SUMMARY UV‐induced synthesis/accumulation of photoprotective pigments and antioxidant activity were investigated in the hot‐spring cyanobacterium Leptolyngbya cf. fragilis. The results indicated that UV radiation may induce biosynthesis of carotenoids, allophycocyanin, phycoerythrin, and scytonemin while phycocyanin degrades in response to longtime UV radiation. Moreover, pigment composition of L. cf. fragilis was significantly altered with increasing UV radiation times, probably due to destruction and resynthesis of accessory pigments as an adaptation strategy to UV stress. The in vitro antioxidant analysis of different extracts of UV treated cyanobacteria exhibited concentration‐dependent antioxidant activity. Ethyl acetate extract of 72 h UV treatment showed maximum total antioxidant activity (IC50 = 71.73 ± 5.3 μg mL−1) followed by ethyl acetate control (non‐UV irradiated) extract (IC50 = 109.43 ± 2.76 μg mL−1). This is the first report for the UV‐induced synthesis of photoprotective pigments and their antioxidant activity in L. cf. fragilis.

This study investigates the spatial and temporal variation of intertidal macroalgae along the eastern coasts of Qeshm Island, Persian Gulf, Iran. Monthly sampling of abundance, biomass, richness and diversity of macroalgae at three intertidal levels was carried out at two different sites during 1 year. The samples were collected every month using quadrats (0.5 × 0.5 m) from October 2012 to September 2013. The species dry weight was applied to examine changes in biomass and assemblage composition of intertidal macroalgae using univariate and multivariate analyses. A total of 42 seaweed species (10 Chlorophyta, 9 Phaeophyceae, and 23 Rhodophyta) were identified. The results confirmed a temporal pattern in the growth of the algal species which also showed a biomass zonation pattern from upper to lower intertidal. The annual mean biomass of macroalgae was highest in winter (29.3 ± 9.8 g dry wt m−2 ) and the lowest in autumn (17.3 ± 13.5 g dry wt m−2 ). The annual dominant species by biomass was Padina sp. followed by Padina australis. The most common species in the area, during the sampling period include Ulva intestinalis, Ulva lactuca, Palisada perforata and Padina sp. According to the similarity percentages analysis (SIMPER), the species Ulva intestinalis, Dictyosphaeria cavernosa (Chlorophyta), Padina australis (Phaeophyceae), Champia spp., Centroceras clavulatum and Palisada perforata (Rhodophyta) were responsible for the most dissimilarity of species composition between four seasons during the sampling period. BIOENV analysis indicated that the main environmental factors structuring macroalgal community at the study area were TDS and pH. The simple macroalgae community on the eastern coast of Qeshm Island and absence of slow-growing perennial macroalgae, such as members of the Sargassaceae, known from the lower shore at other intertidal localities along the island's coast might relate to the predominantly unsuitable sandy-stony substrates unsuitable for their colonization and the unfavourable impact upon them of urbanization.

In this study, a revised checklist of macroalgae of Iran with an updated nomenclature and taxonomy has been compiled based on published records. Using currently accepted names, 309 species and infraspecific taxa of macroalgae have been identified to date, including 78 Chlorophyta (within 15 families), 70 Ochrophyta (Phaeophyceae; within 7 families) and 161 Rhodophyta (within 30 families). The brown alga Sargassum with 25 taxa was the most diverse genus, and the Rhodomelaceae (Rhodophyta) with 36 taxa was the most species-rich family. The Cheney ratio of 3.4 and the species composition of brown seaweeds suggest that the Iranian marine algal flora is warm-temperate. Sørensen similarity indices were used to compare the marine algal flora of Iran with that of Saudi Arabia within the Persian Gulf and the Sultanate of Oman within the Gulf of Oman. The algal diversity of the Iranian coast within the Gulf of Oman is less than that within the Persian Gulf, and this difference is attributed to undercollecting. Given that this is the first inclusive checklist of macroalgae of Iran, covering the coast lying within the Persian Gulf and the Gulf of Oman, it could serve as a foundation for future phycological and biogeographical studies of the taxa in the country and the region.

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