Some aspects of the biology and the present state of the population of protodorvillea kefersteini (Polychaeta: Dorvilleidae) in the coastal zone of the Crimea (the black sea)

Abstract

In the Black Sea, 3 Genus of Dorvilleidae were reported: Dorvillea Parfitt, 1866; Schistomerngos Jumars, 1974; Protodorvillea Rettibone, 1961. In the Black Sea, Protodorvillea kefersteini (Uljanin, 1877) occurs near the shores of Bulgaria and along the Crimean coastline (Kiseleva, Polychaete worms (Polychaeta) of the Black Sea and the Sea of Azov, Kola Research Centre Press RAS, Apatity, 409 p, 2004; Marinov, Bull Zool Inst Bulg. Bulgarian Academy of Sciences 21:69-75, 1966). The aims of the present paper are to learn more about the biology of P. kefersteini and to increase our knowledge about the present state of its population structures along the coast of Crimea. Samples of macrobenthos were collected from different areas of the Crimean coastal zone (the Black Sea), during 2006-2011. More than 800 benthos samples were collected from the pseudolitoral zone by using a hand bottom-sampler with the 0.04 m2 capture area. Pseuvdolitoral is a narrow strip of beach. It is between the top edge of the splash and riprap beach. Polychaetes P. kefersteini usually inhabits coastal coarse sandy with a mixture of gravel, shell, sandy soil or sand with a mixture of mud. The annual density fluctuations of the polychaeta P. kefersteini was investigated in the coastal zone of the Crimea. The number was significantly different in different regions of the Crimea coast. In different seasons of the year spatial distribution of P. kefersteini by depths was different. Over the entire observation time abundance of the polychaetes was greatest in the belt below the water edge. In summer and autumn polychaetes P. kefersteini were absent above the water edge, and in winter and spring-along the water edge. Though population of P. kefersteini includes polychaetes of different body sizes. For the first time growth and development of juvenile (0.3-1.45-mm large) P. kefersteini were studied and the time at which chaetae first arose on the body. Conclusions. Carrying out this work, we for the first time explored distribution of the polychaeta P. kefersteini along the Crimean shoreline and by pseudolitoral depths. In the size structure of P. kefersteini population inhabiting the pseudolitoral zone 20-35-mm long worms dominate (75%); with increasing depth they occur more and more rarely, decreasing to 21% at 1 m and to 1% at 1.5 m depths. For the first time growth and development of juvenile (0.3-1.45-mm large) P. kefersteini were studied and the time at which chaetae first arose on the body determined; in particular, forked chaeta appeared in the individuals with 2-3-segment bodies.