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Comparative study of the effects of MCPA, butylate, atrazine, and cyanazine on Selenastrum capricornutum.
1996
Caux P.Y. | Menard L. | Kent R.A.
Ultraphytoplankton community structure in subsurface waters along a North-South Mediterranean transect
2022
Boudriga, Ismail | Thyssen, Melilotus | Zouari, Amel | Garcia, Nicole | Tedetti, Marc | Bel Hassen, Malika
Here we assessed the subsurface ultraphytoplanktonic (< 10 μm) community along a North-South round-trip Mediterranean transect as part of a MERITE-HIPPOCAMPE cruise campaign in April–May 2019. Temperature, salinity, and nutrient concentrations in subsurface waters (2–5 m depth) were also measured along the transect. The subsurface ultraphytoplankton community structure was resolved with a spatial resolution of few kilometers and temporal resolution of 30-min intervals using automated pulse shape recording flow cytometry. The subsurface waters were clustered into seven areas based on temperature and salinity characteristics. Synechococcus were by far the most abundant group in all prospected zones, and nanoeukaryotes were the main biomass component, representing up to 51 % of ultraphytoplanktonic carbon biomass. Apparent net primary productivity (NPP) followed a decreasing gradient along the transect from north to south and was mostly sustained by Synechococcus in all zones. These findings are likely to have implications in terms of the trophic transfer of contaminants in planktonic food webs, as they highlight the potential role of nanoplankton in contaminants bioaccumulation processes and the potential role of Synechococcus in a likely transfer via grazing activities.
显示更多 [+] 显示较少 [-]Inorganic carbon utilization of tropical calcifying macroalgae and the impacts of intensive mariculture-derived coastal acidification on the physiological performance of the rhodolith Sporolithon sp
2020
Narvarte, Bienson Ceasar V. | Nelson, W. A. (Wendy A.) | Roleda, Michael Y.
Fish farming in coastal areas has become an important source of food to support the world’s increasing population. However, intensive and unregulated mariculture activities have contributed to changing seawater carbonate chemistry through the production of high levels of respiratory CO₂. This additional CO₂, i.e. in addition to atmospheric inputs, intensifies the effects of global ocean acidification resulting in localized extreme low pH levels. Marine calcifying macroalgae are susceptible to such changes due to their CaCO₃ skeleton. Their physiological response to CO₂-driven acidification is dependent on their carbon physiology. In this study, we used the pH drift experiment to determine the capability of 9 calcifying macroalgae to use one or more inorganic carbon (Cᵢ) species. From the 9 species, we selected the rhodolith Sporolithon sp. as a model organism to investigate the long-term effects of extreme low pH on the physiology and biochemistry of calcifying macroalgae. Samples were incubated under two pH treatments (pH 7.9 = ambient and pH 7.5 = extreme acidification) in a temperature-controlled (26 ± 0.02 °C) room provided with saturating light intensity (98.3 ± 2.50 μmol photons m⁻² s⁻¹). After the experimental treatment period (40 d), growth rate, calcification rate, nutrient uptake rate, organic content, skeletal CO₃⁻², pigments, and tissue C, N and P of Sporolithon samples were compared. The pH drift experiment revealed species-specific Cᵢ use mechanisms, even between congenerics, among tropical calcifying macroalgae. Furthermore, long-term extreme low pH significantly reduced the growth rate, calcification rate and skeletal CO₃⁻² content by 79%, 66% and 18%, respectively. On the other hand, nutrient uptake rates, organic matter, pigments and tissue C, N and P were not affected by the low pH treatments. Our results suggest that the rhodolith Sporolithon sp. is susceptible to the negative effects of extreme low pH resulting from intensive mariculture-driven coastal acidification.
