细化搜索
结果 921-930 的 2,512
Variability of factors driving spatial and temporal dispersion in river plume and Chattonella antiqua bloom in the Yatsushiro Sea, Japan 全文
2014
Aoki, Kazuhiro | Onitsuka, Goh | Shimizu, Manabu | Kuroda, Hiroshi | Matsuo, Hitoshi | Kitadai, Yuuki | Sakurada, Kiyonari | Ando, Hidenori | Nishi, Hiromi | Tahara, Yoshio
The dynamics of river plume in relation to harmful blooms of the raphidophycean flagellate, Chattonella antiqua in summer 2008–2010 in the Yatsushiro Sea, Japan were studied using a hydrodynamic model and monitoring data. In the southern area, the bloom formed in the waters stratified by a halocline caused by the southward expansion of riverine water from the Kuma River after the bloom initially forming in the northern area. The timing of the southward riverine water advection can be explained by the balance between the wind stress term and the pressure gradient term calculated from the horizontal density difference between the northern and southern areas. The wind stress and pressure gradient terms were evaluated using the sea surface temperature, salinity, wind speed and direction at two stations. Real time monitoring or continuous observations in these areas will enable nowcasts of bloom expansion when a bloom develops in the northern area.
显示更多 [+] 显示较少 [-]Acute hypoxic exposure affects gamete quality and subsequent fertilization success and embryonic development in a serpulid polychaete 全文
2014
Shin, P.K.S. | Leung, J.Y.S. | Qiu, J.W. | Ang, P.O. | Chiu, J.M.Y. | Thiyagarajan, V. | Cheung, S.G.
Hypoxia likely compromises the reproductive success of those marine organisms carrying out external fertilization because their gametes and embryos are inevitably exposed to the external environment. Hydroides elegans, a dominant serpulid polychaete in Hong Kong waters, can spawn throughout the year but the number of recruits drops during summer when hypoxia commonly occurs. This study attempted to explain such observation by investigating the gamete quality, including sperm motility, egg size, complexity and viability, after 1-h hypoxic exposure (1mg O2l−1). In addition, how gamete quality affects fertilization success and embryonic development was examined. After 1-h hypoxic exposure, sperm motility was significantly reduced, compromising fertilization success. Although the eggs remained viable, more malformed embryos and retarded embryonic development were observed. We interpreted that the harmful effect of hypoxia on embryonic development was attributed to the teratogenicity and induced oxidative stress, ultimately causing the reduction in recruitment during summer.
显示更多 [+] 显示较少 [-]Heavy metal concentration in mangrove surface sediments from the north-west coast of South America 全文
2014
Fernández-Cadena, J.C. | Andrade, S. | Silva-Coello, C.L. | De la Iglesia, R.
Mangrove ecosystems are coastal estuarine systems confined to the tropical and subtropical regions. The Estero Salado mangrove located in Guayaquil, Ecuador, has suffered constant disturbances during the past 20years, due to industrial wastewater release. However, there are no published data for heavy metals present in its sediments and the relationship with anthropogenic disturbance. In the present study, metal concentrations were evaluated in surface sediment samples of the mangrove, showing that B, Cd, Cu, Pb, Se, V, and Zn levels exceeded those declared in international environmental quality standards. Moreover, several metals (Pb, Sn, Cd, Ag, Mo, Zn and Ni) could be linked to the industrial wastewater present in the studied area. In addition, heavy metal levels detected in this mangrove are higher than previous reports on mangrove sediments worldwide, indicating that this mangrove ecosystem is one of the most disrupted on earth.
显示更多 [+] 显示较少 [-]A fault tree model to assess probability of contaminant discharge from shipwrecks 全文
2014
Landquist, H. | Rosen, L. | Lindhe, A. | Norberg, T. | Hassellöv, I.-M. | Lindgren, J.F. | Dahllöf, I.
Shipwrecks on the sea floor around the world may contain hazardous substances that can cause harm to the marine environment. Today there are no comprehensive methods for environmental risk assessment of shipwrecks, and thus there is poor support for decision-making on prioritization of mitigation measures. The purpose of this study was to develop a tool for quantitative risk estimation of potentially polluting shipwrecks, and in particular an estimation of the annual probability of hazardous substance discharge. The assessment of the probability of discharge is performed using fault tree analysis, facilitating quantification of the probability with respect to a set of identified hazardous events. This approach enables a structured assessment providing transparent uncertainty and sensitivity analyses. The model facilitates quantification of risk, quantification of the uncertainties in the risk calculation and identification of parameters to be investigated further in order to obtain a more reliable risk calculation.
