Bacterial community dynamics during a harmful algal bloom of Heterosigma akashiwo

Abstract

Phytoplankton bloom events result in distinct changes in the composition and availability of nutrients as well as physical conditions within aquatic ecosystems, resulting in significant effects on bacterial communities. Using a metabarcoding approach, this study investigated the effect of a harmful algal bloom (HAB) of Heterosigma akashiwo in the Sundays Estuary, South Africa, on bacterial community structures in this estuarine ecosystem over an entire bloom event. The occurrence of bacterial lineages occurring in both the oxygen-rich surface water and hypoxic bottom waters in this study reflects the respiratory flexibility and potential for both aerobic and anaerobic metabolism across a wide range of bacterial phylogenetic lineages. A close correlation between the bacterial community profiles and the physiological state of the bloom was observed, with Flavobacteria found in increased relative abundances during the H. akashiwo HAB. Flavobacteria are commonly reported in the literature associated with algal blooms, which is indicative of their central role in the degradation of algal-derived organic matter. Halieaceae were prevalent during the bloom, whilst Synechococcales, Cryomorphaceae and Sporichthyaceae were found to be positively correlated with the decay of the H. akashiwo bloom. Rhodobacteraceae correlated significantly with the H. akashiwo bloom; however, unlike the Rhodobacteraceae specific bloom-associated genera reported in literature (predominantly Roseobacter), up to 74% of the Rhodobacteraceae sequence reads in this study were assigned to the genus Litorimicrobium. The distinct bacterial community profiles recorded throughout the H. akashiwo HAB can be attributed to the influence of the bloom-forming species as well as under-representation of estuarine-occurring HABs in the literature.

Substantial microbial community shifts in response to an exceptional harmful algal bloom in coastal Southern California

“…Previous work has identified consistent taxonomic shifts in portions of the heterotrophic community in response to 'typical' sized blooms (Teeling et al, 2016;Wilson et al, 2021) and succession in the bacterial community has been observed following a HAB of Heterosigma akashiwo (Matcher et al, 2021). In particular, members of Flavobacteriales (Kirchman, 2002;Avci et al, 2020;Ferrer-Gonzalez et al, 2020;Matcher et al, 2021;Wilson et al, 2021) and Rhodobacterales Buchan et al, 2014) have both been shown to increase in response to phytoplankton-derived polysaccharides from variously sized blooms. A majority of work analyzing microbial responses to phytoplankton blooms, however, are either based on time series with 'typical' seasonal and small non-seasonal blooms (Wear et al, 2015;Teeling et al, 2016;Wilson et al, 2021) or based on opportunistic encounters with large-scale harmful blooms (Matcher et al, 2021), which makes comparing the magnitude of change in microbial taxonomy and function to HABs difficult.…”

“…These bacteria, archaea, and heterotrophic eukaryotes are particularly important for remineralizing bloom-derived organic matter (Buchan et al, 2014). Previous work has identified consistent taxonomic shifts in portions of the heterotrophic community in response to 'typical' sized blooms (Teeling et al, 2016;Wilson et al, 2021) and succession in the bacterial community has been observed following a HAB of Heterosigma akashiwo (Matcher et al, 2021). In particular, members of Flavobacteriales (Kirchman, 2002;Avci et al, 2020;Ferrer-Gonzalez et al, 2020;Matcher et al, 2021;Wilson et al, 2021) and Rhodobacterales Buchan et al, 2014) have both been shown to increase in response to phytoplankton-derived polysaccharides from variously sized blooms.…”

“…In particular, members of Flavobacteriales (Kirchman, 2002;Avci et al, 2020;Ferrer-Gonzalez et al, 2020;Matcher et al, 2021;Wilson et al, 2021) and Rhodobacterales Buchan et al, 2014) have both been shown to increase in response to phytoplankton-derived polysaccharides from variously sized blooms. A majority of work analyzing microbial responses to phytoplankton blooms, however, are either based on time series with 'typical' seasonal and small non-seasonal blooms (Wear et al, 2015;Teeling et al, 2016;Wilson et al, 2021) or based on opportunistic encounters with large-scale harmful blooms (Matcher et al, 2021), which makes comparing the magnitude of change in microbial taxonomy and function to HABs difficult. We were able to circumvent this shortcoming when an exceptional bloom of the dinoflagellate Lingulodinium polyedra occurred in coastal Southern California over an area where existing time-series data are collected by the Scripps Ecological Observatory (SEO), the Southern California Coastal Ocean Observing System (SCCOOS), and the Scripps Ocean Acidification Real-Time Monitoring Program (SOAR) (Table 1).…”

Individual and Binary Mixture Toxicity of Five Nanoparticles in Marine Microalga Heterosigma akashiwo

“…However, it should be highlighted that H. akashiwo does not have a shell like most of the algae species, but it has amorphous vesicles under the cell wall. H. akashiwo has a mixed form of feeding, which includes photosynthesis, direct nutrition uptake, and the eating of bacterium [62].…”

Taxonomic difference in marine bloom-forming phytoplanktonic species affects dynamics of both bloom-responding prokaryotes and prokaryotic viruses

“…Some species like Heterosigma akashiwo (Raphidophyceae) and Chaetoceros spp. (Diatomea) eventually form blooms in coastal areas through local and seasonal massive growth (Buchan et al, 2014;Needham and Fuhrman, 2016;Tomaru et al, 2018;Matcher et al, 2021).…”