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Inorganic nutrients have a significant, but minimal, impact on a coastal microbial community's response to fresh diluted bitumen
2019
Ortmann, Alice C. | Cobanli, Susan E. | Wohlgeschaffen, Gary | Thamer, Peter | McIntyre, Claire | Mason, Jennifer | King, Thomas L.
Microbes capable of degrading hydrocarbons in oil are present in low abundances in coastal waters, but quickly respond to oil following a spill. When estimating potential biodegradation rates in the laboratory, high concentrations of inorganic nutrients are often added to prevent nutrient limitation. In this study, we tested the short term response of coastal microbes to fresh diluted bitumen under varying nutrient conditions in a cold water regime. Total hydrocarbon concentrations changed minimally over five days; however, oil composition changed over time and the abundance of microbes increased in all treatments. Addition of phosphate, with or without nitrogen, resulted in rapid changes in community composition, but after three days treatments no longer differed. Nutrients were never depleted in any treatment suggesting that, even at low inorganic nutrient concentrations, microbial communities can quickly respond to hydrocarbons following a spill.
Показать больше [+] Меньше [-]Spatio-temporal monitoring of coastal floating marine debris in the Balearic Islands from sea-cleaning boats
2019
Compa, Montserrat | March, David | Deudero, Salud
Mismanaged waste is accumulating at an alarming rate in the marine environment. Its presence has caused local authorities in the Balearic Islands to develop a coastal sea-cleaning boat service covering the region, identifying the floating marine debris, and removing it from the coastal areas. This study considered daily monitoring from May to October spanning from 2005 to 2015. Plastic marine debris composed over 54% of all floating marine debris removed daily across the Balearic Islands. The spatio-temporal patterns indicate a heterogeneous distribution of plastic in the coastal areas, with higher concentrations in the north-western and south-eastern regions of the islands and debris peaking during the month of August. Furthermore, floating marine debris was more easily collected during calm seas as well as using an integrated monitoring approach to facilitate its removal. Overall, sea-cleaning boats are highly effective in removing coastal floating marine debris.
Показать больше [+] Меньше [-]Beach litter in Ecuador and the Galapagos islands: A baseline to enhance environmental conservation and sustainable beach tourism
2019
Mestanza, Carlos | Botero, Camilo M. | Anfuso, Giorgio | Chica-Ruiz, J Adolfo | Pranzini, Enzo | Mooser, Alexis
The presence and characterization of beach litter was investigated, according to the EA/NALG (2000) methodology, at 59 sites along four provinces of Ecuador, i.e., three continental and the Galapagos Islands Province. The methodology, which has been verified in several countries, was used to classify beaches into four grades (from “A” – excellent to “D” – poor) according to the content of nine types of litter. Twenty-two sites (i.e., 37% of total) obtained Grade “C”, 18 (31%) Grade “B”, 12 (20%) Grade “A”, and 7 (12%) Grade “D”. The province that showed excellent litter grades was the Galapagos Islands where 88% of beaches obtained Grade “A”, whereas Santa Elena and Esmeraldas provinces presented the worst beaches in terms of litter content and abundance. Environmental authorities should focus more attention on continental beaches by improving adequate cleaning operations to make them more attractive to national and international tourism.
Показать больше [+] Меньше [-]Effects of microphytobenthos Cylindrotheca closterium on the fate of di-n-butyl phthalate in an aquatic microcosm
2019
Zhang, Fan | Ding, Zheng | Gong, Haofei | Chi, Jie
Effects of Cylindrotheca closterium, a marine benthic diatom, on the fate of di-n-butyl phthalate (DBP) in a water-sediment system were investigated. Model calculation results showed that DBP residue was 38.5% lower in the system with C. closterium than in the system without C. closterium. The net flux from water to sediment increased by 7.3 times in the presence of C. closterium. As a result, the total biodegradation flux of DBP in the system with C. closterium was increased by 25.6%. According to the 16 s rDNA sequencing, the presence of C. closterium decreased the bacterial population as well as bacterial community diversity in sediments. Moreover, the population of C. closterium, capable of efficiently degrading DBP, was much higher than that of the dominant DBP-degrading bacteria, demonstrating that degradation of DBP by C. closterium should be the main reason for the degradation enhancement in sediments.
Показать больше [+] Меньше [-]Differential toxicity of functionalized polystyrene microplastics to clams (Meretrix meretrix) at three key development stages of life history
2019
Luan, Liping | Wang, Xiao | Zheng, Hao | Liu, Liuqingqing | Luo, Xianxiang | Li, Fengmin
Little knowledge is available on impact of microplastics (MPs) on the bivalve larvae at different developmental stages throughout their life history, especially for metamorphic stage. Therefore, this study aims to evaluate the toxic responses of carboxylated (PS-COOH) and amino (PS-NH2) polystyrene MPs on the developing clam larvae at three key life stages, i.e., fertilized eggs, D-veliger larvae, and umbo larvae. PS-COOH and PS-NH2 significantly decreased the hatching rates by 5.79–39.5% and developmental rates by 4.78–7.86% of the clam larvae relative to the unexposed clam larvae. The toxicity of MPs followed the order: hatching stage > metamorphosis > D-veliger larvae stage, showing stage-dependent toxic effects. Moreover, PS-NH2 with a smaller hydrodynamic diameter showed a greater toxicity to the developing larvae compared to PS-COOH. Our study highlighted the stage-dependent toxic effects of MPs on the developing clam larvae, thus posing ecological risks to population succession of marine bivalves and aquatic ecosystems.
