Influence of Temperature on the Growth, Coenosarc Pulsations, and Hydroplasm Movement in the Colonial Hydroid Dynamena pumila (L., 1758)

Abstract

The dependence of the growth and functioning of the transport system of colonial organisms on water temperature has been studied. Time-lapse microvideo recording was used to measure the coenosarc pulsations of the stolon and shoot in the colonial hydroid Dynamena pumila (L., 1758) reared in seawater at 10, 15, 20, 25, and 28°C. As a result, it was possible to determine that microvideo recording of coenosarc pulsations made it possible to track the colony reaction to temperature change for 2 h. The reaction of growth pulsations, lateral pulsations, and hydroplasmtic flows to the changes in the water temperature turned out to be nonlinear. The reaction of the stolon to the changes in the water temperature was more pronounced than those in the shoot. The optimal temperature range was 10–20°C, which displayed the highest growth rate, the most intensive hydroplasm movements, and the largest volume of transferred hydroplasm. At 28°C, the pulsations of the stolon coenosarc became unstable, the growth tended to slow, and the hydroplasm movements were less active. Consequently, according to the results of analysis of coenosarc pulsations, the upper temperature limit of normal life activity for D. pumila colonies inhabiting the White Sea was 25–28°C.