خيارات البحث
النتائج 1811 - 1820 من 4,896
Effects of increased CO2 and temperature on the physiological characteristics of the golden tide blooming macroalgae Sargassum horneri in the Yellow Sea, China
2019
Wu, Hailong | Feng, Jingchi | Li, Xinshu | Zhao, Chunyan | Liu, Yanhong | Yu, Jintao | Xu, Juntian
The golden tide, caused by the brown algae Sargassum horneri, exerts severe influences on the Pyropia aquaculture of Jiangsu coast, China. To study the outbreak of the golden tide in response to increasing greenhouse gas emissions, S. horneri was cultured under four conditions: ambient condition (10 °C, 400 μatm), elevated temperature condition (14 °C, 400 μatm), elevated CO₂ level (10 °C, 1000 μatm), and potential greenhouse condition (14 °C, 1000 μatm). The growth, photosynthetic performances, and inorganic carbon affinity of S. horneri were studied. The results showed that elevated temperature exerted a more pronounced positive influence on S. horneri growth, photosynthesis, and carbon assimilation than CO₂ enrichment. The growth of S. horneri was significantly improved by moderately elevated temperatures, especially under concurrently elevated CO₂ levels. This suggests that the greenhouse effect will benefit growth and carbon sequestration of S. horneri, which may enhance the frequency and scale of golden tides.
اظهر المزيد [+] اقل [-]Quantitative evaluation of n-alkanes, PAHs, and petroleum biomarker accumulation in beach-stranded tar balls and coastal surface sediments in the Bushehr Province, Persian Gulf (Iran)
2019
Dashtbozorg, Mehdi | Riyahi Bakhtiari, Alireza | Shushizadeh, Mohammad Reza | Taghavi, Lobat
Coastal areas within the Bushehr Province (BP), Persian Gulf, Iran, face great challenges due to the heavy organic contamination caused by rapid industrialization, and the presence of numerous oil fields. In addition, in 2014, a significant number of tar balls are found along the coasts of BP. A total of 96 samples (48 coastal sediments and 48 tar balls) were taken from eight sampling points at the BP coast during the summer of 2014. These samples were analyzed to identify the sources and characteristics of their organic matter using diagnostic ratios and fingerprint analysis based on the distribution of the source-specific biomarkers of n-alkanes, PAHs,¹1Polycyclic Aromatic Hydrocarbons hopanes and steranes. Mean concentration of n-alkanes (μg g⁻¹ dw) and PAHs (ng g⁻¹ dw) varied respectively from 405 to 220,626, and 267 to 23,568 in coastal sediments, while ranged respectively from 664 to 145,285 and 390 to 46,426 in tar balls. In addition, mean concentration of hopanes and steranes (ng g⁻¹ dw) were between 18.17 and 3349 and 184.66 to 1578 in coastal sediments, whereas in tar balls were 235–1899 and 520–1504, respectively. Pri/Phy²2Pristane/Phytane ratio was 0.25 to 1.51 (0.65) and 0.36 to 1 (0.63) in coastal sediment and tar ball samples, respectively, and the occurrence of UCM³3Unresolved Complex Mixture in both matrices, reflecting the petrogenic OM⁴4Organic Matter inputs and chronic oil contamination, respectively. The C₃₀ and C₂₉ homologues followed Gammacerane were detected in both matrices, in particular those collected from intensive industrial activities, suggesting petrogenic sources of OM. The coastal sediment PAHs profiles were significantly dominated by HMW⁵5Higher Molecular Weight-PAHs in the Bahregan Beach (BAB) (78% of total PAHs), Bandare-Genaveh (GP) (66%), and Bandare-Bushehr (BUB) (61%) stations, while the Bashi Beach (BSB) (40%), Bandare-Kangan (KP) (57%), and Bandare-Asaluyeh (AP) (51%) stations exhibited higher proportion of LMW⁶6Lower Molecular Weight-PAHs. PCA⁷7Principal Component Analysis indicated that the tar ball and coastal sediment samples deposited along the Southwest of the BP beaches are most likely originated from the Abuzar oil. Based on the intensity of the anthropogenic activities, NPMDS⁸8Non-Parametric Multi-Dimensional Scaling analysis revealed that the GP, BAB, NNP, AP, and KP sampling sites had a high concentration of detected organic pollutants. To the best of our knowledge, this is the first study that investigates oil pollution in costal sediments and tar balls in the BP, providing insights in to the fate of oil in the coastal areas of the Persian Gulf, Iran.
