Stress tolerance and reactive oxygen metabolism in the intertidal red seaweeds Mastocarpus stellatus and Chondrus crispus

Mastocarpus stellatus and Chondrus crispus are morphologically similar red seaweeds that co-occur on rocky intertidal seashores in the Northern Atlant ic. Mastocarpus stellatus grows higher on the shore and is more tolerant of environmental stress, caused by factors such as freezing and desiccation, than C. crispus Here we report a correlation between reactive oxygen metabo lism and stress tolerance, which suggests that reactive oxygen metabolism m ay play a role in stress tolerance of intertidal red seaweeds, Mastocarpus stellatus scavenged added H2O2 slightly faster, and was more resistant to o xidative stress induced by addition of H2O2 and Rose Bengal, than C. crispu s. These data were consistent with higher levels of ascorbate and beta-caro tene and higher activities of catalase and glutathione reductase, in M. ste llatus. Tocopherol content and activities of superoxide dismutase and ascor bate peroxidase were similar in both species. Activities of reactive oxygen scavenging enzymes generally increased with tidal height in M. stellatus; this was, however, not a consistent trend in C. crispus.