显示更多 [+] 显示较少 [-]Ultraphytoplankton community structure in subsurface waters along a North-South Mediterranean transect
2022
Boudriga, Ismail | Thyssen, Melilotus | Zouari, Amel | Garcia, Nicole | Tedetti, Marc | Bel Hassen, Malika
Here we assessed the subsurface ultraphytoplanktonic (< 10 μm) community along a North-South round-trip Mediterranean transect as part of a MERITE-HIPPOCAMPE cruise campaign in April–May 2019. Temperature, salinity, and nutrient concentrations in subsurface waters (2–5 m depth) were also measured along the transect. The subsurface ultraphytoplankton community structure was resolved with a spatial resolution of few kilometers and temporal resolution of 30-min intervals using automated pulse shape recording flow cytometry. The subsurface waters were clustered into seven areas based on temperature and salinity characteristics. Synechococcus were by far the most abundant group in all prospected zones, and nanoeukaryotes were the main biomass component, representing up to 51 % of ultraphytoplanktonic carbon biomass. Apparent net primary productivity (NPP) followed a decreasing gradient along the transect from north to south and was mostly sustained by Synechococcus in all zones. These findings are likely to have implications in terms of the trophic transfer of contaminants in planktonic food webs, as they highlight the potential role of nanoplankton in contaminants bioaccumulation processes and the potential role of Synechococcus in a likely transfer via grazing activities.
显示更多 [+] 显示较少 [-]Remote sensing of early-stage green tide in the Yellow Sea for floating-macroalgae collecting campaign
2018
Xing, Qianguo | Wu, Lingling | Tian, Liqiao | Cui, Tingwei | Li, Lin | Kong, Fanzhou | Gao, Xuelu | Wu, Mengquan
The world's largest green tide originated from the Jiangsu Shoal of the Yellow Sea was due to fast reproduction of floating green macroalgae (Ulva prolifera). It brought significant impacts on marine environment and ecosystem in the Yellow Sea. In this study, we examined the expansion of green tide from the Jiangsu Shoal during the period from 29 April to 25 June 2016. Using high-resolution satellite images, we revealed a declined growth rate during the northward drifting of early-stage green tide for the first time, i.e., the green tide had higher growth rate (up to 25% per day) in the turbid waters of the Jiangsu Shoal in May and a lower growth rate (low to 3% per day) in the relatively clear waters in the middle of the western Yellow Sea in June, which suggests that water clarity might not be the key factor controlling the growth rate of the floating macroalgae in the surface waters under natural conditions. The high growth rate led to shortened time windows for controlling the green tide by employing macroalgae collecting campaigns at the initial sites of the green tide, which was no more than 14 days in the 2016 case.
显示更多 [+] 显示较少 [-]Assessing the toxicity of triphenyltin to different life stages of the marine medaka Oryzias melastigma through a series of life-cycle based experiments
2017
Yi, Xianliang | Leung, Kenneth M.Y.
Toxic effects of triphenyltin (TPT) to different life stages of the marine medaka Oryzias melastigma were investigated through a series of life-cycle based exposure experiments. In embryo stage, TPT exposure could elevate the heartbeat rate at Day 6–8 post-fertilization and increase the expression levels of five heart development related genes (i.e., ATPase, COX2, BMP4, GATA4 and NKX2.5). In larval stage, TPT shortened the body length at ≥10μg/L and suppressed the swimming activity of the fish larvae at Day 1 post-hatching at 50μg/L. In reproductive stage, TPT exposure resulted in a male-biased sex ratio (2μg/L) and reduced the gonadosomatic index (GSI) in females (≥ 0.1μg/L), which might in turn lead to a decline in their population fitness. The reproductive stage of O. melastigma was more sensitive to TPT than other stages, while the GSI of female medaka was the most sensitive endpoint.
显示更多 [+] 显示较少 [-]Ingestion and effects of micro- and nanoplastics in blue mussel (Mytilus edulis) larvae
2019
Rist, Sinja | Baun, Anders | Almeda, Rodrigo | Hartmann, Nanna B.
