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1.
Environ Monit Assess ; 193(3): 130, 2021 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-33587190

RESUMEN

Land use/cover change is the main driving force of urban expansion which influences human-environment interactions. Generally, the formation of urban heat islands (UHIs) can be referred to as a negative "by-product" of urbanization. In the context of rapid urbanization, the present paper aims to capture the landscape changes and three patterns of urban expansion (i.e., infill, extension, and leapfrog), and provide a better understanding of the formation of the surface urban heat island (SUHI) in Dongguan, China, during the past 20+ years. Urban land increased from 28.87 × 103 ha in 1994 to 78.89 × 103 ha in 2005 and 101.05 × 103 ha in 2015, with a compound annual urban growth rate of 9.57% (1994-2005) and 2.51% (2005-2015), respectively. Based on the mean land surface temperature difference (Δ mean LST) between urban land (UL) and green space (GS), the SUHI intensity (SUHII) increased from 1.46 °C in 1994 to 2.32 °C in 2005 and 3.83 °C in 2015 in Dongguan. Overall, the Δ mean LST of urban areas increased from 2.61 °C (1994-2005) to 4.78 °C (2005-2015). The Δ mean LST between the city center and its surrounding areas decreased from 1994 to 2015, and the Δ mean LST between the city center and the suburbs gradually increased, primarily in 2015. In particular, both dense urban and the infill pattern of urban expansion had high mean LSTs in Dongguan, thus having negative impacts on sustainable urban development. The limited green space and open land should be strictly controlled or prohibited for transformation in urban areas. Particularly in dense regions, green roofs, green areas, and urban renewal actions could be considered for mitigating the urban heat island effect.


Asunto(s)
Calor , Remodelación Urbana , China , Ciudades , Monitoreo del Ambiente , Humanos , Islas , Urbanización
2.
Nat Commun ; 12(1): 50, 2021 01 04.
Artículo en Inglés | MEDLINE | ID: mdl-33397914

RESUMEN

Gene flow is predicted to impede parallel adaptation via de novo mutation, because it can introduce pre-existing adaptive alleles from population to population. We test this using Hawaiian crickets (Teleogryllus oceanicus) in which 'flatwing' males that lack sound-producing wing structures recently arose and spread under selection from an acoustically-orienting parasitoid. Morphometric and genetic comparisons identify distinct flatwing phenotypes in populations on three islands, localized to different loci. Nevertheless, we detect strong, recent and ongoing gene flow among the populations. Using genome scans and gene expression analysis we find that parallel evolution of flatwing on different islands is associated with shared genomic hotspots of adaptation that contain the gene doublesex, but the form of selection differs among islands and corresponds to known flatwing demographics in the wild. We thus show how parallel adaptation can occur on contemporary timescales despite gene flow, indicating that it could be less constrained than previously appreciated.


Asunto(s)
Adaptación Fisiológica/genética , Flujo Génico , Gryllidae/genética , Gryllidae/fisiología , Animales , Regulación del Desarrollo de la Expresión Génica , Sitios Genéticos , Variación Genética , Genética de Población , Genoma de los Insectos , Geografía , Hawaii , Islas , Masculino , Selección Genética , Alas de Animales/anatomía & histología
3.
Extremophiles ; 25(1): 77-84, 2021 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-33416982

RESUMEN

We evaluated the fungal diversity in two lakes on the South Shetland Islands, using DNA metabarcoding through high-throughput sequencing (HTS). A microcosm experiment was deployed for two consecutive years in lakes on Deception and King George islands to capture potential decomposer freshwater fungi. Analyses of the baits revealed 258,326 DNA reads distributed in 34 fungal taxa of the phyla Ascomycota, Basidiomycota, Mortierellomycota, Chytridiomycota and Rozellomycota. Tetracladium marchalianum, Tetracladium sp., Rozellomycota sp., Fungal sp. 1 and Fungal sp. 2 were the most common taxa detected. However, the majority of the communities comprised intermediate and rare taxa. Both fungal communities displayed moderate indices of diversity, richness and dominance. Only six taxa were detected in both lakes, including the most dominant T. marchalianum and Tetracladium sp. The high numbers of reads of the known aquatic saprotrophic hyphomycetes T. marchalianum and Tetracladium sp. in the baits suggest that these fungi may digest organic material in Antarctic lakes, releasing available carbon and nutrients to the other aquatic organisms present in the complex lake food web. Our data confirm that the use of cotton baits together with HTS approaches can be appropriate to study the diversity of resident freshwater fungi present in Antarctic lakes.


