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Sources and fate of organic matter in constructed versus natural coastal waterways Texte intégral
2018
Pitt, Kylie A. | Lee, Shin Yip | Connolly, Rod M. | Bui, Thi Hong Hanh | Doriean, Nic
Coastal wetlands are increasingly being converted into canal estates with potential consequences for ecosystem functioning. We compared the sources and fate of organic matter and water quality at four types of canal habitats (entrances and ends of canals, canal lakes and lake edges) and shallow and deep natural habitats (four replicates of each habitat). The fate of labile organic matter was assessed by measuring rates of scavenging of carrion. Surface sediments were analysed for organic carbon content and stable carbon isotopes, fatty acid biomarkers and compound specific stable isotope analysis of selected fatty acids were used to elucidate sources of sedimentary organic matter. Canal lakes differed from other habitats and were characterised by negligible scavenging, larger quantities of organic matter comprised of higher contributions from diatoms, and hypoxia. Despite some trends, natural habitats were statistically indistinguishable from canal entrances and ends. Variation among replicate habitats was large.
Afficher plus [+] Moins [-]Unraveling the performance of the benthic index AMBI in a subtropical bay: The effects of data transformations and exclusion of low-reliability sites Texte intégral
2018
Checon, Helio H. | Corte, Guilherme N. | Muniz, Pablo | Brauko, Kalina M. | Di Domenico, Maikon | Bícego, Marcia C. | Siegle, Eduardo | Figueira, Rubens C.L. | Amaral, A. Cecília Z.
We investigated the relationship between the AMBI index and different contamination proxies in an urbanized bay in South America (SE Brazil), and the effect of (a) abundance data transformation and (b) exclusion of low-reliability sites (high SD; low N) on the index' performance. Poor ecological quality and opportunistic species were related to an increase in contaminants concentrations and mud content. Good ecological status and sensitive species (EG I) were mainly related to increased hydrodynamics. Data transformation caused minimal changes to the overall relationships, but exclusion of low-reliability sites improved the relationship between ecological groups and contamination proxies. Our results show that AMBI is robust in detecting effects of different contaminants in the area and reinforce the importance of the index as a tool for coastal management, but local joint efforts are needed to improve and adjust local species classification in ecological groups to improve the index' performance.
Afficher plus [+] Moins [-]Acute toxicity test of copper pyrithione on Javanese medaka and the behavioural stress symptoms Texte intégral
2018
Mohamat-Yusuff, Ferdaus | Sarah-Nabila, Ab Ghafar | Zulkifli, Syaizwan Zahmir | Azmai, Mohammad Noor Amal | Ibrahim, Wan Norhamidah Wan | Yusof, Shahrizad | Ismail, Ahmad
This study was conducted to investigate the median lethal concentration (LC50) of copper pyrithione (CuPT) at 96-hr exposure on adult Javanese medaka (Oryzias javanicus) in revealing toxicological effects of CuPT contamination in the tropical area. Wild stock fishes were acclimatized for 14-days prior analysis. Triplicate of test tanks for seven test concentrations were placed with ten fishes each, this includes two control tanks. The behaviour of the tested fishes was manually observed through a camera. The LC50 of CuPT at 96-h was found to be 16.58mg/L. Tested fishes swam slowly in vertical movement and swam fast towards food during feeding time as the sign of stress behaviour. Meanwhile, fishes in the two control groups swam actively in a horizontal manner and no excitement during feeding time. No mortality in control groups. Results indicate CuPT to be toxic to Javanese medaka at low concentration and caused behavioural stress.
Afficher plus [+] Moins [-]Overall bacterial community composition and abundance of nitrifiers and denitrifiers in a typical macrotidal estuary Texte intégral
2018
Zhu, Weijing | Wang, Cheng | Sun, Faqian | Zhao, Liancheng | Dou, Wenjie | Mao, Zhihua | Wu, Weixiang
Coupled nitrogen cycling processes can alleviate the negative effects of eutrophication caused by excessive nitrogen load in estuarine ecosystems. The abundance and diversity of nitrifiers and denitrifiers across different environmental gradients were examined in the sediment of Hangzhou Bay. Quantitative PCR and Pearson's correlation analyses suggested that the bacterial ammonia-oxidizers (AOB) were the dominant phylotypes capable of ammonia oxidation, while the nirS-encoding denitrifiers predominated in the denitrification process. Simultaneously, nitrite and pH were found to be the two major factors influencing amoA and nir gene abundances, and the distribution of bacterial communities. Moreover, the ratio of nirS/AOB amoA gene abundance showed negative correlation with nitrite concentration. Fluorescence in situ hybridization further demonstrated that AOB and acetate-denitrifying cells were closely connected and formed obvious aggregates in the sediment. Together, all these results provided us a preliminary insight for coupled nitrification-denitrification processes in the sediment of Hangzhou Bay.
