Variability of the bioluminescence characteristics of the Black Sea ctenophores-aliens in connection with different conditions of nutrition

Abstract

Many ecological-physiological characteristics of ctenophores-aliens <i> Mnemiopsis leidyi </i> A. Agassiz, 1865 and <i> Beroe ovata </i> Mayer, 1912 are studied quite well because they play a very important ecological role in the Black Sea ecosystem. However, bioluminescence, one of the most important elements of the ctenophores ecology and its connection with feeding regime were not studied sufficiently. Experiments have shown that characteristics of the ctenophores bioluminescence differed considerably in dependence of food supplies. Thus, amplitude and light-emitting energy of the fed ctenophores <i> B. ovata </i> are maximal, 3 times more than analogical indices of the just-caught individuals and 4 times more than ones of starving individuals. More prolonged flash signal (to 3.5 s), which exceeds light-emitting duration of the starving individuals twice, can be registered from the fed ctenophores. Investigation of the M. leidyi bioluminescence has shown that amplitude and light-emitting energy of the just-caught ctenophores were two times more than those of the starving individuals. At the same time, light-emitting amplitude of the fed individuals is 6.5 times and light-emitting energy is 3 - 4 times higher than that of the just-caught ctenophores. The light-emitting duration of the starving and justcaught organisms is practically the same. The most prolonged signal is registered from the fed ctenophores—up to 2.8 s. The data obtained testify that characteristics of the ctenophores bioluminescence can be conditioned not only by nutritional value but by the composition of the food as well.