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

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 Pseudonitzschia, 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 Resale or republication not permitted without written consent of the publisher

Complete sequence and analysis of plastid genomes of Pseudo-nitzschia multiseries (Bacillariophyta)

“…Pseudo nitzschia multiseries can form blooms in coastal and ocean, which have harmful impact on marine ecosystems (Xu et al, 2015). Meanwhile, the neurotoxin was produced by this species can cause amnesic shellfish poisoning in both marine mammals and human beings (Dortch et al, 1997).…”

“…In the past several years, numerous data for plastid genomic sequences in algae have been reported and being applied in the phylogeny genome (Maul et al, 2002;Oudot-Le Secq et al, 2007;Wand et al, 2013) due to the slow evolutionary rate and independent genetic mechanism of plastid (Bock & Knoop, 2012). Up to date, the research of P. multiseries mainly focus on the mechanism of blooming and toxic produce (Xu et al, 2015), there is still lack the plastid genome of P. multiseries. To gain further insight into its gene content, structure and evolutionary relationships, the whole plastid genome of P. multiseries was obtained.…”

Diatom blooms and primary production in a channel ecosystem of central Patagonia

“…In a highly mixed and disturbed environment, enhanced competitive ability for resources is probably the main factor favouring the dominance of certain species. However it is interesting to note that field and laboratory experiments have shown that Skeletonema and Pseudo-nitzschia species can release allelophatic compounds (e.g., Lundholm et al, 2005;Yamasaki et al, 2010;Xu et al, 2015) that could also be a factor in promoting mono-specific blooms in the channel.…”

Potential mechanisms of coexistence between two globally important Pseudo-nitzschia (Bacillariophyta) species

“…Even though domoic acidan N-based toxin known to be excreted by Pseudonitzschia spp.-has been reported not to present allelopathic effects (Lundholm et al, 2005), there are indications of allelopathy due to other toxins excreted by Pseudo-nitzschia spp. (Xu et al, 2015).…”