Comparison of carbon and opal export rates between summer and spring bloom periods in the region of the Antarctic Polar Front, SE Atlantic.

Although primary production in the Antarctic Circumpolar Current is not above the world average and carbon burial rates are low, 70% of the world's opal burial occurs in this zone and it has been suggested that blooms of large diatoms are responsible for this extraordinary situation. Here we compare export fluxes during bloom and steady-state situations near the Antarctic Polar Front in the SE Atlantic.In a previous expedition during the austral spring, we observed the development of a bloom that led to the sudden export of particles (Rutgers van der Loeff et al., 1997). Here we report the results of a second expedition to the same area in summer (Dec-Jan), 3 years later. 234Th was monitored in the surface water and in Rosette casts down to a water depth of 500m as tracer of export production in an intensive sampling program within a box of 275 x 375 km.The distribution of particulate and dissolved 234Th was remarkably constant over time and location. Total (dissolved + particulate) 234Th activities were depleted relative to its parent 238U at the surface (234Th/238U activity ratio approximately 83%), reaching equilibrium at a depth of around 190m. This constant depletion corresponds to a 234Th export rate of 1115 dpm m-2 d-1, 35% of the value observed during the spring bloom

Scientific cruise report Elisabeth Mann-Borgese SUMMIX-MESO

Objectives: It was intended to investigate the meso-scale and sub-meso-scale dynamics of the upper layers (upper 80 m) in the central Baltic Sea, using towed instruments and acoustic profilers, to better understand the physical conditions for cyanobacteria blooms. Under optimal weather conditions, we intended to carry out 10 one-day quasi-synoptic surveys by cruising in large meandering patterns (see fig. 1) covering areas of 15 X 15 nautical miles or 8 X 8 nautical miles, depending on the survey mode, see below. This cruise was the meso-scale component of the two-ship SUMMIX experiment together with RV Meteor (Physical and biochemical exchange-, mixing- and transformation processes in the central Baltic Sea during summer stratification and their controls on the cyanobacterial summer bloom) which was intended to be located at a fixed position nearby RV Elisabeth Mann Borgese in order to survey the water column in high vertical, spatial and parameter resolution, including biogeochemical experiments on board. In addition to the physical parameters, also vertical and horizontal zooplankton net tows as well as water samples taken by CTD bottles were planned

Molecular analyses of gut contents: elucidating the feeding of co-occurring salps in the Lazarev Sea from a different perspective

The diet of Antarctic salps was elucidated by investigating their gut content using “Automated Ribosomal Intergenic Spacer Analysis” and 454-pyrosequencing. Salp samples were collected during the Lazarev Krill Study in the Western Weddell Sea (summer 2005/06 and 2007/08, fall 2004, and winter 2006). Two salp species, Salpa thompsoni and Ihlea racovitzai, both occur in the Southern Ocean, can overlap geographically and seasonally. Here we provide evidence that despite the non-selective feeding mechanism, the two co-occuring salp species might have different niches within one given habitat. ARISA-patterns of 93 salp gut content samples revealed strong differences between the two salp species, even at the same sampling site. These differences were confirmed by 454-pyrosequencing of the V4-18S rDNA of ten salps. The pyrosequencing data indicate that flagellates, in particular dinophyceae constitute a high proportion of the sequence reads identified in the gut content of both salp species. However, within the dinophyceae differences in the read composition were detected between the two salp species. This supports the findings of a previous study where fatty acid signatures indicate a flagellate based diet of salps, even though microscopic analyses identified diatoms as the dominant component of salp gut contents

Handling the phosphorus paradox in agriculture and natural ecosystems: scarcity, necessity, and burden of P

This special issue of Ambio compiles a series of contributions made at the 8th International Phosphorus Workshop (IPW8), held in September 2016 in Rostock, Germany. The introducing overview article summarizes major published scientific findings in the time period from IPW7 (2015) until recently, including presentations from IPW8. The P issue was subdivided into four themes along the logical sequence of P utilization in production, environmental, and societal systems: (1) Sufficiency and efficiency of P utilization, especially in animal husbandry and crop production; (2) P recycling: technologies and product applications; (3) P fluxes and cycling in the environment; and (4) P governance. The latter two themes had separate sessions for the first time in the International Phosphorus Workshops series; thus, this overview presents a scene-setting rather than an overview of the latest research for these themes. In summary, this paper details new findings in agricultural and environmental P research, which indicate reduced P inputs, improved management options, and provide translations into governance options for a more sustainable P use

Marine sustainability in an age of changing oceans and seas

The report is the result of fruitful collaboration between EASAC and the JRC. It has been prepared by a working group of experts drawn from the European National Science Academies, which was supported by the JRC. It is hoped that the report will prove useful in the further development and implementation of European Union marine and maritime policy as well as the organisation of supporting science needed to inform and guide these policies. The last ten years have seen a growth in marine and maritime policymaking within the European Union with a key feature being the concept of the ecosystem approach to guide sustainable use of the seas. In view of this increasing focus on coherent marine and maritime policy and governance within the EU, as well as globally, the EASAC Council decided in December 2013 to conduct a study on the issue of marine sustainability. This decision particularly acknowledged the need to provide advice from the point of view of the European science academies on this new direction of marine policy and to highlight the particular challenges that this poses to the organisation of science. The report has the aim of contributing to the governance challenge of how to integrate the various aspects of marine policy (fisheries management, biodiversity conservation and marine environmental protection) as part of a coherent ecosystem approach. It considers how current science knowledge on marine ecosystems and the organisation of science can support an integrated approach to management of the seas. The report looks at a number of key aspects for sustainable development in changing oceans and seas, and particularly highlights the key scientific challenges in addressing these issues. The report presents both recommendations from science for policy development, and recommendations on policy for science. The health of the oceans and coastal seas is vital for the future well-being of all of Europe, indeed of entire mankind, and sustainable management of this sensitive and fast changing component of the global ecosystem is essential.JRC.A.3-Inter-institutional, International Relations and Outreac

pyMANGA: A modular, open and extendable software platform for modeling of forest and vegetation dynamics

Agent-based vegetation models are a widely used tool in ecology, for example, to understand and predict the response of vegetation to environmental change. Models are based on well-established descriptions of processes such as vegetation establishment, growth and mortality. However, they are often developed from scratch, which can be inefficient. Here we present pyMANGA, a free and open-source platform for plant growth modelers. pyMANGA's modular design allows for the combination of different concepts and theories of how plants establish, grow or compete in response to above- and below-ground resource availability. New or alternative modules describing, e.g., competition or facilitation, can be easily added. The interchangeability of modules supports the systematic testing of different hypotheses, e.g., on dominant processes in soil-plant feedback loops. Here we further present the thorough benchmarking strategy to maintain the platform and how pyMANGA can be used to compare models with different levels of abstraction and complexity