## 5 Conclusions  
Our study is the first carried out on the Romanian coast of the Black Sea, which investigates the potential effects of beam trawl fishing on benthic communities in a marine protected area. Beam trawling has developed extensively in the past 10 years in Romanian waters, particularly in the northern area covered by soft bottoms, corresponding to the marine zone of the Danube Delta Biosphere Reserve. By analyzing the available beam trawl catch dynamics information (for the target species _R. venosa_), VMS data, geophysical investigations, and macrozoobenthos sampling, we performed a preliminary assessment of the actual impact of physical disturbance on soft bottoms. Our research shows that beam trawling activities can cause changes in the benthic habitat structure. As such, mussel biogenic reefs on soft substrata (the so-called mussel \"clumps\"), unique in this region, were basically absent from the samples collected during the study period. Moreover, the low number of benthic taxa identified also suggests that the habitats here may be threatened by constant physical disturbance. More recent and denser beam trawl marks (finding also supported by VMS lines clustering) are concentrated in the northern area of the MPA, which corresponds to the lowest recorded number of taxa. Additionally, the benthic community species richness (S), Shannon diversity index (H\({}^{\prime}\)), total abundance (A), and biomass declined with increasing trawling disturbance, as well as the values of the M-AMBI\({}^{\prime}\)(n) index. Based on the M-AMBI\({}^{\prime}\)(n) scores, most of the area investigated was in non-GES, suggesting that beam trawling may impact the substrate in the area. In order to allow the recovery of the affected benthic habitats, an ecosystem-based management approach is proposed, by establishing certain Fisheries Restricted Areas (FRAs) beyond the 20 m isobath, considering both temporal and spatial bans within the Danube Delta--Marine Zone, by alternating defined areas undergoing fishing with biological recovery polygons. These particular FRAs should be designated only after performing thorough dedicated investigations and before-after comparative studies of the impact of beam trawling on the seabed in ROSCI0066, with a particular focus on circalittoral muds with _M. galloprovincialis_. The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/w15122241/s1](https://www.mdpi.com/article/10.3390/w15122241/s1)]([https://www.mdpi.com/article/10.3390/w15122241/s1](https://www.mdpi.com/article/10.3390/w15122241/s1)), Table S1: Sampling locations; Table S2: Summary of catch data and beam trawling fishing pressure in the study area (2015-2022); Table S3: List of macrozoobethnic taxa found in the study area; Table S4: Ecological quality assessment of circalittoral habitats using M-AMBI\({}^{\prime}\)(n) index [the threshold value of the M-AMBI\({}^{\prime}\)(n) index was used according to [PERSON] et al. (2020), [9]]. Conceptualization, M.N., V.N., A.T. and T.B. ; methodology, M.N., V.N., A.T. and A.P. ; software, A.T. and A.P. ; validation M.N. and A.T.; investigation, M.N., V.N., A.T., A.P. and T.B. ; writing--original draft preparation, M.N., V.N., A.T., A.P. and T.B. ; writing--review and editing, M.N. and T.B. ; supervision, V.N. and A.T.; funding acquisition, T.B. All authors have read and agreed to the published version of the manuscript. This research was funded by the Romanian Ministry of Research, Innovation, and Digitization in the framework of the national NUCLEU Programs, projects: PN 23300202 and PN 23230301, POIM project \"Revision of the Danube Delta Biosphere Reserve Management Plan and Regulation\", SMIS Code 123322, contract number 253/18.06.2019, the Program Development of the National R&D system--AMBI AQUA--no. 23 PFE, and the European Union's Horizon 2020 BRIDGE-BS project under grant agreement no. 101000240, and the DOORS project under grant agreement no. 101000518. Not applicable.