Показать больше [+] Меньше [-]Micro(nano)plastics: Unignorable vectors for organisms
2019
Shen, Maocai | Zhu, Yuan | Zhang, Yaxin | Zeng, Guangming | Wen, Xiaofeng | I-Huan, | Ye, Shujing | Ren, Xiaoya | Song, Biao
Micro(nano)plastics, as emerging contaminants, have attracted worldwide attention. Nowadays, the environmental distribution, sources, and analysis methods and technologies of micro(nano)plastics have been well studied and recognized. Nevertheless, the role of micro(nano)plastic particles as vectors for attaching organisms is not fully understood. In this paper, the role of micro(nano)plastics as vectors, and their potential effects on the ecology are introduced. Micro(nano)plastics could 1) accelerate the diffusion of organisms in the environment, which may result in biological invasion; 2) increase the gene exchange between attached biofilm communities, causing the transfer of pathogenic and antibiotic resistance genes; 3) enhance the rate of energy, material and information flow in the environment. Accordingly, the role of microplastics as vectors for organisms should be further evaluated in the future research.
Показать больше [+] Меньше [-]Distribution, sources, and risk assessment of polycyclic aromatic hydrocarbons (PAHs) in surface sediments of the Subei Shoal, China
2019
In this study, 16 polycyclic aromatic hydrocarbons (PAHs) were detected in surface sediments of the Subei Shoal. Eleven of the 16 PAHs were detected, namely, Nap, Fl, Phe, Flu, Pyr, BaAnt, Chr, BaFlu, BaPyr, Ind-1,2,3-cdPyr, and BghiPer, and the remaining five (Acy, Ace, Ant, BkFlu, and DBahAnt) were not detected. Total PAH concentrations ranged from <DL to 25.24 ng/g dw, with an average of 5.88 ng/g dw. The highest concentrations were found in the intermediate sections (stations 6–1), followed by those in the northernmost regions (stations 9–5). The lowest concentrations were found in the south of section 2. High-molecular-weight PAHs (4 and 5 rings) were found to be dominant, constituting 70% of the PAHs tested. Principal component analysis showed that PAHs in sediments came mainly from coal combustion, transportation (oil combustion), coke processing, and petroleum sources. Both effect range low/effect range median values and mean effects range–median quotient showed that PAHs were present at a low toxicity risk level in the Subei Shoal.
Показать больше [+] Меньше [-]Sorption of polybrominated diphenyl ethers by microplastics
2019
Xu, Pengcheng | Ge, Wei | Chai, Chao | Zhang, Yan | Jiang, Tao | Xia, Bin
The sorption of polybrominated diphenyl ethers (PBDEs) onto polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyamide (PA) microplastics was analyzed using different kinetic and isotherm models, and under various environmental conditions, including temperature, pH, salinity and dissolved organic matter (DOM). The sorption capacity was in the order of PS > PA > PP > PE, due to the different crystallinity, specific surface area, and surface structure. PS demonstrated the equilibrium sorption capacity, namely, 6.41 ng/g BDE-47, 12.83 ng/g BDE-99, and 14.42 ng/g BDE-153. The second-order kinetic model described the sorption kinetics of PBDEs, and surface sorption was the main mechanism. The sorption of PBDEs by microplastics was a multilayer and physical process. Low temperatures reduced BDE-47 sorption on microplastics, and sorption was a spontaneous and endothermic process. The sorption of BDE-47 was not significantly influenced by pH and salinity. However, DOM exerted a negative effect on the sorption of BDE-47.
Показать больше [+] Меньше [-]Examining derelict pot impacts on harvest in a commercial blue crab Callinectes sapidus fishery
2019
DelBene, James A. | Bilkovic, Donna M. | Scheld, Andrew M.
Pot fisheries occur worldwide with a significant proportion of the gear becoming derelict. Derelict pots induce detrimental ecological and economic impacts, and more recently were found to reduce blue crab harvests in the Chesapeake Bay commercial fishery. We simulated the presence of derelict pots near actively fished pots in seasonal field experiments to quantify the effect derelict pots have on blue crab harvest. Derelict pots reduced harvests by 30% during the summer, but not during the fall. Female blue crab capture rates were consistently lower when derelict pots were present; while capture rates of the less abundant males were not negatively affected by derelict pots. Variable responses to derelict pots may be due to seasonal differences in female and male blue crab behavior and movements. The costly effect that derelict pots have on harvest should be investigated in other pot fisheries to recognize the magnitude and mechanisms behind these impacts.
Показать больше [+] Меньше [-]Functional consumers regulate the effect of availability of subsidy on trophic cascades in the Yellow River Delta, China
2019
Yan, Jiaguo | Cui, Baoshan | Huang, Honghui | O'Flynn, Sarah | Bai, Junhong | Ysebaert, Tom
Understanding the environmental context where heterogeneous ecological processes affect biotic interactions is a key aim of ecological research. However, mechanisms underlying spatial variation in trophic interactions linked to resource availability across ecosystem gradients remains unclear. We experimentally manipulated the interactive effects of predator fish and quantitative gradient of leaf detritus on macroinvertebrates and benthic algae. We found that non-linear changes in the strength of trophic cascades were strongly linked to the retention rates of experimental leaf detritus and also determined by predatory consumers. Retention rate of leaf detritus influenced the recruitment of predatory invertebrates and foraging preference of predators, accounting for largely the variations in shift of strengthening and weakening trophic cascades. Our results highlight the importance to identify joint processes of recruitment and foraging responses of functional consumer in understanding the impacts of both anthropogenic and natural alterations in subsidy on trophic interaction of coastal food webs.
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