Macroalgal blooms alter community structure and primary productivity in marine ecosystems

Abstract

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.

World’s Largest Macroalgal Blooms Altered Phytoplankton Biomass in Summer in the Yellow Sea: Satellite Observations

“…Macroalgal blooms (MABs), caused by the fast growth and accumulation of macroalgae, have increased remarkably in the global oceans in recent years [1], and thus it is pressing to understand the ecological consequences of these blooms [2]. Since 2008, the world's largest MABs of Ulva prolifera (also called green tides) have occurred every summer in the Yellow Sea [3][4][5][6] (Figure 1).…”

A reconstruction of the palaeoecology and environmental dynamics of the Bahariya Formation of Egypt

“…While the exact effects vary depending on the taxa in question (Lyons et al 2014); in general such blooms initially boost productivity, but lead to a decline in species richness in the long term (Dolbeth et al 2003;Worm & Lotze, 2006;Lyons et al 2014). This suggests that Bahariyan ecological stability would have begun to fail towards the Cenomanian/Turonian boundary as a result of nutrient overloading and the subsequent over-productivity of plankton & aerobic bacteria.…”

What evidence exists on the local impacts of energy systems on marine ecosystem services: a systematic map

“…The initial list of search terms for the outcome variable built on those from Rilov et al [17] and Lyons et al [18] given that the focus of these systematic reviews were to investigate impacts on the wide array of marine organisms and ecosystem processes that concerned the current study. These search term strings were then further developed by combining them with lists of the specific intervention (i.e.…”