Search results for "Climate"
showing 10 items of 4934 documents
Carbon dynamics in highly heterotrophic subarctic thaw ponds
2015
Abstract. Global warming has accelerated the formation of permafrost thaw ponds in several subarctic and arctic regions. These ponds are net heterotrophic as evidenced by their greenhouse gas (GHG) supersaturation levels (CO2 and CH4), and generally receive large terrestrial carbon inputs from the thawing and eroding permafrost. We measured seasonal and vertical variations in the concentration and type of dissolved organic matter (DOM) in five subarctic thaw (thermokarst) ponds in northern Quebec, and explored how environmental gradients influenced heterotrophic and phototrophic biomass and productivity. Late winter DOM had low aromaticity indicating reduced inputs of terrestrial carbon, wh…
Autochthonous organic matter promotes DNRA and suppresses N2O production in sediments of the coastal Baltic Sea
2021
Coastal environments are nitrogen (N) removal hot spots, which regulate the amount of land-derived N reaching the open sea. However, mixing between freshwater and seawater creates gradients of inorganic N and bioavailable organic matter, which affect N cycling. In this study, we compare nitrate reduction processes between estuary and offshore archipelago environments in the coastal Baltic Sea. Denitrification rates were similar in both environments, despite lower nitrate and carbon concentrations in the offshore archipelago. However, DNRA (dissimilatory nitrate reduction to ammonium) rates were higher at the offshore archipelago stations, with a higher proportion of autochthonous carbon. Th…
Biogenic Fenton process - A possible mechanism for the mineralization of organic carbon in fresh waters.
2020
To explore the mechanisms that mineralize poorly bioavailable natural organic carbon (OC), we measured the mineralization of OC in two lake waters over long-term experiments (up to 623 days) at different pH and iron (Fe) levels. Both the microbial and photochemical mineralization of OC was higher at pH acidified to 4 than at the ambient pH 5 or an elevated pH 6. During 244 days, microbes mineralized up to 60% of OC in the 10-mu m filtrates of lake water and more than 27% in the 1-mu m filtrates indicating that large-sized microbes/grazers enhance the mineralization of OC. A reactivity continuum model indicated that the acidification stimulated the microbial mineralization of OC especially i…
The effect of temperature on cercariae production of two Rhipidocotyle trematodes parasitizing freshwater mussel, Anodonta anatina.
2013
Two bucephalid trematodes, Rhipidocotyle campanula and R. fennica are known to infect the duck mussel, Anodonta anatina. The infection will lead to decrease growth, reproduction and survival of A. anatina. Given the important role of temperature on cercariae production, a vital component of the parasite’s transmission and life cycle success, the effect of temperature on cercariae production of two Rhipidocotyle sp. in their molluscan host, Anodonta anatina, was investigated. Mussels were collected from the Rivers, Haajaistenjoki and Kuusaankoski, marked and allocated to three temperature treatments—high, intermediate and low. Between May 31-October 28, 2011, clams were individually monitore…
Major loss of coralline algal diversity in response to ocean acidification
2021
[Abstract] Calcified coralline algae are ecologically important in rocky habitats in the marine photic zone worldwide and there is growing concern that ocean acidification will severely impact them. Laboratory studies of these algae in simulated ocean acidification conditions have revealed wide variability in growth, photosynthesis and calcification responses, making it difficult to assess their future biodiversity, abundance and contribution to ecosystem function. Here, we apply molecular systematic tools to assess the impact of natural gradients in seawater carbonate chemistry on the biodiversity of coralline algae in the Mediterranean and the NW Pacific, link this to their evolutionary h…
Species distributions models may predict accurately future distributions but poorly how distributions change: A critical perspective on model validat…
2023
Aim: Species distribution models (SDMs) are widely used to make predictions on how species distributions may change as a response to climatic change. To assess the reliability of those predictions, they need to be critically validated with respect to what they are used for. While ecologists are typically interested in how and where distributions will change, we argue that SDMs have seldom been evaluated in terms of their capacity to predict such change. Instead, typical retrospective validation methods estimate model's ability to predict to only one static time in future. Here, we apply two validation methods, one that predicts and evaluates a static pattern, while the other measures change…
¿Cómo se trata el tiempo atmosférico y el clima en la Educación Primaria? Una exploración a partir de los recursos y actividades de los manuales de t…
2020
El estudio del clima y del tiempo atmosférico constituye una tarea fundamental en la formación del alumnado (en todos sus niveles) debido a la enorme transcendencia social que tiene para gran parte de las actividades cotidianas. El objetivo de esta investigación es analizar los recursos y actividades sobre Climatología que se proponen en los manuales de texto de Primaria (3er Ciclo; Ciencias Sociales) de la Comunidad Valenciana (España). Metodológicamente se han consultado las principales editoriales que se utilizan en esta región. Los resultados indican que actualmente los libros de texto son meramente informativos y transmisivos. Respecto a los recursos, gran parte de los que se utilizan …
Natural acidification changes the timing and rate of succession, alters community structure, and increases homogeneity in marine biofouling communiti…
2017
Ocean acidification may have far-reaching consequences for marine community and ecosystem dynamics, but its full impacts remain poorly understood due to the difficulty of manipulating pCO2 at the ecosystem level to mimic realistic fluctuations that occur on a number of different timescales. It is especially unclear how quickly communities at various stages of development respond to intermediate-scale pCO2 change and, if high pCO2 is relieved mid-succession, whether past acidification effects persist, are reversed by alleviation of pCO2 stress, or are worsened by departures from prior high pCO2 conditions to which organisms had acclimatized. Here, we used reciprocal transplant experiments al…
Long-term monitoring of the TeV emission from Mrk 421 with the ARGO-YBJ experiment
2011
ARGO-YBJ is an air shower detector array with a fully covered layer of resistive plate chambers. It is operated with a high duty cycle and a large field of view. It continuously monitors the northern sky at energies above 0.3 TeV. In this paper, we report a long-term monitoring of Mrk 421 over the period from 2007 November to 2010 February. This source was observed by the satellite-borne experiments Rossi X-ray Timing Explorer and Swift in the X-ray band. Mrk 421 was especially active in the first half of 2008. Many flares are observed in both X-ray and gamma-ray bands simultaneously. The gamma-ray flux observed by ARGO-YBJ has a clear correlation with the X-ray flux. No lag between the X-r…
Critiquing and Joining Intersections of Disaster, Conflict, and Peace Research
2020
AbstractDisaster research, conflict research, and peace research have rich and deep histories, yet they do not always fully intersect or learn from each other, even when they investigate if and how disasters lead to conflict or peace. Scholarship has tended to focus on investigating causal linkages between disaster (including those associated with climate change) and conflict, and disaster diplomacy emerged as a thread of explanatory research that investigates how and why disaster-related activities do and do not influence peace and conflict. However, definitive conclusions on the disaster-conflict-peace nexus have evaded scientific consensus, in part due to conceptual, methodological, and …