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1.
Sci Total Environ ; 751: 141810, 2021 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-32882566

RESUMO

The channel and fjord region of southern Chilean Patagonia hosts giant kelp forests (Macrocystis pyrifera) that have little known site-specific responses to diverse physical gradients. In this study, the functionality of the bio-optical, morphological and biochemical features of the kelps, that determine their light trapping and acclimation, were studied along a gradient of varying turbidity and light conditions at the land-terminating glacier of fjord Yendegaia in the Beagle Channel. These habitats are marked by glacial retreat, and M. pyrifera has successfully colonized new areas due to the effects of warming. Results indicated that under a sharp gradient of turbidity and light availability, the kelps have adapted shading characteristics. The photobiological traits (e.g. light absorption, pigment concentration, photochemistry and blade optics) of algae from depths between 6 and 13 m varied in relation to the degree of turbidity along the fjord. However, these populations did not show obvious intra-thallus variation along the longitudinal profile e.g. blades located at different depths showed relatively similar acclimation potential to the prevailing light field. Only basal sporophylls showed general differences in comparison with the vegetative fronds. Otherwise, the high phenolic (phlorotannin) content, which was reflected in the massive presence of intracellular physodes, suggests that these organisms could be biochemically well-equipped to cope with changes in physical conditions or the presence of herbivore invertebrates (e.g. sea urchins).


Assuntos
Macrocystis , Animais , Chile , Cães , Estuários , Camada de Gelo , Fotobiologia
2.
Nature ; 586(7827): 29-30, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32999477
3.
Nature ; 586(7827): 7-8, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32999488
4.
Nat Commun ; 11(1): 5071, 2020 10 08.
Artigo em Inglês | MEDLINE | ID: mdl-33033235

RESUMO

Identifying species that are both geographically restricted and functionally distinct, i.e. supporting rare traits and functions, is of prime importance given their risk of extinction and their potential contribution to ecosystem functioning. We use global species distributions and functional traits for birds and mammals to identify the ecologically rare species, understand their characteristics, and identify hotspots. We find that ecologically rare species are disproportionately represented in IUCN threatened categories, insufficiently covered by protected areas, and for some of them sensitive to current and future threats. While they are more abundant overall in countries with a low human development index, some countries with high human development index are also hotspots of ecological rarity, suggesting transboundary responsibility for their conservation. Altogether, these results state that more conservation emphasis should be given to ecological rarity given future environmental conditions and the need to sustain multiple ecosystem processes in the long-term.


Assuntos
Aves/fisiologia , Conservação dos Recursos Naturais , Ecossistema , Internacionalidade , Mamíferos/fisiologia , Animais , Geografia , Humanos , Camada de Gelo , Filogenia , Análise de Componente Principal , Especificidade da Espécie
5.
Nat Commun ; 11(1): 5364, 2020 10 23.
Artigo em Inglês | MEDLINE | ID: mdl-33097697

RESUMO

Over the last ten years, satellite and geographically constrained in situ observations largely focused on the northern hemisphere have suggested that annual phytoplankton biomass cycles cannot be fully understood from environmental properties controlling phytoplankton division rates (e.g., nutrients and light), as they omit the role of ecological and environmental loss processes (e.g., grazing, viruses, sinking). Here, we use multi-year observations from a very large array of robotic drifting floats in the Southern Ocean to determine key factors governing phytoplankton biomass dynamics over the annual cycle. Our analysis reveals seasonal phytoplankton accumulation ('blooming') events occurring during periods of declining modeled division rates, an observation that highlights the importance of loss processes in dictating the evolution of the seasonal cycle in biomass. In the open Southern Ocean, the spring bloom magnitude is found to be greatest in areas with high dissolved iron concentrations, consistent with iron being a well-established primary limiting nutrient in this region. Under ice observations show that biomass starts increasing in early winter, well before sea ice begins to retreat. The average theoretical sensitivity of the Southern Ocean to potential changes in seasonal nutrient and light availability suggests that a 10% change in phytoplankton division rate may be associated with a 50% reduction in mean bloom magnitude and annual primary productivity, assuming simple changes in the seasonal magnitude of phytoplankton division rates. Overall, our results highlight the importance of quantifying and accounting for both division and loss processes when modeling future changes in phytoplankton biomass cycles.


