Eutrophication, driven by excessive nutrient enrichment from sources like agricultural runoff, industrial discharge, and urbanisation, has severely impacted the Black Sea since the 1980s. This study aimed to assess eutrophication dynamics in the Romanian Exclusive Economic Zone from 2020 to 2022 using the Black Sea Eutrophication Assessment Tool (BEAST), an integrated approach to the causes and effects of eutrophication. Data were collected from 68 stations during five oceanographic expeditions, analysing 617 water samples for nutrients, chlorophyll a, zooplankton species Noctiluca scintillans, and dissolved oxygen. Additionally, 179 zoobenthic and 251 phytobenthic community samples were collected. The results indicate that coastal waters exhibit higher nutrient levels and algal blooms compared to offshore waters, necessitating significant reductions in nutrient concentrations to achieve good environmental status. In transitional waters, within the Danube Delta Biosphere Reserve, a 55% reduction in inorganic phosphorus and a 43% reduction in inorganic nitrogen concentrations are required, while coastal waters need reductions of 38% and 37%, respectively. The study highlights the need for improved wastewater treatment, stricter agricultural runoff controls, and continuous monitoring. Effective ecosystem-based management strategies, integrated coastal zone management, and international cooperation are essential to mitigate eutrophication and promote the long-term health of the Black Sea ecosystem.

Marine ecosystems are becoming increasingly vulnerable to cumulative anthropogenic effects and pressures. Therefore, various methodological approaches and tools have been designed to apply cumulative impact appraisal schemes and better assess the dynamics and interactions among pressures affecting marine ecosystems. This study aims to apply the Spatial Cumulative Assessment of Impact Risk for Management (SCAIRM) tool for the Black Sea coastal waters considering human activities, pressures, and effects on different ecosystem components coupled with one management scenario development for actual and new emerging sectors. According to the SCAIRM, the primary pressure on the marine ecosystem was identified as introducing or spreading non-indigenous species from shipping. Additionally, when considering cumulative impact, activities related to coastal defense and flood protection, particularly beach nourishment works, were found to have the highest impact. This is due to the cumulative scores associated with the physical loss from permanent alteration or removal of seabed substrates, and temporary or reversible physical disturbances to the seabed. The scenario development indicated that after shipping, oil and gas exploitation is anticipated to become the second-highest risk sector for additional impact in the Romanian Black Sea. Additionally, the increased military activities related to the war in Ukraine present escalating risks that must be considered in EBM strategies. The results assess the possible effects of human activities and the associated pressures to direct management toward achieving sustainability, biodiversity protection, and the marine ecosystem’s integrity.

This study aims to develop a methodology for identifying predominant pressures on the marine ecosystem, emphasizing the significance of examining these pressures and the necessity for management scenarios. The research focuses on how the Black Sea ecosystem responds to the combined effects of human pressures, climate change, and policies. An in-depth analysis was conducted on environmental pressures affecting the Romanian Black Sea, highlighting dominant pressures such as physical habitat loss, hydrocarbon introduction, and non-indigenous species invasion. The research employs a novel methodological approach to assess the implications of these pressures under different Shared Socioeconomic Pathways (SSPs): SSP1 “Taking the Green Road”, SSP2 “Middle of the Road”, and SSP5 “Taking the Highway”. The findings reveal a complex interplay between economic development and environmental conservation, with each pathway presenting distinct outcomes for marine ecosystems. Recent developments, including beach rehabilitation, maritime transport, and oil and gas exploitation, have overshadowed traditional pressures such as nutrient introduction and fishing. The study identifies the increasing vulnerability of critical habitats to anthropogenic pressures, with the rehabilitation of these ecosystems remaining challenging even under reduced pressures. The results underscore the need for adaptive management strategies to enhance the Black Sea ecosystem’s sustainability and resilience. The study’s insights are important for developing management strategies that address ongoing environmental challenges. This research provides knowledge for policymakers and stakeholders involved in marine management and conservation efforts in the Black Sea region, emphasizing the importance of adaptive strategies to mitigate the adverse effects of human activities and climate change on marine ecosystems.

