Toxicity and growth characteristics of epiphytic dinoflagellate Gambierdiscus silvae in Japan

Hiroshi Funaki; Tomohiro Nishimura; Takuya Yoshioka; Taichi Ataka; Yuta Tanii; Kana Hashimoto; Haruo Yamaguchi; Masao Adachi

doi:10.1016/j.hal.2022.102230

Toxicity and growth characteristics of epiphytic dinoflagellate Gambierdiscus silvae in Japan

Harmful Algae. 2022 Jun:115:102230. doi: 10.1016/j.hal.2022.102230. Epub 2022 Apr 5.

Authors

Hiroshi Funaki¹, Tomohiro Nishimura², Takuya Yoshioka³, Taichi Ataka⁴, Yuta Tanii⁵, Kana Hashimoto⁶, Haruo Yamaguchi⁷, Masao Adachi⁸

Affiliations

¹ Laboratory of Aquatic Environmental Science (LAQUES), Faculty of Agriculture and Marine Science, Kochi University, 200 Otsu, Monobe, Nankoku, Kochi 783-8502, Japan; The United Graduate School of Agricultural Sciences, Ehime University, 3-5-7 Tarumi, Matsuyama, Ehime 790-8566, Japan. Electronic address: hiroshifunakisci@gmail.com.
² Laboratory of Aquatic Environmental Science (LAQUES), Faculty of Agriculture and Marine Science, Kochi University, 200 Otsu, Monobe, Nankoku, Kochi 783-8502, Japan. Electronic address: aquariumuirauqa@gmail.com.
³ Laboratory of Aquatic Environmental Science (LAQUES), Faculty of Agriculture and Marine Science, Kochi University, 200 Otsu, Monobe, Nankoku, Kochi 783-8502, Japan. Electronic address: taku94104@gmail.com.
⁴ Laboratory of Aquatic Environmental Science (LAQUES), Faculty of Agriculture and Marine Science, Kochi University, 200 Otsu, Monobe, Nankoku, Kochi 783-8502, Japan. Electronic address: taichi.ataka@gmail.com.
⁵ Laboratory of Aquatic Environmental Science (LAQUES), Faculty of Agriculture and Marine Science, Kochi University, 200 Otsu, Monobe, Nankoku, Kochi 783-8502, Japan. Electronic address: taniiyuta0123@icloud.com.
⁶ Laboratory of Aquatic Environmental Science (LAQUES), Faculty of Agriculture and Marine Science, Kochi University, 200 Otsu, Monobe, Nankoku, Kochi 783-8502, Japan. Electronic address: kana062441@gmail.com.
⁷ Laboratory of Aquatic Environmental Science (LAQUES), Faculty of Agriculture and Marine Science, Kochi University, 200 Otsu, Monobe, Nankoku, Kochi 783-8502, Japan; The United Graduate School of Agricultural Sciences, Ehime University, 3-5-7 Tarumi, Matsuyama, Ehime 790-8566, Japan. Electronic address: yharuo@kochi-u.ac.jp.
⁸ Laboratory of Aquatic Environmental Science (LAQUES), Faculty of Agriculture and Marine Science, Kochi University, 200 Otsu, Monobe, Nankoku, Kochi 783-8502, Japan; The United Graduate School of Agricultural Sciences, Ehime University, 3-5-7 Tarumi, Matsuyama, Ehime 790-8566, Japan. Electronic address: madachi@kochi-u.ac.jp.

PMID: 35623687
DOI: 10.1016/j.hal.2022.102230

Abstract

The genus Gambierdiscus is a marine benthic/epiphytic dinoflagellate that has been investigated worldwide as the causative agent of ciguatera poisoning (CP). In Japan, CP occurs mainly in the subtropical region and sporadically in the temperate region. To understand the mechanism of CP outbreaks in the coastal regions, identifying the species of Gambierdiscus occurring in the regions and determining their toxicity and growth characteristics, such as growth responses to temperature, salinity, and light intensity, are important. Recently, the occurrence of G. silvae in the Japanese temperate and subtropical regions has been revealed through metabarcoding. However, the toxicity and growth characteristics of G. silvae have not yet been investigated. In this study, three strains of Gambierdiscus were isolated from a depth of 30 m in subtropical waters in Japan and were identified as Gambierdiscus silvae based on morphological characteristics and phylogenetic positions. A dichloromethane soluble fraction (DSF) and aqueous methanol soluble fraction (MSF) of the three strains showed high mouse toxicity by intraperitoneal injection, but only the DSF of the three strains showed toxicity by gavage. All strains grew in the range of 17.5-30 °C and salinity range of 25-40, and grew well at 25 °C and salinity 30. The optimal light intensity for growth of the strains was 42.0-83.0 μmol photons/m²/s. These results suggest that G. silvae has the potential to be widely distributed from temperate to subtropical/ regions and in shallow to deep coastal waters of Japan. Understanding the growth characteristics of this species would be useful in predicting the occurrence of this species in Japanese coastal waters. Finally, the results obtained in this study suggest that G. silvae showing high toxicity is one of the causative agents of CP in Japan, and knowledge of this species would be useful in understanding the mechanism of CP outbreaks in Japan.

Keywords: Ciguatera poisoning; Gambierdiscus silvae; Light intensity; Mouse bioassay; Salinity; Temperature.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Ciguatera Poisoning*
Dinoflagellida* / physiology
Japan
Mice
Phylogeny