Refine search
Results 1741-1750 of 5,149
Sediment characteristics influence the fertilisation success of the corals Acropora tenuis and Acropora millepora Full text
2018
Ricardo, Gerard F. | Jones, Ross J. | Clode, Peta L. | Humanes, Adriana | Giofre, Natalie | Negri, Andrew P.
Elevated suspended sediment concentrations (SSCs) often impact coral fertilisation success, but sediment composition can influence effect thresholds, which is problematic for accurately predicting risk. Here, we derived concentration–response thresholds and cause-effect pathways for SSCs comprising a range of realistic mineral and organic compositions on coral fertilisation success. Effect concentration thresholds (EC10: 10% fertilisation inhibition) varied markedly, with fertilisation highly sensitive to inshore organic-clay rich sediments and bentonite clay at <5 mg L−1. Mineral clays and organic matter within these sediments likely promoted flocculation of the coral sperm, which in turn reduced fertilisation. In contrast, sediments lacking these properties bound less sperm, leading to higher SSC thresholds for coral fertilisation (EC10 > 40 mg L−1). The effect thresholds for relevant sediment types were combined with in situ turbidity data from locations near dredging operations to assess the risks posed by dredging to coral fertilisation at these locations.
Show more [+] Less [-]The potential for dispersant use as a maritime oil spill response measure in German waters Full text
2018
Grote, Matthias | van Bernem, Carlo | Böhme, Birgit | Callies, Ulrich | Calvez, Ivan | Christie, Bernard | Colcomb, Kevin | Damian, Hans-Peter | Farke, Hubert | Gräbsch, Carolin | Hunt, Alex | Höfer, Thomas | Knaack, Jürgen | Kraus, Uta | Le Floch, Stephane | Le Lann, Gilbert | Leuchs, Heiko | Nagel, Almut | Nies, Hartmut | Nordhausen, Walter | Rauterberg, Jens | Reichenbach, Dirk | Scheiffarth, Gregor | Schwichtenberg, Fabian | Theobald, Norbert | Voss, Joachim | Wahrendorf, Dierk-Steffen
The potential for dispersant use as a maritime oil spill response measure in German waters Full text
2018
Grote, Matthias | van Bernem, Carlo | Böhme, Birgit | Callies, Ulrich | Calvez, Ivan | Christie, Bernard | Colcomb, Kevin | Damian, Hans-Peter | Farke, Hubert | Gräbsch, Carolin | Hunt, Alex | Höfer, Thomas | Knaack, Jürgen | Kraus, Uta | Le Floch, Stephane | Le Lann, Gilbert | Leuchs, Heiko | Nagel, Almut | Nies, Hartmut | Nordhausen, Walter | Rauterberg, Jens | Reichenbach, Dirk | Scheiffarth, Gregor | Schwichtenberg, Fabian | Theobald, Norbert | Voss, Joachim | Wahrendorf, Dierk-Steffen
In case of an oil spill, dispersant application represents a response option, which enhances the natural dispersion of oil and thus reduces coating of seabirds and coastal areas. However, as oil is transferred to the water phase, a trade-off of potential harmful effects shifted to other compartments must be performed. This paper summarizes the results of a workshop on the current knowledge on risks and benefits of the use of dispersants with respect to specific conditions encountered at the German sea areas. The German North Sea coast is a sensitive ecosystem characterised by tidal flats, barrier islands and salt marshes. Many prerequisites for a potential integration of dispersants as spill response option are available in Germany, including sensitivity maps and tools for drift modelling of dispersed and undispersed oil. However, open scientific questions remain concerning the persistence of dispersed oil trapped in the sediments and potential health effects.
