Refinar búsqueda
Resultados 511-520 de 1,956
Biological impacts of enhanced alkalinity in Carcinus maenas Texto completo
2013
Cripps, Gemma | Widdicombe, Stephen | Spicer, John I. | Findlay, Helen S
Biological impacts of enhanced alkalinity in Carcinus maenas Texto completo
2013
Cripps, Gemma | Widdicombe, Stephen | Spicer, John I. | Findlay, Helen S
Further steps are needed to establish feasible alleviation strategies that are able to reduce the impacts of ocean acidification, whilst ensuring minimal biological side-effects in the process. Whilst there is a growing body of literature on the biological impacts of many other carbon dioxide reduction techniques, seemingly little is known about enhanced alkalinity. For this reason, we investigated the potential physiological impacts of using chemical sequestration as an alleviation strategy. In a controlled experiment, Carcinus maenas were acutely exposed to concentrations of Ca(OH)2 that would be required to reverse the decline in ocean surface pH and return it to pre-industrial levels. Acute exposure significantly affected all individuals’ acid–base balance resulting in slight respiratory alkalosis and hyperkalemia, which was strongest in mature females. Although the trigger for both of these responses is currently unclear, this study has shown that alkalinity addition does alter acid–base balance in this comparatively robust crustacean species.
Mostrar más [+] Menos [-]Biological impacts of enhanced alkalinity in Carcinus maenas Texto completo
2013
Cripps, Gemma | Widdicombe, Stephen | Spicer, John I | Findlay, Helen S
Further steps are needed to establish feasible alleviation strategies that are able to reduce the impacts of ocean acidification, whilst ensuring minimal biological side-effects in the process. Whilst there is a growing body of literature on the biological impacts of many other carbon dioxide reduction techniques, seemingly little is known about enhanced alkalinity. For this reason, we investigated the potential physiological impacts of using chemical sequestration as an alleviation strategy. In a controlled experiment, Carcinus maenas were acutely exposed to concentrations of Ca(OH)2 that would be required to reverse the decline in ocean surface pH and return it to pre-industrial levels. Acute exposure significantly affected all individuals' acid-base balance resulting in slight respiratory alkalosis and hyperkalemia, which was strongest in mature females. Although the trigger for both of these responses is currently unclear, this study has shown that alkalinity addition does alter acid-base balance in this comparatively robust crustacean species.
Mostrar más [+] Menos [-]Setting the maximum ecological potential of benthic communities, to assess ecological status, in heavily morphologically-modified estuarine water bodies Texto completo
2013
Borja, Angel | Chust, Guillem | del Campo, Andrea | González, Manuel | Hernandez, Carlos
Investigations on setting benthic macroinvertebrates reference conditions in natural waters have increased recently. Under the European Water Framework Directive, importance is given to research in morphological heavily-modified water bodies (HMWBs), which are very common in countries with high human pressure. However, research has not been undertaken on setting the maximum ecological potential (MEP), as a reference in HMWB. The objective of the present investigation is to set the MEP of two metrics (diversity and richness), used in assessing the ecological status in different benthic indices. The Oiartzun estuary (Basque Country) is used as a case study, which changed morphologically in the 19th Century, following harbour construction. Data obtained from 1874 and the present were used to model changes in currents, water residence time, salinity, volume, and intertidal area. Benthic macroinvertebrate data, from 1995 to 2011, were used to predict 19th Century and present MEP. Changes in the estuary were described: loss of all of the intertidal areas; doubling of the volume; residence time, changing from 2 to 95days; current velocity reduced by 50%; salinity increase. All these factors have led to changes in the benthic communities and the structural variables. Predicted richness and diversity, for 1874, were lower (48–76%) than those at present. Taking into account the differences between natural and modified waters, it is proposed to utilize 75% of the natural reference conditions, as the MEP values for Basque HMWB.
Mostrar más [+] Menos [-]Polychlorinated biphenyls in sediments of the Yellow Sea: Distribution, source identification and flux estimation Texto completo
2013
Duan, Xiaoyong | Li, Yanxia | Li, Xianguo | Zhang, Dahai | Li, Mengfang
Although there is no direct major riverine input, a large quantity of waste produced in mainland China and Korea is transported continuously to the Yellow Sea (YS) through atmospheric deposition, currents and tides; therefore, the environment is distinctly influenced by man-made pollution. This study focuses on the associated pollutant transport mechanisms and fluxes by sampling polychlorinated biphenyls (PCBs). PCBs (Σ24PCB) in YS sediments ranged between 99pg/g and 3.13ng/g of dry sediment (with a mean value of 715pg/g). PCBs produced unintentionally by industrial and other processes appeared to be the major source of PCBs in the sediments, accounting for 60.5%. Industrially synthesized PCBs with 3Cl and 5Cl accounted for 15.5% and 24.0%, respectively. PCBs were mainly from atmospheric deposition (84.5%), followed by continental runoff (15.5%). The average atmospheric deposition flux of technical PCBs was 789ng/(m2a) and flux of surface runoff was 2.27ng/L.