Assuntos
Biomassa , Fitoplâncton/crescimento & desenvolvimento , Estações do Ano , Água do Mar/microbiologia , Biodiversidade , Carbono/análise , Clorofila/análise , Clima , Ecologia , Camada de Gelo , Luz , Biologia Marinha , Meteorologia , Nutrientes , Oceanos e Mares , Dinâmica Populacional , Microbiologia da Água
6.
Mar Environ Res ; 162: 105181, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33091683

RESUMO

Body size is one of the most important traits of organisms that affects their behavioral life histories, physiologies, and energy requirements. For sediment-dwelling organisms, such as free-living nematodes, body size is a direct adaptation for living in sediments with a particular particle size, but other environmental factors, e.g., water depth and food availability, directly or indirectly shape nematode morphology. Nevertheless, our knowledge of meiofaunal organisms sizes still lags far behind that of other aquatic fauna, particularly for high-latitude fauna. Therefore, to gain insight into the nematode community size structure, we investigated eight stations located in the seasonal sea-ice zone north of Svalbard (Yermak Plateau, Nansen Basin, and Northern Svalbard shelf) during Arctic spring. Sample locations covered a wide depth gradient, different sea-ice concentrations and subsequent bloom stages. Our study provides previously unavailable data on nematode morphometry for this Arctic region during ecologically important spring to summer transition times. We analyzed nematode biomass, body shape and morphometric attributes, along with respective feeding types and life stage information. Our results show that differences in nematode densities, biomass and allometric attributes most likely reflect differences in the flux of organic material to the seafloor and in the biogeochemical properties of the sediments. Nematode assemblages appeared to respond to spatial gradients in ice cover duration and therefore pelagic productivity from the northern Svalbard shelf to the Yermak Plateau as evidenced by decreasing density, biomass and body size. Considering the entire community, as well as different life stages, average individual body weight decreased northward. Biomass dominance in the lower weight classes and the significantly lower abundance of long and thick morphotype nematodes observed on the Yermak Plateau than in the two other regions were striking. This was in contrast with the assemblage observed on the shelf, where prevailing environmental conditions influenced the presence of other morphotypes - markedly longer and wider organisms. Ongoing changes in sea-ice cover and primary production in the Arctic may significantly affect nematode functioning, as they are expected to have pronounced impacts on nematode morphological characteristics. In this regard, the size-based approach becomes a useful tool for detecting changes in the community and has important implications for predicting the direction of change with regard to benthic productivity.


Assuntos
Camada de Gelo , Nematoides , Animais , Regiões Árticas , Biomassa , Svalbard
7.
Nat Commun ; 11(1): 4403, 2020 09 02.
Artigo em Inglês | MEDLINE | ID: mdl-32879312

RESUMO

Bacteriophage genomes rapidly evolve via mutation and horizontal gene transfer to counter evolving bacterial host defenses; such arms race dynamics should lead to divergence between phages from similar, geographically isolated ecosystems. However, near-identical phage genomes can reoccur over large geographical distances and several years apart, conversely suggesting many are stably maintained. Here, we show that phages with near-identical core genomes in distant, discrete aquatic ecosystems maintain diversity by possession of numerous flexible gene modules, where homologous genes present in the pan-genome interchange to create new phage variants. By repeatedly reconstructing the core and flexible regions of phage genomes from different metagenomes, we show a pool of homologous gene variants co-exist for each module in each location, however, the dominant variant shuffles independently in each module. These results suggest that in a natural community, recombination is the largest contributor to phage diversity, allowing a variety of host recognition receptors and genes to counter bacterial defenses to co-exist for each phage.