Asunto(s)
Código de Barras del ADN Taxonómico , Hongos/clasificación , Lagos/microbiología , Regiones Antárticas , Biodiversidad , ADN de Hongos/genética , Islas
4.
Oecologia ; 195(2): 435-451, 2021 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-33484348

RESUMEN

Turnover in species composition between sites, or beta diversity, is a critical component of species diversity that is typically influenced by geography, environment, and biotic interactions. Quantifying turnover is particularly challenging, however, in multi-host, multi-parasite assemblages where undersampling is unavoidable, resulting in inflated estimates of turnover and uncertainty about its spatial scale. We developed and implemented a framework using null models to test for community turnover in avian haemosporidian communities of three sky islands in the southwestern United States. We screened 776 birds for haemosporidian parasites from three genera (Parahaemoproteus, Plasmodium, and Leucocytozoon) by amplifying and sequencing a mitochondrial DNA barcode. We detected infections in 280 birds (36.1%), sequenced 357 infections, and found a total of 99 parasite haplotypes. When compared to communities simulated from a regional pool, we observed more unique, single-mountain haplotypes and fewer haplotypes shared among three mountain ranges than expected, indicating that haemosporidian communities differ to some degree among adjacent mountain ranges. These results were robust even after pruning datasets to include only identical sets of host species, and they were consistent for two of the three haemosporidian genera. The two more distant mountain ranges were more similar to each other than the one located centrally, suggesting that the differences we detected were due to stochastic colonization-extirpation dynamics. These results demonstrate that avian haemosporidian communities of temperate-zone forests differ on relatively fine spatial scales between adjacent sky islands. Null models are essential tools for testing the spatial scale of turnover in complex, undersampled, and poorly known systems.


Asunto(s)
Enfermedades de las Aves , Haemosporida , Parásitos , Plasmodium , Animales , Haemosporida/genética , Islas , Filogenia , Sudoeste de Estados Unidos
5.
Ecol Lett ; 24(3): 533-542, 2021 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-33404198

RESUMEN

In ectothermic predator-prey relationships, evasion of predation by prey depends on physiological and behavioural responses relating to the thermal biology of both predator and prey. On Japan's Izu Islands, we investigated a prey lizard's physiological and thermal responses to the presence of a snake predator over geologic time in addition to recent climatic warming. Foraging lizard body temperatures increased by 1.3 °C from 1981 to 2019 overall, yet were 2.9 °C warmer on snake islands relative to snake-free islands. We also detected snake predator-induced selection on hind leg length, which in turn is a major determinant for sprint speed only in lizard populations exposed to predation by snakes. Accordingly, we found that warmer prey body temperatures result in faster sprint speeds by the prey at temperatures suboptimal for the snake predator, and therefore contribute to escaping predation. Given recent climatic change, further warming could irrevocably alter this and other ectothermic predator-prey relationships.


Asunto(s)
Lagartos , Animales , Temperatura Corporal , Cambio Climático , Islas , Conducta Predatoria
6.
J Environ Manage ; 282: 111953, 2021 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-33440317

RESUMEN

The research hypothesis considered in this study is that decisions adopted on beach use and management in arid environments can result in significant changes in the biogeomorphological processes of the beach-dune system of which it forms part. Different information sources and geographical information systems were used to make a spatiotemporal analysis of possible correlations between the presence of beach equipment, services and uses in the backshore area of an arid beach-dune system, such as the beach named Playa del Inglés (Gran Canaria island, Spain) and environmental changes detected in the same area. The period considered in the study covers from 1961 (before the development of the mass tourism on the island) to 2018. Significant variations in vegetation cover over the course of the study period were detected, as well as an overall increase in erosion (topographic and erosive aeolian landforms) and foredune fragmentation and a decrease in geomorphological resilience. The study found not only relationships between management decisions and environmental impacts, but also that environmental impacts of management decisions on beach use made in the 1970s and 1980s continue to be felt today. Moreover, the results also reinforce the idea that management decisions made based on the results of scientific research studies (management-research binomial) can lead to more environmentally sustainable actions.