Show more [+] Less [-]The potential for dispersant use as a maritime oil spill response measure in German waters. Full text
2018
Grote, Matthias | van Bernem, Carlo | Böhme, Birgit | Callies, Ulrich | Calvez, Ivan | Christie, Bernard | Colcomb, Kevin | Damian, Hans-Peter | Farke, Hubert | Gräbsch, Carolin | Hunt, Alex | Höfer, Thomas | Knaack, Jürgen | Kraus, Uta | Le Floch, Stephane | Le Lann, Gilbert | Leuchs, Heiko | Nagel, Almut | Nies, Hartmut | Nordhausen, Walter | Rauterberg, Jens | Reichenbach, Dirk | Scheiffarth, Gregor | Schwichtenberg, Fabian | Theobald, Norbert | Voß, Joachim | Wahrendorf, Dierk-Steffen
In case of an oil spill, dispersant application represents a response option, which enhances the natural dispersion of oil and thus reduces coating of seabirds and coastal areas. However, as oil is transferred to the water phase, a trade-off of potential harmful effects shifted to other compartments must be performed. This paper summarizes the results of a workshop on the current knowledge on risks and benefits of the use of dispersants with respect to specific conditions encountered at the German sea areas. The German North Sea coast is a sensitive ecosystem characterised by tidal flats, barrier islands and salt marshes. Many prerequisites for a potential integration of dispersants as spill response option are available in Germany, including sensitivity maps and tools for drift modelling of dispersed and undispersed oil. However, open scientific questions remain concerning the persistence of dispersed oil trapped in the sediments and potential health effects.
Show more [+] Less [-]Bioaccumulation and biomagnification of potentially toxic elements in the octopus Octopus hubbsorum from the Gulf of California Full text
2018
Roldán-Wong, Nefertiti Taydé | Kidd, Karen A. | Marmolejo-Rodríguez, Ana Judith | Ceballos-Vázquez, Bertha Patricia | Shumilin, Evgueni | Arellano-Martínez, Marcial
The concentrations of 21 potentially toxic elements (PTEs) were determined in the tissues of Octopus hubbsorum from three locations along the Gulf of California coast: two near Santa Rosalia (SR), a site with historical metal contamination, and one in La Paz Bay, a reference site. Concentrations of Cd, Co, Cr, Mn, Ni, Pb, and Zn in octopus from the two SR sites were higher than those from the reference site, reflecting the higher sediment concentrations at the mining-impacted locations. The highest bioaccumulation and biomagnification of elements was found in digestive gland and branchial hearts, while the lowest was observed in the mantle, where the mean concentration of PTEs did not exceed international standards for human consumption of octopus. This study found elevated PTEs in octopus from sites with high metal contamination, and presents the first data on these elements in octopus from the Gulf of California.
Show more [+] Less [-]Chemical characteristics of dissolved mercury in the pore water of Minamata Bay sediments Full text
2018
Matsuyama, Akito | Yano, Shinichiro | Taninaka, Takaaki | Kindaichi, Michiaki | Sonoda, Ikuko | Tada, Akihide | Akagi, Hirokatsu
Methylmercury concentrations in fish from the historically polluted Minamata Bay remain higher than in fish from other coastal seas around Japan. To obtain a better understanding of this phenomenon, the chemical characteristics of pore water from Minamata Bay sediments were investigated. Samples were taken from two stations over a 1-year period. Total average values in the pore water at the two stations for dissolved total mercury and methylmercury concentrations were 6.64±4.93 and 2.69±2.07ng/l, respectively. The pore water was centrifuged at 1000rpm to 3000rpm. The highest ratio of dissolved methylmercury to dissolved total mercury exceeded 60% for pore water centrifuged at 3000rpm. Furthermore, because total average values of Log Kd of total mercury and methylmercury in sediment (St1 and St2) were 5.42 and 2.32 (Lkg−1), methylmercury in Minamata Bay sediment is more eluted than other mercury species.
Show more [+] Less [-]Oxidative conversion of potential perfluoroalkyl acid precursors in Jiaozhou Bay and nearby rivers and sewage treatment plant effluent in China Full text
2018
Wang, Shiliang | Cao, Xuezhi | Zhang, Hui | Yang, Yuewei | Zhang, Min
Precursors that can be transformed into perfluoroalkyl acids (PFAAs) have not been investigated in detail. In this study, the levels of potential PFAA precursors in the Jiaozhou Bay, inflowing rivers, and STP (sewage treatment plant) effluents were investigated by converting all PFAA precursors into perfluorinated carboxylic acids (PFCAs) by chemical oxidation. The significance of controlling PFAA precursors was indicated by the ratios of PFCAs converted by the oxidative treatment of precursors to PFAAs before oxidation (∑△[PFCAC4-C12]/∑[PFAA]before oxidation). The higher levels of △[PFCAC4-C12] (average = 18.89 ng/L) and lower ratios (∑△[PFCAC4-C12]/∑[PFAA]before oxidation, average = 0.21) were revealed in the STP effluents rather than in the water of the Jiaozhou Bay and rivers, which implied the precursors conversion during the sewage treatment process. The concentrations of △[PFCAs] and the aforementioned ratios showed apparent spatial and temporal differences. These results indicated that STPs were the important sources of precursors to other water bodies.