Assuntos
Bacteriófagos/genética , Camada de Gelo/virologia , Metagenoma , Cianobactérias/virologia , Ecossistema , Transferência Genética Horizontal , Genes Virais , Genoma Viral , Interações entre Hospedeiro e Microrganismos/genética , Camada de Gelo/microbiologia , Metagenômica , Filogenia
8.
Ecotoxicol Environ Saf ; 203: 111037, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32888596

RESUMO

Glacier studies as of late have ruffled many eyeballs, exploring this frigid ecology to understand the impact of climate change. Mapquesting the glaciers led to the discovery of concealed world of "psychrophiles" harboring in it. In the present study, the antibiotic resistance genes (ARGs) and heavy metal resistance genes (MRGs) were evaluated through both the culture-dependent and culture-independent methods. Samples were collected from two different glaciers, i.e., debris-covered glacier (Changme Khangpu) and debris-free glacier (Changme Khang). Functional metagenomics of both the glacier samples, provided evidence of presence of resistant genes against various antibiotic groups. Bacitracin resistant gene (bacA) was the predominant ARG in both the glaciers. MRGs in both the glacier samples were diversified as the genes detected were resistant against various heavy metals such as arsenic, tungsten, mercury, zinc, chromium, copper, cobalt, and iron. Unique MRGs identified from Changme Khangpu glacier were resistant to copper (cutA, cutE, cutC, cutF, cueR, copC, and copB) and chromium (yelf, ruvB, nfsA, chrR, and chrA) whereas, from Changme Khang glacier they showed resistance against cobalt (mgtA, dmef, corD, corC, corB, and cnrA), and iron (yefD, yefC, yefB, and yefA) heavy metals. ARGs aligned maximum identity with Gram-negative psychrotolerant bacteria. The cultured bacterial isolates showed tolerance to high concentrations of tested heavy metal solutions. Interestingly, some of the antibiotic resistant bacterial isolates also showed tolerance towards the higher concentrations of heavy metals. Thus, an introspection of the hypothesis of co-occurrence and/co-selection of ARGs and MRGs in such environments has been highlighted here.


Assuntos
Adaptação Biológica/genética , Antibacterianos/toxicidade , Resistência Microbiana a Medicamentos/genética , Poluentes Ambientais/toxicidade , Genes Bacterianos/efeitos dos fármacos , Camada de Gelo/microbiologia , Metais Pesados/toxicidade , Adaptação Biológica/efeitos dos fármacos , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Negativas/genética , Camada de Gelo/química , Índia , Metagenômica , Siquim
9.
Oecologia ; 194(1-2): 51-63, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32897468

RESUMO

Polar bears (Ursus maritimus) rely on annual sea ice as their primary habitat for hunting marine mammal prey. Given their long lifespan, wide geographic distribution, and position at the top of the Arctic marine food web, the diet composition of polar bears can provide insights into temporal and spatial ecosystem dynamics related to climate-mediated sea ice loss. Polar bears with the greatest ecological constraints on diet composition may be most vulnerable to climate-related changes in ice conditions and prey availability. We used quantitative fatty acid signature analysis (QFASA) to estimate the diets of polar bears (n = 419) in two western Canadian Arctic subpopulations (Northern Beaufort Sea and Southern Beaufort Sea) from 1999 to 2015. Polar bear diets were dominated by ringed seal (Pusa hispida), with interannual, seasonal, age- and sex-specific variation. Foraging area and sea ice conditions also affected polar bear diet composition. Most variation in bear diet was explained by longitude, reflecting spatial variation in prey availability. Sea ice conditions (extent, thickness, and seasonal duration) declined throughout the study period, and date of sea ice break-up in the preceding spring was positively correlated with female body condition and consumption of beluga whale (Delphinapterus leucas), suggesting that bears foraged on beluga whales during entrapment events. Female body condition was positively correlated with ringed seal consumption, and negatively correlated with bearded seal consumption. This study provides insights into the complex relationships between declining sea ice habitat and the diet composition and foraging success of a wide-ranging apex predator.


