Lethal exposure times and preconditioning to upper temperature limits of some temperate North Atlantic red algae

Using the red alga Polyneura hilliae as an example, the minimum time taken for lethal temperature exposure, with no regeneration capacity left, was 2 weeks. Employing this exposure time, the upper temperature limits of the following 13 red algal species belonging to four biogeographical distribution groups were determined:Callophyllis lacinita, Polyneura hilliae, Hypoglossum hypoglossoides, Halurus equisetifolius, Lomentaria articulata, Cryptopleura ramosa, Calliblepharis ciliata (warm-temperate Mediterranean-Atlantic group);Callithamnion tetragonum, Lomentaria orcadensis (amphiatlantic-temperate group);Grinnellia americana, Lomentaria baileyana, Agardhiella subulata (northeast American tropical-temperate group),Solieria tenera (amphiatlantic tropical-temperature group). Pre-incubation temperatures of 10 and 20°C for one month (or 15 and 25°C for the two last-mentioned distribution groups) did not measurably affect the critical survival temperature.