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Populations inhabiting the periphery of a species' distribution suffer the immediate pressure of the environmental changes. Studying their physiology under stressful conditions is essential in the context of climate change. We characterized two morphotypes with measurements of length, thickness and width of the thallus of the macroalga Fucus guiryi in two localities (north and south) in Tenerife (Canary Islands), the southern limit of distribution of the species. We hypothesized that the individuals from the north locality, especially the large morphotype, would be more vulnerable to desiccation and high temperatures than those from the south. Tolerance to desiccation was tested through two long desiccation experiments and by comparing the vegetative and reproductive blades. Tolerance to high temperatures was tested by keeping the individuals in seawater (26–32 °C) for 24 h. The recovery of physiological functions after the stressful conditions was estimated through maximal photochemical efficiency of PSII. Results indicate that both of the two morphometrically differentiated morphotypes were tolerant to prolonged desiccation; however, the small one was more affected, particularly in the northern locality. The reproductive blades were hardly affected, indicating greater tolerance to desiccation than the vegetative blades. Fucus guiryi showed tolerance to high temperatures (32 °C) suggesting plasticity to future warming scenarios. [ABSTRACT FROM AUTHOR]

Phenology and spatial-temporal variation patterns during an annual cycle of Sargassum orotavicum from the Canaries have been studied for the first time. Data on morphological variation of general habit, stipes, primary and secondary branches, primary and secondary blades, vesicles and receptacles are presented. Sargassum orotavicum is a pseudoperennial species showing a significant seasonality in most parameters that have been studied. This species has four phases within the year: (1) regeneration, from perennial stipes and holdfasts in late autumn; (2) growth, with the beginning of the development of thallus structures that renew every year, in winter; (3) reproductive, with a vegetative climax prior to the reproductive, in spring; and (4) senescence and degeneration, with detachment of thallus structures that renew yearly, in summer. Biomass of branches, blades, vesicles and receptacles showed a significant seasonal variation, with maximum values in spring and minimum in late summer and autumn. This warm-temperate species exhibited a phenological behaviour intermediate between tropical and cold-temperate species of Sargassum . Analysis of within- and between-individual stability of eleven continuous traits indicated that the highest variation occurred temporally. [ABSTRACT FROM AUTHOR]

Nine species of sublittoral and deep-water red and brown algae are reported from the Canary Islands for the first time. The reports of the Western Atlantic species Gloiocladia atlantica (Searles) R. E. Norris and Rosenvingea antillarum (P. et H. Crouan) M. J. Wynne are the first from the Eastern Atlantic Ocean. The presence of Feldmannophycus rayssiae (J. et G. Feldmann) Augier et Boudouresque, Fauchea repens (C. Agardh) Montagne et Bory and Halichrysis depressa (J. Agardh) F. Schmitz, previously known from the Mediterranean Sea and the adjacent Atlantic coasts, place their southernmost known limit of distribution in the Canary Islands. Stypopodium schimperi (Buchinger ex Kützing) Verlaque et Boudouresque is reported for the first time in the Atlantic Ocean, although it is present in the Mediterranean Sea, probably as a Lessepsian species. The records of the widely distributed Stylonema cornu-cervi Reinsch, Acrochaetium infestans M. Howe et Hoyt and Spatoglossum schroederi (C. Agardh) Kützing were not unexpected. Data concerning morphology, habitat and geographical distribution of these species are presented. Observations on the scantly documented sublittoral species Schim-melmanniaschousboei (J. Agardh) J. Agardhand Dictyopteris plagiogramma (Montagne)Vickers are also given. In the dioecious Schimmelmannia schousboei, which has been formerly accepted as a doubtful record for the Canary Islands, the reproductive morphology is described including the previously unreported spermatangia. Dictyopteris plagiogramma was recently included in a checklist of Canarian species of Dictyopteris and is discussed in detail here. [ABSTRACT FROM AUTHOR]