Search

Green algae, Ulva Linnaeus, 1753 (Ulvales, Chlorophyta), is found abundantly in intertidal regions of the coasts. Members of the genus exist in foliose, filamentous, and tubular forms and may be distromatic or monostromatic. This study investigates the phylogenetic distribution of foliose Ulva from various geographical locations in India. The morphological and microscopic features of 20 specimens were studied, and ITS, tufA, 18S, and atpB regions were sequenced using specific primers. BLAST results were used for similarity search and MEGAX for phylogenetic reconstruction using these amplified sequences. A total of 35 sequences were generated and used to trace back the evolution of different species and the effects of geographical locations on the cryptic diversity of Ulva. Also, this study reports the occurrence of Ulva fasciata, Ulva reticulata, Ulva taeniata, Ulva linza, and Ulva ohnoi. A pressed herbarium voucher was prepared for future records of each sample. [ABSTRACT FROM AUTHOR]

Introduction: Studies have shown that the macroalga Ulva lactuca is the largest CO2 receptor. In Cuba, the possibility of installing a plant for its intensive cultivation is being evaluated, which contributes to mitigate CO2 and allows obtaining algal biomass in a sustainable way. For design calculations, equipment selection and operating conditions, it is necessary to know the maximum biomass yieldand its photosynthetic equation. Objective: To estimate quantitatively the CO2 fixation mechanism of the macroalga Ulva lactuca, using different alternatives of the photosynthesis equation based on the calculation of stoichiometric coefficients. Materials and Methods: To calculate the yield and the amounts of substrate and nutrients that the biomass is able to assimilate, mass balances are carried out to optimize the production of algal biomass, applying the method of stoichiometric coefficients in the photosynthesis reaction. Results and Discussion: The maximum cell yield of Ulva lactuca is 63.5 %. Of the photosynthesis equations proposed, alternative four has values closer to photosynthetic reality, since there is a great correspondence between the stoichiometry of microalgae growth and product formation, together with the availability of nitrogen and phosphorus sources. Both results allow us to deduce the production of microalgal biomass to implement an economically and environmentally profitable technology. Conclusions: The maximum biomass yield and the photosynthetic equation allow for design calculations, equipment selection and operating conditions to scale up the technological process. [ABSTRACT FROM AUTHOR]

Ulva is a green macroalgal genus with rich species diversity and worldwide distribution. While current knowledge on Ulva diversity focuses on temperate regions, genetic and morphological data in tropical and subtropical areas are scarce and the species richness is not clearly defined. The genus is known for its bloom-forming ability that can induce green tides leading to severe environmental and economic damage. In the last two decades, several important blooms of Ulva spp. have occurred in New Caledonia, requiring further investigations to identify the species involved. As knowledge of New Caledonian Ulva diversity is limited, an update to the Ulva spp. inventory in the area is essential. Based on Ulva specimens collected throughout New Caledonia (Grande Terre, Isle of Pines and Loyalty Islands), we (1) reassessed species diversity using species delimitation methods, (2) analysed morpho-anatomical characters to identify species and/or enrich their diagnosis, and (3) reconstructed a multilocus phylogeny (ITS, rbcL, tufA) of the genus. We found 21 secondary species hypotheses (SSHs) among our dataset, from which five were successfully assigned to U. lactuca, U. ohnoi, U. tepida, U. meridionalis and U. taeniata. Ten SSHs were defined as new species for which we provided taxonomic description, and six other SSHs were singletons that will need to be data-enriched for better interpretation. Our concatenated multilocus matrix included 61 Ulva species. Of these, 15 species were found in New Caledonia and were moderately to strongly supported. Among the Ulva species found in New Caledonia, seven are known to be bloom-forming which highlights the need for strict regulation and regular monitoring of water quality, particularly in areas exposed to strong nutrient input where these species can form green tides. Ulva diversity in New Caledonia was reassessed with 15 species highlighted. Ten new species have been discovered in New Caledonia. Indigenous species caused recent green tides in New Caledonia. [ABSTRACT FROM AUTHOR]

The green seaweed Ulva is important from ecological and economic perspectives, but the identification of species is often problematic. Here we assessed and discussed different perspectives to establish a stable taxonomic framework for Ulva, which will benefit both ecological and applied research. We evaluated (1) the performance of commonly used DNA-barcode markers (ITS rDNA, rbcL, and tufA) using species delimitation methods (PTP and GMYC), (2) the usage of species names in the literature, and (3) the geographic coverage of genetic data to identify poorly sampled regions. Species delimitation employing the tufA gene was the most consistent across methods. Not surprisingly, DNA-based species delimitation was often in disagreement with traditional morphology-based species definitions. Biological species concepts, where tested, proved to be generally narrower than DNA-based species delimitation. Although the use of molecular markers has greatly improved our view of Ulva diversity, the names associated with DNA sequences in public databases are often unreliable, complicating species identification. Recently, sequencing type materials has considerably reduced the gap between DNA sequence data and Linnaean names, but our knowledge on Ulva diversity remains inadequate, especially in tropical regions. Perspectives for Ulva taxonomy include the consistent use of multiple DNA-barcode markers assisted by species delimitation methods, applications of genomic data, and crossing experiments. To arrive at a stable nomenclature, we outline the benefits and shortcomings of adhering to the rules and practices of the International Code of Nomenclature for algae, fungi, and plants, for example, by sequencing name-bearing types and discuss alternative approaches. [ABSTRACT FROM AUTHOR]

Supralittoral and shallow water seaweed communities are particularly exposed to impacts such as climate change and disturbance by humans. Therefore, their classification, the study of composition, and the monitoring of their structural changes are particularly important. A phytosociological survey of the supralittoral and upper sublittoral vegetation of the South West Baltic Sea revealed eight phytobenthos communities with two variants comprising 35 taxa of macrophytes (18 taxa of Chlorophyta, 13 taxa of Rhodophyta and four taxa of Phaeophyceae, Ochrophyta). Five of the eight communities were dominated by Ulvales (Ulva intestinalis, Kornmannia leptoderma, and three Blidingia species), the other three by Fucus vesiculosus. Most Fucus vesiculosus-dominated communities contained U. intestinalis and U. linza as subdominants. Only one of the communities had until now been described as an association (Ulvetum intestinalis Feldman 1937). The syntaxonomic composition of the investigated vegetation includes both phytocenoses with the domination of green algae (Ulvetum intestinalis Feldman 1937 and communities of Blidingia marginata, unidentified Blidingia spp. and Kornmannia leptoderma), as well as a number of communities dominated by Fucus vesiculosus. Mainly boreal Atlantic species and cosmopolitans make up the bulk of the species in these associations. [ABSTRACT FROM AUTHOR]