Aanderaa (Norway)

<strong class="journal-contentHeaderColor">Abstract.</strong> Sedimentary recycling of phosphorus is a key aspect of coastal eutrophication. Here, we present data on benthic fluxes of dissolved inorganic phosphorus (DIP) from the Baltic Sea, an area with a long eutrophication history. The presented dataset contains 499 individual fluxes measured in situ with three types of benthic chamber landers at 59 stations over 20 years, and data cover most of the Baltic Sea sub-basins (Hyl&eacute;n et al., 2025; <a href="https://doi.org/10.5281/zenodo.14812160" target="_blank" rel="noopener">https://doi.org/10.5281/zenodo.14812160</a>). The dataset further contains information about bottom-water dissolved oxygen (O₂) concentrations, sedimentary organic carbon (OC) content and sediment type. The DIP fluxes differ considerably between basins depending on OC loading and the level of O₂ depletion and generally increase from the coast to the central basins. Several stations have been visited on multiple occasions, also at times with different O₂ concentrations, which enables investigation of the immediate effects of shifting bottom-water O₂ concentrations on the benthic DIP release. The Baltic Sea-wide benthic DIP release is estimated to be 391 &ndash; 489 kton y^-1 based on a data integration based on sediment type and O₂ conditions during three years with varying extents of hypoxia and anoxia (2004, 2013 and 2018). The dataset reveals a lack of flux measurements in winter months, coastal areas and sandy sediments; these should be targeted in future studies. Overall, the data is of high quality and will be important for marine management and studies on mechanisms in benthic phosphorus cycling.

This work presents the steps followed in the design and implementation of a marine observatory that provides the current state and forecast of oceanic conditions relevant to the aquaculture sector. Examples of successful implementation of these guidelines are presented in the framework of the EuroSea project (H2020 grant agreement No. 862626) for two aquaculture sites: Deenish Island in Ireland and El Campello in Spain. In-situ essential ocean measurements, remote-sensing observations and modelled forecasts are jointly provided to the aquaculture end users. The process begins with stakeholder interaction to understand their main needs and concerns, followed by software architecture design and development to facilitate data acquisition, post-processing and visualization on an open-access web platform. User input regarding the development of the observatory and web platform content and frequent feedback are of paramount importance during the whole process to ensure that the services offered match the needs of the aquaculture sector.

Earthquake-induced submarine slope destabilization is known to cause debris flows and turbidity currents, but the hydrodynamic processes associated with these events remain poorly understood. Records are scarce and this notably limits our ability to interpret marine paleoseismological sedimentary records. An instrumented frame comprising a pressure recorder and a Doppler recording current meter deployed at the seafloor in the Sea of Marmara Central Basin recorded consequences of a MW = 5.8 earthquake occurring Sept 26, 2019 and of a Mw = 4.7 foreshock two days before. The smaller event caused sediment resuspension but no strong current. The larger event triggered a complex response involving a mud flow and turbidity currents with variable velocities and orientations, which may result from multiple slope failures. A long delay of 10 hours is observed between the earthquake and the passing of the strongest turbidity current. The distance travelled by the sediment particles during the event is estimated to several kilometres, which could account for a local deposit on a sediment fan at the outlet of a canyon, but not for the covering of the whole basin floor. We show that after a moderate earthquake, delayed turbidity current initiation may occur, possibly by ignition of a cloud of resuspended sediment. Some caution is thus required when tying seismoturbidites with earthquakes of historical importance. However, the horizontal extent of the deposits should remain indicative of the size of the earthquake.

The presented work focuses on optimizing properties of the transmission pulse of a Doppler Current Profiler in order to reduce the measurement noise to improve acoustic directional wave detection. In addition, different methods for ambiguity correction for current and wave measurement are presented. Due to strong attenuation of short waves with increasing depth, a low noise measurement is required in order to extend the bandwidth used for wave height calculation. For ordinary current measurements, low noise gives the possibility to either reduce the variance in the measurement, or to reduce the instrument power consumption by reducing the number of pings. The presented methods consist of a combination of a wave height dependent adaptive transmission pulse combined with robust ambiguity resolution methods. These methods have been tested, validated and implemented in the SeaGuardII DCP Wave instrument in an offshore installation off the west coast of Norway.