The Future of Harmful Algal Blooms: An Empirical Approach to Predicting the Combined Impacts of Rising CO2, Temperature, and Eutrophication

EPA Grant Number: R833221
Title: The Future of Harmful Algal Blooms: An Empirical Approach to Predicting the Combined Impacts of Rising CO2, Temperature, and Eutrophication
Investigators: Hutchins, David A. , Coyne, Kathryn J. , Warner, Mark A
Institution: University of Delaware , University of Southern California
EPA Project Officer: Hiscock, Michael
Project Period: March 15, 2007 through March 14, 2010
Project Amount: $549,993
RFA: Ecology and Oceanography of Harmful Algal Blooms (2006) RFA Text |  Recipients Lists
Research Category: Aquatic Ecosystems , Ecosystems , Water


Recent worldwide increases in harmful algal blooms (HABs) are almost certainly linked to cultural eutrophication of coastal environments. Virtually no attention has been given, however, to how other major anthropogenic impacts such as rising CO2 and greenhouse warming could affect HABs. The combination of nutrient enrichment with rapidly increasing “CO2 eutrophication” and warmer water temperatures could provide ideal conditions for the growth of toxic algae over the coming decades. Preliminary data suggest that HAB species such as raphidophytes may benefit disproportionately under projected year 2100 “greenhouse ocean” conditions, relative to other algal groups such as diatoms. It is imperative that preparations begin for global change-induced increases in damaging toxic bloom events throughout the rest of this century, and beyond. Goals for this project are to evaluate the cumulative impacts of increasing CO2, temperature and nutrients on HAB raphidophytes and dinoflagellates that co-occur in the Delaware Inland Bays (DIB).


1) Rising CO2 and temperature in concert with increased eutrophication will favor the dominance of raphidophytes and dinoflagellates over competing non-harmful algal species; and 2) These effects will be manifested through changes in gene expression, cell physiology, and ecological dominance. Objectives: (i) quantitatively assess the effects of increases in CO2, temperature and nutrients on the growth rates and photosynthetic physiology of HAB species, relative to non-HAB species; (ii) evaluate differential expression of critical nutrient and CO2 -regulated genes; and (iii) carry out manipulative experiments with natural algal communities containing HAB species to determine their responses to global change.


An empirical approach will examine the genetic, physiological, and community-level responses of HAB species from the DIB to changes in CO2, temperature and nutrients. This interdisciplinary investigation will examine global change impacts on expression of carbon- and nutrient-regulated genes (PI Coyne) and cellular nutrient and photosynthetic physiology (PI Warner), as well as holistic determinations of shifts in estuarine algal community structure and HAB dynamics (PI Hutchins).

Expected Results:

This project will begin to provide definitive answers to the crucial question: How will HAB events respond to the ever-accelerating pace of anthropogenic global change? Results of this investigation will provide a broad picture of genetic to ecosystem level responses of these HAB groups to a changing world, and supply information that is urgently needed to inform managers and policy makers about future trends in HAB occurrences and impacts.

Publications and Presentations:

Publications have been submitted on this project: View all 19 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 8 journal articles for this project

Supplemental Keywords:

water, watersheds, global climate, estuary, ecological effects, cellular, population, biology, ecology, Midatlantic, Delaware, DE, ecosystem, aquatic, habitat,, RFA, Scientific Discipline, Water, Ecosystem Protection/Environmental Exposure & Risk, Oceanography, Environmental Monitoring, algal blooms, Ecological Risk Assessment, marine ecosystem, eutrophication, bloom dynamics, HAB ecology, water quality, algal bloom detection

Progress and Final Reports:

  • 2007 Progress Report
  • 2008 Progress Report
  • Final Report