Asunto(s)
Conservación de los Recursos Naturales , Erosión del Suelo , Toma de Decisiones , Islas , España , Análisis Espacio-Temporal
7.
Bull Environ Contam Toxicol ; 106(2): 278-288, 2021 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-33420571

RESUMEN

This study is aimed at investigation of various potential contaminants (arsenic, mercury and polycyclic aromatic hydrocarbons) content in soils of different landscapes of Eastern Antarctica ice-free areas. Our data not only showed that intensive human impact might result in significant direct contamination of surrounding landforms, but also revealed a specific role of ornithogenic transport in distribution of contaminants. Analysis revealed that the contents of investigated elements were 0.100-8.055 mg kg-1 (arsenic), 0.025-0.027 mg kg-1 (mercury) in Larsemann Hills and 0.100-1.213 mg kg-1 (arsenic), 0.023-0.593 mg kg-1 (mercury) in vicinities of Mirny station and Fulmar Island. Accumulation of some elements in guano-derived and moss materials lead to higher values of other soil pollution indices at natural sites. Results of our study revealed the predominance of light molecular weight PAHs (fluorene and acenaphthylene) in studied soils. Results of our study are not completely in agreement with the idea of an practically uncontaminated Antarctic ecosystem which was previously reported for Eastern Antarctica ice-free areas. Various human activities carried out at local scale have been found to be responsible for increase of metal levels in studied Antarctic environments.


Asunto(s)
Arsénico , Mercurio , Hidrocarburos Policíclicos Aromáticos , Contaminantes del Suelo , Regiones Antárticas , Ecosistema , Monitoreo del Ambiente , Humanos , Islas , Hidrocarburos Policíclicos Aromáticos/análisis , Suelo , Contaminantes del Suelo/análisis
8.
Mar Pollut Bull ; 163: 111988, 2021 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-33461074

RESUMEN

This study characterizes the spectral behavior of tarmats and maps the tarmat deposits found along the coast of Ras Rakan Island off Qatar using WorldView-3 (WV-3) sensor data. The laboratory spectra of tar materials showed diagnostic absorptions features at 0.6 and 1.1 µm in the visible and near-infrared (VNIR) and 1.52, 1.73, 2.04, and 2.31 µm in the short wave infrared (SWIR) region. The panchromatic grayscale image and FCC showed the tarmat deposit as a linear warp feature between beach and water. The mapping of deposits using WV-3 data by decorrelation stretch and Linear Spectral Unmixing (LSU) methods discriminated the tarmats from the sandy soil, vegetation and sabkha features in a different tone. The capability of WV-3 sensor and the potential of image processing methods were verified by mapping the tar distribution of the Ras Ushayriq and NE of Al Ruwais.


Asunto(s)
Modelos Teóricos , Suelo , Islas , Qatar , Agua
9.
Mar Pollut Bull ; 163: 111971, 2021 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-33503565

RESUMEN

This study investigates the concentration of heavy metals in the macroalgae, seagrasses, mangroves, and crabs collected from Hare Island, Gulf of Mannar Marine Biosphere Reserve. The concentration of heavy metals ranged between 0.06 (Hg)-259 (Fe) µg/g in macroalgae, 0.09 (Pb)-377 (Fe) µg/g in seagrasses, 0.112 (Cd)-122 (Fe) µg/g in mangroves, and 0.11 (Cd) -240 (Fe) µg/g in crabs. The levels of heavy metals in the analyzed samples were found below the maximum residual limits (MRLs) prescribed by various National and International agencies. The result suggests that exposure to the analyzed metals through macroalgae consumption does not cause potential health risks to consumers (target hazard quotient (THQ), estimated exposure dose (EED), and hazard index (HI) <1). Hence, this study concludes that macroalgae that grow in the Gulf of Mannar regions are safe for human consumption and are suitable to prepare food supplements and bioceutical products.


