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Результаты 1411-1420 из 4,309
Characteristics of trace metals and phosphorus in seawaters offshore the Yangtze River Полный текст
2017
Su, Han | Yang, Rujun | Zhang, Aibin | Li, Yan | Qu, Shenglu | Wang, Xuchen
This study presents the spatial distribution of total dissolved Cu, Zn, Co, and V during an autumn survey in the East China Sea (ECS). Dissolved Fe and its organic complexation were also investigated. The present study aimed to evaluate the relationship between Cu, Zn, Co, V, D-Fe and its organic ligands and total dissolved phosphate (TDP) in the coastal waters of the ECS. A correlation analysis shows that Cu, Zn and D-Fe were nutrient-like metals, whereas Co and V were non-nutrient-like metals. A multivariate statistical analysis showed that TDP was associated with D-Fe, Cu, Zn and Co, but was not associated with V. Furthermore, TDP was observed to be positively related with D-Fe, while negatively with Fe′, which indicated that the limitation of TDP decreased the uptake of Fe′. This paper improves our understanding of the association among trace metals, TDP and phytoplankton biomass in the ECS.
Показать больше [+] Меньше [-]Effects of CO2-driven sediment acidification on infaunal marine bivalves: A synthesis Полный текст
2017
Clements, Jeff C. | Hunt, Heather L.
While ocean acidification (OA) effects on marine organisms are well documented, impacts of sediment acidification on infaunal organisms are relatively understudied. Here we synthesize CO2-driven sediment acidification effects on infaunal marine bivalves. While sediment carbonate system conditions can already exceed near-future OA projections, sediments can become even more acidic as overlying seawater pH decreases. Evidence suggests that infaunal bivalves experience shell dissolution, more lesions, and increased mortality in more acidic sediments; effects on heavy metal accumulation appear complex and uncertain. Infaunal bivalves can avoid negative functional consequences of sediment acidification by reducing burrowing and increasing dispersal in more acidic sediments, irrespective of species or life stage; elevated temperature may compromise this avoidance behaviour. The combined effects of sediment acidification and other environmental stressors are virtually unknown. While it is evident that sediment acidification can impact infaunal marine bivalves, more research is needed to confidently predict effects under future ocean conditions.
Показать больше [+] Меньше [-]Presence of plastic litter in pellets from Great Cormorant (Phalacrocorax carbo) in Ireland Полный текст
2017
Acampora, Heidi | Berrow, Simon | Newton, Stephen | O'Connor, Ian
Plastic pollution has been the subject of much research in the last decade. Seabirds can mistake plastic fragments for prey, which can perforate or block the digestive tract and cause ulcers. Most commonly, seabirds accumulate this indigestible matter in their stomachs, obtaining no nutrition and may die from starvation. Certain species of seabirds however, have the ability of regurgitating indigestible matter in the form of pellets. This study aimed to investigate the ingestion of plastics by live seabirds through the examination of regurgitated pellets (n=92) from a Great Cormorant (Phalacrocorax carbo) breeding colony and a winter roost in Ireland. Plastic prevalence was consistently 3.2% at both sites. The presence of plastic litter highlights the fact that all species of seabird are susceptible to interact with marine litter regardless of feeding habits, although at different rates. More research is needed to understand the driving factors involved in plastic ingestion among different species.
Показать больше [+] Меньше [-]Trace element concentrations in reef associated sediments of Koswari Island, Gulf of Mannar biosphere reserve, southeast coast of India Полный текст
2017
Krishnakumar, S. | Ramasamy, S. | Chandrasekar, N. | Simon Peter, T. | Gopal, V. | Godson, Prince S. | Magesh, N.S.
Extensive field work was conducted in order to assess the sediment pollution level and potential ecological risk on coral reef ecosystem. Thirty three surface sample was collected using grid sampling technique. The calcium carbonate and organic matter were primarily controlled by the distribution of coral rubbles and seagrass meadows. The concentration of trace elements is higher than the crustal average in few locations and the same result was derived from index calculations. However, the significant concentration of lead was observed throughout the study area. The elevated level of lead is probably due to coal incinerating power plants, and confluence of urban runoff from the nearby coastal areas. Based on the sediment pollution index, the majority of the sediments belongs to highly polluted to dangerously polluted category. The ecological risk indicates that the sediments are under low risk to moderate risk category and this result was proved by correlation analysis.
