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Influence of proximity to an urban center in the pattern of contamination by marine debris
2014
Leite, A.S. | Santos, L.L. | Costa, Y. | Hatje, V.
In order to test the relationship between the occurrence of marine debris and the distance from urban areas, nine beaches in the metropolitan area of Salvador, Bahia, Brazil and the adjacent northern coast were studied. Marine debris were collected, sorted in several categories and weighed. It was observed that plastics were numerically the most abundant component of the collected debris. As expected, the beaches closest to Salvador presented the largest density of debris, with the exception of the Porto da Barra beach, which has an efficient public cleaning system and does not have any vegetation, making it difficult toaccumulate solid waste. Linear regression analyses showed significant relationships between the distance from the urban center (Salvador) and the number of marine debris per m2, the total number of debris per beach (abundance), and the diversity of debris types (richness). The results showed that proximity to urban regions was a key factor in the marine debris distribution along the coast.
Afficher plus [+] Moins [-]Airborne molds and mycotoxins in Serpula lacrymans–damaged homes
2014
Pottier, Didier | André, Véronique | Rioult, Jean–Philippe | Bourreau, Alain | Duhamel, Chantal | Bouchart, Valerie Kientz | Richard, Estelle | Guibert, Mathieu | Verite, Philippe | Garon, David
For some years, the degradation of homes by the dry rot fungus Serpula lacrymans increased. This study described, for the first time, the fungal contamination in homes located in Low–Normandy (France) and damaged by Serpula lacrymans. Wood–decaying fungi, airborne molds, fungal species growing on building materials were investigated by cultural and molecular methods. Mycotoxins in the air were quantified by HPLC–MS/MS and the mutagenicity of fungal aerosols was also evaluated using the Ames test. The results showed that Serpula lacrymans was detected in the air for one third of homes with sometimes the co–occurrence of other ligninolytic basidiomycetes species like Donkioporia expansa. Various molds in the air and on materials (117 and 103 species, respectively) were also identified indicating the complexity of indoor mycoflora. Certain recurrent species like Aspergillus versicolor and Penicillium fellutanum were observed both on building materials and in the air. The presence of cellulolytic molds in fungal aerosols and on building materials could be used as an indicator of home degradation. Airborne culturable fungal levels were measured up to 5.8x105 Colony Forming Units (CFU) per cubic meter of the air (CFU/m3) depending on the home. Fungal concentrations also depended on the type of collector (filter or liquid) and were significantly correlated with the median of particles between 2–15μm in size. Two mycotoxins (alternariol and/or ochratoxin A) were observed in 4 homes but no mutagenic activity was found.
Afficher plus [+] Moins [-]Disturbance influences the invasion of a seagrass into an existing meadow
2014
McKenzie, Len J. | Yoshida, Rudi L. | Unsworth, Richard K.F.
Future impacts from climate change and human activities may increase the likelihood of invasions of native marine species into existing habitats as a result of range shifts. To provide an understanding of the invasion of a native seagrass species (Syringodiumisoetifolium) into a tropical multi-species meadow, detailed field assessments were conducted over a six year period. After establishing in a discrete patch, the extent and standing crop of S.isoetifolium increased 800 and 7000 fold, respectively, between 1988 and 2003 (∼300–260,000 m2 and<1kgDW to 7596±555kgDW). The expansion of S.isoetifolium was confined to subtidal areas and appears primarily from clonal growth. The observed expansion of this species into a new locality was found to be clearly influenced by cumulative impacts and chronic small-scale physical disturbances. This study has immediate relevance to managing impacts which influence the spread of invasive species.
Afficher plus [+] Moins [-]Inshore capture-based tuna aquaculture impact on Posidonia oceanica meadows in the eastern part of the Adriatic Sea
2014
Kružić, Petar | Vojvodić, Vjeročka | Bura-Nakić, Elvira
Mapping and monitoring of the seagrass Posidonia oceanica in the eastern (Croatian) part of the Adriatic Sea since 2004 indicates a significant decline in meadow density in an area impacted by inshore capture-based tuna aquaculture. The density and overall condition of P. oceanica meadows impacted by tuna farms near Fulija Islet was compared to two reference sites (Iž Island and Mrtovnjak Islet). The factors with the most significant influence on P. oceanica meadows were found to be the input of organic matter originating from the cages, as well as high epiphyte biomass caused by nutrient enrichment. Significant differences in nutrient concentrations were found between the sites impacted by tuna farms (Fulija Islet) and the control stations. Shoot density of the P. oceanica meadows decreased at the stations in close vicinity to the tuna farm, which suggests that the tuna farm activity strongly affected the surrounding meadows.
Afficher plus [+] Moins [-]Can we predict temperature-dependent chemical toxicity to marine organisms and set appropriate water quality guidelines for protecting marine ecosystems under different thermal scenarios?
2014
Zhou, Guang-Jie | Wang, Zhen | Lau, Edward Tak Chuen | Xu, Xiang-Rong | Leung, Kenneth Mei Yee
Temperature changes due to climate change and seasonal fluctuation can have profound implications on chemical toxicity to marine organisms. Through a comprehensive meta-analysis by comparing median lethal or effect concentration data of six chemicals for various saltwater species obtained at different temperatures, we reveal that the chemical toxicity generally follows two different models: (1) it increases with increasing temperature and (2) it is the lowest at an optimal temperature and increases with increasing or decreasing temperature from the optimal temperature. Such observations are further supported by temperature-dependent hazardous concentration 10% (HC10) values derived from species sensitivity distributions which are constructed using the acute toxicity data generated at different temperatures. Considering these two models and natural variations of seawater temperature, we can scientifically assess whether applying an assessment factor (e.g. 10) to modify water quality guidelines of the chemicals can adequately protect marine ecosystems in tropics, subtropics and temperate regions, respectively.