Show more [+] Less [-]Combined effects of fishing and oil spills on marine fish: Role of stock demographic structure for offspring overlap with oil Full text
2018
Stige, Leif Chr | Ottersen, Geir | Yaragina, Natalia A. | Vikebø, Frode B. | Stenseth, Nils Chr | Langangen, Øystein
Combined effects of fishing and oil spills on marine fish: Role of stock demographic structure for offspring overlap with oil Full text
2018
Stige, Leif Chr | Ottersen, Geir | Yaragina, Natalia A. | Vikebø, Frode B. | Stenseth, Nils Chr | Langangen, Øystein
It has been proposed that the multiple pressures of fishing and petroleum activities impact fish stocks in synergy, as fishing-induced demographic changes in a stock may lead to increased sensitivity to detrimental effects of acute oil spills. High fishing pressure may erode the demographic structure of fish stocks, lead to less diverse spawning strategies, and more concentrated distributions of offspring in space and time. Hence an oil spill may potentially hit a larger fraction of a year-class of offspring. Such a link between demographic structure and egg distribution was recently demonstrated for the Northeast Arctic stock of Atlantic cod for years 1959–1993. We here estimate that this variation translates into a two-fold variation in the maximal proportion of cod eggs potentially exposed to a large oil spill. With this information it is possible to quantitatively account for demographic structure in prospective studies of population effects of possible oil spills.
Show more [+] Less [-]Combined effects of fishing and oil spills on marine fish: Role of stock demographic structure for offspring overlap with oil Full text
2018
Stige, Leif Christian | Ottersen, Geir | Yaragina, Nathalia A. | Vikebø, Frode Bendiksen | Stenseth, Nils Christian | Langangen, Øystein
It has been proposed that the multiple pressures of fishing and petroleum activities impact fish stocks in synergy, as fishing-induced demographic changes in a stock may lead to increased sensitivity to detrimental effects of acute oil spills. High fishing pressure may erode the demographic structure of fish stocks, lead to less diverse spawning strategies, and more concentrated distributions of offspring in space and time. Hence an oil spill may potentially hit a larger fraction of a year-class of offspring. Such a link between demographic structure and egg distribution was recently demonstrated for the Northeast Arctic stock of Atlantic cod for years 1959–1993. We here estimate that this variation translates into a two-fold variation in the maximal proportion of cod eggs potentially exposed to a large oil spill. With this information it is possible to quantitatively account for demographic structure in prospective studies of population effects of possible oil spills.
Show more [+] Less [-]Combined effects of fishing and oil spills on marine fish: Role of stock demographic structure for offspring overlap with oil Full text
2018
Stige, Leif Christian | Ottersen, Geir | Yaragina, Nathalia A. | Vikebø, Frode Bendiksen | Stenseth, Nils Christian | Langangen, Øystein
It has been proposed that the multiple pressures of fishing and petroleum activities impact fish stocks in synergy, as fishing-induced demographic changes in a stock may lead to increased sensitivity to detrimental effects of acute oil spills. High fishing pressure may erode the demographic structure of fish stocks, lead to less diverse spawning strategies, and more concentrated distributions of offspring in space and time. Hence an oil spill may potentially hit a larger fraction of a year-class of offspring. Such a link between demographic structure and egg distribution was recently demonstrated for the Northeast Arctic stock of Atlantic cod for years 1959–1993. We here estimate that this variation translates into a two-fold variation in the maximal proportion of cod eggs potentially exposed to a large oil spill. With this information it is possible to quantitatively account for demographic structure in prospective studies of population effects of possible oil spills. | acceptedVersion
Show more [+] Less [-]Seasonal variations and environmental risk assessment of trace elements in the sediments of Uppanar River estuary, southern India Full text
2018
Gopal, V. | Nithya, B. | Magesh, N.S. | Jayaprakash, M.