اظهر المزيد [+] اقل [-]Non-native plant species in the Atlantico Department Coastal Dune Systems, Caribbean of Colombia: A new management challenge
2019
Gracia C., Adriana | Rangel-Buitrago, Nelson | Castro-Barros, Julian Dario
Although coastal dunes exhibit typical vegetation which involves species adapted to extreme environmental conditions, the mobilization and colonization by non-native species represents a challenge in its conservation and management. In this work, eight dune systems located along the Atlantico Department, Caribbean coast of Colombia were surveyed, finding within them the presence of two plant species recognized as invasive: Calotropis procera and Cryptostegia madagascariensis. The impacts of these two invasive plant species can be significant at all ecological levels in the dune systems. The above demands the implementation of urgent management actions. Eradication seems the optimal control alternative, however preventing invasive plant species from infesting new areas is more cost-effective and efficient than trying to restore the system after it is infested. Data presented in this paper is the first step in the future development of an early detection program in the study area.
اظهر المزيد [+] اقل [-]Marine litter in the Croatian part of the middle Adriatic Sea: Simultaneous assessment of floating and seabed macro and micro litter abundance and composition
2019
Palatinus, Andreja | Kovač Viršek, Manca | Robič, Uroš | Grego, Mateja | Bajt, Oliver | Šiljić, Jasna | Suaria, Giuseppe | Liubartseva, Svitlana | Coppini, Giovanni | Peterlin, Monika
In this study, abundance, distribution and composition of floating and seabed macro and micro litter in the Central Adriatic Sea were assessed. Floating macro litter observations were made. Floating and seabed micro litter were sampled with manta net and Van Veen grab, respectively. Micro litter particles visually found under the microscope were chemically analyzed with Fourier Transform Infrared microscope. Average calculated concentrations of floating macro (175 items/km2), floating micro (127 thousand particles/km2) and seabed micro litter (36 particles/100 g dry weight) show similar values as other published studies from the Mediterranean Sea. A statistically significant (p < 0.01) correlation between the floating micro and macro litter concentrations was found for the sites located in the channel waters. Disagreement between model and observations revealed gaps in our knowledge concerning the sea circulation and litter sources. Simultaneous samplings and observations of marine litter in different marine compartments proved possible, efficient and informative.
اظهر المزيد [+] اقل [-]Description of buoyant fibers adhering to Argonauta nouryi (Cephalopoda: Argonautidae) collected from the stomach contents of three top predators in the Mexican South Pacific
2019
del Carmen Alejo-Plata, María | Herrera-Galindo, Eduardo | Cruz-González, Diana Guadalupe
Argonauta nouryi Lorois, 1852 is an octopod that inhabits the holopelagic zone, the objective of this study was to describe the occurrence of buoyant fibers adhering to the body and mantle cavity of A. nouryi females found in the stomach contents from Euthynnus lineatus (skipjack), Coryphaena hippurus (dolphinfish), and Istiophorus platypterus (sailfish). Stomach contents from 224 individuals were examined. All female evaluated presented fibers adhering to the mantle cavity; 92.6% of the fibers measured 0.25 to 5 mm in length and hyaline was the dominant color (72%). The amount of fibers in the fish stomach contents with A. nouryi was significantly greater than in stomachs without; this suggests that the fibers might be introduced via A. nouryi. Findings of this work could be related to the discharge of solid materials in the water column.
اظهر المزيد [+] اقل [-]Boat noise affects the early life history of two damselfishes
2019
Fakan, E.P. | McCormick, M.I.
Anthropogenic noise can have a negative effect on the physiology and survival of marine fishes. Most research has focused on later life-stages, and few studies have investigated the effects of human-induced noise on embryogenesis. The current study investigated whether playback of motorboat noise affected the embryogenesis of the coral reef damselfishes, Amphiprion melanopus and Acanthochromis polyacanthus. Embryos reared under the playback of boat noise had faster heart rates compared to the ambient reef controls. The effects of noise on morphological development differed between species and the fundamental interrelationships between early life history characteristics changed dramatically under boat noise for Ac. polyacanthus. Noise treatments did not alter the survival rates of embryos under laboratory conditions. Although species specific, our findings suggest that anthropogenic noise causes physiological responses in fishes during embryogenesis and these changes have direct impacts on their development and these alterations may have carry-over effects to later life stages.