显示更多 [+] 显示较少 [-]Deep-sea faunal communities associated with a lost intermodal shipping container in the Monterey Bay National Marine Sanctuary, CA 全文
2014
Taylor, Josi R. | DeVogelaere, Andrew P. | Burton, Erica Janis | Frey, Oren | Lundsten, Lonny | Kuhnz, Linda Ann | Whaling, P.J. | Lovera, Christopher | Buck, Kurt R. | Barry, James P.
Carrying assorted cargo and covered with paints of varying toxicity, lost intermodal containers may take centuries to degrade on the deep seafloor. In June 2004, scientists from Monterey Bay Aquarium Research Institute (MBARI) discovered a recently lost container during a Remotely Operated Vehicle (ROV) dive on a sediment-covered seabed at 1281m depth in Monterey Bay National Marine Sanctuary (MBNMS). The site was revisited by ROV in March 2011. Analyses of sediment samples and high-definition video indicate that faunal assemblages on the container’s exterior and the seabed within 10m of the container differed significantly from those up to 500m. The container surface provides hard substratum for colonization by taxa typically found in rocky habitats. However, some key taxa that dominate rocky areas were absent or rare on the container, perhaps related to its potential toxicity or limited time for colonization and growth. Ecological effects appear to be restricted to the container surface and the benthos within ∼10m.
显示更多 [+] 显示较少 [-]PAH concentrations in Coquina (Donax spp.) on a sandy beach shoreline impacted by a marine oil spill 全文
2014
Snyder, Richard A. | Vestal, Alexandra | Welch, Christina | Barnes, Gracie | Pelot, Robert | Ederington-Hagy, Melissa | Hileman, Fredrick
The BP MC252 well failure in the Gulf of Mexico, April 2010 caused concern for crude oil and polycyclic aromatic hydrocarbon (PAHs) exposure along the sandy beaches of the Florida Panhandle. We began collections of Coquina clams (Donax spp.) from the surf zone of Florida Panhandle beaches to monitor PAH contamination to compliment analysis of surf zone sand samples. These clams had higher levels of PAHs relative to ambient sand, and this allowed us to continue to monitor PAH levels after sand concentrations fell below limits of detection. PAH levels in the Coquina tissues were highly variable, perhaps indicative of the heterogeneous distribution of oil and tar on the beaches and exposure to tar particles. Overall, PAH levels decreased continuously in both sand and Coquina tissues, reaching limits of detection within one and two years respectively after oil landed on Florida Panhandle beaches. Our work suggests these surf zone molluscs may be used to monitor pollutant exposure along high energy sandy beach shorelines.
显示更多 [+] 显示较少 [-]Regulation of solid waste management at Brazilian ports: Analysis and proposals for Brazil in light of the European experience 全文
2014
Jaccoud, Cristiane | Magrini, Alessandra
With a coastline of 8500km, Brazil has 34 public ports and various private terminals, which together in 2012 handled 809 million tonnes of goods. The solid wastes produced (from port activities, ships and cargoes) pose a highly relevant problem, both due to the quantity and diversity, requiring a complex and integrated set of practices resulting from legal requirements and proactive initiatives. The main Brazilian law on solid waste management is recent (Law 12,305/2010) and the specific rules on solid waste in ports are badly in need of revision to meet the challenges caused by expansion of the sector and to harmonize them with the best global practices. This paper analyzes the current legal/regulatory framework for solid waste management at Brazilian ports and compares this structure with the practice in Europe. At the end, we suggest initiatives to improve the regulation of solid wastes at Brazilian ports.
显示更多 [+] 显示较少 [-]An alert system for triggering different levels of coastal management urgency: Tunisia case study using rapid environmental assessment data 全文
2014
Price, A.R.G. | Jaoui, K. | Pearson, M.P. | Jeudy de Grissac, A.
