Drought in forest understory ecosystems – a novel rainfall reduction experiment Biogeosciences DOI 10.5194/bg-12-961-2015 17 February 2015 This paper introduces a novel rainfall reduction experiment to investigate drought effects on soil-forest-understory-ecosystems. An annual drought with a return period of 40 years was imposed, while other ecosystem variables (humidity, air & soil temperature) remained unaffected. The first year of drought showed considerable changes in soil moisture dynamics, which affected leaf stomatal conductance of understory species as well as evapotranspiration rates of the forest understory ecosystem. Read more
Simulated anthropogenic CO2 storage and acidification of the Mediterranean Sea Biogeosciences DOI 10.5194/bg-12-781-2015 10 February 2015 Different observational-based estimates of CO2 uptake and resulting acidification of the Mediterranean Sea vary widely. A new study finds that even the smallest of those is an upper limit because the approach used assumes air-sea CO2 equilibrium. Then along with a lower limit from new fine-scale numerical model simulations, the authors bracket Mediterranean Sea CO2 uptake and acidification rates. They conclude that its rate of surface acidifcation is much like that for typical ocean waters. Read more
Technical Note: Maximising accuracy and minimising cost of a potentiometrically regulated ocean acidification simulation system Biogeosciences DOI 10.5194/bg-12-713-2015 5 February 2015 This article describes a low-cost, easy set-up, ocean acidification simulation system that reliably mimics the effects of elevated atmospheric carbon dioxide on seawater chemistry. The accessible design of this system, along with our suggestions for the validation of pH control and characterisation of seawater chemistry, will enable researchers on a limited budget to generate high quality, repeatable data documenting the response of marine organisms to ocean acidification. Read more
Processes determining the marine alkalinity and calcium carbonate saturation state distributions Biogeosciences DOI 10.5194/bg-11-7349-2014 19 December 2014 We examine and discuss the portion of ocean alkalinity that varies in response to carbonate cycling and riverine alkalinity inputs using a new tracer, Alk*. We use this tracer to quantify the controls on marine carbonate saturation: At depth, we find carbonate cycling to be a minor control relative to organic matter cycling and pressure changes. In well-equilibrated surface water, we find carbonate cycling to be less important than temperature changes and freshwater cycling. Read more
Estimated stocks of circumpolar permafrost carbon with quantified uncertainty ranges and identified data gaps Biogeosciences DOI 10.5194/bg-11-6573-2014 1 December 2014 This study provides an updated estimate of organic carbon stored in the northern permafrost region. The study includes estimates for carbon in soils (0 to 3 m depth) and deeper sediments in river deltas and the Yedoma region. We find that field-data is still scarce from many regions. Total estimated carbon storage is ~1300 Pg with an uncertainty range of between 1100 to 1500 Pg. Around 800 Pg carbon is perennially frozen, equivalent to all carbon dioxide currently in the Earths atmosphere. Read more
Long-term trends at the Boknis Eck time series station (Baltic Sea), 1957–2013: does climate change counteract the decline in eutrophication? Biogeosciences DOI 10.5194/bg-11-6323-2014 24 November 2014 A time series of 9 oceanic parameters from the coastal time series station Boknis Eck (BE, South Western Baltic Sea) in the period of 1957-2013 is analysed with respect to seasonal cycles and longterm trends. Most striking was a paradoxical decreasing trend in oxygen with a simultaneous decline in eutrophication. Possible reasons for this paradox, e.g. processes related to warming temperatures such as increased decomposition of organic matter or altered ventilation, are discussed. Read more
Gas emissions at the continental margin west of Svalbard: mapping, sampling, and quantification Biogeosciences DOI 10.5194/bg-11-6029-2014 6 November 2014 The authors mapped, sampled, and quantified gas emissions at the continental margin west of Svalbard in late summer 2012. They found that gas emissions occurred widespread between about 80 and 415 m water depth, which indicates that hydrate dissolution might only be one of several triggers for active hydrocarbon seepage in that area. Read more
Release of hydrogen peroxide and antioxidants by the coral Stylophora pistillata to its external milieu Biogeosciences DOI 10.5194/bg-11-4587-2014 1 September 2014 This paper presents a laboratory characterisation of hydrogen peroxide (H2O2) and antioxidant activity release kinetics by intact, non-stressed Stylophora pistillata. Experimenting with bleached and non-bleached corals and different stirring speeds, the authors explored the sources and modes of H2O2 and antioxidant release. Read more
Diverse coral communities in mangrove habitats suggest a novel refuge from climate change Biogeosciences DOI 10.5194/bg-11-4321-2014 19 August 2014 This paper characterises the first natural, non-reef coral refuge from thermal stress and ocean acidification and identifies resiliency factors for mangrove–coral habitats. Read more
Ecosystem function and services provided by the deep sea Biogeosciences DOI 10.5194/bg-11-3941-2014 29 July 2014 In this manuscript we aim to provide a foundation for informed conservation and management of the deep sea by summarizing the important role of the deep sea in society. Read more
