Beschreibung: 1. A resampling of 38 small farmland ponds in Belgium after 10 years revealed a high temporal species turnover for both phytoplankton and zooplankton communities, associated with substantial changes in abiotic factors, especially a reduction in total phosphorus concentration. 2. Across ponds, phytoplankton biomass decreased while evenness and richness increased between the samplings in 2003 and 2013. By contrast, the zooplankton assemblage was characterised by lower biomass, richness and evenness in 2013. Ponds experiencing larger environmental change showed stronger changes in phytoplankton richness and evenness. 3. Resource use efficiency (RUE) of zooplankton increased with greater environmental change and zooplankton evenness, which points to a switch towards species with higher RUE or greater variety in food sources in higher trophic levels. 4. As ponds are important habitats for freshwater biodiversity and ecosystems services, the strong but predictable species turnover and the opposing effects of environmental change on different trophic levels need to be embedded in conservation and management plans.

Beschreibung: Poseidon cruise 518 (leg 1 and 2) took place in the framework of the Horizon 2020 project STEMM-CCS of the EU. The project’s main goal is to develop and test strategies and technologies for the monitoring of subseafloor CO2 storage operations. In this context a small research-scale CO2 gas release experiment is planned for 2019 in the vicinity of the Goldeneye platform located in the British EEZ (central North Sea). Cruise POS518 aimed at collecting necessary oceanographic and biogeochemical baseline data for this release experiment. During Leg 1 ROV PHOCA was used to deploy MPI’s tool for high-precision measurements of O2, CO2 and pH in the bottom water at Goldeneye. In addition, ROV push cores and gravity cores were collected in the area for sediment biogeochemical analyses, and video-CTD casts were conducted to study the water column chemistry. The stereo-camera system and a horizontally looking multibeam echosounder, both, for determining gas bubble emissions at the seafloor were deployed at the Figge Maar blowout crater in the German Bight. Investigations were complemented by hydroacoustic surveys detecting gas bubble leakages at several abandoned wells in the North Sea as well as the Figge Maar. Surface water alkalinity as well as CH4, CO2, and water partial pressures in the air above the sea surface were measured continuously during the cruise. During Leg 2 three different benthic lander systems were deployed to obtain baseline data of oceanographic and biogeochemical parameters for a small research-scale CO2 gas release experiment planned for 2019. The first lander was equipped with an acoustic Doppler current profiler (ADCP), a CTD and an O2 optode. It was deployed for 6 days close to Goldeneye to obtain high resolution data which can be linked to the long-term measurements of the NOC-Lander. This lander is equipped with a suite of sensors to monitor temperature, conductivity, pressure, current speed and direction, hydro-acoustic, pH, pCO2, O2 and nutrients over a period of about 10 months with popup telemetry units for data transmission via IRIDIUM satellite telemetry every 3 months. Two short-term deployments of the Biogeochemical Observatory (BIGO) were conducted to study the molar ratio between oxygen and CO2-fluxes at the seafloor. Sediment cores obtained by gravity and multi corer were collected for sediment biogeochemical analyses and video-CTD casts were used to study the chemistry of the water column.

Beschreibung: There is significant commercial and research interest in the application of sea cucumbers as nutrient recyclers and processors of particulate waste in polyculture or integrated multitrophic aquaculture (IMTA) systems. The following article reviews examples of existing IMTA systems operating with sea cucumbers, and details the role and effect of several sea cucumber species in experimental and pilot IMTA systems worldwide. Historical observations and quantification of impacts of sea cucumber deposit-feeding and locomotion are examined, as is the development and testing of concepts for the application of sea cucumbers in sediment remediation and site recovery. The extension of applied IMTA systems is reported, from basic piloting through to economically viable farming systems operating at commercial scales. The near-global recognition of the ecological and economic value of deposit-feeding sea cucumbers in IMTA applications within existing and developing aquaculture industries is discussed. Predictions and recommendations are offered for optimal development of sea cucumber IMTA globally. Future directions within the industry are indicated, and key areas of ecological, biological and commercial concern are highlighted to be kept in mind and addressed in a precautionary manner as the industry develops.

Beschreibung: Large amounts of organic carbon are stored in Arctic permafrost environments, and microbial activity can potentially mineralize this carbon into methane, a potent greenhouse gas. In this study, we assessed the methane budget, the bacterial methane oxidation (MOX) and the underlying environmental controls of arctic lake systems, which represent substantial sources of methane. Five lake systems located on Samoylov Island (Lena Delta, Siberia) and the connected river sites were analyzed using radiotracers to estimate the MOX rates, and molecular biology methods to characterize the abundance and the community composition of methane-oxidizing bacteria (MOB). In contrast to the river, the lake systems had high variation in the methane concentrations, the abundance and composition of the MOB communities, and consequently, the MOX rates. The highest methane concentrations and the highest MOX rates were detected in the lake outlets and in a lake complex in a floodplain area. Though, in all aquatic systems we detected both, Type I and II MOB, in lake systems we observed a higher diversity including MOB, typical of the soil environments. The inoculation of soil MOB into the aquatic systems, resulting from permafrost thawing, might be an additional factor controlling the MOB community composition and potentially methanotrophic capacity.

