Abstract:The intertidal marine red alga Porphyra umbilicalis reproduces asexually in the Northwest Atlantic. We looked for population substructure among typical opencoastal and atypical estuarine habitats in seven asexual populations of P. umbilicalis from Maine to New Hampshire using eight expressed sequence tag-simple sequence repeats (EST-SSR) or microsatellite loci. Six genotypes were identified, four of which may represent recombinant genotypes from a recombination event that took place locally, or that took place prior to introduction to the Northwest Atlantic. Genotypic diversity was lowest in a population from Wiscasset, Maine, which inhabits an atypical habitat high in the intertidal zone of a bridge piling in an estuarine tidal rapid. Genotypic diversity was highest in the southernmost populations from New Hampshire; we identified two genotypes that were unique to the southernmost populations, and probably represent the most derived genotypes. We looked at genetic distances among populations in similar habitats, and found that populations were more closely related to their closest neighboring population than to a population in a similar habitat. We show that genotypic diversity within P. umbilicalis populations in the Gulf of Maine is relatively high and thus fits a model of high steady-state variation within asexual populations.
Seaweed aquaculture in the Northwest Atlantic is a growing industry that is currently based on winter-spring kelp production. Aquaculture of Pyropia leucosticta, a species of economically valuable nori, could provide a spring-summer crop and diversify the industry. The objectives of this study were to determine the optimum conditions for the production of the foliose blade phase and the conditions for advancement from the microscopic conchocelis to the foliose blade phase of P. leucosticta. Foliose blades were grown under a matrix of temperatures (10, 15, and 20°C), photoperiods (8:16, 12:12, and 16:8 L:D), and light levels (30, 60, 110, and 250 μmol photons m −2 s −1 ) for a period of 1 month. Free-living conchocelis was grown under a matrix of temperatures (10, 15, and 20°C), photoperiods (8:16, 12:12, and 16:8 L:D), and ammonium concentrations (20 and 500 μM) for 8-12 weeks. Blades grew optimally at 10 to 15°C, ≥110 μmol photons m −2 s −1 and ≥12 h of light in the day, with growth rates of over 18 % day −1 recorded. Phycobilin content of blades significantly decreased with increasing day length, while protein content significantly decreased with increasing light level. Conchospore release and germination was observed after approximately 40 days under all tested photoperiods, temperatures, and ammonium concentrations and none of these treatments significantly affected the time until germination. Overall, this study provides important background information required for the establishment of Pyropia leucosticta aquaculture in the Northwest Atlantic.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.