Asunto(s)
Braquiuros , Liebres , Metales Pesados , Algas Marinas , Contaminantes Químicos del Agua , Animales , Monitoreo del Ambiente , Contaminación de Alimentos/análisis , Humanos , India , Islas , Metales Pesados/análisis , Medición de Riesgo , Contaminantes Químicos del Agua/análisis
10.
Ecotoxicol Environ Saf ; 208: 111665, 2021 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-33396175

RESUMEN

Microplastics are ubiquitous in aquatic ecosystems, but little information is currently available on the dangers and risks to living organisms. In order to assess the ecotoxicity of environmental microplastics (MPs), samples were collected from the beaches of two islands in the Guadeloupe archipelago, Petit-Bourg (PB) located on the main island of Guadeloupe and Marie-Galante (MG) on the second island of the archipelago. These samples have a similar polymer composition with mainly polyethylene (PE) and polypropylene (PP). However, these two samples are very dissimilar with regard to their contamination profile and their toxicity. MPs from MG contain more lead, cadmium and organochlorine compounds while those from PB have higher levels of copper, zinc and hydrocarbons. The leachates of these two samples of MPs induced sublethal effects on the growth of sea urchins and on the pulsation frequency of jellyfish ephyrae but not on the development of zebrafish embryos. The toxic effects are much more marked for samples from the PB site than those from the MG site. This work demonstrates that MPs can contain high levels of potentially bioavailable toxic substances that may represent a significant ecotoxicological risk, particularly for the early life stages of aquatic animals.


Asunto(s)
Organismos Acuáticos/efectos de los fármacos , Estadios del Ciclo de Vida/efectos de los fármacos , Microplásticos/toxicidad , Contaminantes Químicos del Agua/toxicidad , Animales , Organismos Acuáticos/crecimiento & desarrollo , Ecosistema , Ecotoxicología , Islas , Microplásticos/química , Escifozoos/efectos de los fármacos , Escifozoos/crecimiento & desarrollo , Erizos de Mar/efectos de los fármacos , Erizos de Mar/crecimiento & desarrollo , Contaminantes Químicos del Agua/química
11.
Chemosphere ; 267: 129316, 2021 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-33352370

RESUMEN

Persistent halogenated compounds (PHC) are of concern for human and environmental health. Persistent Organic Pollutants (POPs) are regulated by international treaties, but alternative compounds such as novel brominated flame retardants (NBFRs) and Dechlorane Plus (DP) are not-yet they are increasingly used. There are no data on PHCs in coral reef biota from tropical islands in the western Indian Ocean (WIO). For this assessment, three hard coral genera, two soft coral genera, and ember parrotfish (Scarus rubroviolaceus) were collected from the remote Rodrigues, Agalega, and St. Brandon's Atoll (Republic of Mauritius) in the Mascarene Basin of the WIO. Five compounds - Pentabromotoluene (PBT), γ-HCH, p,p'-DDE, HCB, and BDE-47- were quantifiable in all samples. Hard coral consistently contained the lowest concentrations of PHCs, except for NBFRs. The presence of BDE-47 suggests long-range aerial transport. We quantified DP, currently a candidate POP, in coral reef biota. PBT was measured in all samples also suggests long-range transport. Because the hard coral, soft coral, and fish had differing concentrations and patterns of PHCs, future surveys should stratify sampling accordingly. Agalega and St. Brandon's Atoll can be considered as locations to monitor changes in background concentrations of pollutants due to their remoteness.