Показать больше [+] Меньше [-]Characterizing light attenuation within Northwest Florida Estuaries: Implications for RESTORE Act water quality monitoring Полный текст
2017
Conmy, Robyn N. | Schaeffer, Blake A. | Schubauer-Berigan, Joseph | Aukamp, Jessica | Duffy, Allyn | Lehrter, John C. | Greene, Richard M.
Water Quality (WQ) condition is based on ecosystem stressor indicators (e.g. water clarity) which are biogeochemically important and critical when considering the Deepwater Horizon oil spill restoration efforts under the 2012 RESTORE Act. Nearly all of the proposed RESTORE projects list restoring WC as a goal, but 90% neglect water clarity. Here, dynamics of optical constituents impacting clarity are presented from a 2009–2011 study within Pensacola, Choctawhatchee, St. Andrew and St. Joseph estuaries (targeted RESTORE sites) in Northwest Florida. Phytoplankton were the smallest contribution to total absorption (at-wPAR) at 412nm (5–11%), whereas colored dissolved organic matter was the largest (61–79%). Estuarine at-wPAR was significantly related to light attenuation (KdPAR), where individual contributors to clarity and the influence of climatic events were discerned. Provided are conversion equations demonstrating interoperability of clarity indicators between traditional State-measured WQ measures (e.g. secchi disc), optical constituents, and even satellite remote sensing for obtaining baseline assessments.
Показать больше [+] Меньше [-]Mid-Atlantic elasmobranchs: Suitable metal scouts? Полный текст
2017
Torres, Paulo | Tristão da Cunha, Regina | Rodrigues, Armindo dos Santos
Heavy metals are a hazard to marine fauna and human health. In this study we assess stable isotopes and metal content in Prionace glauca and Isurus oxyrinchus and analyse these results within and among other species and across regions and geographical areas. Also, we evaluate their suitability, together with Raja clavata and Galeorhinus galeus, as Mid-Atlantic bioindicators. Prionace glauca and I. oxyrinchus shared the same trophic level in a pelagic food web and did not present significant differences between genders or metals, except for As. Arsenic and Hg accumulated while Cd and Pb were not detected. One I. oxyrinchus presented Hg values above regulatory limits. A high Hg exposure was associated with I. oxyrinchus since its maximum weekly intake was exceeded. Elasmobranchs can be used as metal sentinels, each presenting different key features which defines a good marine bioindicator, allowing long-term monitoring at different temporal and spatial scales.
Показать больше [+] Меньше [-]Impacts of turbidity on corals: The relative importance of light limitation and suspended sediments Полный текст
2017
Bessell-Browne, Pia | Negri, Andrew P. | Fisher, Rebecca | Clode, Peta L. | Duckworth, Alan | Jones, Ross
As part of an investigation of the effects of water quality from dredging/natural resuspension on reefs, the effects of suspended sediment concentrations (SSCs) (0, 30, 100mgL−1) and light (~0, 1.1, 8.6molphotonsm−2d−1) were examined alone and in combination, on the corals Acropora millepora, Montipora capricornis and Porites spp. over an extended (28d) period. No effects were observed at any sediment concentrations when applied alone. All corals in the lowest light treatments lost chlorophyll a and discoloured (bleached) after a week. Coral mortality only occurred in the two lowest light treatments and was higher when simultaneously exposed to elevated SSCs. Compared to water quality data collected during large dredging programs and natural resuspension events (and in the absence of sediment deposition as a cause-effect pathway) these data suggest the light reduction associated with turbidity poses a proportionally greater risk than effects of elevated SSCs alone.
