Two New and Nontoxigenic Pseudo‐nitzschia species (Bacillariophyceae) from Chinese Southeast Coastal Waters

Domoic acid (DA) is produced by almost half of the species belonging to the diatom genus Pseudo-nitzschia and causes amnesic shellfish poisoning (ASP). It is, therefore, important to investigate the diversity and toxin production of Pseudo-nitzschia species for ASP risk assessments. Between 2018 and 2020, seawater samples were collected from various sites around Aotearoa New Zealand, and 130 clonal isolates of Pseudo-nitzschia were established. Molecular phylogenetic analysis of partial large subunit ribosomal DNA and/or internal transcribed spacer regions revealed that the isolates were divided into 14 species (Pseudo-nitzschia americana, Pseudo-nitzschia arenysensis, Pseudo-nitzschia australis, Pseudo-nitzschia calliantha, Pseudo-nitzschia cuspidata, Pseudo-nitzschia delicatissima, Pseudo-nitzschia fraudulenta, Pseudo-nitzschia galaxiae, Pseudo-nitzschia hasleana, Pseudo-nitzschia multiseries, Pseudo-nitzschia multistriata, Pseudo-nitzschia plurisecta, Pseudo-nitzschia pungens, and Pseudo-nitzschia cf. subpacifica). The P. delicatissima and P. hasleana strains were further divided into two clades/subclades (I and II). Liquid chromatography-tandem mass spectrometry was used to assess the production of DA and DA isomers by 73 representative strains. The analyses revealed that two (P. australis and P. multiseries) of the 14 species produced DA as a primary analogue, along with several DA isomers. This study is the first geographical distribution record of P. arenysensis, P.cuspidata, P. galaxiae, and P. hasleana in New Zealand coastal waters.

Section: Discussionmentioning

confidence: 99%

“…heimii ] [ 10 ]. Over the last decade, 23 additional species have been described globally (12 of those being known DA producers), resulting in 58 species as of 2021 [ 13 ], with 26 of those being DA producers.…”

Section: Introductionmentioning

confidence: 99%

Update of the Planktonic Diatom Genus Pseudo-nitzschia in Aotearoa New Zealand Coastal Waters: Genetic Diversity and Toxin Production

Nishimura

Murray

Boundy

et al. 2021

“…The pennate diatoms Pseudo-nitzschia are cosmopolitan [ 1 , 2 , 3 ]. About 60 species are currently described, and some of them are considered toxic, i.e., able to produce a neurotoxin—domoic acid (DA) [ 4 , 5 ]. DA is transferred to various organisms within marine food webs when toxic Pseudo-nitzschia species are ingested by bivalves (mussels, oysters, scallops), zooplankton (copepods), or planktivorous fish [ 1 , 3 ].…”

Section: Introductionmentioning

confidence: 99%

Interactions between Filter-Feeding Bivalves and Toxic Diatoms: Influence on the Feeding Behavior of Crassostrea gigas and Pecten maximus and on Toxin Production by Pseudo-nitzschia

Sauvey

Denis

Hégaret

et al. 2021

Among Pseudo-nitzschia species, some produce the neurotoxin domoic acid (DA), a source of serious health problems for marine organisms. Filter-feeding organisms—e.g., bivalves feeding on toxigenic Pseudo-nitzschia spp.—are the main vector of DA in humans. However, little is known about the interactions between bivalves and Pseudo-nitzschia. In this study, we examined the interactions between two juvenile bivalve species—oyster (Crassostrea gigas) and scallop (Pecten maximus)—and two toxic Pseudo-nitzschia species—P. australis and P. fraudulenta. We characterized the influence of (1) diet composition and the Pseudo-nitzschia DA content on the feeding rates of oysters and scallops, and (2) the presence of bivalves on Pseudo-nitzschia toxin production. Both bivalve species fed on P. australis and P. fraudulenta. However, they preferentially filtered the non-toxic Isochrysis galbana compared to Pseudo-nitzschia. The presence of the most toxic P. australis species resulted in a decreased clearance rate in C. gigas. The two bivalve species accumulated DA in their tissues (up to 0.35 × 10−3 and 5.1 × 10−3 µg g−1 for C. gigas and P. maximus, respectively). Most importantly, the presence of bivalves induced an increase in the cellular DA contents of both Pseudo-nitzschia species (up to 58-fold in P. fraudulenta in the presence of C. gigas). This is the first evidence of DA production by Pseudo-nitzschia species stimulated in the presence of filter-feeding bivalves. The results of this study highlight complex interactions that can influence toxin production by Pseudo-nitzschia and accumulation in bivalves. These results will help to better understand the biotic factors that drive DA production by Pseudo-nitzschia and bivalve contamination during Pseudo-nitzschia blooms.

“…Marine planktonic diatoms of the genus Pseudo-nitzschia are found in polar, warm and tropical regions; most of their species are cosmopolitan [1][2][3]. Currently, 56 species [4,5] of this genus have been reported, 26 of them producing the neurotoxic compound domoic acid (DA) [6]. Examination of the morphology by optical microscopy is frequently inconclusive, and for this reason scanning and/or transmission electron microscopy is also required.…”

Section: Introductionmentioning

confidence: 99%

First Report of Domoic Acid Production from Pseudo-nitzschia multistriata in Paracas Bay (Peru)

Tenorio

Álvarez

Quijano-Scheggia

et al. 2021

The Peruvian sea is one of the most productive ecosystems in the world. Phytoplankton production provides food for fish, mammals, mollusks and birds. This trophic network is affected by the presence of toxic phytoplankton species. In July 2017, samples of phytoplankton were obtained from Paracas Bay, an important zone for scallop (Argopecten purpuratus) aquaculture in Peru. Morphological analysis revealed the presence of the genus Pseudo-nitzschia, which was isolated and cultivated in laboratory conditions. Subsequently, the monoclonal cultures were observed by scanning electron microscopy (SEM), and identified as P. multistriata, based on both the morphological characteristics, and internal transcribed spacers region (ITS2) sequence phylogenetic analysis. Toxin analysis using liquid chromatography (LC) with high-resolution mass spectrometry (HRMS) revealed the presence of domoic acid (DA) with an estimated amount of 0.004 to 0.010 pg cell−1. This is the first report of DA from the coastal waters of Peru and its detection in P. multistriata indicates that it is a potential risk. Based on our results, routine monitoring of this genus should be considered in order to ensure public health.