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Morphology, phylogeny, dynamics, and ichthyotoxicity of P heopolykrikos hartmannii ( D inophyceae) isolates and blooms from N ew Y ork, USA
Author(s) -
Tang Ying Zhong,
Harke Matthew J.,
Gobler Christopher J.
Publication year - 2013
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1111/jpy.12114
Subject(s) - biology , dinoflagellate , phylogenetics , phylogenetic tree , clade , sister group , botany , genetics , gene
We report on morphological observations, phylogenetic analyses, bloom dynamics, and ichthyotoxicity of the common but poorly characterized dinoflagellate P heopolykrikos hartmannii ( Z immermann) Matsuoka et Fukuyo. From 2008 to 2010 in the F orge R iver E stuary, NY , USA , P . hartmannii bloomed during summer and early fall, achieving densities exceeding 8,000 cells · mL −1 and often dominating microphytoplankton communities. Large subunit ( LSU ) and small subunit ( SSU ) rDNA sequences demonstrated that NY isolates of P . hartmannii sequences were 99%–100% identical to P . hartmannii isolates from eastern US and K orea. In both the LSU and SSU rDNA phylogenies, the clades containing P . hartmannii sequences were distinct sister clades to those composed of P olykrikos schwartzii and P . kofoidii . In the LSU rDNA phylogeny, however, the clade composed of P . hartmannii and a sequence of the photosynthetic P olykrikos lebourae was well separated from the clade composed of 10 entries of P olykrikos schwartzii and P . kofoidii . In addition, a gap of ~180 bases was observed when the LSU rDNA sequences of P . hartmannii were aligned with P . schwartzii and P . kofoidii but was not observed in the alignment between P . hartmannii and P . lebourae . Using scanning electron microscopy, several morphological features previously not reported for P . hartmannii were observed: a ventral groove located in the sulcus, a deep arc‐like apical concavity within the area of apical groove, scale‐like vesicles, and a shallow, completely enclosed, loop‐like apical groove. Resting cysts with arrow‐like surface spines were produced heterothallically by crossing clonal isolates and germinated single gymnoid cells. Finally, filtered and unfiltered bloom water from the F orge R iver and clonal cultures of P . hartmannii exhibited acute ichthyotoxicity to juvenile sheepshead minnows ( C yprinodon variegates ) and aeration did not mitigate this effect, suggesting P . hartmannii is an ichthyotoxic, harmful alga.