It is well known that mussels are exposed to microplastics but ingestion and potential effects on mussel larvae are not well understood. We quantified ingestion and egestion of 100 nm and 2 μm polystyrene beads in blue mussel larvae after 4 h exposure and 16 h depuration using different plastic-to-microalgae ratios. Effects on growth and development of mussel larvae were investigated at 0.42, 28.2 and 282 μgL−1 within 15 days of exposure. We found that, on a mass basis, larvae ingested a higher amount of 2 μm than 100 nm beads, while egestion was independent of particle size and the plastics-to-algae ratio. Although particle egestion occurred readily, microplastics remained inside the larvae. Larval growth was not affected but abnormally developed larvae increased after exposure to polystyrene beads. Malformations were more pronounced for 100 nm beads, at higher concentration and after longer exposure time.
显示更多 [+] 显示较少 [-]Interactive effect of nitrogen source and high CO2 concentration on the growth of the dinoflagellate Alexandrium tamarense and its toxicity to zebrafish (Danio rerio) embryos
2018
Guan, Wanchun | Si, Ranran | Li, Xi | Cai, Jingbo | Chen, Shaobo
The effects and interactive effects of different nitrogen (N) sources (ammonium, nitrate, and urea) and carbon dioxide (CO₂) concentrations were investigated on Alexandrium tamarense, a harmful marine dinoflagellate, by measuring its growth (μ), extracellular carbonic anhydrase (CA), and its toxicity to zebrafish (Danio rerio) embryo. The μ and CA were influenced more strongly by CO₂ concentrations rather than by N sources; significant effects of CO₂ on μ and CA were observed under low CO₂ concentration (LC) conditions compared to high CO₂ concentration (HC) conditions. The ammonium and nitrate media under LC conditions had the maximum μ and CA, which was inhibited under HC conditions. The embryotoxic effects were influenced more strongly by the N sources than by CO₂ concentrations, thus excluding the lower deformation in urea under HC conditions. Moreover, the antioxidant enzymes superoxide dismutase (SOD), glutathione peroxidase (GPX), glutathione S-transferase (GST), and catalase (CAT) were detected in normal (untreated) zebrafish embryos, and among them, the level of SOD was the highest. In summary, this study provides a clear insight for understanding the effects and interactive effects of N sources and CO₂ concentrations on the growth and toxicity of harmful dinoflagellates.
显示更多 [+] 显示较少 [-]Spatio-temporal variations in bloom of the red-tide dinoflagellate Karenia mikimotoi in Imari Bay, Japan, in 2014: Factors controlling horizontal and vertical distribution
2017
Aoki, Kazuhiro | Kameda, Takahiko | Yamatogi, Toshifumi | Ishida, Naoya | Hirae, Sou | Kawaguchi, Mayumi | Syutou, Toshio
A massive bloom of the dinoflagellate Karenia mikimotoi appeared in 2014 in Imari Bay, Japan. Bloom dynamics and hydrographical conditions were examined by field survey. The bloom initially developed in the eastern area of Imari Bay, subsequently after rainfall during the neap tides, cell density exceeded over 10,000cellsml. Vertical distribution of K. mikimotoi was primarily controlled by the light intensity and secondarily by the water quality during the daytime. Almost all cell-density maxima occurred in depths with weak daytime light intensities of <300μmolm−2s−1. In some cases of weak light intensity, cell-density maxima occurred in depths with favorable hydrodynamic conditions for the growth. Spatially classified areas were identified by cluster analysis using the growth rate calculated from seawater temperature and salinity. This study quantitatively evaluated the environmental factors of the eastern area, where the bloom initially occurred, during the development of the bloom.
显示更多 [+] 显示较少 [-]Growth and yield responses of wheat plants to elevated levels of CO2 and SO2, singly and in combination
1999
Deepak, S.S. | Madhoolika Agrawal (Ecology Research Laboratory, Department of Botany, Banaras Hindu University, Varanasi 221 005 (India))