Linking the physiology and ecology of Cochlodinium to better understand harmful algal bloom events: A comparative approach

The red tide forming dinoflagellate genus Cochlodinium appears to be expanding globally, as well as blooming and/or causing more economic losses within its previously reported geographic distribution. Despite the widespread occurrence of this organism in the Pacific, Atlantic, and Indian oceans, relatively few studies of its ecophysiology have been conducted. Here we summarize the ecophysiological characteristics through both a literature review and by assessing recent bloom events in Monterey Bay, CA, USA. Using this comparative approach, we identify the basic characteristics of this organism: Cochlodinium is found in both warm and cool (11-30 °C) waters in the western and eastern Pacific, respectively, at moderate salinities (30-34). The production of pelagic vegetative seed banks or benthic seed beds by this organism and ability to survive ballast water transport likely facilitate its ability to colonize and establish itself in new habitats. It is a strong vertical migrator capable of utilizing both inorganic and organic nitrogen sources as well as mixotrophy and may be associated with moderate nutrient loading. These characteristics provide Cochlodinium with an adaptive capability conducive to rapid colonization of newly opened ecological niches, which may partially explain the apparent global expansion of its geographic range and bloom frequency.