Gdynia Maritime University

Chronic eutrophication and declining coastal livelihoods in the Baltic Sea drive the search for sustainable solutions such as regenerative ocean farming (ROF). ROF is a nature-based form of aquaculture using low-trophic species like seaweeds and bivalves that extract nutrients from enriched waters. It is framed as a response to combined environmental and socioeconomic challenges, not as a stand-alone technical concept. Despite growing interest, no comprehensive assessment of ROF readiness exists for the Baltic Sea. This study addresses this gap by examining stakeholder perceptions across five dimensions: socio-economic, techno-economic, environmental, regulatory, and social acceptance. Using a series of co-assessment workshops with stakeholders from Estonia, Latvia, Lithuania, Poland, and Germany, we identify key barriers including weak regulatory frameworks, low public awareness, limited infrastructure, and underdeveloped value chains. We also highlight enabling factors such as targeted training, policy reform, and improved monitoring. Results indicate that ROF remains in an early stage of development across all countries, with Germany showing the highest overall readiness. Technological and monitoring capabilities score highest, while socio-economic, and social acceptance and especially regulatory dimensions lag behind. The findings highlight the need for coordinated actions to build institutional capacities, streamline licensing, and foster public support to advance ROF as a sustainable solution for environmental restoration and coastal economic resilience in the Baltic Sea.

Reliance on GNSS continues to grow across the application space: from critical infrastructure to the burgeoning autonomy sector. At the same time, instances of radio frequency interference (RFI) affecting GNSS are becoming more widespread and can endanger lives with such dependence on GNSS. Currently, GNSS jamming and spoofing has become widespread around areas of conflict, especially surrounding Russia and Ukraine. But this has also spread more broadly and numerous reports, using Automatic Dependent Surveillance-Broadcast (ADS-B) aviation-based sensors, have come out of regions around the south Baltic Sea, significantly away from the current conflict regions. To explore the extent of the RFI, a low size, weight, power and cost (SWaP-C) GNSS monitor was deployed in Gdynia, Poland, which confirmed the presence of the RFI at the Gulf of Gdansk on the Polish coast. This initial effort was extended to deploy networked GNSS intermediate-frequency (IF) samplers around the Gulf of Gdansk on the Polish Baltic coast to further understand and attempt to localize the source of the interference using time-difference-of-arrival (TDOA). TDOA results are presented from the period of April-June 2025, where a circular spoofer was detected and localized, along with a separate jammer. The IF data allowed for the tracking of the circular spoofing signal, giving valuable insight into this emerging threat.

Hydrographic surveys must comply with the IHO S-44 standard. For the most stringent orders (Exclusive, Special, and 1a), 100% seafloor coverage is required, posing challenges in shallow waters near the 1 m isobath. Recent advancements in unmanned surface vehicles (USVs) and the miniaturisation of hydroacoustic devices now enable high-precision surveys even in hard-to-access areas. This study presents an analysis of bathymetric data coverage and density obtained using singlebeam echosounders (SBES) and multibeam echosounders (MBES) systems mounted on unmanned surface vehicle (USVs). The SBES survey employed the AutoDron USV, while MBES data were collected with the HydroDron-1 USV. Coverage analysis used a 1×1 m grid. The results reveal significant differences between the two systems. The MBES achieved an average density of 7.71 pts∙m−2 (>94% of grid cells meeting the NOAA- recommended minimum of 5 pts∙m−2). Data of MBES also exhibited uniform coverage, supporting the development of high-resolution bathymetric models. By contrast, SBES produced an average density of only 0.69 pts∙m−2, with a sparse and irregular point distribution. Only 1.79% of grid cells met the recommended threshold, while 63.79% contained no data. Nevertheless, SBES proved effective in the very shallow nearshore zone inaccessible to MBES. To achieve full coverage in compliance with International Hydrographic Organization’s requirements, complementary methods such as bathymetric light detection and ranging, Global Navigation Satellite Systems-real time kinematic surveys, or structure from motion photogrammetry are essential. Integrating these technologies is required to produce reliable and complete seafloor models.

This paper analyzes the properties of two photovoltaic installations located in close proximity to each other. One is stationary, while the other abruptly changes the orientation of its panels, which follow the apparent daily movement of the Sun. Measurement results illustrating the daily variations in the productivity of both installations across four seasons are presented and discussed. The rationale for using a mobile installation on the analyzed days is demonstrated.