Ocean climate change, phytoplankton community responses, and harmful algal blooms: a formidable predictive challenge

• Published in: Journal of Phycology
• Main Author: Hallegraeff, GM
• Format: Article in Journal/Newspaper
• Language: English
• Published: Blackwell Publishing Inc 2010
• Subjects: Biological Sciences; Plant Biology; Phycology (incl. Marine Grasses); North Atlantic; North Atlantic oscillation; Ocean acidification
• Online Access: http://onlinelibrary.wiley.com/; https://doi.org/10.1111/j.1529-8817.2010.00815.x; http://ecite.utas.edu.au/67829

Prediction of the impact of global climate changeon marine HABs is fraught with difficulties. However,we can learn important lessons from the fossilrecord of dinoflagellate cysts; long-term monitoringprograms, such as the Continuous Plankton Recordersurveys; and short-term phytoplankton communityresponses to El Nino Southern Oscillation(ENSO) and North Atlantic Oscillation (NAO) episodes.Increasing temperature, enhanced surfacestratification, alteration of ocean currents, intensificationor weakening of local nutrient upwelling,stimulation of photosynthesis by elevated CO2,reduced calcification through ocean acidification(the other CO2 problem), and heavy precipitationand storm events causing changes in land runoffand micronutrient availability may all produce contradictoryspecies- or even strain-specific responses.Complex factor interactions exist, and simulatedecophysiological laboratory experiments rarely allowfor sufficient acclimation and rarely take intoaccount physiological plasticity and genetic straindiversity. We can expect: (i) range expansion ofwarm-water species at the expense of cold-water species,which are driven poleward; (ii) speciesspecificchanges in the abundance and seasonalwindow of growth of HAB taxa; (iii) earlier timing ofpeak production of some phytoplankton; and (iv)secondary effects for marine food webs, notablywhen individual zooplankton and fish grazers are differentiallyimpacted (match-mismatch) by climatechange. Some species of harmful algae (e.g., toxicdinoflagellates benefitting from land runoff and ⁄ orwater column stratification, tropical benthic dinoflagellatesresponding to increased water temperaturesand coral reef disturbance) may become more successful,while others may diminish in areas currentlyimpacted. Our limited understanding of marine ecosystemresponses to multifactorial physicochemicalclimate drivers as well as our poor knowledge of thepotential of marine microalgae to adapt geneticallyand phenotypically to the unprecedented pace ofcurrent climate change are emphasized. The greatestproblems for human society will be caused by beingunprepared for significant range expansions or theincrease of algal biotoxin problems in currentlypoorly monitored areas, thus calling for increasedvigilance in seafood-biotoxin and HAB monitoringprograms. Changes in phytoplankton communitiesprovide a sensitive early warning for climate-drivenperturbations to marine ecosystems.