Afficher plus [+] Moins [-]Ozone Production Efficiency in Highly Polluted Environments Texte intégral
2018
Wang, Junhua | Ge, Baozhu | Wang, Zifa
When developing ozone control strategies, the empirical kinetic modeling approach curve cannot easily be applied to practical problems. On this basis, the ozone production efficiency (OPE) is proposed as an indicator to represent the effects of NOₓ on ozone. The research results of the OPE are reviewed and include the definition and calculation of OPE, observations and model simulations, several factors affecting the OPE, and the application of OPE. The measurements and applications of the OPE have improved and become widespread after decades of development. OPE is mostly used to measure regional atmospheric oxidation characteristics, which play an important role when developing ozone control strategies (especially in highly polluted areas). However, there have been few studies on the advancement of chemical mechanisms in the OPE in recent years. In addition, there is no detailed interpretation of the strong linear correlation between ozone and NOz. The results may be significant for improving simulation results and understanding the formation of ozone.
Afficher plus [+] Moins [-]Underwater noise assessment outside harbor areas: The case of Port of Civitavecchia, northern Tyrrhenian Sea, Italy Texte intégral
2018
Cafaro, Valentina | Piazzolla, Daniele | Melchiorri, Cristiano | Burgio, Calogero | Fersini, Giorgio | Conversano, Francesca | Piermattei, Viviana | Marcelli, Marco
Underwater noise assessment is particularly important in coastal areas where a wide range of natural and anthropogenic sounds generate complex and variable soundscapes. In the last century, the number and size of noise sources has increased significantly, thereby increasing the ocean's background noise. Shipping is the main source of lower-frequency underwater noises (<500 Hz). This research aimed to provide an initial assessment of underwater noise levels in a coastal area of the northern Tyrrhenian Sea (Italy) using short-term recordings. Spatial and temporal variations in the noise level, and the type and number of ships sailing through the port were recorded. A significant correlation was found between ferry boats and sound pressure levels, indicating their role as a prevalent source of low frequency underwater noise in the project area. This research could provide the baseline for implementation of distribution and point-source underwater noise models that are required for sustainable coastal management.
Afficher plus [+] Moins [-]Experimental and modeled thermoregulatory costs of repeated sublethal oil exposure in the Double-crested Cormorant, Phalacrocorax auritus Texte intégral
2018
Mathewson, Paul D. | Hanson-Dorr, Katie C. | Porter, Warren P. | Bursian, Steven J. | Dean, Karen M. | Healy, Kate | Horak, Katherine | Link, Jane E. | Harr, K.E. | Dorr, Brian S.
To fully understand the impact of oil exposure, it is important to understand sublethal effects like how increased thermoregulatory costs may affect survival and reproduction. However, it is difficult and time-consuming to measure these effects in wild animals. We present a novel use of a bioenergetics model, Niche Mapper™, to estimate thermoregulatory impacts of oiling, using data from captive Double-crested Cormorants (Phalacrocorax auritus) experimentally exposed to oil. Oiled cormorants had significant increases in surface body temperatures following exposure. Niche Mapper accurately predicted surface temperatures and metabolic rates for unoiled and oiled cormorants and predicted 13–18% increased daily energetic demands due to increased thermoregulatory costs of oiling, consistent with increased food consumption observed in experimentally oiled cormorants. We show that Niche Mapper can provide valuable insight into sublethal oiling effects by quantifying the extent to which thermoregulatory costs divert energy resources away from important life processes like maintenance, reproduction and migration.
Afficher plus [+] Moins [-]Carbon economy of Mediterranean seagrasses in response to thermal stress Texte intégral
2018
Marín-Guirao, L. | Bernardeau-Esteller, J. | García-Muñoz, R. | Ramos, A. | Ontoria, Y. | Romero, J. | Perets, Mikhaʼel ben Yosef | Ruiz, J.M. | Procaccini, G.
Carbon economy of Mediterranean seagrasses in response to thermal stress Texte intégral
2018
Marín-Guirao, L. | Bernardeau-Esteller, J. | García-Muñoz, R. | Ramos, A. | Ontoria, Y. | Romero, J. | Perets, Mikhaʼel ben Yosef | Ruiz, J.M. | Procaccini, G.
