Application of a Quantitative PCR to Investigate the Distribution and Dynamics of Two Morphologically Similar Species, Karenia mikimotoi and K. papilionacea (Dinophyceae) in Korean Coastal Waters

Abstract

Species of the marine dinoflagellate genus Karenia are known to produce various potent biotoxins and can form noxious blooms that cause mass mortalities of fish and shellfish. To date, harmful blooms of the species K. mikimotoi have been reported in Korea, but K. papilionacea was recently recorded off the southern coast of Korea. Here, we developed a quantitative real-time PCR (qRT-PCR) assay with specific primer pairs for the accurate detection and quantification of these two similar-looking unarmored species, K. mikimotoi and K. papilionacea, and investigated their distribution and dynamics in Korean coastal waters. Overall, K. papilionacea had not only a wider distribution, but also higher cell abundances (15–2553 cells L−1) than K. mikimotoi (3–122 cells L−1) in surface waters. Of 18 sampling sites, the two Karenia species were found to coexist at two sites. During monitoring at a fixed station (S5), K. papilionacea was generally predominant over K. mikimotoi; however, the two species exhibited similar dynamics and occasionally co-occurred. Both Karenia species showed similar physiological responses to temperature and salinity, requiring similar conditions for optimum growth. These results suggest that blooms of the two species may co-occur and induce a synergistic adverse effect on marine environments.

An Unprecedented Bloom of Oceanic Dinoflagellates (Karenia spp.) Inside a Fjord within a Highly Dynamic Multifrontal Ecosystem in Chilean Patagonia

“…Blooms with a mixture of several Kareniaceae are not uncommon [ 14 , 15 , 16 , 17 ] and noxious effects reported are species’ strain-dependent and may include neurotoxic shellfish poisoning (NSP or brevetoxicity), breathing difficulty by the inhalation of sea spray-borne toxins, anoxic events, and mass mortalities of marine fauna and aquaculture resources [ 13 , 18 ]. To date, the small list of unambiguously confirmed bioactive compounds of Karenia species include brevetoxins in K. brevis from Florida [ 19 ], gymnodimines from K. selliformis in New Zealand [ 20 , 21 ], brevisulcenals in K. brevisulcata [ 22 ], gymnocines in K. mikimotoi [ 23 ], polyunsaturated fatty acids (PUFAs) [ 24 ], sterols [ 25 ], and other toxins of unknown mechanisms of action [ 26 ].…”

“…Karenia species are naked dinoflagellates with high morphological variability, including small cell formation; cells become deformed and difficult to identify with light microscopy in phytoplankton samples with standard Lugol’s fixative [ 12 , 14 ]. In recent years, the application of molecular probes has revealed previous misidentifications of species morphologically similar to K. brevis , such as some Pacific phylotypes of K. papilionacea , during blooms of Karenia in New Zealand and Japan [ 15 , 29 ].…”