اظهر المزيد [+] اقل [-]Phytoplankton biomass and size structure in Xiangshan Bay, China: Current state and historical comparison under accelerated eutrophication and warming
2019
Jiang, Zhibing | Du, Ping | Liu, Jingjing | Chen, Yue | Zhu, Yuanli | Shou, Lu | Zeng, Jiangning | Chen, Jianfang
To explore the effects of coastal eutrophication and warming on phytoplankton biomass and cell size, we analyzed current and historical data for size-fractionated chlorophyll a (chla) in Xiangshan Bay, China. Results showed that micro- and nanophytoplankton overwhelmingly dominated (>84%) in all seasons. The contribution of micro-chla was significantly lower in warm than in cold seasons, whereas contribution of pico-chla showed the opposite result. Overall, the micro-chla contribution increased with decreasing pico-chla contribution from the stable, clear, eutrophic upper bay to the turbulent, turbid lower bay, indicating that phytoplankton size structure on a spatial scale was largely shaped by water column stability and light rather than by nutrients. Since the 1980s, phytoplankton biomass, primary productivity, and micro-chla contribution in Xiangshan Bay have increased sharply with increasing nutrient amounts and temperature. Additionally, it seems that algal bloom seasonality has shifted forward from spring to winter since the power plant operations in 2006.
اظهر المزيد [+] اقل [-]Performance and herbivory of the tropical topshell Trochus histrio under short-term temperature increase and high CO2
2019
Grilo, Tiago F. | Repolho, Tiago | Rosa, Rui | Cardoso, Patrícia G.
Within tropical environments, short-term impacts of increased seawater temperature and pCO₂ on algae-herbivore interactions remain poorly understood. We investigated the isolated and combined 7-day effects of increased temperature (+4 °C) and pCO₂ (~1000 μatm) on the trophic interaction Ulva sp./Trochus histrio, by assessing: i) topshells’ survival and condition index; ii) grazer consumption rates, nutritional composition and interaction strength expressed as a dynamic index. No survival differences were observed whilst body condition varied significantly. Topshells under high pCO₂ displayed poor performance, concomitant with lower consumption of macroalgae. Individuals exposed to increased temperature had better physical condition, thus stimulating herbivory, which in turn was negatively correlated with carbon and nitrogen contents. The dynamic index was temperature- and pCO₂- interactively dependent, suggesting lower grazing pressure under single acidification. Despite some limitations inherent to a short-term exposure, this study provides new insights to accurately predict tropical species' phenotypic responses in a changing ocean.
اظهر المزيد [+] اقل [-]Analysis of anatomical changes and cadmium distribution in Aegiceras corniculatum (L.) Blanco roots under cadmium stress
2019
Li, Jian | Yu, Junyi | Du, Daolin | Liu, Jingchun | Lu, Haoliang | Yan, Chongling
Heavy metal stress changes the morphological and anatomical structure of plant organs. In this study, we determined the anatomical changes and Cd distribution in the roots of Aegiceras corniculatum (L.) Blanco (Black mangrove) under Cd stress. The results showed that Cd levels in A. corniculatum root tissues decreased in the following order: endodermis > pith > xylem > epidermis and exodermis > phloem > cortex. The endodermis secondary casparian strip replaces exodermis casparian strip and plays a role in the “retardation mechanism”, which sort of compensates for the missing exodermis retardation effect. The xylem and pith both show high affinity for Cd and contain enriched Cd. This creates a low-Cd environment for phloem and protects the nutrient transport function of the vasculature against Cd toxicity. The present study provides new evidences suggesting that Cd regional enrichment and anatomical structure changes are an adaptive strategy of mangrove plants to HM tolerance.
اظهر المزيد [+] اقل [-]Taking control of persistent solid waste pollution
2019
Coe, James M. | Antonelis, George “Bud” | Moy, Kirsten
The complexity and scale of the sources, types and environmental impacts of persistent solid waste pollution (PSWP) continue to overwhelm the capabilities of government and private efforts to control it. Global cumulative production of virgin plastics is expected to quadruple by 2050 with a concomitant doubling of plastic waste. All nations must take significant steps to realize eventual mitigation of PSWP. These will include adopting a long-term PSWP elimination policy, creating an overarching authority to lead and coordinate a comprehensive national solid waste management program, and creating an International Convention for the Prevention of PSWP to enable global solutions for this global pollution. Initiating these changes will necessitate major, coordinated efforts on the part of environmental organizations, their supporting foundations and concerned citizens.
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