Asunto(s)
Antozoos , Retardadores de Llama , Animales , Arrecifes de Coral , Monitoreo del Ambiente , Retardadores de Llama/análisis , Éteres Difenilos Halogenados/análisis , Humanos , Océano Índico , Islas
12.
J Environ Manage ; 278(Pt 2): 111508, 2021 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-33129026

RESUMEN

Responding to accelerating climate change impacts requires broad and effective engagement with stakeholders, at multiple geographic and governance levels. Stakeholder participation has been hailed as a facilitated approach in climate change adaptation that supports social learning, depolarization of perceptions, and fosters collective action. But stakeholder participation remains loosely interpreted and evaluating measures are limited. This study employs social network analysis (SNA) to investigate how social relations among stakeholders, which emerge as a result of participation, are associated with stakeholder learning, as changes in perceptions of climate change. We hypothesized that reciprocal ties of understanding, respect, and influence can predict changes in perceptions of climate change. This approach was applied to a case study in Deal Island Peninsula, Maryland (USA) where local residents, scientists, and government officials met from 2016 to 2018 to collaboratively manage the impacts of sea-level rise in their communities. We found that social relations based on mutual understanding, respect,and influence are positively associated with perceptions of climate change. We provide a detailed conceptualization and implementation of a network-based approach that may serve as a potential quantitative performance measure of stakeholder participation processes in climate change adaptation. Overall, this study provides empirical evidence of the role that emerging social relations have on enhancing or constraining social learning among stakeholders in the Deal Island Peninsula project.


Asunto(s)
Aclimatación , Cambio Climático , Islas , Maryland , Participación de los Interesados
13.
Chemosphere ; 263: 128057, 2021 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-33297065

RESUMEN

Samples of adipose tissue, meat and livers from pigs, cows, sheep and goats from Curaçao were analysed for polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), and dioxin-like (dl-) and non-dioxin-like (ndl-) PCBs (polychlorinated biphenyls). Levels in many samples of adipose tissue were higher than the EU maximum levels (MLs) for PCDD/Fs and the sum of PCDD/Fs and dl-PCBs (sum-TEQ), indicating unusually high levels. Median sum-TEQ (Toxic Equivalents) levels for pigs, cows, sheep and goats were 0.9 (range 0.3-35), 3.0 (0.5-14), 5.7 (0.3-28) and 6.5 (0.5-134) pg TEQ g-1 fat. For most samples, the congener pattern pointed to the burning of waste as the major source, in line with the fact that most animals forage outside. MLs for ndl-PCBs were also exceeded in some of the samples, indicating that some areas are additionally contaminated with PCBs. Meat levels showed similar lipid based levels as adipose tissue, contrary to liver levels, which were much higher in most animals. Pigs showed liver sequestration at lower levels in adipose tissue than the ruminants. The relatively high levels observed in this study are likely to result in high exposure of consumers and measures were taken to reduce the contamination of areas where animals forage.


Asunto(s)
Benzofuranos , Dioxinas , Bifenilos Policlorados , Dibenzodioxinas Policloradas , Animales , Benzofuranos/análisis , Bovinos , Curazao , Dibenzofuranos , Dibenzofuranos Policlorados , Dioxinas/análisis , Femenino , Contaminación de Alimentos/análisis , Cabras , Islas , Hígado/química , Carne/análisis , Bifenilos Policlorados/análisis , Dibenzodioxinas Policloradas/análisis , Ovinos , Porcinos
14.
Sci Total Environ ; 751: 142268, 2021 Jan 10.
Artículo en Inglés | MEDLINE | ID: mdl-33181977

RESUMEN

Noble scallop Chlamys nobilis is an important marine bivalve that has been extensively cultured in the south coast of China since the 1980s. Unfortunately, since the late 1990s, the farmed scallops often suffered from regional mass mortality, which results in enormous economic losses to farmers and industries. In 2017, another mass mortality event occurred in Nan'ao Island, Shantou, China. In this study, the cause of C. nobilis mass mortality in 2017 was first investigated in the field, and then validated in a laboratory experiment. In the field, three sampling sites were selected according to the scallop mortality rate: Hunter Bay (90% mortality), Baisha Bay (67% mortality) and Longhai (6% mortality). Meanwhile, environmental parameters (temperature, salinity, DO, pH and chlorophyll a) of each site were also measured in situ. Then, water and scallop samples were collected randomly for the analysis of phytoplankton diversity and algal toxin activity using 18S rDNA and PP2A inhibition assay, respectively. In laboratory, healthy scallops were challenged with Karenia mikimotoi (1 × 103 cells/mL) for 30 h. The field results showed that no significant difference in those environmental parameters existed among the three sites, but the relative abundance of K. mikimotoi in seawater and scallops' intestines in Hunter Bay and Baisha Bay was significantly higher than that in Longhai, and sick scallops contained significantly higher algal toxin activity than healthy ones. Laboratory results revealed that challenged scallops with K. mikimotoi showed significantly higher mortality rate and algal toxin activity than healthy ones, and low density of K. mikimotoi (1 × 103 cells/mL) was sufficient to cause >50% scallops' mortality within 26 h. This study provides the first evidence that low K. mikimotoi cell density can cause massive mortality in C. nobilis, and provides useful information as guide to prevent scallop mass mortality in the future.


