Terrestrial input of herbicides has significant impacts on phytoplankton and bacterioplankton communities in coastal waters

Abstract

Herbicide use has increased very rapidly worldwide in recent decades, and some of these herbicides eventually enter the ocean. At present, herbicide pollution in the ocean has become a global environmental problem. Here, in a field investigation of 22 commonly used herbicide residues (triazine, phenylurea, and amide) in the Bohai Sea and the Yellow Sea, we found that the detection rate of herbicide residues within 100 km from shore was 100%. Notably, triazine herbicides have reached concentrations (up to 12.07 nmol L À1 ) that can significantly disturb phytoplankton and bacterioplankton communities in microcosm experiments. Under exposure to triazine herbicides at close to their total in situ concentrations, the photosynthesis of the phytoplankton community was significantly inhibited, which was reflected by the significant decrease of F v /F m (28.7-63.8%) of the phytoplankton community and dissolved oxygen content (18.1-32.2%) in seawater. Concurrently, the phytoplankton community structure underwent significant changes with the dominant group shifting from diatoms to dinoflagellates, due to the higher atrazine sensitivity of diatoms compared to facultative dinoflagellates. Triazine herbicide also significantly altered the bacterioplankton community structure and inhibited their metabolism of many carbon sources including carbohydrates, amino acids, and carboxylic acids. As phytoplankton and bacterioplankton are closely related, the impact of herbicide on the bacterioplankton community was clearly aggravated by the phytoplankton community. In view of the significance of phytoplankton and bacterioplankton communities in supporting marine food webs and biogeochemical cycles, a continuous increase in herbicide input in the future may seriously affect the stability of coastal oceans.

Atypical Seasonality of the Silicon Cycle in the Yellow River Estuary and Bohai Sea Revealed by Stable Silicon Isotopes

“…This is also supported by synchronous low DSi concentrations of the Yellow River water (Li et al, 2022) and low Chl a concentrations of the Bohai seawater (Cui et al, 2024). In addition, due to the long residence time of freshwater, diatom production in summer could be suppressed by the pollution of atrazine that is heavily used in spring, but this effect is only detected within limited areas (Yang et al, 2021). Figure 5.…”

“…Diatoms and dinoflagellates are the two dominant phytoplankton in the Bohai Sea, with diatoms accounting for ∼80% of total phytoplankton abundance (Li et al., 2021; Wei et al., 2022). The Bohai Sea is one of the most populated catchments in the world and has been greatly perturbed by human activities, such as offshore oilfields, petrochemical plants, and aquaculture areas (Ding et al., 2021; Liu et al., 2017; Xin et al., 2019; Yang et al., 2021). The excessive nutrient load has resulted in eutrophication and stimulated harmful algae blooms, which are currently devastating the Bohai Sea ecosystem (Ding et al., 2021; Liu et al., 2017; Maure et al., 2021; Wang et al., 2019; Wu et al., 2013; Xin et al., 2019; Zheng et al., 2020).…”

Marine Microbiota Responses to Shipping Scrubber Effluent Assessed at Community Structure and Function Endpoints

“…Due to their immense abundance and level of activity, these organisms can rapidly respond to environmental gradients and changes employing a multitude of biological interplays with other microbes and higher organisms (Bunse & Pinhassi, 2017). Phytoplankton and bacterioplankton are closely interconnected communities in marine environments through the exchange of organic matter and inorganic nutrients (Yang et al, 2021). Their microscale interactions underpin ocean biogeochemistry (Smriga et al, 2016), and their community structure is key to the functioning of ecosystems (Fuhrman, 2009).…”

Herbicide leakage into seawater impacts primary productivity and zooplankton globally

“…Our previous study found that some dominant offshore species (e.g., Phaeodactylum tricornutum and Chaetoceros sp.) were extremely sensitive to triazine herbicides, and atrazine at ambient concentrations (1 μg L − 1 ) significantly inhibited their photosynthesis (approximately 57% of photosynthetic genes were significantly downregulated) and weakened their chlorophyll a fluorescence intensity 9 , 10 . Marine phytoplankton contribute approximately 50% of the total global primary productivity and play a vital role in global carbon cycling 11 .…”