Assuntos
Ecossistema , Ursidae , Animais , Regiões Árticas , Canadá , Dieta , Feminino , Camada de Gelo , Masculino
10.
J Environ Manage ; 276: 111338, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32937234

RESUMO

Lake ice is an essential and integral part of the cryosphere and freshwater systems. The formation of lake ice affects the physical, hydrological, and biological conditions of ecological systems. Global warming may contribute to even shorter periods of ice cover in the lakes of the Frigid Zone, which adversely affects the growth of phytoplankton and primary productivity. This study was conducted for the purpose of evaluating the growth of phytoplankton and factors involved, in 28 ice-covered lakes across the Songnen Plain, in the Northeast of China, to understand how they take part in the whole-ecosystem functioning. A total of 1026 water samples were collected in April, September, and January during the period 2014-2018. In the frozen period, the concentration levels of dissolved organic carbon (DOC), total nitrogen (TN), and total phosphorus (TP) were all comparable with the spring and autumn. Despite the limited light availability and low temperature, the phytoplankton survived in sub-ice waters during winter with a low concentration of chlorophyll a (Chla). Its average concentration was positively correlated with the concentration observed in the previous autumn (rp = 0.563, p < 0.01). According to the regression tree analysis, during the winter period, Chla was mainly related to the concentration of TN in sub-ice water (TNwater) and with the difference of concentration of TP between water and ice (TPcd). Furthermore, either in ice or in sub-ice water, the concentration of Chla was also significantly affected by total suspended matter (TSM) (p < 0.05). The levels of TNwater, TPcd, and TSM could explain the 77.8% of the variance in the concentration of Chla during winter with contributions in the ranges of 25.5%-35.0%, 9.2%-11.3%, and 21.5%-34.0%, respectively (p < 0.05). This research substantially contributes to comprehending how the existing conditions under-ice affect the whole ecosystem when the ice cover is reduced lakes or rivers.


Assuntos
Camada de Gelo , Lagos , China , Clorofila , Clorofila A , Ecossistema , Monitoramento Ambiental , Fósforo/análise , Fitoplâncton , Estações do Ano
12.
Proc Natl Acad Sci U S A ; 117(36): 22293-22302, 2020 09 08.
Artigo em Inglês | MEDLINE | ID: mdl-32839321

RESUMO

During austral summer field seasons between 1999 and 2018, we sampled at 91 locations throughout southern Victoria Land and along the Transantarctic Mountains for six species of endemic microarthropods (Collembola), covering a latitudinal range from 76.0°S to 87.3°S. We assembled individual mitochondrial cytochrome c oxidase subunit 1 (COI) sequences (n = 866) and found high levels of sequence divergence at both small (<10 km) and large (>600 km) spatial scales for four of the six Collembola species. We applied molecular clock estimates and assessed genetic divergences relative to the timing of past glacial cycles, including collapses of the West Antarctic Ice Sheet (WAIS). We found that genetically distinct lineages within three species have likely been isolated for at least 5.54 My to 3.52 My, while the other three species diverged more recently (<2 My). We suggest that Collembola had greater dispersal opportunities under past warmer climates, via flotation along coastal margins. Similarly increased opportunities for dispersal may occur under contemporary climate warming scenarios, which could influence the genetic structure of extant populations. As Collembola are a living record of past landscape evolution within Antarctica, these findings provide biological evidence to support geological and glaciological estimates of historical WAIS dynamics over the last ca 5 My.