Asunto(s)
Carotenoides , Pectinidae , Animales , Carotenoides/análisis , China/epidemiología , Clorofila A , Islas
15.
Sci Total Environ ; 750: 142183, 2021 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-33182173

RESUMEN

To evaluate the transboundary pollution of organic aerosols from Northeast Asia, a highly time-resolved measurement of organic compounds was performed in March 2019 at Oki Island located in Japan, which is a remote site and less affected by local anthropogenic sources. PM2.5, water-soluble organic carbon (WSOC) concentrations, and WSOC fraction in PM2.5 showed high values on March 22-23 (high-WSOC period (HWSOC)) when the air mass passed through the area where many fire spots were detected in Northeast China. Biomass burning tracers showed higher concentration, especially levoglucosan exceeded 1 µg/m3 during the HWSOC than the low-WSOC period (LWSOC). Notably, high time-resolved measurements of biomass burning tracers and back trajectory analysis during HWSOC revealed a difference in the variation of lignin pyrolyzed compounds and anhydrous sugars on 22 and 23 March. The air mass passed to different areas in Northeast China in which fire spots were detected, such as the eastern area on the 22nd and the western area on the 23rd. Almost-organic compounds also showed high concentration and strong correlations with levoglucosan and sulfate during HWSOC. Moreover, low-carbon dicarboxylic acids (e.g., adipic acid) and secondary products from anthropogenic volatile organic compounds (e.g., 2,3-dihydroxy-4-oxopentanoic, phthalic, 5-nitrosalicylic acids), also showed a strong correlation with sulfate ions during the HWSOC and LWSOC, respectively. These higher concentrations and strong correlations with levoglucosan and sulfate during the HWSOC propose that their generation could be enhanced by biomass burning. The ratios of organics (e.g., levoglucosan/mannnosan, pinic/3-methylbutane-1,2,3-tricarboxylic acids) suggest that the high concentrations of PM2.5 and WSOC observed during the HWSOC were caused by aged organic aerosols that originated from the combustion of herbaceous plants transported from Northeast China. Our findings indicate that biomass combustion in Northeast China could significantly affect the chemical compositions and the characterization of organic aerosols in downwind regions of Northeast China.


Asunto(s)
Contaminantes Atmosféricos , Material Particulado , Aerosoles/análisis , Contaminantes Atmosféricos/análisis , Biomasa , Carbono/análisis , China , Monitoreo del Ambiente , Islas , Japón , Material Particulado/análisis , Estaciones del Año
16.
Sci Total Environ ; 750: 141602, 2021 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-32882495

