Progress in Understanding Algal Bloom-Mediated Fish Kills: The Role of Superoxide Radicals, Phycotoxins and Fatty Acids

Dorantes-Aranda, Juan José; Seger, Andreas; Mardones, Jorge I.; Nichols, Peter D.; Hallegraeff, Gustaaf M.

doi:10.1371/journal.pone.0133549

Cited by 114 publications

(75 citation statements)

References 70 publications

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“…Comparable to these observations in the Chilean waters, only 10 cells ml −1 of P. verruculosa were enough to cause mortality of salmon in New Zealand (MacKenzie et al, 2011). There might be a few experimental conditions that can explain our findings: (1) gill cells were shortly exposed to P. verruculosa toxic compounds (1 h) compared to other studies (Dorantes-Aranda et al, 2015;Mardones et al, 2015). Mardones et al (2015) showed that some strains of the toxic dinoflagellate Alexandrium catenella were able to reduce gill cell viability down to 20% of controls at 4,000 cells ml −1 after 2 h exposure due to net K + efflux from fish gill cells (Mardones et al, 2018).…”

Section: Lytic Activity Of P Verruculosasupporting

confidence: 45%

“…Despite this, research on the toxic compounds produced by this species is incipient and has proven to be difficult. The fish cell line RTgill-W1 assay has been widely used to assess cell viability in ichthyotoxic-microalgal studies (Dorantes-Aranda et al, 2015). In this work, we experimentally demonstrated lytic activity of the Chilean P. verruculosa ARC498 strain toward the RTgill-W1 cells, although ecologically realistic P. verruculosa bloom concentrations (10,000-100,000 cells ml −1 ) exhibited only very limited loss of viability (down to max.…”

Section: Lytic Activity Of P Verruculosamentioning

confidence: 81%

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Salinity-Growth Response and Ichthyotoxic Potency of the Chilean Pseudochattonella verruculosa

et al. 2019

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Despite salmon farmers suffering the worst damage from a harmful algal bloom in Chile's history (US$800M) due to a massive outbreak of the dictyochophyte Pseudochattonella verruculosa in 2016 (∼7000-20,000 cells ml −1), the effect of environmental drivers and the potency of lytic toxins produced by the local clones of this species remain still largely unexplored. Based on the drastic oceanographic anomalies observed in the Chilean fjords during the 2016-El Niño "Godzilla" event, the role of salinity (15 to 35 psu) on Pseudochattonella cell growth and cytotoxicity was studied by culturing, scanning electron microscopy (SEM) and using a rainbow trout cell line RTgill-W1 assay to define: (1) vegetative growth rates, (2) cell taxonomy, (3) ichthyotoxicity of monoclonal cultures at 25 and 35 psu in salinity, (4) differences in toxicity of lysed cells and supernatant at different cell concentrations (from 10 to 100,000 cells ml −1), and (5) temporal stability of lytic compounds. This study formally confirms the presence of P. verruculosa in Chilean waters using the large subunit (LSU) of the nuclear ribosomal RNA gene. The Chilean P. verruculosa ARC498 strain showed maximum cell densities at 30 psu (max. 84,333 ± 4,833 cells ml −1) and maximum growth rates (µ max) at 20 psu (1.44 cells d −1). Cultures at 15 psu showed suppressed maximum cell density (max. 269 ± 71 cell ml −1) but high µ max were recorded at the beginning of the exponential growth (1.31 cells d −1). No significant differences were observed between lysed cells and supernatant treatments in the two salinity levels, suggesting that the most lytic portion is released into the cell-free media instead of remaining cell bound. Cytotoxicity was correlated to cell abundance, reducing gill cell viability down to 80 and 65% compared to controls at 10,000 and 100,000 cells ml −1 , respectively. Unexpectedly, lytic compounds from P. verruculosa ARC498 at 35 psu showed to be less toxic than cultures at 25, where a noticeable presence of peripheral mucocysts were observed by SEM. Lytic compounds from in vitro experiments are weakly toxic even at high cell concentrations, highly unstable and rapidly degraded in the light after 5 days of storage at 15 • C. Our results point to the important effect of salinity on growth and ichthyotoxic potency of Pseudochattonella species and highlight the need for a deeper insight into the role of mucocysts in fish gill damage, which would provide a greater understanding as to the harmful modes of action of this species.