Twenty four surface sediments were gathered from the Uppanar river estuary, southern India to evaluate the trace element contamination risk in the sediments. The circulation of organic matter and calcium carbonate were controlled by algal blooms and shell fragments. Moreover, the concentrations of iron and manganese in the estuarine sediments were possibly contributed by riverine sources and geogenic processes. The geoaccumulation index, enrichment factor and contamination factor reveals that the sediments were contaminated by copper and chromium. The pollution load index recommends that the estuarine sediments have the risk of pollution. The sediment pollution index highlights that the majority of the sediments are low polluted sediments. The potential ecological risk index discloses that the Uppanar river estuary is under moderate risk. The statistical analysis reveals that the organic matter content is managed by fine fractions and the majority of the trace elements are associated with each other having similar origin.
Show more [+] Less [-]Long-term variations and influence factors of nutrients in the western North Yellow Sea, China Full text
2018
Yang, Fuxia | Wei, Qinsheng | Chen, Hongtao | Yao, Qingzhen
This study investigated the long-term variations and compositions of nutrients and the associated controlling factors in the western North Yellow Sea on the basis of historical data. The NO3-N and DIN concentrations and N/P showed continuous increases over the past two decades, which were dominantly affected by riverine inputs, such as inputs from the Yellow River, Yalujiang River and Jia River and atmospheric deposition. However, due to human activities, such as dam construction in rivers and climate change, the SiO3-Si concentrations and Si/P ratios decreased before the early 1990s and then gradually increased. The vertical distributions of nutrients displayed higher concentrations at the bottom than those at the surface in summer, which was attributed to the combined influence of the thermocline, the Yellow Sea Cold Water Mass, the Yellow Sea Warm Current and biological activities.
Show more [+] Less [-]Microplastics pollution in different aquatic environments and biota: A review of recent studies Full text
2018
Rezania, Shahabaldin | Park, Junboum | Md Din, Mohd Fadhil | Mat Taib, Shazwin | Talaiekhozani, Amirreza | Kumar Yadav, Krishna | Kamyab, Hesam
Microplastics (MPs) are generated from plastic and have negative impact to our environment due to high level of fragmentation. They can be originated from various sources in different forms such as fragment, fiber, foam and so on. For detection of MPs, many techniques have been developed with different functions such as microscopic observation, density separation, Raman and FTIR analysis. Besides, due to ingestion of MPs by wide range of marine species, research on the effect of this pollution on biota as well as human is vital. Therefore, we comprehensively reviewed the occurrence and distribution of MPs pollution in both marine and freshwater environments, including rivers, lakes and wastewater treatment plants (WWTPs). For future studies, we propose the development of new techniques for sampling MPs in aquatic environments and biota and recommend more research regarding MPs release by WWTPs.
Show more [+] Less [-]Contribution of individual rivers to Great Barrier Reef nitrogen exposure with implications for management prioritization Full text
2018
Wolff, Nicholas H. | da Silva, Eduardo Teixeira | Devlin, Michelle | Anthony, Kenneth R.N. | Lewis, Stephen | Tonin, Hemerson | Brinkman, Richard | Mumby, P. J. (Peter J.)
Dissolved inorganic nitrogen (DIN) runoff from Great Barrier Reef (GBR) catchments is a threat to coral reef health. Several initiatives address this threat, including the Australian Government's Reef 2050 Plan. However, environmental decision makers face an unsolved prioritization challenge: determining the exposure of reefs to DIN from individual rivers. Here, we use virtual river tracers embedded within a GBR-wide hydrodynamic model to resolve the spatial and temporal dynamics of 16 individual river plumes during three wet seasons (2011−2013). We then used in-situ DIN observations to calibrate tracer values, allowing us to estimate the contribution of each river to reef-scale DIN exposure during each season. Results indicate that the Burdekin, Fitzroy, Tully and Daintree rivers pose the greatest DIN exposure risk to coral reefs during the three seasons examined. Results were used to demonstrate a decision support framework that combines reef exposure risk with river dominance (threat diversity).
Show more [+] Less [-]