RESUMEN

Microorganisms play a key role in the carbon (C) cycle through soil organic matter (SOM). The rate of SOM mineralization, the influence of abiotic factors on this rate and the potential behaviour of SOM are of particular interest in the northern Antarctic Peninsula and offshore islands. This is one of the most rapidly warming regions on Earth with numerous ice-free areas, some with abundant wildlife and with the greatest known soil organic carbon (SOC) storage in Antarctica. The latter implies extended Antarctic summer conditions promote increased terrestrial plant growth and soil microbial activity (SMA). SMA, determined by respirometry, is a measure of ecosystem function, and depends on microclimatic conditions and soil environmental properties. SMA and the effect of abiotic variables have been analysed in locations with different soil types, on Cierva Point (Antarctic Peninsula), Deception Island and Fildes Peninsula (King George Island). Soil microbial biomass carbon (SMBC) ranged from 5.66 to 196.6 mg SMBC kg-1and basal respiration (BR) from 2.86 to 160.67 mg CO2 kg-1 d-1. SMBC and BR values were higher in Cierva Point, followed by Fildes Peninsula and Deception Island, showing the same trend of SOM abundance. Except for Cierva Point, low nitrogen, phosphorus and C concentrations were observed. SMBC/total organic carbon (TOC) levels indicated that SOC was recalcitrant and SOM content was closely related to the extent of vegetation cover observed in situ. High metabolic quotient values obtained at Cierva Point and Deception Island (median values 7.27 and 6.53 mg C-CO2 g SMBC-1 h-1) and low SMBC/TOC in Cierva Point suggest a poor efficiency of the microbial populations in the consumption of the SOC. High SMBC/TOC values obtained in Deception Island indicates that SMBC may influence SOM stabilization. Mineralization rates were very low (negligible values to 1.44%) and sites with the lowest values had the highest SOM.


Asunto(s)
Carbono , Suelo , Regiones Antárticas , Carbono/análisis , Ecosistema , Islas , Microbiología del Suelo
17.
Sci Total Environ ; 752: 141866, 2021 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-32889282

RESUMEN

Inshore coral habitats are at high risk of loss due to a combination of climate warming and regional-scale human impacts. As a result, they have undergone significant declines. Direct evidence of acute and chronic disturbance on most inshore coral assemblages is limited. Long-term, periodical surveys and historical baseline data essential for effective management are lacking. Using high-precision uranium-thorium (UTh) dating, we reconstruct a ~100-year-long history of extensive coral loss, changes in coral community structure, and a shifting baseline. The data were collected at Weizhou Island, northern South China Sea (SCS), which has highly disturbed inshore coral habitats that are typical globally. According to our UTh dates, major coral mortalities around Weizhou Island have occurred since the 1950s, with increasing frequency and severity since the 1980s. The extensive loss of branching Acropora and collapse of coral communities with peaks around 1960, 1984, and 1998 are accompanied by a shift toward low coral cover and noncoral-dominated assemblages. Prior to this collapse, the local coral community structure sustained remarkable long-term stability over millennia. The timing of the Acropora loss and massive coral mortalities coincides with multiple acute and chronic, natural and anthropogenic disturbance events. We suggest that priority should be given to directly addressing the causes of degradation and effectively controlling chronic disturbances before attempting to restore reef ecosystems. This is probably the only way to solve the "wicked problem" of sustaining the key functions and ecosystem services of inshore coral habitats such as those of Weizhou Island, northern SCS.


Asunto(s)
Antozoos , Uranio , Animales , China , Arrecifes de Coral , Ecosistema , Monitoreo del Ambiente , Humanos , Islas , Torio
18.
Sci Total Environ ; 753: 142054, 2021 Jan 20.
Artículo en Inglés | MEDLINE | ID: mdl-32896729

RESUMEN

Sediment microorganisms are influenced by various biotic and abiotic factors. However, information concerning the spatial factors that determine the functional diversity of sediment bacterial communities at an island scale is limited. Here, we conducted an island-scale study to assess the driving forces governing the functional diversity of sediment bacterial communities in different mangroves around the coast of Hainan Island, southern China. For mangrove sediments in Hainan Island, differences in the metabolic activity and functional diversity among four sites were context dependent, while that showed a trend of East > North > West > South. Furthermore, total carbon, nitrite nitrogen, and salinity are important environmental factors that determine the metabolic functional diversity of bacterial communities. This study also provided important insights for explaining the metabolic functional diversity of bacterial communities in tropical mangrove sediments. The metabolic activity had a significantly response to environmental variables (13.2% of pure variance was explained) and spatial variables (12.4%). More importantly, given that spatial variables may contribute to the bacterial functional as important as environmental variables, this spatial variety of bacterial functional provides new insight into studying bacterial functional biogeographic patterns and impacts on sediment-associated function.