Rapid environmental assessment (REA) involves scoring abundances of ecosystems/species groups and magnitude of pressures, concurrently, using the same logarithmic (0–6) assessment scale. We demonstrate the utility of REA data for an alert system identifying different levels of coastal management concern. Thresholds set for abundances/magnitudes, when crossed, trigger proposed responses. Kerkennah, Tunisia, our case study, has significant natural assets (e.g. exceptional seagrass and invertebrate abundances), subjected to varying levels of disturbance and management concern. Using REA thresholds set, fishing, green algae/eutrophication and oil occurred at ‘low’ levels (scores 0–1): management not (currently) necessary. Construction and wood litter prevailed at ‘moderate’ levels (scores 2–4): management alerted for (further) monitoring. Solid waste densities were ‘high’ (scores 5–6): management alerted for action; quantities of rubbish were substantial (20–200itemsm−1 beach) but not unprecedented. REA is considered a robust methodology and complementary to other rapid assessment techniques, environmental frameworks and indicators of ecosystem condition.
显示更多 [+] 显示较少 [-]Sperm swimming in the polychaete Galeolaria caespitosa shows substantial inter-individual variability in response to future ocean acidification 全文
2014
Schlegel, Peter | Havenhand, Jon N. | Obadia, Nicolas | Williamson, Jane E.
Sperm swimming in the polychaete Galeolaria caespitosa shows substantial inter-individual variability in response to future ocean acidification 全文
2014
Schlegel, Peter | Havenhand, Jon N. | Obadia, Nicolas | Williamson, Jane E.
The rapidity of ocean acidification intensifies selection pressure for resilient phenotypes, particularly during sensitive early life stages. The scope for selection is greater in species with greater within-species variation in responses to changing environments, thus enhancing the potential for adaptation. We investigated among-male variation in sperm swimming responses (percent motility and swimming speeds) of the serpulid polychaete Galeolaria caespitosa to near- (ΔpH −0.3) and far-future ocean acidification (ΔpH −0.5). Responses of sperm swimming to acidification varied significantly among males and were overall negative. Robust sperm swimming behavior under near-future ocean acidification in some males may ameliorate climate change impacts, if traits associated with robustness are heritable, and thereby enhance the potential for adaptation to far-future conditions. Reduced sperm swimming in the majority of male G. caespitosa may decrease their fertilization success in a high CO2 future ocean. Resultant changes in offspring production could affect recruitment success and population fitness downstream.
显示更多 [+] 显示较少 [-]Seawater carbonate chemistry and sperm swimming speed of the polychaete Galeolaria caespitosa in lab experiment 全文
2014
Schlegel, Peter | Havenhand, Jonathan N | Obadia, Nicolas | Williamson, Jane E
The rapidity of ocean acidification intensifies selection pressure for resilient phenotypes, particularly during sensitive early life stages. The scope for selection is greater in species with greater within-species variation in responses to changing environments, thus enhancing the potential for adaptation. We investigated among-male variation in sperm swimming responses (percent motility and swimming speeds) of the serpulid polychaete Galeolaria caespitosa to near- (delta pH 0.3) and far-future ocean acidification (delta pH 0.5). Responses of sperm swimming to acidification varied significantly among males and were overall negative. Robust sperm swimming behavior under near-future ocean acidification in some males may ameliorate climate change impacts, if traits associated with robustness are heritable, and thereby enhance the potential for adaptation to far-future conditions. Reduced sperm swimming in the majority of male G. caespitosa may decrease their fertilization success in a high CO2 future ocean. Resultant changes in offspring production could affect recruitment success and population fitness downstream.
显示更多 [+] 显示较少 [-]Eutrophication threatens Caribbean seagrasses – An example from Curaçao and Bonaire 全文
2014
Govers, Laura L. | Lamers, Leon P.M. | Bouma, Tjeerd J. | de Brouwer, Jan H.F. | van Katwijk, Marieke M.
Seagrass beds are globally declining due to human activities in coastal areas. We here aimed to identify threats from eutrophication to the valuable seagrass beds of Curaçao and Bonaire in the Caribbean, which function as nursery habitats for commercial fish species. We documented surface- and porewater nutrient concentrations, and seagrass nutrient concentrations in 6 bays varying in nutrient loads. Water measurements only provided a momentary snapshot, due to timing, tidal stage, etc., but Thalassia testudinum nutrient concentrations indicated long-term nutrient loads. Nutrient levels in most bays did not raise any concern, but high leaf % P values of Thalassia in Piscadera Bay (∼0.31%) and Spanish Water Bay (∼0.21%) showed that seagrasses may be threatened by eutrophication, due to emergency overflow of waste water and coastal housing. We thus showed that seagrasses may be threatened and measures should be taken to prevent loss of these important nursery areas due to eutrophication.
显示更多 [+] 显示较少 [-]