09A3
Sea caves
Relationships with habitat classifications. EUNIS: A1.4 Features of littoral rock, A3.7 Features of infralittoral rock, A3.71 Robust faunal cushions and crusts in surge gullies and caves; PAL. CLASS.: 12.72 Complex sea caves, 11.26 Sublittoral cave communities, 11.294 Mediolittoral cave and overhang communities; HD 92/43: 8330 Submerged or partially submerged sea caves.
Conservation status. BDA, BC, HD.
Category. Endangered [EN – A1, 2 C3 D2 E2 F1 H3 I J L1].
General characteristics. Almost all caves of this type are a result of the abrasive strength of the sea surf and there are no natural cave formations. In Bulgaria there are no systematic data available on the distribution and number of these caves, nor about their morphometric data (length and height). The access to all caves is only from the sea. The height of the entrance varies from 50 cm up to 25 m depending on the strength of the waves. The length of the water gallery is between 5 and 50 m, followed by dry or semidry galleries with sand, gravel and larger stones. Natural light does not reach the bottom of only the longest caves. The temperature strongly depends on that is outside, although fluctuations are smaller and no extremely high or low values have been recorded. No typical troglophils or troglobites have been established in these caves. From April until September some of these caves are inhabited by colonies of the bat species Miniopterus schreibersii, Myotis blythii, M. myotis and M. capaccinii. Often bird species nest at the entrance of the caves. The caves with sandy underground banks have been regularly inhabited by the Monk Seal (Monachus monachus). Presently, and only as an exception, only single, most often roaming male seals can be observed.
Characteristic taxa.
- Animals: Myriapoda: Scutigera coleoptrata; Aves: Apus melba, Columba livia, Delichon urbica, Phalacrocorax aristotelis; Mammalia: Miniopterus schreibersii, Monachus monachus, Myotis blythii, M. capaccinii, M. myotis.
Distribution in Bulgaria. In the Sarmatian limestone of the rocky northern Black Sea (between Kavarna and Shabla) and in the non-sediment rocks of the southern Black Sea coast between Sozopol and Rezovo, especially in the cliff at Maslen Nos Cape; 0 up to 20 m alt.
Conservation importance. The sea caves are the only suitable underground dwellings for the reproduction of the large cave bat colonies along the whole Black Sea coast.
Threats. Natural erosion and rock-slide processes of the coastal rocks; potential threats are the construction and exploitation activities that can take place on the rocky coast. In the 1960s the gravel for the coastal roads to the north from Kavarna was obtained through blasting of the rocks between Tyulenovo and Shabla. The bats and the rock birds can be disturbed during their reproductive period by visits of people. Plastic waste and wood particles have been found accumulated by the sea surf at the bottom of almost all caves.
Conservation measures taken. The habitat is included in Annex №1 of the national Biodiversity Act as a priority habitat for conservation. Some of the caves at the northern Black Sea coast are included in Kaliakra Strict Nature Reserve, Yailata and Silistar Protected Sites and in the Rock formations, fiords, and the Seal Cave Nature Monument in Maslen Nos Cape. Sea caves are included in sites of the European Ecological Network NATURA 2000 in Bulgaria.
Conservation measures needed. Elaboration of management plans for the existing protected areas, including sea caves, and regulation of the people access in summer.
References. Benda et al. 2003; Beron 1972, 1994; Peshev et al. 2005; Popov et al. 2007.
Authors: Boyan Petrov, Ivan Pandourski