Afficher plus [+] Moins [-]Temperature extremes reduce seagrass growth and induce mortality
2014
Collier, C.J. | Waycott, M.
Extreme heating (up to 43°C measured from five-year temperature records) occurs in shallow coastal seagrass meadows of the Great Barrier Reef at low tide. We measured effective quantum yield (ϕPSII), growth, senescence and mortality in four tropical seagrasses to experimental short-duration (2.5h) spikes in water temperature to 35°C, 40°C and 43°C, for 6 days followed by one day at ambient temperature. Increasing temperature to 35°C had positive effects on ϕPSII (the magnitude varied between days and was highly correlated with PPFD), with no effects on growth or mortality. 40°C represented a critical threshold as there were strong species differences and there was a large impact on growth and mortality. At 43°C there was complete mortality after 2–3days. These findings indicate that increasing duration (more days in a row) of thermal events above 40°C is likely to affect the ecological function of tropical seagrass meadows.
Afficher plus [+] Moins [-]Temporal pattern in the bloom-forming macroalgae Chaetomorpha linum and Ulva pertusa in seagrass beds, Swan Lake lagoon, North China
2014
Zhang, Xiaomei | Zhou, Yi | Liu, Peng | Wang, Feng | Liu, Bingjian | Liu, Xujia | Xu, Qiang | Yang, Hongsheng
Seagrasses that are distributed over a large area of the Swan Lake, Weihai, China, support a productive ecosystem. In recent years, however, frequent macroalgal blooms have changed the ecosystem structure and threatened the seagrasses. To understand the bloom-forming macroalgae we conducted a yearly field survey of Swan Lake. Results indicated that the macroalgae Chaetomorpha linum and Ulva pertusa both exhibited a much higher productivity and attained a greater maximum biomass (of 1712±780gDWm−2 and 1511±555gDWm−2, respectively) than was the case for the seagrasses. The mean annual atomic ratios of C/N, C/P and N/P in C. linum were 14.31±4.45, 402.82±130.25, and 28.12±2.08, respectively. The δ15N values (11.09±0.91‰ for C. linum; 9.27±2.83‰ for U. pertusa) indicated a land-based source of N enrichment to the macroalgal blooms. High concentrations of nitrogen and phosphorus in the lagoon, particularly near the river mouth, supported the blooms.
Afficher plus [+] Moins [-]The effect of suspended sediment on fertilization success in the urchin Evechinus chloroticus: Analysis of experimental data using hierarchical Bayesian methods
2014
Miller, S.L. | Richardson, K. | Edwards, P.A.
Terrestrial sediments are a significant stressor on coastal ecosystems, with both suspended and deposited sediment having adverse effects on aquatic organisms. However, information on the effect of suspended sediments on fertilization success for urchin species is lacking. Using sediment levels similar to those encountered in situ, a controlled experiment was conducted to test whether suspended sediment affects fertilization success in the urchin Evechinus chloroticus. Analyses used generalized linear mixed models (GLMMs) and hierarchical Bayesian (HB) regression. Both approaches showed a significant decrease in fertilization success with increased suspended sediment levels. Uncertainties in estimates were narrower for HB models, suggesting that this approach has advantages over GLMMs for sparse data problems sometimes encountered in laboratory experiments. Given future global change scenarios, this work is important for predicting the effects of stressors such as sedimentation that may ultimately impact marine populations.
Afficher plus [+] Moins [-]Mercury in Caribbean dolphins (Stenella longirostris and Stenella frontalis) caught for human consumption off St. Vincent, West Indies
2014
Fielding, Russell | Evans, David W.
The island of St. Vincent in the Lesser Antilles supports an ongoing, legal cetacean hunt, which targets several species for human consumption. Little is known regarding the healthfulness and potential health risks of these foods in this setting. Following established methodologies we analyzed 39 raw muscle tissue samples and 38 raw blubber samples from two cetacean species for total mercury and methyl-mercury. We also analyzed samples of muscle tissue from an unknown cetacean species prepared for consumption. We report high concentrations of total mercury and methyl-mercury in these tissues as compared to published data for other seafood products. Further, our findings indicate that the traditional preparation method most often used locally in St. Vincent yields a finished food product with a much higher mercury concentration than the unprocessed tissue. Our results highlight the potential for negative human health effects related to the consumption of these food products in St. Vincent.
Afficher plus [+] Moins [-]The past and future of fish consumption: Can supplies meet healthy eating recommendations?
2014
Thurstan, Ruth H. | Roberts, Callum M.
In many developed countries fish and shellfish are increasingly promoted as healthy alternatives to other animal protein. We analysed how much fish was available to UK and global populations after accounting for processing losses, and compared this to recommended levels of fish consumption. In 2012, UK domestic fish landings per capita fell 81% below the recommended intake, although declines were masked by increased imports and aquaculture from the 1970s onwards. Global wild fish supply per capita declined by 32% from its peak in 1970. However, overall fish supplies per capita increased by 10% over the same period due to rapidly expanding aquaculture production. Whilst aquaculture has so far prevented a downturn in global fish supplies, many developed nations continue to aspire to consume more fish than they produce. Until demand is balanced with sustainable methods of production governments should consider carefully the social and environmental implications of greater fish consumption.
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