Marine microbial communities of the Great Barrier Reef lagoon are influenced by riverine floodwaters and seasonal weather events

Abstract

The role of microorganisms in maintaining coral reef health is increasingly recognized. Riverine floodwater containing herbicides and excess nutrients from fertilizers compromises water quality in the inshore Great Barrier Reef (GBR), with unknown consequences for planktonic marine microbial communities and thus coral reefs. In this baseline study, inshore GBR microbial communities were monitored along a 124 km long transect between 2011 and 2013 using 16S rRNA gene amplicon sequencing. Members of the bacterial orders Rickettsiales (e.g., Pelagibacteraceae) and Synechococcales (e.g., Prochlorococcus), and of the archaeal class Marine Group II were prevalent in all samples, exhibiting a clear seasonal dynamics. Microbial communities near the Tully river mouth included a mixture of taxa from offshore marine sites and from the river system. The environmental parameters collected could be summarized into four groups, represented by salinity, rainfall, temperature and water quality, that drove the composition of microbial communities. During the wet season, lower salinity and a lower water quality index resulting from higher river discharge corresponded to increases in riverine taxa at sites near the river mouth. Particularly large, transient changes in microbial community structure were seen during the extreme wet season 2010–11, and may be partially attributed to the effects of wind and waves, which resuspend sediments and homogenize the water column in shallow near-shore regions. This work shows that anthropogenic floodwaters and other environmental parameters work in conjunction to drive the spatial distribution of microorganisms in the GBR lagoon, as well as their seasonal and daily dynamics.

Signatures of selection in the coral holobiont reveal complex adaptations to inshore environments driven by Holocene climate change

“…The northern gradient captures the wet tropics region where multiple rivers influence water quality. Here the plume location, Dunk Island is highly exposed (>67% of wet season days) to plume waters from the Tully and to a lesser extent the Herbert rivers 59,99 while Fitzroy Island receives flood waters from the Johnstone and Russell-Mulgrave river catchments much less often (lower end of 33-67% of wet season days).…”

Response of the bacterioplankton composition to inorganic nutrient loading and phytoplankton in southern Korean coastal waters: A mesocosm study

“…However, these methods often provide insufficient coverage to describe and compare actual microbial communities in the field (Curtis et al., 2006). On the other hand, the more recently developed pyrosequencing method, which allows the simultaneous collection of thousands of sequences from a large number of samples (Andersson et al., 2008; Angly et al., 2016; Hamady, Walker, Harris, Gold, & Knight, 2008; Zhang, Deng, Xie, & Jiao, 2016), can provide a more comprehensive understanding of microbial community structure in environmental samples (Herlemann et al., 2011; Kim, Gwak, et al., 2019; Kim, Kim, et al., 2019; Sogin et al., 2006).…”

Population structure determined by comparative amplicon gene sequencing in biofilm and planktonic bacterial communities from pesticide-contaminated water

“…Aquatic environments are complex [28]; therefore, the analysis of changes in the structure of communities of microorganisms that are made to adapt to environmental contaminants is difficult. Restricted environments with a high number of agrochemicals, such as those presented in this paper, allow basic hypotheses to be tested with increased safety before being tested at a larger environmental scale.…”

“…16S rRNA gene amplicon sequencing was used to verify the impact of herbicides and fertilizers on planktonic marine microbial communities at the Great Barrier Reef. Water characteristics, such as salinity, rainfall, temperature and water quality, have a great influence on the composition of microbial communities [28]. Aquatic environments are complex and subject to various physicochemical interferences, making it difficult to understand the impact of agrochemicals on microbiomes.…”