Combined effects of temperature and the herbicide diuron on Photosystem II activity of the tropical seagrass Halophila ovalis

Wilkinson, Adam; Collier, Catherine; Flores, Florita; Langlois, Lucas; Ralph, Peter J.; Negri, Andrew P.

doi:10.1038/srep45404

Cited by 24 publications

(11 citation statements)

References 77 publications

(147 reference statements)

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“…The expulsion of symbionts from GBR coral Pocillopora damicornis was observed at 10 μg/L of diuron in both recruits and adult colonies (Negri et al, 2005). Generally, a detrimental and mostly additive effect of elevated temperature combined with diuron on corals and other marine organisms has been documented (Negri et al, 2011; van Dam et al, 2012, 2015; Wilkinson et al, 2017). Jones and Kerswell (2003) found that diuron phytotoxicity of Symbiodiniceae within the coral Seriatopora hystrix was less at 30°C than 20°C and the toxicity of diuron appears to increase on either side of the thermal optimum for marine species (Negri et al, 2011 and Wilkinson et al, 2017).…”

Section: Discussionmentioning

confidence: 99%

Thermal and Herbicide Tolerances of Chromerid Algae and Their Ability to Form a Symbiosis With Corals

2019

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Reef-building corals form an obligate symbiosis with photosynthetic microalgae in the family Symbiodiniaceae that meet most of their energy requirements. This symbiosis is under threat from the unprecedented rate of ocean warming as well as the simultaneous pressure of local stressors such as poor water quality. Only 1°C above mean summer sea surface temperatures (SSTs) on the Great Barrier Reef (GBR) can trigger the loss of Symbiodiniaceae from the host, and very low concentrations of the most common herbicide, diuron, can disrupt the photosynthetic activity of microalgae. In an era of rapid environmental change, investigation into the assisted evolution of the coral holobiont is underway in an effort to enhance the resilience of corals. Apicomplexan-like microalgae were discovered in 2008 and the Phylum Chromerida (chromerids) was created. Chromerids have been isolated from corals and contain a functional photosynthetic plastid. Their discovery therefore opens a new avenue of research into the use of alternative/additional photosymbionts of corals. However, only two studies to-date have investigated the symbiotic nature of Chromera velia with corals and thus little is known about the coral-chromerid relationship. Furthermore, the response of chromerids to environmental stressors has not been examined. Here we tested the performance of four chromerid strains and the common dinoflagellate symbiont Cladocopium goreaui (formerly Symbiodinium goreaui , ITS2 type C1) in response to elevated temperature, diuron and their combined exposure. Three of the four chromerid strains exhibited high thermal tolerances and two strains showed exceptional herbicide tolerances, greater than observed for any photosynthetic microalgae, including C. goreaui . We also investigated the onset of symbiosis between the chromerids and larvae of two common GBR coral species under ambient and stress conditions. Levels of colonization of coral larvae with the chromerid strains were low compared to colonization with C. goreaui . We did not observe any overall negative or positive larval fitness effects of the inoculation with chromerid algae vs. C. goreaui . However, we cannot exclude the possibility that chromerid algae may have more important roles in later coral life stages and recommend this be the focus of future studies.

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Section: Discussionmentioning

confidence: 99%

Thermal and Herbicide Tolerances of Chromerid Algae and Their Ability to Form a Symbiosis With Corals

2019

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“…Using the spreadsheet in Supplement 2 , the change in net plant productivity can be estimated for any given rise in water temperature. It is important to note, however, that rises in water temperature could increase vulnerability to other stressors including light limitation (Collier et al, 2016 ), contaminants (Wilkinson et al, 2017 ), disease susceptibility (Kaldy, 2014 ), and sulfide intrusion (Koch et al, 2007 ; Kilminster et al, 2008 ).…”

Section: Discussionmentioning

confidence: 99%

Optimum Temperatures for Net Primary Productivity of Three Tropical Seagrass Species

Collier

Langlois

et al. 2017

Front. Plant Sci.

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Rising sea water temperature will play a significant role in responses of the world's seagrass meadows to climate change. In this study, we investigated seasonal and latitudinal variation (spanning more than 1,500 km) in seagrass productivity, and the optimum temperatures at which maximum photosynthesis and net productivity (for the leaf and the whole plant) occurs, for three seagrass species (Cymodocea serrulata, Halodule uninervis, and Zostera muelleri). To obtain whole plant net production, photosynthesis, and respiration rates of leaves and the root/rhizome complex were measured using oxygen-sensitive optodes in closed incubation chambers at temperatures ranging from 15 to 43°C. The temperature-dependence of photosynthesis and respiration was fitted to empirical models to obtain maximum metabolic rates and thermal optima. The thermal optimum (Topt) for gross photosynthesis of Z. muelleri, which is more commonly distributed in sub-tropical to temperate regions, was 31°C. The Topt for photosynthesis of the tropical species, H. uninervis and C. serrulata, was considerably higher (35°C on average). This suggests that seagrass species are adapted to water temperature within their distributional range; however, when comparing among latitudes and seasons, thermal optima within a species showed limited acclimation to ambient water temperature (Topt varied by 1°C in C. serrulata and 2°C in H. uninervis, and the variation did not follow changes in ambient water temperature). The Topt for gross photosynthesis were higher than Topt calculated from plant net productivity, which includes above- and below-ground respiration for Z. muelleri (24°C) and H. uninervis (33°C), but remained unchanged at 35°C in C. serrulata. Both estimated plant net productivity and Topt are sensitive to the proportion of below-ground biomass, highlighting the need for consideration of below- to above-ground biomass ratios when applying thermal optima to other meadows. The thermal optimum for plant net productivity was lower than ambient summer water temperature in Z. muelleri, indicating likely contemporary heat stress. In contrast, thermal optima of H. uninervis and C. serrulata exceeded ambient water temperature. This study found limited capacity to acclimate: thus the thermal optima can forewarn of both the present and future vulnerability to ocean warming during periods of elevated water temperature.

