Loss of Natural Seabed and Benthic Habitats Along the Bulgarian Black Sea Coast as a Consequence of Infrastructure Development

Abstract

The Marine Strategy Framework Directive (MSFD) is a framework for collective action in the marine environmental policy established by Directive 2008/56/EC of the European Parliament and the Council on 17 June 2008. It calls for EU Member States to create national marine strategies to achieve good environmental status (GES) by 2020 or to maintain it in areas where it already exists. Five factors are laid out in Commission Decision (EU) 2017/848 for GES assessment in regard to a number of broad habitat types, as two of them were assessed in the article. Criterion D6C1 represents the spatial extent and distribution of physical loss of the natural seabed. Criterion D6C4 estimates the extent of loss of the habitat types resulting from anthropogenic pressures that should not exceed a specified proportion of the natural extent of the habitat types in the assessment areas. These criteria were evaluated for five coastal Marine Reporting Units (MRU) distributed in the Bulgarian sector of the Black Sea. The objective of the study is to evaluate the physical loss of the natural seabed and broad benthic habitat type as a result of coastal infrastructure development in each of the coastal MRUs and for the national Black Sea biogeographic region. The cumulative loss from the 1970s to 2017 was calculated. The period between 1970 and 1983 was chosen as a reliable historical baseline for which 1:5000-scale topographic maps are available. In addition, the study provides estimates of the natural seabed and habitat loss for the long-term period 1970/83 to 2017 and the 6- year assessment period under MSFD 2012 to 2017. GIS procedures include a compilation of vector files of shoreline and MRUs for the assessment periods 1970/83, 2012, and 2017, from which changes were evaluated Criterion D6C1: Spatial extent and distribution of physical loss of the natural seabed. Finally, spatial intersect analysis between seabed loss and broad benthic habitat types allowed assessment of Criterion D6C4: The extent of loss of the habitat type resulting from anthropogenic pressures. The work identified 302 designated hydrotechnical facilities, 33 of which were constructed during the most recent assessment period (2012-2017), which have left a significant negative imprint on the Bulgarian coast. Prominent accumulation of artificial structures was registered along Burgas, Varna, Balchik, and Nessebar. After the 1970s, due to the construction of coastal hydro-technical facilities and port infrastructure, the Bulgarian Black Sea shoreline increased by more than 11%, from 461.9 km (1970/83-2012) to 511.2 km (2012) and to 513.6 km (2017). The MRUs Cape Emine - Cape Maslen and Cape Kaliakra - Cape Galata are the most affected coastal areas by seafloor sealing and land reclamation. Infralittoral sand in Cape Emine - Cape Maslen Nos MRU represents the habitat with the highest absolute loss of 1.43 km2 and of 1.19% as a proportion of the total habitat area. The Infralittoral rock was assessed to have lost the most significant proportion of a broad benthic habitat type along the Varna shoreline - 3.39% (absolute area 0.35 km2), which is getting close to the critical threshold of 5% in the Cape Kaliakra-Cape Galata MRU. GISaided analysis showed that the most impacted broad benthic habitat types at the national scale are the Infralittoral sand and Infralittoral rock, with losses of 1.48 km2 and 0.528 km2, respectively. However, neither of the habitats exceeded the 5% threshold of habitat loss in any of the assessment areas. Finally, this article presented a pilot assessment of geomorphological seabedforms loss. Along the Bulgarian Black Sea coast, a distinguished loss was observed on the shallow-water accumulative slope or beach face corresponding to the Infralittoral sand (1.476 km2), Infralittoral mud (0.003 km2), infralittoral mixed sediment (0.02 km2) and infralittoral coarse sediment (0.09 km2). Respectively, the largest loss of abrasion-structural seabed or bench was observed in the Infralittoral rock (0.533 km2).