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Plastic pollution is widely recognised as a pervasive anthropogenic pressure on coastal environments. Yet, beach-dune systems and dune vegetation remain considerably less studied than marine waters, beach sediments and aquatic biota. This paper presents a critical narrative review, supported by a spatial overview of the principal beach-dune systems along the Bulgarian Black Sea Coast based on recent dune inventory, mapping and litter-assessment data, with particular emphasis on microplastics, their occurrence, tra...

Long-term changes in fishery landings are important indicators of stock status and ecosystem condition, particularly in semi-enclosed and data-limited marine systems such as the Black Sea. These trends are also relevant to the broader international debate on sustainable fisheries management, as they can provide early warning of persistent declines where full analytical stock assessments are limited. This study assesses temporal trends in the annual landings of three Mugilidae species (Mugil cephalus, Chelon auratu...

This study applies an adapted Living Planet Index (LPI) to assess long-term trends in fish populations in the Veleka River (southeastern Bulgaria) from 2010 to 2024. Based on standardized electrofishing data across seven stations, 11 native and naturalized species were analyzed using log-transformed abundance time series. The LPI declined from 1.0 in 2010 to 0.28 in 2024, indicating a 72% reduction in average fish abundance. Potamodromous species (e.g., Barbus cyclolepis, Chondrostoma vardarense) exhibited decline...

Hermaphroditism in the flathead grey mullet (Mugil cephalus), manifested as intersex conditions, is linked to various environmental factors and anthropogenic pressures. Key contributors include exposure to endocrine-disrupting compounds (EDCs), heavy metals, and pollutants that disrupt hormonal regulation, leading to sexual development abnormalities. Research indicates that Mugil cephalus is particularly sensitive to EDCs in coastal and brackish ecosystems. Our findings reveal that 19% of male individuals from the...

The study presents the first comprehensive spatio-temporal analysis of eutrophication and the consequent loss of sensitive aquatic habitats in the transitional water bodies along the Kamchiya-Shkorpilovtsi sector of the Bulgarian Black Sea coast. The research focuses on the Maznia Azmak Lake, an old Kamchiya riverbed integral to the Kamchia Nature Reserve and two Natura 2000 protected areas. The primary objective was to assess the scale and rate of eutrophication and its impact on aquatic habitats, employing moder...

Marine litter is a significant and growing environmental problem with global implications, affecting oceans and seas. This study analyzes marine litter's composition and density, specifically at Kamchiya-Shkorpilovtsi, the longest beach on the Bulgarian Black Sea coast. The monitoring period from 2018 to 2022 covers an area of 7645 m2. To effectively study the area, it was divided into four monitoring transects: Kamchiya- Mouth, Kamchiya-South (Novo Oryahovo Beach), Shkorpilovtsi, and Shkorpilovtsi- South. During ...

The food spectrum of three fish species from the Mugilidae family in different age groups was studied. The samples were collected in 2019 - 2021 from the river estuaries and the coastal brackish lakes at the Bulgarian Black Sea coast. The research aims to establish the food spectrum of mullets and thus make a connection between food components. The results show that the predominant groups in the stomachs of the three mullet species are detritus, zoobenthos (Rissoa sp. And Trochammina inflate - 64.28%) and macrophy...

The Varna and Beloslav lakes are the most strongly anthropogenized water bodies along the Bulgarian coast. At present, the lakes are again subject to deepening of the navigable channel, which significantly changes the quality of the habitats. An ecosystem approach was used to assess the status of the populations of fish species from the Varna-Beloslav Lake Complex. The paper's main purpose is to provide up-to-date information on the ichthyofauna of the largest northern Bulgarian Black sea brackish water bodies - V...

The Durankulak Lake is the northernmost Bulgarian Black Sea lagoon. The hydrological regime of the lake is, for the most part, the inflow of water in karst underground cracks. Over the years, the rare cases of digging a sea-lake canal have been a significant cause of the oligohaline estuarine wetlands nature of the water body. The publication aims to present current research on the structure of the lake bottom, the heart of the substrate and changes over the years, using data from a multi-beam echo sounder and sid...

For the period 2011-2021, 231 fish species from 18 families were established in protected area BG0000271 -Mandra-Poda-, 345 fish species from 7 families in protected area BG0001502 -Otmanli- and 169 species from 11 families in a protected area BG0000242 -Chengene skele Bay-. One hundred eighty-seven of the species were freshwater, 256 were typical marine fish species, and the other one hundred and fifteen were anadromous and brackish species. Protected species are Rhodeus amarus, Cobitis taenia, Chalcalburnus chal...

Transitional (brackish) water bodies host extremely vulnerable ecosystems. They are highly sensitive to pollution, changes in the water currents, nutrient levels, etc. Over the course of the 20th century in Bulgaria, many of them were purposely drained or strongly altered. Today, these fragile ecosystems account for just 0.1% of Bulgaria’s area, and hence they are listed among the country’s top priority nature conservation sites. The long-term preservation and survival of numerous rare or threatened hydrobionts de...