Macroalgal cultures are currently of great interest worldwide. Although along the Romanian Black Sea coast, there is no tradition in this sense, currently, a major interest in developing this direction exists, taking into consideration that the overexploitation of wild seaweed resources involves the disturbance of the marine environment, with implications that can sometimes be irreversible. Porphyra and Pyropia species (also known as nori algae) are considered the world’s most valuable mariculture algal products due to their high nutritional value and multiple active principles, considered unique representatives of marine algae. Considering these aspects, attention was focused on the only nori species from the Romanian Black Sea coast, namely, Pyropia leucosticta. The species was cultivated in controlled laboratory conditions for 5.5 months by manipulating its reproductive elements. The aim was to establish a simple, low-cost method by avoiding the complicated conchocelis phase of the species; therefore, reproduction and further species development were achieved by collecting the released neutral spores and isolating them in culture vessels, ensuring, at the same time, proper nutrient conditions, using sterile enriched seawater and mimicking ambient conditions. At the end of the experiment, specimens of almost 80−90 mm were obtained, making this method suitable for obtaining ex situ P. leucosticta blades on the Romanian Black Sea shore.

Seagrass meadows, including those formed by Zostera noltei, play a crucial role in marine ecosystem health by providing habitat stability and coastal protection. In the Romanian Black Sea, Z. noltei meadows are critically endangered due to pressures from eutrophication, habitat loss, and climate change. This study presents a comprehensive baseline assessment of Z. noltei meadows near Mangalia, Romania, utilizing in situ field methods and UAV mapping conducted in the spring and summer of 2023. Seven meadow sites (Z1–Z7) were identified, with notable variability in density, shoot counts, and coverage across sites. Site Z1 exhibited the highest density (1223 shoots/m⁻²) and Z5 and Z7 the longest leaves (an average of 60 cm), reflecting possible environmental influences. Statistical analyses revealed significant inter-site differences in shoot density and leaf length, with density emerging as a primary differentiator. Ex situ analyses of epiphyte load indicated a median, balanced epiphyte load. This baseline dataset supported the selection of Z1 as a reference donor site for seagrass relocation activities along the Romanian coast in 2023. By providing critical insights into Z. noltei structure and health, this study supports future conservation efforts and evidence-based management of these vulnerable coastal habitats.

Opportunistic macroalgae are those species with an accentuated reproductive capacity, able of generating significant algal deposits during summer season. Opportunistic species associations are an important component of the upper infralittoral rock with variable annual green and red macroalgae habitat, sub-type of the broad habitat infralittoral rock and biogenic reef. For a better overview of the evolution of these species, a long data series (2009 – 2021) was analysed. Samples were collected from depths between 0 and 8 m, along Năvodari towards Vama Veche, where opportunistic species experience an abundant development especially during summer season. In the last decade, quantitatively dominant were the green algae of the genera Ulva (mainly U. rigida, with a biomass variation between 5 and 2500 g/m2) and Cladophora (mainly C. vagabunda, with a biomass variation between 3 and 2800 g/m2). At Agigea, U. rigida recorded high biomass values (the largest U. rigida field can be found here, with a spatial distribution between 1 and 3 m depth), whilst Eforie proved to be more favorable for the development of Cladophora spp. Regarding the quantitative evolution of the opportunistic species, 4 scenarios have emerged during 2009 - 2021: during 2009 summer season, the dominant quantitative genus was Ulva; 2010 summer came with abnormal high water temperatures and nutrients values, extreme factors that proved favorable for the development of Cladophora species; starting with 2014 until 2019, the quantitative dominance returned to Ulva spp., but with lower biomass values compared to Cladophora spp. Starting with 2019, a new increase of Cladophora biomass was recorded.