Assuntos
Variação Genética , Invertebrados/genética , Solo , Animais , Regiões Antárticas , Mudança Climática , Camada de Gelo , Estações do Ano
13.
Mar Pollut Bull ; 159: 111485, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32763559

RESUMO

Increased knowledge about the fate and behaviour of weathered oil in different sea ice conditions is essential for our ability to model oil spill trajectories in ice more precisely and for oil spill response decision making in northern and Arctic areas. As part of the 3-year project: "Fate, Behaviour and Response to Oil Drifting into Scattered Ice and Ice Edge in the Marginal Ice Zone", a novel wave and current flume was built to simulate these processes in the laboratory. This paper discusses some of the findings from this project, which included Marine Gas Oil and four Norwegian crude oils. All crude oils were weathered prior to testing, simulating having drifted on the sea surface for a period (tentatively 1-3 days) before encountering ice. The build-up of oil drifting against an ice barrier and horizontal and vertical migration of oil droplets under solid ice and in frazil ice was studied.


Assuntos
Poluição por Petróleo/análise , Petróleo , Regiões Árticas , Camada de Gelo , Noruega
14.
Environ Monit Assess ; 192(9): 597, 2020 Aug 24.
Artigo em Inglês | MEDLINE | ID: mdl-32833127

RESUMO

The study, first of its kind in the Kashmir Valley, uses a time series of satellite data (1980-2018) to determine the glacier health, which is critical for sustaining the perenniality of the rivers originating from the area. The role of topography, morphology and climate on the observed glacier recession was investigated. In total, 147 glaciers were mapped from 1980 image; ~ 72% of the glaciers have area ≤ 3 km2 and a majority of them (123) are having size < 1 km2. The glaciers have reduced from 101.73 ± 16.79 km2 in 1980 to 72.41 ± 4.7 km2 in 2018 showing a recession of 29.32 ± 12.09 km2 during the period (28.82%). The observed glacier loss is higher (0.77 ± 0.31 km2 a-1) compared with the other Himalayan regions. The results indicated that there is strong influence of altitude, aspect, slope and climate on glacier recession. The glaciers with area ≤ 1 km2 have receded significantly more (41.20 ± 6.20%) than the larger glaciers > 3 km2 in area (15.97 ± 5.13%). The glaciers situated between 4200 and 4400 m altitudes have receded more (~ 55 ± 5.01%) than those situated at altitudes > 4800 m (~ 19 ± 6.9%). Furthermore, the glaciers with steep slope (> 25) have witnessed lower recession (0.25 ± 0.15 km2 a-1) compared to the glaciers with gentle slope (0.51 ± 0.22 km2 a-1). The south-facing glaciers showed higher recession (~ 38%) compared with the north-facing glaciers (~ 27%). The findings suggest that the increase in temperature and decline in winter solid precipitation have resulted in the glacier recession with the consequent depletion of the streamflows, which, if continued in the future, would adversely affect the economy in the region.


Assuntos
Monitoramento Ambiental , Camada de Gelo , Altitude , Índia , Rios
15.
Nature ; 584(7821): 393-397, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32814886

RESUMO

The rate of global-mean sea-level rise since 1900 has varied over time, but the contributing factors are still poorly understood1. Previous assessments found that the summed contributions of ice-mass loss, terrestrial water storage and thermal expansion of the ocean could not be reconciled with observed changes in global-mean sea level, implying that changes in sea level or some contributions to those changes were poorly constrained2,3. Recent improvements to observational data, our understanding of the main contributing processes to sea-level change and methods for estimating the individual contributions, mean another attempt at reconciliation is warranted. Here we present a probabilistic framework to reconstruct sea level since 1900 using independent observations and their inherent uncertainties. The sum of the contributions to sea-level change from thermal expansion of the ocean, ice-mass loss and changes in terrestrial water storage is consistent with the trends and multidecadal variability in observed sea level on both global and basin scales, which we reconstruct from tide-gauge records. Ice-mass loss-predominantly from glaciers-has caused twice as much sea-level rise since 1900 as has thermal expansion. Mass loss from glaciers and the Greenland Ice Sheet explains the high rates of global sea-level rise during the 1940s, while a sharp increase in water impoundment by artificial reservoirs is the main cause of the lower-than-average rates during the 1970s. The acceleration in sea-level rise since the 1970s is caused by the combination of thermal expansion of the ocean and increased ice-mass loss from Greenland. Our results reconcile the magnitude of observed global-mean sea-level rise since 1900 with estimates based on the underlying processes, implying that no additional processes are required to explain the observed changes in sea level since 1900.


