AME 74:29-41 (2015)  -  DOI:

Ability of the marine diatoms Pseudo-nitzschia multiseries and P. pungens to inhibit the growth of co-occurring phytoplankton via allelopathy

Ning Xu1,*, Ying Zhong Tang2,3,*, Junlian Qin1, Shunshan Duan1, Christopher J. Gobler2,**

1Institute of Hydrobiology, Jinan University, Guangzhou 510632, PR China
2School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, New York 11794-5000, USA
3Key Laboratory of Marine Ecology and Environmental Sciences, Institute of Oceanology, Chinese Academy of Science, Qingdao 266071, PR China
*These authors contributed equally to this work**Corresponding author:

ABSTRACT: Diatoms within the genus Pseudo-nitzschia can form near-monospecific blooms in both natural and iron-fertilized high-nutrient, low-chlorophyll (HNLC) regions and can have detrimental impacts on marine ecosystems. Here, we demonstrate the ability of P. pungens isolated from the South China Sea and 2 strains of P. multiseries isolated from the Bay of Fundy, Canada, to produce extracellular compounds capable of lysing and/or inhibiting the growth of multiple phytoplankton species. Since the allelopathic activity was found in both P. multiseries, which produces domoic acid (DA), and P. pungens, which produces little if any DA, the allelopathic effects of Pseudo-nitzschia spp. seem to be unrelated to this compound. Allelopathic inhibition of other phytoplankton was documented during exponential and stationary growth phases of Pseudo-nitzschia, and the strongest allelopathic effects were obtained from sonicated cultures, suggesting that the sudden release of allelochemicals via processes such as cell lysis or zooplankton grazing may have the strongest effect in an ecosystem setting. Differences in the responses of target species to Pseudo-nitzschia spp. suggest these algae may produce multiple compounds that vary in their allelopathic potency and composition as a function of species, strain, growth stage, and perhaps other factors. Collectively, these results suggest that the allelopathy may affect competition between Pseudo-nitzschia spp. and other phytoplankton and may play an important role in the formation and persistence of natural and iron-fertilized blooms.

KEY WORDS: Allelopathy · Pseudo-nitzschia multiseries · Pseudo-nitzschia pungens · Harmful algal bloom (HAB) · Competition · Phytoplankton

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Cite this article as: Xu N, Tang YZ, Qin J, Duan S, Gobler CJ (2015) Ability of the marine diatoms Pseudo-nitzschia multiseries and P. pungens to inhibit the growth of co-occurring phytoplankton via allelopathy. Aquat Microb Ecol 74:29-41.

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