Abstract
The genus Oxyrrhis is a heterotrophic dinoflagellate found in diverse marine environments. Oxyrrhis spp. have received attention owing to their ecological and industrial importance, high lipid contents, and docosahexaenoic acid formation. To the best of our knowledge, contrary to O. marina, ecophysiological characterization studies on O. maritima have not yet been reported. Therefore, we investigated the taxonomy and ecophysiology of four strains of O. marina from coastal waters and two strains of O. maritima from the littoral tidepool waters of Korea. Based on phylogenetic trees constructed using internal transcribed spacer ribosomal DNA (ITS rDNA) and SSU rDNA of dinoflagellates, the clade of all four O. marina strains was divergent from that of the two O. maritima strains. We measured the growth rates of both species at various water temperatures (10–36 °C), salinities (5–90), and light intensities (0–100 µE·m−2·s−1). The lowest (O. marina and O. maritima: 10 °C) and highest temperatures (O. marina: <35 °C, O. maritima: >35 °C) revealed that O. maritima has more tolerance to high salinity. This study provides a basis for understanding the ecophysiology of O. marina and O. maritima and their population dynamics in marine ecosystems.
Highlights
We focused on Heterotrophic dinoflagellates (HTDs) Oxyrrhis marina (O. marina) and Oxyrrhis maritima (O. maritima)
The ratio of the cell length to width of living cells starved for 5 d was larger than that of cells fed with P. minimum
We established four different strains of O. marina isolated from the coastal waters off GS, MS, SH, and KRR, Korea, and two strains of O. maritima isolated from littoral tide pool waters in Jeju Island, Korea, and confirmed that O. maritima from JJ and HD were highly divergent from O. marina
Summary
Academic Editors: Zita Gasiunaite, Piotr Margonski and Javier Gilabert. Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Heterotrophic dinoflagellates (HTDs) are of great importance in the marine food web because they coexist as predators and prey for other species [1]. We focused on HTDs Oxyrrhis marina (O. marina) and Oxyrrhis maritima (O. maritima). There are advantages to using Oxyrrhis as a model for other HTD natural samples, to identify and manipulate in experiments, and to study the model of evolution and exploitation of this species. Free-living, and ecologically important HTD [2,3,4,5]
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