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Section: Lytic Activity Of P Verruculosasupporting

confidence: 45%

Section: Lytic Activity Of P Verruculosamentioning

confidence: 81%

Salinity-Growth Response and Ichthyotoxic Potency of the Chilean Pseudochattonella verruculosa

et al. 2019

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“…, Dorantes‐Aranda et al. ); (ii) production of mucus by fish due to the presence of H. akashiwo cells; fish mucus has been shown to increase ROS production by raphidophytes in a concentration‐dependent manner that could enhance ROS‐mediated toxicity (Nakamura et al. , Kim and Oda ), and potentially explain the lesions observed on affected fish gills (Chang et al.…”

Section: Discussionmentioning

confidence: 99%

The effects of salinity on the cellular permeability and cytotoxicity of Heterosigma akashiwo

Ikeda

Cochlan

Bronicheski

et al. 2016

Journal of Phycology

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A laboratory study using the fish-killing raphidophyte Heterosigma akashiwo was conducted to examine its capability to grow at salinities below oceanic, and to test the perceived relationship between reduced salinities and increased cytotoxicity. A nonaxenic strain of H. akashiwo isolated from the U.S. Pacific Northwest was exposed to a combination of three salinity (32, 20, and 10) and five temperature (14.7°C, 18.4°C, 21.4°C, 24.4°C and 27.8°C) conditions. Our results demonstrate that cell permeability and cytotoxicity are strongly correlated in unialgal cultures of H. akashiwo, which both increased as salinity decreased from 32 to 10. Furthermore, over a broad median range of salinities (10 and 20), neither temperature nor specific growth rate was correlated with cytotoxicity. However, in cultures grown at the salinity of 32, both temperature and specific growth rate were inversely proportional to toxicity; this relationship was likely due to the effect of contamination by an unidentified species of Skeletonema in those cultures. The presence of Skeletonema sp. resulted in a cytotoxic response from H. akashiwo that was greater than the response caused by salinity alone. These laboratory results reveal the capability of H. akashiwo to become more toxic not only at reduced salinities but also in competition with another algal species. Changes in cell permeability in response to salinity may be an acclimation mechanism by which H. akashiwo is able to respond rapidly to different salinities. Furthermore, due to its strong positive correlation with cytotoxicity, cellular permeability is potentially associated with the ichthyotoxic pathway of this raphytophyte.

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“…This is in concordance with the recent findings of Dorantes‐Aranda et al . (). Other products assayed were disinfectants (i.e.…”

Section: Chemical and Physical–chemical Methodsmentioning

confidence: 97%

A critical review on control methods for harmful algal blooms

Gallardo

Astuya-Villalón

Llanos-Rivera

et al. 2018

Reviews in Aquaculture

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The impacts of harmful algal blooms on human health, tourism, fisheries and ecosystems have increased in recent decades. Eutrophication and the feared climate change are believed to further challenge authorities and those whose activity depends on coastal resources. While in most of the affected countries, regulatory steps have been taken to protect consumers of contaminated food, there has been an unequal focus on management systems. Some countries such as EEUU and Canada have focused on monitoring and prediction programs, whereas others (e.g. Korea, China) have relied on direct control of blooms in the sea. Here, we review current control methods for HABs including their fundamentals and the last scientific advances. A thorough revision of all considered approaches so far has been included. Ecological studies of the impact of the countermeasures were also considered.

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Progress in Understanding Algal Bloom-Mediated Fish Kills: The Role of Superoxide Radicals, Phycotoxins and Fatty Acids

Cited by 114 publications

References 70 publications

Salinity-Growth Response and Ichthyotoxic Potency of the Chilean Pseudochattonella verruculosa

Salinity-Growth Response and Ichthyotoxic Potency of the Chilean Pseudochattonella verruculosa

The effects of salinity on the cellular permeability and cytotoxicity of Heterosigma akashiwo

A critical review on control methods for harmful algal blooms

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