Assuntos
Temperatura Alta , Camada de Gelo/química , Água do Mar/análise , Água do Mar/química , Monitoramento Ambiental , Aquecimento Global/estatística & dados numéricos , Groenlândia , História do Século XX , História do Século XXI , Probabilidade , Incerteza
16.
Mar Pollut Bull ; 160: 111571, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32861940

RESUMO

The article is devoted to the study of the activity values of natural radionuclides 40K, 232Th and 226Ra and technogenic radionuclide 137Cs in the bottom sediments of the Barents Sea, which is distinguished from the rest of the Arctic seas by the fact that the largest number of radiation objects are concentrated here. The activity levels of natural radionuclides were within the range of activity values corresponding to marine sediments around the world. The highest radionuclide activities were found within the deepwater shelf of the Barents Sea. The current level of activity of the technogenic radionuclide 137Cs is low and does not exceed 6.5 Bq·kg-1. However, due to global climatic changes, the secondary source of radiation pollution of the sea may be the Novaya Zemlya ice sheet, in which huge quantities of technogenic radionuclides were deposited during atmospheric tests of the 1950s and 1960s.


Assuntos
Poluentes Radioativos da Água , Regiões Árticas , Sedimentos Geológicos , Camada de Gelo , Oceanos e Mares , Poluentes Radioativos da Água/análise
17.
Proc Natl Acad Sci U S A ; 117(36): 21928-21937, 2020 09 08.
Artigo em Inglês | MEDLINE | ID: mdl-32839314

RESUMO

Ice nucleation and the resulting cloud glaciation are significant atmospheric processes that affect the evolution of clouds and their properties including radiative forcing and precipitation, yet the sources and properties of atmospheric ice nucleants are poorly constrained. Heterogeneous ice nucleation caused by ice-nucleating particles (INPs) enables cloud glaciation at temperatures above the homogeneous freezing regime that starts near -35 °C. Biomass burning is a significant global source of atmospheric particles and a highly variable and poorly understood source of INPs. The nature of these INPs and how they relate to the fuel composition and its combustion are critical gaps in our understanding of the effects of biomass burning on the environment and climate. Here we show that the combustion process transforms inorganic elements naturally present in the biomass (not soil or dust) to form potentially ice-active minerals in both the bottom ash and emitted aerosol particles. These particles possess ice-nucleation activities high enough to be relevant to mixed-phase clouds and are active over a wide temperature range, nucleating ice at up to -13 °C. Certain inorganic elements can thus serve as indicators to predict the production of ice nucleants from the fuel. Combustion-derived minerals are an important but understudied source of INPs in natural biomass-burning aerosol emissions in addition to lofted primary soil and dust particles. These discoveries and insights should advance the realistic incorporation of biomass-burning INPs into atmospheric cloud and climate models. These mineral components produced in biomass-burning aerosol should also be studied in relation to other atmospheric chemistry processes, such as facilitating multiphase chemical reactions and nutrient availability.


Assuntos
Aerossóis/química , Cinza de Carvão/química , Camada de Gelo/química , Minerais/química , Atmosfera/química , Biomassa , Mudança Climática , Congelamento , Gelo/análise , Tamanho da Partícula , Incêndios Florestais
18.
Proc Natl Acad Sci U S A ; 117(36): 22590-22596, 2020 09 08.
Artigo em Inglês | MEDLINE | ID: mdl-32843343

