autonomous Behaving Lagrangian Explorer drifters (ABLEs) that exhibited biomimetic vertical migration responses to the external environment demonstrated a benthically-oriented movement pattern in response to natural light and cues correlated with elevated near-benthic nutrients. Average measurements of nutrients and light from the bottom 2 m of the water column in a potential bloom-forming region of the WFS were higher than the model-generated requirements for growth, suggesting that coastal nutrient distributions could support a benthic population offshore. Under upwelling conditions, such populations could be advected inshore to frontal convergence zones and form toxic ‘red tide’ blooms.


KEY WORDS: Harmful algal blooms · Benthic orientation · Karenia brevis · Nutrient limitation · Biomimetic · Lagrangian drifter


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Cite this article as: Waters LG, Wolcott TG, Kamykowski D, Sinclair G (2015) Deep-water seed populations for red tide blooms in the Gulf of Mexico. Mar Ecol Prog Ser 529:1-16. https://doi.org/10.3354/meps11272

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