Показать больше [+] Меньше [-]Superstars: Assessing nutrient thresholds for enhanced larval success of Acanthaster planci, a review of the evidence Полный текст
2017
Wolfe, Kennedy | Graba-Landry, Alexia | Dworjanyn, Symon A. | Byrne, Maria
Crown-of-thorns starfish, Acanthaster planci (COTS), predation is a major cause of coral reef decline, but the factors behind their population outbreaks remain unclear. Increased phytoplankton food resulting from eutrophication is suggested to enhance larval survival. We addressed the hypothesis that larval success is associated with particular chl-a levels in tightly controlled larval:algal conditions. We used chl-a conditions found on coral reefs (0.1–5.0μgchl-aL−1), including nominal threshold levels for disproportionate larval success (≥1.0μgchl-aL−1). High success to the juvenile occurred across an order of magnitude of chl-a concentrations (0.5–5.0μgchl-aL−1), suggesting there may not be a narrow value for optimal success. Oligotrophic conditions (0.1μgchl-aL−1) appeared to be a critical limit. With a review of the evidence, we suggest that opportunistic COTS larvae may be more resilient to low food levels than previously appreciated. Initiation of outbreak populations need not require eutrophic conditions.
Показать больше [+] Меньше [-]Assessment and source identification of pollution risk for touristic ports: Heavy metals and polycyclic aromatic hydrocarbons in sediments of 4 marinas of the Apulia region (Italy) Полный текст
2017
Mali, Matilda | Dell'Anna, Maria Michela | Mastrorilli, Piero | Damiani, Leonardo | Piccinni, Alberto Ferruccio
The Apulia region in Italy has the longest Adriatic coastline; thus, maritime tourism is the driving force for its economic development. Pollution risk for four representative touristic ports of the region was assessed by determining the concentrations of 10 metals, 16 polycyclic aromatic hydrocarbons (PAHs) congeners, and the main nutrients. The cumulative mean Effects Range–Median quotient (mERMq) was used to assess the hazard degree, while the distribution patterns and content ratios of different PAH sediment concentrations were investigated to identify the pollution sources. Principal component analyses indicated an anomalous pollution trend for one of the small touristic ports assessed; this trend emerged from contamination by heavy metals and PAHs to a larger extent than expected, considering the main activity in this port, especially in its inner basin. The reason of this anomaly is thought to be the hydrodynamic and/or other stress factors.
Показать больше [+] Меньше [-]Selective suppression of in situ proliferation of scyphozoan polyps by biofouling Полный текст
2017
Feng, Song | Wang, Shi-Wei | Zhang, Guang-Tao | Sun, Song | Zhang, Fang
An increase in marine artificial constructions has been proposed as a major cause of jellyfish blooms, because these constructions provide additional substrates for organisms at the benthic stage (polyps), which proliferate asexually and release a large amount of free-swimming medusae. These hard surfaces are normally covered by fouling communities, the components of which have the potential to impede the proliferation of polyps. In this study, we report an in situ experiment of polyp survival of four large scyphozoan species found in East Asian marginal seas that were exposed to biofouling, a universal phenomenon occurring on marine artificial constructions. Our results showed that the polyps of three species (Nemopilema nomurai, Cyanea nozaki, and Rhopilema esculentum) attached to the artificial surfaces were completely eliminated by biofouling within 7–8months, and only those of moon jellyfish (Aurelia sp.1) in the upper layers could multiply on both artificial materials and other organisms (e.g., ascidians and bryozoans). Fouling-associated competition and predation and suppressed asexual reproduction of podocysts were observed to contribute to the loss of polyps. This study shows that the natural distribution of polyps is defined by the biofouling community that colonizes the surfaces of artificial constructions. Consequently, the contribution of marine constructions to jellyfish bloom is limited only to the ability of the jellyfish species to reproduce asexually through budding and inhabit solid surfaces of fouling organisms in addition to inhabiting original artificial materials.We anticipate that fragile polyps will colonize and proliferate in harsh environments that are deleterious to biofouling, and we propose special attention to polyps in antifouling practices for excluding the possibility that they occupy the available ecological space.
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