Distephanus/Dictyocha Ratios and Seawater Temperature (Cl.: Mastigophorea, Order: Silicoflagellida)

Abstract

AbstractThe ratio in abundance of the two silicoflagellate genera Distephanus and Dictyocha in sediment and plankton samples has been used to identify seawater temperature: over a range of 0° to 30°C the ratio should shift from 100% Distephanus to 100% Dictyocha. Studies of plankton samples showed that this shift is found in the South Atlantic but not in the North Atlantic. Near 11°C in the North Atlantic the ratio rather abruptly reverses, which points to a different temperature sensitivity in the north and the south. The findings indicate that the relation between sea-surface temperature and Distephanus/Dictyocha ratio is different in the four seasons of the year and in different geographic areas.