Mostrar más [+] Menos [-]Benthic foraminifera show some resilience to ocean acidification in the northern Gulf of California, Mexico Texto completo
2013
Pettit, L.R. | Hart, M.B. | Medina-Sánchez, A.N. | Smart, C.W. | Rodolfo-Metalpa, R. | Hall-Spencer, J.M. | Prol-Ledesma, R.M.
Extensive CO2 vents have been discovered in the Wagner Basin, northern Gulf of California, where they create large areas with lowered seawater pH. Such areas are suitable for investigations of long-term biological effects of ocean acidification and effects of CO2 leakage from subsea carbon capture storage. Here, we show responses of benthic foraminifera to seawater pH gradients at 74–207m water depth. Living (rose Bengal stained) benthic foraminifera included Nonionella basispinata, Epistominella bradyana and Bulimina marginata. Studies on foraminifera at CO2 vents in the Mediterranean and off Papua New Guinea have shown dramatic long-term effects of acidified seawater. We found living calcareous benthic foraminifera in low pH conditions in the northern Gulf of California, although there was an impoverished species assemblage and evidence of post-mortem test dissolution.
Mostrar más [+] Menos [-]Biodegradation of phenanthrene in bioaugmented microcosm by consortium ASP developed from coastal sediment of Alang-Sosiya ship breaking yard Texto completo
2013
Patel, Vilas | Patel, Janki | Madamwar, Datta
A phenanthrene-degrading bacterial consortium (ASP) was developed using sediment from the Alang–Sosiya shipbreaking yard at Gujarat, India. 16S rRNA gene-based molecular analyses revealed that the bacterial consortium consisted of six bacterial strains: Bacillus sp. ASP1, Pseudomonas sp. ASP2, Stenotrophomonas maltophilia strain ASP3, Staphylococcus sp. ASP4, Geobacillus sp. ASP5 and Alcaligenes sp. ASP6. The consortium was able to degrade 300ppm of phenanthrene and 1000ppm of naphthalene within 120h and 48h, respectively. Tween 80 showed a positive effect on phenanthrene degradation. The consortium was able to consume maximum phenanthrene at the rate of 46mg/h/l and degrade phenanthrene in the presence of other petroleum hydrocarbons. A microcosm study was conducted to test the consortium’s bioremediation potential. Phenanthrene degradation increased from 61% to 94% in sediment bioaugmented with the consortium. Simultaneously, bacterial counts and dehydrogenase activities also increased in the bioaugmented sediment. These results suggest that microbial consortium bioaugmentation may be a promising technology for bioremediation.
Mostrar más [+] Menos [-]Abundance of class 1–3 integrons in South Carolina estuarine ecosystems under high and low levels of anthropogenic influence Texto completo
2013
Uyaguari, Miguel I. | Scott, Geoffrey I. | Norman, R Sean
The impact of human activity on the spread of antibiotic resistant bacteria throughout coastal estuarine ecosystems is not well characterized. It has been suggested that laterally transferred genetic agents, such as integrons, play a role in the spread of resistant bacteria throughout ecosystems. This study compares the distribution of three integron classes throughout a coastal estuarine ecosystem. To determine integron distribution patterns, DNA was extracted from sediment and water collected at seven sites throughout two estuaries with different levels of anthropogenic input and integrons analyzed using quantitative PCR. The data show that while all three integron classes are present, the relative abundance is different, with class 2 integrons significantly elevated in areas of high anthropogenic input and class 1 integrons elevated in areas of low input. Our results provide a foundation for using integron gene distribution as a biomarker of urban impact on antibiotic resistance gene flow and ecosystem health.
Mostrar más [+] Menos [-]Looking at the aquatic contamination through fish eyes – A faithful picture based on metals burden Texto completo
2013
Pereira, Patrícia | Raimundo, Joana | Canário, João | Almeida, Armando | Pacheco, Mario
Looking at the aquatic contamination through fish eyes – A faithful picture based on metals burden Texto completo
2013
Pereira, Patrícia | Raimundo, Joana | Canário, João | Almeida, Armando | Pacheco, Mario
This study describes for the first time metal accumulation in the eyes of native golden grey mullet (Liza aurata) coupled with water/sediment quality assessment. Sampling was performed in the Tagus estuary (Portugal) where a confined area (Barreiro) is severely contaminated by metal/loids. Levels of As, Cu, Pb, Hg and Cd in sediments from Barreiro were one order of magnitude higher than those from the reference site. Data on water column pointed also to a higher availability of Cu, Pb, Cd and Hg (including MeHg) at Barreiro. Accordingly, fish eyes accumulated higher levels of metal/loids at Barreiro than at the reference site. These findings support the use of fish eyes as a target organ in environmental health assessment since they reflect sediment and water contamination. It points also to the importance of evaluate eye changes at structural/functional levels in order to examine in what extent accumulated metals could compromise this perceptive system.
