ALBERT

Description: We proposed to test the hypothesis that large gelatinous macrozooplankton (e.g. tunicates, hydrozoans) are a significant carbon storage in midwater, and a vector for carbon from midwater to the ocean floor in Cape Verde. To test this hypothesis, we studied 1) the distribution, diversity and abundance of gelatinous organisms in the epi-, meso-, and bathypelagic zone, 2) their role in transporting carbon through the pelagic foodweb to the seafloor and 3) their behavior and associations. We worked in the coastal deep sea off Santo Antão and Fogo as well as in the open ocean at the time series station CVOO and an eddy. A manned submersible was used for mesopelagic surveys, to document the behaviour and associations of deep-sea organisms and to collect living specimens. We performed pelagic video transects, discrete net sampling, and eDNA sampling down to 3000 m. ADCP and CTD transects allowed a detailed reconstruction of the effect of the islands on currents and productivity. To quantify the carbon flux of pelagic foodfalls, we also surveyed the seafloor. Sample and video analysis is still in progress, but first results indicate the impact of the pelagic tunicate Pyrosoma atlanticum, which is an upwelling-favored species largely absent from the oligotrophic open ocean, in the nearshore regions of Cape Verde as well as in the cyclonic eddy sampled. It was also observed on the seafloor and resembles a food source and a habitat in the water column and in the benthos. Specimens of pelagic fauna were collected that allow new species descriptions. New records and a new species for the region were also observed during benthic surveys. The cruise was documented in various outreach activities including national television in Cabo Verde.

Description: A slim python library to link maps and sampling data with prediction methods. PyQuickMaps can do interpolation (with scipy.interpolate.griddata), kriging (with pykrige) and random forest regression (with sklearn.ensemble.RandomForestRegressor). It also features plotting nice geographical maps with matplotlib and storing those to geotiff with rasterio. Coordinate transforms are managed internally with osgeo/gdal.

Description: The AL561 cruise was conducted in the framework of the project APOC (“Anthropogenic impacts on Particulate Organic Carbon cycling in the North Sea”). This collaborative project between GEOMAR, AWI, HEREON, UHH, and BUND is to understand how particulate organic carbon (POC) cycling contributes to carbon sequestration in the North Sea and how this ecosystem service is compromised and interlinked with global change and a range of human pressures include fisheries (pelagic fisheries, bottom trawling), resource extraction (sand mining), sediment management (dredging and disposal of dredged sediments) and eutrophication. The main aim of the sampling activity during AL561 cruise was to recover undisturbed sediment from high accumulation sites in the Skagerrak/Kattegat and to subsample sediment/porewater at high resolution in order to investigate sedimentation transport processes, origin of sediment/POC and mineralization processes over the last 100- 200 years. Moreover, the actual processes of sedimentation and POC degradation in the water column and benthic layer will be addressed by sampling with CTD and Lander devices. In total 9 hydroacoustic surveys (59 profiles), 4 Gravity Corer, 7 Multicorer, 3 Lander and 4 CTD stations were successfully conducted during the AL561 cruise.

Description: Post-processing of sonar data is a common task in ocean science. This includes the creation of bathymetric maps, the use of seafloor backscatter information to determine sediment types as well as the analysis of water column data, e.g. for the assessment of fish populations or the quantification of gas releases from the seafloor at methane seeps. Many commercial and free post processing tools for these tasks exist, but since there is a wide range of sonar manufactures with individual data formats not every format is supported by these applications. The DSM Sonar Software is a collection of software libraries and applications to facilitate access to sonar data of various formats and convert between different formats. The conversion of an unsupported format into a commonly supported one makes it possible to process sonar data with existing post processing tools. The target users for our converters are scientists and hydrographers. The different data format descriptions and sonar tool libraries are valuable for software developers in the field of automated sonar data analysis. The modular approach and structure of the DSM Sonar Software enables that developers pick only necessary components to include them in their own software project.

Description: A Pyhton-based toolbox to remap daily runoff fields of the JRA55-do reanalysis (Tsujino et al., 2018, https://doi.org/10.1016/j.ocemod.2018.07.002) onto any ocean model grid. Runoff from the original global JRA grid is collected and redistributed to a given model coastline. A particular feature is the optional treatment of river mouths: runoff from grid nodes, which is of exceptionally large magnitude after the basic remapping, can be radially spread to ocean nodes farther offshore. The scripts were tested successfully for NEMO ocean model configurations of various resolution (global grids ORCA025 and ORC05 as well as regional nests VIKING10, ORION10, VIKING20X and INALT20X) at GEOMAR, Kiel (see Biastoch et al., 2021, https://doi.org/10.5194/os-2021-37 for an application). General instructions are provided for how to process the original JRA runoff files and also for the optional river mouth treatment. The technique is illustrated by examples of the fragmented coast of Greenland and the Amazon river mouth. While the code is versatile, examples are given for an application with the NEMO ocean model.

Description: Cruise AL534/2 is part of a multi-disciplinary research initiative as part of the JPI Oceans project HOTMIC and sought to investigate the origin, transport and fate of plastic debris from estuaries to the oceanic garbage patches. The main focus of the cruise was on the horizontal transfer of plastic debris from major European rivers into shelf regions and on the processes that mediate this transport. Stations were originally chosen to target the outflows of major European rivers along the western Europe coast between Malaga (Spain) and Kiel (Germany), although some modifications were made in response to inclement weather. In total, 16 stations were sampled along the cruise track. The sampling scheme was similar for most stations, and included: 1) a CTD cast to collect water column salinity and temperature profiles, and discrete samples between surface and seafloor, 2) sediment sampling with Van Veen grab and mini-multi corer (mini-MUC), 3) suspended particle and plankton sampling using a towed Bongo net and vertical WP3 net, and 4) surface neusten sampling using a catamaran trawl. At a subset of stations with deep water, suspended particles were collected using in situ pumps deployed on a cable. During transit between stations, surface water samples were collected from the ship’s underway seawater supply, and during calm weather, floating litter was counted by visual survey teams. The samples and data collected on cruise AL534/2 will be used to determine the: (1) abundance of plastic debris in surface waters, as well as the composition of polymer types, originating in major European estuaries and transported through coastal waters, (2) abundance and composition of microplastics (MP) in the water column at different depths from the sea surface to the seafloor including the sediment, (3) abundance and composition of plastic debris in pelagic and benthic organisms (invertebrates), (4) abundance and identity of biofoulers (bacteria, protozoans and metazoans) on the surface of plastic debris from different water depths, (5) identification of chemical compounds (“additives”) in the plastic debris and in water samples.

Description: Port Calls: Gdynia, Poland: 19.08. – 20.08.2017