• genus;
  • intertidal;
  • molecular;
  • New Zealand;
  • Porphyra;
  • Rhodophyta;
  • seasonal;
  • spatial;
  • temporal;
  • zonation

Molecular studies have shown that New Zealand’s rocky shores are a habitat for >30 species of Porphyra, but little is known of their seasonal and zonal distribution. The spatial and temporal distribution of bladed Porphyra gametophytes at Brighton Beach, southeast New Zealand, were monitored for 32 months. Molecular markers were used for species identification, and a total of nine species was observed as being present during this time. Two species, P. cinnamomea and Porphyra sp. “ROS 54,” were the most common, and both were present for most months, while the remaining seven species were present sporadically, for only a few weeks at a time. P. cinnamomea W. A. Nelson and Porphyra sp. “ROS 54” were most common in the midintertidal, and both showed a similar seasonality with the highest presence during spring. They also showed a similar trend of seasonal dieback resulting in at least 1 month (May) in two consecutive years when they were both absent. This is one of the few studies investigating spatial and temporal distribution within a genus and over a 3-year period. Our results show no distinct intertidal zonation patterns within the genus, and we conclude that morphologically similar species in a similar habitat rely on physiological mechanisms for survival.