RESUMO

The Arctic is experiencing a rapid shift toward warmer regimes, calling for a need to understand levels of biodiversity and ecosystem responses to climate cycles. This study presents genetic data for 109 Arctic marine forest species (seaweeds), which revealed contiguous populations extending from the Bering Sea to the northwest Atlantic, with high levels of genetic diversity in the east Canadian Arctic. One-fifth of the species sampled appeared restricted to Arctic waters. Further supported by hindcasted species distributions during the Last Glacial Maximum, we hypothesize that Arctic coastal systems were recolonized from many geographically disparate refugia leading to enriched diversity levels in the east Canadian Arctic, with important contributions stemming from northerly refugia likely centered along southern Greenland. Our results suggest Arctic marine biomes persisted through cycles of glaciation, leading to unique assemblages in polar waters, rather than being entirely derived from southerly (temperate) areas following glaciation. As such, Arctic marine species are potentially born from selective pressures during Cenozoic global cooling and eventual ice conditions beginning in the Pleistocene. Arctic endemic diversity was likely additionally driven by repeated isolations into globally disparate refugia during glaciation. This study highlights the need to take stock of unique Arctic marine biodiversity. Amplification of warming and loss of perennial ice cover are set to dramatically alter available Arctic coastal habitat, with the potential loss of diversity and decline in ecosystem resilience.


Assuntos
Organismos Aquáticos , Biodiversidade , Ecossistema , Camada de Gelo , Refúgio de Vida Selvagem , Regiões Árticas , Florestas
19.
Science ; 369(6500): 198-202, 2020 07 10.
Artigo em Inglês | MEDLINE | ID: mdl-32647002

RESUMO

Historically, sea ice loss in the Arctic Ocean has promoted increased phytoplankton primary production because of the greater open water area and a longer growing season. However, debate remains about whether primary production will continue to rise should sea ice decline further. Using an ocean color algorithm parameterized for the Arctic Ocean, we show that primary production increased by 57% between 1998 and 2018. Surprisingly, whereas increases were due to widespread sea ice loss during the first decade, the subsequent rise in primary production was driven primarily by increased phytoplankton biomass, which was likely sustained by an influx of new nutrients. This suggests a future Arctic Ocean that can support higher trophic-level production and additional carbon export.


Assuntos
Camada de Gelo , Fitoplâncton/crescimento & desenvolvimento , Regiões Árticas , Biomassa , Carbono/metabolismo , Oceanos e Mares , Estações do Ano
20.
Int J Syst Evol Microbiol ; 70(8): 4583-4590, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32639224

RESUMO

Three strains, designated as LB1R34T, LB3P52T and ZT4R6T, were isolated from glaciers located on the Tibetan Plateau, PR China. The strains were Gram-stain-negative, aerobic, rod-shaped, non-motile and yellow. Phylogenetic analysis based on the 16S rRNA gene and genomic sequences indicated that they were related to the members of the genus Flavobacterium. The 16S rRNA gene sequences similarities between the three strains were 92.31-96.93 %. The average nucleotide identity values and digital DNA-DNA hybridization values between these three strains and their closest relatives were 76.80-91.33 % and 21.3-44.2 %, respectively. LB1R34T, LB3P52T and ZT4R6T contained MK-6 as the major menaquinone, summed feature 3 (comprising C16 : 1ω7c and/or C16 : 1ω6c) and iso-C15 : 0 as the major fatty acids. Phosphatidylethanolamine was present in their polar lipids profiles. On the basis of the phenotypic characteristics, he results of phylogenetic analysis and genotypic data, three novel species, Flavobacterium restrictum sp. nov. (type strain=LB1 R34T=CGMCC 1.11493T=NBRC 113650T), Flavobacterium rhamnosiphilum sp. nov. (type strain=LB3 P52T=CGMCC 1.11446T=NBRC 113776T) and Flavobacterium zepuense sp. nov. (type strain=ZT4 R6T=CGMCC 1.11919T=NBRC 113653T) are proposed.


Assuntos
Flavobacterium/classificação , Camada de Gelo/microbiologia , Filogenia , Técnicas de Tipagem Bacteriana , Composição de Bases , China , DNA Bacteriano/genética , Ácidos Graxos/química , Flavobacterium/isolamento & purificação , Hibridização de Ácido Nucleico , Fosfatidiletanolaminas/química , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Vitamina K 2/análogos & derivados , Vitamina K 2/química
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