Toxicity and nutritional inadequacy of Karenia brevis: synergistic mechanisms disrupt top-down grazer control

Abstract

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 444:15-30 (2012) - DOI: https://doi.org/10.3354/meps09401 Toxicity and nutritional inadequacy of Karenia ­brevis: synergistic mechanisms disrupt top-down grazer control Rebecca J. Waggett1,2,*, D. Ransom Hardison1, Patricia A. Tester1 1National Ocean Service, National Oceanic and Atmospheric Administration, 101 Pivers Island Road, Beaufort, North Carolina 28516-9722, USA 2Present address: The University of Tampa, 401 W. Kennedy Blvd., Tampa, Florida 33606, USA *Email: rwaggett@ut.edu ABSTRACT: Zooplankton grazers are capable of influencing food-web dynamics by exerting top-down control over phytoplankton prey populations. Certain toxic or unpalatable algal species have evolved mechanisms to disrupt grazer control, thereby facilitating the formation of massive, monospecific blooms. The harmful algal bloom (HAB)-forming dinoflagellate Karenia brevis has been associated with lethal and sublethal effects on zooplankton that may offer both direct and indirect support of bloom formation and maintenance. Reductions in copepod grazing on K. brevis have been attributed to acute physiological incapacitation and nutritional inadequacy. To evaluate the potential toxicity or nutritional inadequacy of K. brevis, food removal and egg production experiments were conducted using the copepod Acartia tonsa and K. brevis strains CCMP 2228, Wilson, and SP-1, characterized using liquid chromatography-mass spectrometry (LC-MS) as having high, low, and no brevetoxin levels, respectively. Variable grazing rates were found in experiments involving mixtures of toxic CCMP 2228 and Wilson strains. However, in experiments with toxic CCMP 2228 and non-toxic SP-1 strains, A. tonsa grazed SP-1 at significantly higher rates than the toxic alternative. Additionally, A. tonsa experienced significantly greater mortality when exposed to toxic K. brevis strains, particularly after prolonged exposure. Egg production rates of copepods fed toxic K. brevis strains were similar to those of starved copepods, while those of copepods fed non-toxic SP-1 and the nutritious Rhodomonas salina were significantly higher. Analysis indicates that K. brevis impacts grazer populations via multiple synergistic mechanisms: (1) decreased ingestion rates, (2) decreased egg production, and (3) increased mortality of copepods through a combination of toxicity and nutritional inadequacy. KEY WORDS: Copepod grazing · Harmful algae · Toxic dinoflagellate · Chemical deterrent · Karenia brevis · Brevetoxin Full text in pdf format PreviousNextCite this article as: Waggett RJ, Hardison DR, Tester PA (2012) Toxicity and nutritional inadequacy of Karenia ­brevis: synergistic mechanisms disrupt top-down grazer control. Mar Ecol Prog Ser 444:15-30. https://doi.org/10.3354/meps09401 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 444. Online publication date: January 10, 2012 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2012 Inter-Research.