Upper temperature tolerance of North Atlantic and North Pacific geographical isolates of Chondrus species (Rhodophyta)

Abstract

The upper survival temperature for most isolates of Chondrus crispus from localities ranging from northern Norway and Iceland to Spain, and for an isolate from Nova Scotia, was 28 °C after 2 weeks of exposure to temperatures of 20-31 °C at intervals of 1 °C. An upper survival limit of 29 °C was exhibited by a few European isolates from the English Channel, the North Sea, and one Irish isolate from the upper intertidal. The warm-temperate Japanese species C. nipponicus and C. giganteus forma flabellatus survived 30 °C, whereas 29 °C was the upper survival limit for the coldtemperature C. pinnulatus forma pinnulatus from northern Japan. A possible origin of C. crispus in the north Pacific is discussed. © 1987 Biologische Anstalt Helgoland.