Asunto(s)
Sedimentos Geológicos , Humedales , Bacterias/genética , China , Islas
19.
Sci Total Environ ; 754: 142141, 2021 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-32920402

RESUMEN

Antimicrobial resistance is a quintessential One Health issue, among the most serious 21st century global threats to human health. Seabirds may act as sentinels of natural and anthropogenic changes in the marine ecosystem health, including pollution by antimicrobial resistance genes (ARGs). We used real time PCR to identify and quantify 22 plasmid-mediated ARGs in the gastrointestinal microbiome of six wild seabird species, comparing an anthropized (Fernando de Noronha Archipelago - FNA) and a pristine biotope (Rocas Atoll - ROA), Brazil. Of 257 birds, 218 (84.8%) were positive to at least one ARG. ARG classes encoding resistance to tetracyclines (75.1%), quinolones (10.5%) and phenicols (10.5%) were the most prevalent, with tetracyclines significantly greater than the remaining classes (p < 0.05). Genes tet(S) (29.2%), tet(A) (28.8%), and tet(B) (24.9%) were the most commonly found and had a significantly greater prevalence when compared to the remaining ARGs (p < 0.05). The anthropized biotope presented statistically significant higher prevalence of sulfonamide- and quinolone-encoding ARGs in comparison with the pristine (respectively, p = 0.01 and p = 0.03), and higher sulII gene prevalence (p = 0.04), consistent with anthropogenic pressure. Migratory species (only present in ROA) showed statistically significant higher mcr-1 (polymyxins) and blaTEM (betalactam) prevalences (respectively, p = 0.009 and p = 0.02), and mcr-1 percentage load (p = 0.0079) in comparison with non-migratory. To our knowledge, this is the largest ARGs survey based on direct detection and quantification in seabirds worldwide, and the first to evaluate non-synanthropic species in oceanic islands. This is the first detection of mcr-1 in wild free-ranging seabirds in Brazil and in free-ranging migratory non-synanthropic seabirds worldwide. Our findings show the importance of biological and ecological factors, highlighting the role of seabirds as anthropization sentinels and ARGs-pollution environmental indicators (even in a pristine biotope), and their involvement in the One Health epidemiological chain of ARGs.


Asunto(s)
Antibacterianos , Salud Única , Animales , Antibacterianos/farmacología , Aves , Brasil , Farmacorresistencia Bacteriana/genética , Ecosistema , Genes Bacterianos , Humanos , Islas
20.
J Environ Manage ; 277: 111367, 2021 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-32947232

RESUMEN

Floating Treatment Systems (FTWs) are known to be an efficient means to treat eutrophic surface waters, but most of the studies are related to the use of FTWs at the laboratory, microcosm or mesocosm level. It is necessary to expand these studies to larger surface areas and to introduce new supporting materials, substrates and plants adapted to the different regional conditions. This study aimed to evaluate the efficiency of temporal and spatial remediation of a floating island system, set up in a 400m2 experimental area delimited in an urban reservoir located on the main campus of the Federal University of Campina Grande-PB, Brazil. The experiment was carried out in three stages and 16 physicochemical and biological variables were monitored at thirteen sampling points regularly distributed in the study area, for a period of eight months. Temporally, the variables turbidity, electrical conductivity and total, fixed and volatile dissolved solids tended to decrease. Spatially, considering the 13 sampling points in sequence, the trend of reductions were found in the total dissolved solids, volatile dissolved solids and electrical conductivity. The trend of elevation was more substantial for the concentrations of ammonia-nitrogen and orthophosphate. In addition, occasional substantial reductions was found in variables that did not show statistical trends, such as chemical oxygen demand and total phosphorus. This study demonstrated the importance of expanding the scale of evaluation of floating island systems, finding significant results in terms of reduction of pollutants and adaptation of new structures and plants to adverse environmental conditions.


Asunto(s)
Contaminantes Químicos del Agua , Brasil , Monitoreo del Ambiente , Islas , Nitrógeno/análisis , Fósforo/análisis , Contaminantes Químicos del Agua/análisis
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