Macroalgal blooms alter community structure and primary productivity in marine ecosystems

Devin A. Lyons, Christos Arvanitidis, Andrew J. Blight, Eva Chatzinikolaou, Tamar Guy-Haim, Jonne Kotta, Helen Orav-Kotta, Ana M. Queirós, Gil Rilov, Paul J. Somerfield, Tasman P. Crowe

Research output: Contribution to journalArticlepeer-review


Eutrophication, coupled with loss of herbivory due to habitat degradation and overharvesting, has increased the frequency and severity of macroalgal blooms worldwide. Macroalgal blooms interfere with human activities in coastal areas, and sometimes necessitate costly algal removal programmes. They also have many detrimental effects on marine and estuarine ecosystems, including induction of hypoxia, release of toxic hydrogen sulphide into the sediments and atmosphere, and the loss of ecologically and economically important species. However, macroalgal blooms can also increase habitat complexity, provide organisms with food and shelter, and reduce other problems associated with eutrophication. These contrasting effects make their overall ecological impacts unclear. We conducted a systematic review and meta-analysis to estimate the overall effects of macroalgal blooms on several key measures of ecosystem structure and functioning in marine ecosystems. We also evaluated some of the ecological and methodological factors that might explain the highly variable effects observed in different studies. Averaged across all studies, macroalgal blooms had negative effects on the abundance and species richness of marine organisms, but blooms by different algal taxa had different consequences, ranging from strong negative to strong positive effects. Blooms' effects on species richness also depended on the habitat where they occurred, with the strongest negative effects seen in sandy or muddy subtidal habitats and in the rocky intertidal. Invertebrate communities also appeared to be particularly sensitive to blooms, suffering reductions in their abundance, species richness, and diversity. The total net primary productivity, gross primary productivity, and respiration of benthic ecosystems were higher during macroalgal blooms, but blooms had negative effects on the productivity and respiration of other organisms. These results suggest that, in addition to their direct social and economic costs, macroalgal blooms have ecological effects that may alter their capacity to deliver important ecosystem services.

Original languageEnglish
Pages (from-to)2712-2724
Number of pages13
JournalGlobal Change Biology
Issue number9
StatePublished - Sep 2014
Externally publishedYes


  • Biodiversity
  • Ecosystem functioning
  • Green tide
  • Harmful algal bloom
  • Macroalgal bloom
  • Macroalgal mat
  • Species richness

ASJC Scopus subject areas

  • Global and Planetary Change
  • Environmental Chemistry
  • Ecology
  • Environmental Science (all)


Dive into the research topics of 'Macroalgal blooms alter community structure and primary productivity in marine ecosystems'. Together they form a unique fingerprint.

Cite this