The sea water temperature impact upon Gonothyraea Loveni (Allman) hydroid development on the artificial substrates in the sevastopl bay (the Black sea)

The effect of seawater temperature on the subsidence and development of the Gonothyraea loveni (Allman) hydroid at a specific point in the water area was discussed This allows us to trace the connection of seasonal changes in sea temperature with the process of sedimentation of planules and the development of hydroid G. loveni on artificial substrates of various exposures in the Sevastopol bay. Observations were carried out over two periods: from 1979 to 1987. and from 2011 to 2015. The temperature range of 5-10 °C corresponds to the subsidence of planul on plates with a community 10 days aged in the autumn and spring periods. The peak of subsidence was detected at a water temperature of 9 °C. At this time, the greatest number of plates with settled hydroids was detected (22%). The number of hydrotecas in the temperature range of 11-19 °C reaches maximum values due to sedimentation and active growth of colonies, since the frequency of occurrence of plates with hydroids during this period is halved and remains at this level at higher temperatures (17-24 °C). With an increase in the exposure of substrates up to 30 days, the bulk of the plates with hydroid (80%) are concentrated in the temperature range of 6–11 °C. When the temperatureof water in the sea is 16-24 °C, plates with hydroids are less than 5%, which is determined in addition to the effect of temperature by the massive subsidence of Botryllys schlosseri (Pallas), which replaces the hydroid. In communities of 2-12 months of age, the hydroid G. loveni develops over a wide range of temperatures, from 5 to 23 °C. Dynamic changes in communities show that the growth of colonies occurs at a temperature of 5-9 °C with a maximum intensity of 10 to 15 °C. At temperatures above 17 °C, the reduction of colonies occurs. Key words: subsidence, development of hydroid Gonothyraea loveni, the temperature of the sea water of the Sevastopol Bay, the Black sea.