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“…As photosystem II and its conservation in plants are the targets of DUR, non-target phytoplankton is equally affected, such as seagrass and corals ( Marques et al, 2020 ; Thomas et al, 2020 ). Plants eventually die due to long-term starvation under moderate irradiation (electron transfer rate inhibition) or oxidative stress under higher levels of radiation ( Diepens et al, 2017 ; Wilkinson et al, 2017 ). Over the past decade, a large volume of published studies has described the toxic effects of DUR on green algae and seagrass in tropical marine environments ( King et al, 2013 ; Negri et al, 2015 ; Diepens et al, 2017 ; Brodie and Landos, 2019 ; Thomas et al, 2020 ).…”

Section: Environmental Occurrence and Toxicitymentioning

confidence: 99%

“…In mammals, including humans, DUR (0.05–0.5 μg/L) is suspected of having carcinogenic, mutagenic, and neurotoxic effects, causing genotoxicity, cytotoxicity, embryotoxicity, and immunotoxicity, as well as a disruption of endocrine, respiratory, and cardiovascular processes ( da Rocha et al, 2013 ; Behrens et al, 2016 ; Manonmani et al, 2020 ). This compound (200 ng/L) is also harmful to fish, plants, aquatic invertebrates, freshwater algae, and microbial species ( Pesce et al, 2010 ; Pereira et al, 2015 ; Wilkinson et al, 2017 ; Pei et al, 2020 ). In addition, some metabolites of DUR, such as 3,4-dichloroaniline (3,4-DCA) and 3-(3,4-dichlorophenyl)-1-methylurea (DCPMU), showed more ecotoxicological effects than their parent compound ( Stork et al, 2008 ; Hussain et al, 2015 ).…”

Section: Introductionmentioning

confidence: 99%

Emerging Strategies for the Bioremediation of the Phenylurea Herbicide Diuron

Zhang

Lin

et al. 2021

Front. Microbiol.

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Diuron (DUR) is a phenylurea herbicide widely used for the effective control of most annual and perennial weeds in farming areas. The extensive use of DUR has led to its widespread presence in soil, sediment, and aquatic environments, which poses a threat to non-target crops, animals, humans, and ecosystems. Therefore, the removal of DUR from contaminated environments has been a hot topic for researchers in recent decades. Bioremediation seldom leaves harmful intermediate metabolites and is emerging as the most effective and eco-friendly strategy for removing DUR from the environment. Microorganisms, such as bacteria, fungi, and actinomycetes, can use DUR as their sole source of carbon. Some of them have been isolated, including organisms from the bacterial genera Arthrobacter, Bacillus, Vagococcus, Burkholderia, Micrococcus, Stenotrophomonas, and Pseudomonas and fungal genera Aspergillus, Pycnoporus, Pluteus, Trametes, Neurospora, Cunninghamella, and Mortierella. A number of studies have investigated the toxicity and fate of DUR, its degradation pathways and metabolites, and DUR-degrading hydrolases and related genes. However, few reviews have focused on the microbial degradation and biochemical mechanisms of DUR. The common microbial degradation pathway for DUR is via transformation to 3,4-dichloroaniline, which is then metabolized through two different metabolic pathways: dehalogenation and hydroxylation, the products of which are further degraded via cooperative metabolism. Microbial degradation hydrolases, including PuhA, PuhB, LibA, HylA, Phh, Mhh, and LahB, provide new knowledge about the underlying pathways governing DUR metabolism. The present review summarizes the state-of-the-art knowledge regarding (1) the environmental occurrence and toxicity of DUR, (2) newly isolated and identified DUR-degrading microbes and their enzymes/genes, and (3) the bioremediation of DUR in soil and water environments. This review further updates the recent knowledge on bioremediation strategies with a focus on the metabolic pathways and molecular mechanisms involved in the bioremediation of DUR.

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Combined effects of temperature and the herbicide diuron on Photosystem II activity of the tropical seagrass Halophila ovalis

Cited by 24 publications

References 77 publications

Thermal and Herbicide Tolerances of Chromerid Algae and Their Ability to Form a Symbiosis With Corals

Thermal and Herbicide Tolerances of Chromerid Algae and Their Ability to Form a Symbiosis With Corals

Optimum Temperatures for Net Primary Productivity of Three Tropical Seagrass Species

Emerging Strategies for the Bioremediation of the Phenylurea Herbicide Diuron

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