Mostrar más [+] Menos [-]Looking at the aquatic contamination through fish eyes - a faithful picture based on metals burden Texto completo
2013
Pereira, Patrícia | Raimundo, Joana | Canário, João | Almeida, Armando | Pacheco, Mário
This study describes for the first time metal accumulation in the eyes of native golden grey mullet (Liza aurata) coupled with water/sediment quality assessment. Sampling was performed in the Tagus estuary (Portugal) where a confined area (Barreiro) is severely contaminated by metal/loids. Levels of As, Cu, Pb, Hg and Cd in sediments from Barreiro were one order of magnitude higher than those from the reference site. Data on water column pointed also to a higher availability of Cu, Pb, Cd and Hg (including MeHg) at Barreiro. Accordingly, fish eyes accumulated higher levels of metal/loids at Barreiro than at the reference site. These findings support the use of fish eyes as a target organ in environmental health assessment since they reflect sediment and water contamination. It points also to the importance of evaluate eye changes at structural/functional levels in order to examine in what extent accumulated metals could compromise this perceptive system. | Patrícia Pereira (SFRH/BPD/69563/2010) and Joana Raimundo (SFRH/BPD/91498/2012) benefit from Pos-doctoral grants supported by “Fundação para a Ciência e a Tecnologia” (FCT). This work as been supported by the following projects also funded by FCT: NEUTOXMER “Neurotoxicity of mercury in fish and association with morphofunctional brain alterations and behavior shifts” (PTDC/AAG-REC/2488/2012) and PROFLUX “Processes and fluxes of mercury and methylmercury in a contaminated coastal ecosystem Tagus Estuary, Portugal” (PTDC/MAR/102748/2008). Authors wish to acknowledge Bárbara Anes and Rute Cesário for the fish sampling support. | published
Mostrar más [+] Menos [-]Multiple environmental factors influence the spatial distribution and structure of reef communities in the northeastern Arabian Peninsula Texto completo
2013
Bauman, Andrew G. | Feary, David A. | Heron, Scott F. | Pratchett, Morgan S. | Burt, John A.
Multivariate analysis revealed distinct sub-regional coral communities among the southern Persian Gulf, Strait of Hormuz, and Gulf of Oman. Differences in community structure among locations were associated with considerable spatial heterogeneity in oceanic conditions, and strong directional environmental gradients. Despite clear community differences, considerable changes to coral community structure have occurred throughout the northeastern Arabian Peninsula as compared with previous studies. The most dramatic of these are the apparent changes from Acropora dominated to poritid and faviid dominated communities, particularly in the southern Persian Gulf and Strait of Hormuz. Although temperature and salinity have previously been cited as the major environmental factors structuring coral communities around the region, additional environmental parameters, including chlorophyll-a, surface currents and winds are shown to be important in structuring reef communities throughout the northeastern Arabian Peninsula.
Mostrar más [+] Menos [-]Selenium in sediments and biota from estuaries of southwest England Texto completo
2013
Turner, Andrew
Selenium concentrations have been measured in sediment, fucoid macroalgae and macroinvertebrates from four estuaries of SW England (Yealm, Plym, Looe, Fal). Sediment concentrations ranged from about 0.4μgg−1 in the Yealm to 1.49μgg−1 at one site in the Plym. Concentrations in Fucus vesiculosus (0.05–0.31μgg−1) and F. ceranoides (0.05–0.51μgg−1) were significantly lower than corresponding concentrations in sediment but there was no correlation between algal and sediment concentrations. Selenium concentrations in Littorina littorea (∼4μgg−1), Hediste diversicolor (2.82–12.68μgg−1), Arenicola marina (∼17μgg−1) and Scrobicularia plana (1.18–6.85μgg−1) were considerably higher than concentrations in macroalga or sediment, suggesting that Se is effectively accumulated from the diet. Although Se concentrations in some invertebrates exceed toxicity thresholds for the diet of predacious birds and fish, no specific evidence for Se toxicity exists in these estuaries.
Mostrar más [+] Menos [-]Entanglement of Antarctic fur seals at Bird Island, South Georgia Texto completo
2013
Waluda, Claire M. | Staniland, Iain J.
Between November 1989 and March 2013, 1033 Antarctic fur seals Arctocephalus gazella were observed entangled in marine debris at Bird Island, South Georgia. The majority of entanglements involved plastic packaging bands (43%), synthetic line (25%) or fishing net (17%). Juvenile male seals were the most commonly entangled (44%). A piecewise regression analysis showed that a single breakpoint at 1994 gave the best description of inter-annual variability in the data, with higher levels of entanglements prior to 1994 (mean=110±28) followed by persistent lower levels (mean=28±4). Records of entanglements from other sites monitored in the Scotia Sea are also presented. Legislation imposed by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) has, to a certain extent, been effective, but persistent low levels of seal entanglements are still a cause for concern at South Georgia.
Mostrar más [+] Menos [-]