First description of the environmental niche of the epibenthic dinoflagellate species Coolia palmyrensis, C. malayensis, and C. tropicalis (Dinophyceae) from Eastern Australia

Abstract

Environmental variables such as temperature, salinity, and irradiance are significant drivers of microalgal growth and distribution. Therefore, understanding how these variables influence fitness of potentially toxic microalgal species is particularly important. In this study, strains of the potentially harmful epibenthic dinoflagellate species Coolia palmyrensis, C. malayensis, and C. tropicalis were isolated from coastal shallow water habitats on the east coast of Australia and identified using the D1‐D3 region of the large subunit (LSU) ribosomal DNA (rDNA). To determine the environmental niche of each taxon, growth was measured across a gradient of temperature (15–30°C), salinity (20–38), and irradiance (10–200 μmol photons · m−2 · s−1). Specific growth rates of Coolia tropicalis were highest under warm temperatures (27°C), low salinities (ca. 23), and intermediate irradiance levels (150 μmol photons · m−2 · s−1), while C. malayensis showed the highest growth at moderate temperatures (24°C) and irradiance levels (150 μmol photons · m−2 · s−1) and growth rates were consistent across the range of salinity levels tested (20–38). Coolia palmyrensis had the highest growth rate of all species tested and favored moderate temperatures (24°C), oceanic salinity (35), and high irradiance (>200 μmol photons · m−2 · s−1). This is the first study to characterize the environmental niche of species from the benthic harmful algal bloom genus Coolia and provides important information to help define species distributions and inform risk management.

Diversity and Toxicity of the Genus Coolia Meunier in Brazil, and Detection of 44-methyl Gambierone in Coolia tropicalis

“…The other three species, C. canariensis [28], C. santacroce and C. palmyrensis (present study), were found exclusively in offshore sites: Trindade Island for C. canariensis, Abrolhos Archipelago for C. santacroce and C. palmyrensis, and an offshore diving site in Pernambuco State for C. palmyrensis. Similar patterns of species distribution have been observed in Australia [22] and in the Iberian Peninsula [24], with C. malayensis more broadly distributed, C. tropicalis restricted to warmer waters, and C. palmyrensis present in offshore sites. Coolia santacroce, in turn, had only been recorded, so far, in the Caribbean Sea (GenBank sequences).…”

“…Thus, a general pattern of Coolia spp. distribution seems to arise from this and previous studies: C. malayensis is globally distributed (see [14]); C. monotis is probably broadly distributed in coastal waters of Europe and the East Atlantic [24]; while distributions of C. tropicalis, C. canariensis, C. santacroce and C. palmyrensis are more restricted, mainly to warmer waters and/or to offshore sites with lower hydrodynamics (present study, [22]).…”

“…The most widely distributed species within the genus is C. malayensis, found in every ocean on both tropical and temperate zones [14,21,22]. Other species like C. tropicalis, C. canariensis and C. palmyrensis are present in both Atlantic and Pacific oceans, but they are likely restricted to tropical areas [19,[22][23][24]. The reported geographical distribution of the remaining species is much more limited.…”

Benthic dinoflagellates in Korean waters

“…For example, Coolia tropicalis has been found only in tropical waters of Malaysia to date (Leaw et al 2016). However, the C. tropicalis UTSHI1D5 strain isolated from Australia can survive in temperatures as low as 10°C (Table 8) (Larsson et al 2019). From 1984 to 2013, the average SST in the South Sea of Korea in February and December was more than 10°C and as high as 19°C around Jeju Island (Kwak et al 2015).…”

“…Therefore, the occurrence of benthic dinoflagellates is a critical concern for scientists, government officers, and people in the aquaculture, dining, and tourism industries. Many benthic dinoflagellate species are distributed in tropical or subtropical waters, and fewer species occur in temperate waters (Besada et al 1982, Tindall and Morton 1998, Zingone et al 2006, Fraga et al 2008, Hallegraeff 2010, Leaw et al 2010, Glibert et al 2012, Parsons et al 2012, Larsson et al 2019, Pavaux et al 2020. However, the distribution of some benthic dinoflagellates living in tropic or subtropic waters has expanded into temperate waters owing to the elevated wa- Pavaux et al 2020.…”