Molecular ecological studies of New England species of Porphyra (Rhodophyta, Bangiales)

Using a combination of morphological, ecological, and molecular methods, the seasonal occurrence and abundance of Porphyra species (Rhodophyta, Bangiales) were evaluated at an open coastal (Fort Stark) and an estuarine tidal rapids site (Dover Point) in New Hampshire, U.S.A. Monthly assessments of presence or absence of the different species, as well as percentage cover, biomass, and mean frond length were made for a year (July 1998-June 1999) on transect lines within the high and low intertidal zones at both sites. Seven species of Porphyra were recorded based upon morphological evaluations and these identifications were confirmed by screening for variation in the ribulose bisphosphate carboxylase large subunit gene (rbcL) with a restriction fragment length polymorphism (RFLP) assay. Four species were found on the transects (Porphyra \u27leucosticta\u27, P. \u27miniata\u27, P. \u27purpurea\u27, and P. \u27umbilicalis\u27) and two others (P. \u27amplissima\u27 and P. \u27linearis\u27) were collected during random sampling of adjacent habitats. A seventh introduced North Pacific species (P. \u27yezoensis\u27), which had previously been confused with P. \u27leucosticta\u27, was found on transects at Dover Point. Its DNA sequence showed 100% identity for nuclear ribosomal DNA internal transcribed spacer (ITS1) of strain NA4 of P. \u27yezoensis\u27 (GenBankAB017076). The rbcL sequence of the Dover Point material was also 100% identical to P. \u27yezoensis\u27 forma narawaensis cultivar F-6 (GenBank AB118590). Taken together these sequence data confirm that the Dover Point material is P. \u27yezoensis\u27. Conspicuous spatial and temporal patterns were recorded for several populations of Porphyra. The high intertidal zone at Fort Stark was dominated throughout the year by the aseasonal annual P. \u27umbilicalis\u27, while the low intertidal at the same site had a distinct summer maximum consisting of P. \u27leucosticta\u27 and P. \u27umbilicalis\u27. By contrast, P. \u27umbilicalis\u27 and P. \u27purpurea\u27 dominated the high intertidal zone at Dover Point, except during winter-early spring months when P. \u27yezoensis\u27 was most conspicuous. Porphyra \u27purpurea\u27 and P. \u27yezoensis\u27 were most abundant within the low intertidal zone at Dover Point, with the former plant being present almost year round and the latter having a distinct winter-early spring maximum. The mean lengths of P. \u27umbilicalis\u27, P. \u27leucosticta\u27 and P. \u27purpurea\u27 were largest during summer and, when present, smallest in winter