QUANTITATIVE REAL‐TIME POLYMERASE CHAIN REACTION FOR COCHLODINIUM FULVESCENS (DINOPHYCEAE), A HARMFUL DINOFLAGELLATE FROM CALIFORNIA COASTAL WATERS¹

Abstract

Harmful blooms formed by species of the dinoflagellate Cochlodinium have caused massive fish kills and substantial economic losses in the Pacific Ocean. Recently, prominent blooms of Cochlodinium have occurred in central and southern California (2004-2008), and Cochlodinium cells are now routinely observed in microscopical analysis of algal assemblages from Californian coastal waters. The first documented economic loss due to a Cochlodinium bloom in California occurred in Monterey Bay and resulted in the mortality of commercially farmed abalone. Increasing occurrences of Cochlodinium blooms, the fact that these cells preserve poorly using standard techniques, and the difficulty of identifying preserved specimens using morphological criteria make Cochlodinium species prime candidates for the development of a quantitative real-time polymerase chain reaction (qPCR) approach. The 18S rDNA gene sequenced from Cochlodinium cells obtained from California coastal waters, as well as GenBank sequences of Cochlodinium, were used to design and test a Molecular Beacon(®) approach. The qPCR method developed in this study is species specific, sensitive for the detection of C. fulvescens that has given rise to the recent blooms in the eastern Pacific Ocean, and spans a dynamic abundance range of seven orders of magnitude. Initial application of the method to archived field samples collected during blooms in Monterey Bay revealed no statistically significant correlations between gene copy number and environmental parameters. However, the onset of Cochlodinium blooms in central California was consistent with previously reported findings of correlations to decreased surface temperature and increased inputs of nitrogenous nutrients.

Harmful algal blooms along the North American west coast region: History, trends, causes, and impacts

“…Genetic characterization confirmed the presence of C. fulvescens in southern and central CA during this period (Howard et al, 2012). Since the 2004-2005 bloom event, Cochlodinium has emerged as a common bloom-forming organism along the CA coastline (Curtiss et al, 2008;Jester et al, 2009;Kudela et al, 2010;Howard et al, 2012;Kudela and Gobler, 2012;CDPH data). Based on nutrient uptake kinetic analyses conducted on samples from a 2006 Monterey Bay Cochlodinium bloom, Kudela et al (2008b) estimated that from 55% (August) to 62% (September) of N uptake was derived from urea, suggesting a role of cultural eutrophication in the recent increase in bloom prevalence.…”

“…More recently, a bloom of Cochlodinium (species not determined, but possibly C. fulvescens, see Iwataki et al, 2008) that extended over 800 km of CA coastline was linked to a 2004-2005 California mussel mortality event in Monterey Bay (Curtiss et al, 2008). Genetic characterization confirmed the presence of C. fulvescens in southern and central CA during this period (Howard et al, 2012). Since the 2004-2005 bloom event, Cochlodinium has emerged as a common bloom-forming organism along the CA coastline (Curtiss et al, 2008;Jester et al, 2009;Kudela et al, 2010;Howard et al, 2012;Kudela and Gobler, 2012;CDPH data).…”

Occurrence of Cochlodinium fulvescens (Gymnodiniales: Dinophyceae) in the southwestern Gulf of California

“…Munir et al (2012), with low densities of C. fulvescens at < 26°C and high densities at 31-32°C. Kudela & Gobler (2012) and Howard et al (2012) state that cells of C. fulvescens are present at low temperatures (14-18°C). Comparing salinity, C. fulvescens was common at 35.…”

Molecular characterization and morphology of Cochlodinium strangulatum , the type species of Cochlodinium , and Margalefidinium gen. nov. for C. polykrikoides and allied species (Gymnodiniales, Dinophyceae)

“…Kofoid and Swezy (1921) reported Margalefidinium citron as a common species from off La Jolla, California. This species name has disappeared from the literature, while currently Margalefidinium fulvescens is a blooming species in Californian waters (Howard et al, 2012; Gárate-Lizárraga, 2014). …”