Beschreibung: In the marine environment elevated electrical conductivities may be caused by sulfide mineralizations within the seafloor as well as hot saline pore fluids. Such conductive targets may be studied with suitable electromagnetic systems like the novel coil-system MARTEMIS1, which we previously used to investigate a known zone of sediment covered mineralization at the Palinuro Seamount (cruises POS483 & POS509) and in the vicinity of the TAG hydrothermal mound at the Mid Atlantic Ridge (cruise JC138). Both the Palinuro site as well as the sites in the vicinity of the TAG hydrothermal mound (Shinkai, Double Mound, MIR) are hydrothermally inactive and, thus, allowed to study, how the responses of an inductive EM system is influenced and shaped by mineralizations within the seafloor without having to consider the effect of of heated pore fluids. In the interpretation of the collected data at these inactive sites we learned that the MARTEMIS system is able to detect conductivity anomalies in the vicinity of mineralizations. (...)

Beschreibung: GEOMAR's project was integrated into the large-scale collaborative project SUGAR-III with 19 partners from industry and academia that was also coordinated by GEOMAR. The ain of the project was to characterize the gas hydrate accumulations in the Danube deep-sea fan geophysically and geochemically, to develop a three-dimensional geological model of the deposit and simulate its formation over geological time scales using the hydrate module developed in the PetroMod software, to investigate the problem of geomechanical destabilization and sand production occurring during hydrate exploitation by means of high-pressure experiments, to further develop the SUGAR gas hydrate technologies on geophysical data analysis, geological basin modelling and geomechanical test units in collaboration with the industrial project partners.

Beschreibung: While there is a lot of data on interactive effects of eutrophication and warming, to date, we lack data to generate reliable predictions concerning possible effects of nutrient decrease and temperature increase on community composition and functional responses. In recent years, a wide‐ranging trend of nutrient decrease (re‐oligotrophication) was reported for freshwater systems. Small lakes and ponds, in particular, show rapid responses to anthropogenic pressures and became model systems to investigate single as well as synergistic effects of warming and fertilization in situ and in experiments. Therefore, we set up an experiment to investigate the single as well as the interactive effects of nutrient reduction and gradual temperature increase on a natural freshwater phytoplankton community, using an experimental indoor mesocosm setup. Biomass production initially increased with warming but decreased with nutrient depletion. If nutrient supply was constant, biomass increased further, especially under warming conditions. Under low nutrient supply, we found a sharp transition from initially positive effects of warming to negative effects when resources became scarce. Warming reduced phytoplankton richness and evenness, whereas nutrient reduction at ambient temperature had positive effects on diversity. Our results indicate that temperature effects on freshwater systems will be altered by nutrient availability. These interactive effects of energy increase and resource decrease have major impacts on biodiversity and ecosystem function and thus need to be considered in environmental management plans.

Beschreibung: Increasing air temperatures are changing the arctic tundra biome. Permafrost is thawing, snow duration is decreasing, shrub vegetation is proliferating, and boreal wildlife is encroaching. Here we present evidence of the recent range expansion of North American beaver (Castor canadensis) into the Arctic, and consider how this ecosystem engineer might reshape the landscape, biodiversity, and ecosystem processes. We developed a remote sensing approach that maps formation and disappearance of ponds associated with beaver activity. Since 1999, 56 new beaver pond complexes were identified, indicating that beavers are colonizing a predominantly tundra region (18,293 km2) of northwest Alaska. It is unclear how improved tundra stream habitat, population rebound following overtrapping for furs, or other factors are contributing to beaver range expansion. We discuss rates and likely routes of tundra beaver colonization, as well as effects on permafrost, stream ice regimes, and freshwater and riparian habitat. Beaver ponds and associated hydrologic changes are thawing permafrost. Pond formation increases winter water temperatures in the pond and downstream, likely creating new and more varied aquatic habitat, but specific biological implications are unknown. Beavers create dynamic wetlands and are agents of disturbance that may enhance ecosystem responses to warming in the Arctic.

Beschreibung: The R/V SONNE expedition SO265 is the central activity of the research project "Shatsky Evolution" that is funded by the Federal Ministry of Education and Research and conducted by the GEOMAR Helmholtz Centre for Ocean Research Kiel in collaboration with international partners. The goal of the project is the investigation of the late stage evolution of Shatsky Rise, a vast, submarine volcanic plateau (Large Igneous Province) in the northwest Pacific. In particular, the project aims to investigate the transition from plateau volcanism (the main body of Shatsky Rise) to postulated hotspot track volcanism (Papanin Ridge and/or Ojin Rise seamounts). Applied methods included bathymetric mapping with the ship's own multi-beam echosounder (KONGSBERG EM 122), subbottom profiling (ATLAS PARASOUND DS P70), and rock sampling with chain bag dredges. The main working areas were the Papanin Ridge (the northern extension of Shatsky Rise) and the Ojin Rise Seamount Province (a broad belt of individual seamounts to the east of Shatsky Rise). Dredge hauls were conducted between ~36°N and ~44°N and ~163°E and ~170°E covering the entire geographic extent of both working areas. A third working area, the northern part of Shatsky Rise dominated by its Shirshov Massif, served as a contingency area and only a few dredge hauls were conducted there. In addition, sampling was successfully executed at Hokkaido Trough (45°06'N, 162°27'E), located ~320 km northwest of Papanin Ridge. A total of 72 dredge hauls in average water depths of 4,640 m were carried out during SO265. Of these, 49 (= 68%) delivered in situ volcanic rocks samples. No deployed equipment was lost or damaged. Post-cruise investigations at GEOMAR and cooperating institutions will include volcanological/petrological, geochronological, and geochemical studies. Furthermore, macro-benthic organisms were collected from the surfaces of the recovered rocks to study the diversity of deep-see invertebrates, and sediment sampling (by small sediment traps installed in the dredges) was conducted for meiofauna studies.