Increased plant mortality in temperate seagrass populations has been recently observed after summer heatwaves, although the underlying causes of plant death are yet unknown. The potential energetic constrains resulting from anomalous thermal events could be the reason that triggered seagrass mortality, as demonstrated for benthic invertebrates. To test this hypothesis, the carbon balance of Posidonia oceanica and Cymodocea nodosa plants from contrasting thermal environments was investigated during a simulated heatwave, by analyzing their photosynthetic performance, carbon balance (ratio photosynthesis:respiration), carbohydrates content, growth and mortality. Both species were able to overcome and recover from the thermal stress produced by the six-week exposure to temperatures 4 °C above mean summer levels, albeit plants from cold waters were more sensitive to warming than plants from warm waters as reflected by their inability to maintain their P:R ratio unaltered. The strategies through which plants tend to preserve their energetic status varied depending on the biology of the species and the thermal origin of plants. These included respiratory homeostasis (P. oceanica warm-plants), carbon diversion from growth to respiration (C. nodosa cold-plants) or storage (P. oceanica warm-plants) and changes in biomass allocation (C. nodosa warm-plants). Findings suggest an important geographic heterogeneity in the overall response of Mediterranean seagrasses to warming with potential negative impacts on the functions and services offered by seagrass meadows including among others their capacity for carbon sequestration and carbon export to adjacent ecosystems.
Afficher plus [+] Moins [-]Carbon economy of Mediterranean seagrasses in response to thermal stress Texte intégral
2018
Marín-Guirao, Lázaro | Bernardeau-Esteller, Jaime | García-Muñoz, María del RocíoR. | Ramos-Cartelle, Ana | Ontoria, Yaiza | Romero, J. | Pérez Rodríguez, Montse | Ruiz-Fernández, Juan Manuel | Procaccini, G.
Increased plant mortality in temperate seagrass populations has been recently observed after summer heatwaves, although the underlying causes of plant death are yet unknown. The potential energetic constrains resulting from anomalous thermal events could be the reason that triggered seagrass mortality, as demonstrated for benthic invertebrates. To test this hypothesis, the carbon balance of Posidonia oceanica and Cymodocea nodosa plants from contrasting thermal environments was investigated during a simulated heatwave, by analyzing their photosynthetic performance, carbon balance (ratio photosynthesis:respiration), carbohydrates content, growth and mortality. Both species were able to overcome and recover from the thermal stress produced by the six-week exposure to temperatures 4 °C above mean summer levels, albeit plants from cold waters were more sensitive to warming than plants from warm waters as reflected by their inability to maintain their P:R ratio unaltered. The strategies through which plants tend to preserve their energetic status varied depending on the biology of the species and the thermal origin of plants. These included respiratory homeostasis (P. oceanica warm-plants), carbon diversion from growth to respiration (C. nodosa cold-plants) or storage (P. oceanica warm-plants) and changes in biomass allocation (C. nodosa warm-plants). Findings suggest an important geographic heterogeneity in the overall response of Mediterranean seagrasses to warming with potential negative impacts on the functions and services offered by seagrass meadows including among others their capacity for carbon sequestration and carbon export to adjacent ecosystems | Peer reviewed
Afficher plus [+] Moins [-]An environmental risk assessment of three organic UV-filters at Lac Bay, Bonaire, Southern Caribbean Texte intégral
2018
Schaap, Iris | Slijkerman, Diana M.E.
Although organic UV filters (OUVFs) benefit human health by preventing skin burns and cancer, several studies revealed that organic UV filters can induce developmental and reproductive toxicity to aquatic organisms. Discharge of OUVFs occurs predominantly at marine recreational hotspots, such as Lac Bay, Bonaire, and is predicted to increase significantly due to growing tourism worldwide. Unfortunately, there is no insight what the current and future discharge of OUVF at Lac Bay is. Therefore, this study aimed to 1) measure concentrations and estimate the risk of specific OUVFs to different nursery habitats at Lac Bay, and 2) compare measured and predicted concentration based risk assessment outcome. Results showed that at least one of the three nurseries at Lac Bay had a potential for adverse effects. Furthermore, predicted environmental concentrations of UV filter discharge can be applied to gain more insight in the order of extent of OUVF discharge by marine tourism.
Afficher plus [+] Moins [-]Sorption behaviors of tris-(2,3-dibromopropyl) isocyanurate and hexabromocyclododecanes on polypropylene microplastics Texte intégral
2018
Liu, Xiaowen | Zheng, Minggang | Wang, Ling | Ke, Runhui | Lou, Yinghua | Zhang, Xiaojun | Dong, Xiaofeng | Zhang, Yu
In recent years, microplastics in oceans have become a serious environmental problem and the focus of attention. In the present study, the sorption of TBC and HBCDs by microplastics in simulated seawater is examined. The effects of particle size, temperature, salinity, and concentration on the adsorption of TBC and HBCDs by microplastics are studied. Results indicate that the first-order adsorption kinetic model is more suitable than the pseudo-second-order kinetic model to describe adsorption. The equilibrium adsorption times are 15 h and 10 h for TBC and HBCDs, respectively. The adsorption capacity increases with the decrease in particle size. The adsorption capacity gradually increases at first and then decreases with the increase in salinity and temperature. The maximum adsorption capacity is at 15 °C and 14% salinity. Compared with the linear and Freundlich models, the Langmuir model is more suitable; this indicates that the main adsorption mechanism might be chemical adsorption.
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