ABSTRACT Compared to other marine eco-regions, the Levantine basin in the eastern Mediterranean Sea is characterized by elevated average temperatures, salinities and solar radiation. Such conditions coupled with ongoing climate changes pose a bleak future for the native marine biota, particularly for species already at the limits of their upper temperature tolerance. In the Israeli Mediterranean Sea, the diversity of marine macroalgae is estimated to be approximately 300 species, a number similar to neighbouring countries within the Levantine basin. In the Israeli Mediterranean Sea, an annual bladed Bangiales herein Porphyra sensu lato (s.l.), typically thrives in the rocky intertidal zone during late winter-early spring. Despite its unique prevalence and distinct seasonality, the exact taxonomic status of this species is unclear. Furthermore, based on morphological features of specimens collected over time, we have speculated that there might be more than one species present on local shores. Hence, we aimed to clarify the taxonomic identity of this Porphyra s.l. within the Israeli Mediterranean Sea and subsequently determine its relationship with other bladed Bangiales species within the Levantine basin. We analysed 16 DNA samples from morphologically distinct specimens collected between 2007 and 2021, and constructed phylogenetic trees for rbcL, COI, ITS1 and SSU molecular markers. Our results revealed that all samples examined belonged to a previously defined ‘Porphyra leucosticta complex’, specifically to the cryptic species Porphyra rosengurttii, a current synonym of the newly accepted name Neopyropia elongata. GenBank data mining and a literature review suggested five bladed Bangiales taxa in the Levantine basin, namely Neopyropia leucosticta, Porphyra atropurpurea, N. koreana, P. umbilicalis and P. linearis, but their precise taxonomic identification is unconfirmed, pending molecular and morphological studies.

ABSTRACT Inflammation is a critical defence mechanism in higher animals but uncontrolled inflammation is implicated in many diseases and can lead to chronic conditions, posing significant challenges to healthcare and the global economy. Conventional therapies often come with limitations and adverse effects, underscoring the need for safer and more effective alternatives. This study investigates the efficacy of C-Phycocyanin (C-PC), a pigment derived from Spirulina platensis cultivated under optimal light conditions, as an anti-inflammatory agent. This research focused on its effects on nitric oxide secretion, which supports the body’s immune system by killing pathogens, and interleukin-1 beta (IL-1β) gene expression as an inflammatory indicator, in phorbol 12-myristate 13-acetate (PMA)-stimulated human chondrocyte cells (C28/I2). The Methyl Thiazol Tetrazolium (MTT) assay was employed to evaluate the metabolic activity of cells and confirm the non-toxicity of C-PC. The results demonstrated that C-PC maintained 99.32% cell viability in the C28/I2 in vitro model after seven days. Notably, C-PC treatment prevented cell death and promoted cell proliferation, increasing the number of viable cells by 12.34% during the same period. Additionally, it significantly reduced IL-1β gene expression and nitric oxide secretion by 70.24% and 91.25%, respectively, effectively reducing levels to those observed in unstimulated conditions. Scanning electron microscopy (SEM) and crystal violet staining showed that C-PC treatment restored normal morphology and protected the cells from inflammation-induced changes.

ABSTRACT In this article we draw attention to the use of cyanotypes in promoting history, science and education. The new photographic process of cyanotypes was utilised by Anna Atkins and between 1843 and 1853 she published the first books illustrated by photography, which were a series of plates of macroalgae. Atkins was working against societal expectations and the role of women in science is explored and how society cannot always stifle personal endeavour. The process of making cyanotypes is described and offers a tool for teaching modern science such as photochemical reactions and their importance in biochemistry and ecology. It demonstrates how the advancement of these subjects is based in incremental discoveries documented in the history of science. It also introduces field work, laboratory work and the application of science outside of educational settings. The method will engage student interest in a practical educational setting culminating with a unique cyanotype which bridges the still controversial area where science and art meet. With care any cyanotype produced will still look pristine in over 180 years’ time as demonstrated by the Atkins books still held in museum collections.

ABSTRACT Industrial development has significantly increased CO2 emissions, from 280 ppm in the pre-industrial era to over 400 ppm today, contributing to the greenhouse effect and climate change. This study investigates the impact of varying CO2 concentrations on the growth, biomass accumulation, and biochemical composition of Euglena gracilis as microalgae-based carbon capture and utilization. E. gracilis was cultivated with CO2 concentrations of 0%, 5%, 10%, and 30%, using white LED lights at 3000 lux. Growth was monitored through cell counts and optical density, while biomass and primary metabolites were analysed using standard methods. Fatty acid content was assessed using GC-MS and GC-FID. The results showed optimal growth at 5% CO2, with biomass reaching 2.3 g l‒1 on the day of harvest. The highest lipid content was obtained in the 15% CO2 treatment with a total lipid of 0.35 g l‒1. As for the decrease in pH, it showed that each treatment experienced a reduction in pH from 3.5 to almost 2.0. Fatty acid content was dominated by polyunsaturated fatty acids (PUFAs), especially in the control group and 15% CO2 treatment, contributing up to 47.66%, and 46.36% to the group, respectively. The study highlights the importance of optimizing CO2 levels for microalgae cultivation to enhance biomass and lipid production. Elevated CO2 levels boost lipid synthesis but can stress cells if too high, suggesting a need for adaptive CO2 addition methods.

ABSTRACT Many governments are evaluating marine carbon sequestration processes for their capacity to mitigate the adverse impacts of climate change. This includes the cultivation of macroalgae to sequester carbon dioxide from the atmosphere, which requires accurate estimates from the field. This study estimated the potential rates of carbon sequestration of cultivated macroalgae by quantifying the amount of biomass released into the environment from a kelp, Saccharina latissima, farm in Strangford Lough, Northern Ireland (54.4° N, 5.58° W). We estimated that a mean of 41% of net primary productivity (NPP) of the cultivated kelp was lost prior to harvest following blade fall-off, equivalent to a mean of 7.4 kg of carbon sequestered per 100 m longline at the site during the cultivation period. Coarse estimates requiring verification predicted that a further 43.2% of NPP may have been lost through chronic erosion and exudation of organic carbon. This rate of sequestration is similar to that of several government-funded agroforestry schemes. There is potential, therefore, that this quantified ecosystem service could be subsidized to incentivize the sustainable development of the macroalgae industry. These findings are essential for those promoting the sustainable development of the macroalgae cultivation industry and are highly relevant for implementation of UN Sustainable Development Goal 13 (Climate action) and Goal 14 (Life below water: “Conserve and sustainably use the oceans, seas and marine resources for sustainable development”).

ABSTRACT Haptophytes are an environmentally important phylum of eukaryotic phytoplankton, forming the second most abundant algal group after diatoms in recent estimates of ocean biodiversity. Haptophytes are phylogenetically and functionally diverse, including globally distributed and bloom-forming calcifying species such as Emiliania and Coccolithus, and non-calcifying orders that may form important components of phytoplankton communities in polar (Phaeocystis, Chrysochromulina) through to sub-tropical latitudes (Pavlova). In this review, we synthesize available phylogenetic, genomic and environmental information concerning the diversity of haptophyte life, considering the origins and placement on the eukaryotic tree; the diversity of the five major orders (Pavlovophyceae, Phaeocystales, Prymnesiales, the CSZ clade, and Isochrysidales); and the contrasting biogeographical distributions of haptophyte groups across different Tara Oceans sampling stations and size fractions. We additionally consider outstanding questions within the fields of haptophyte diversity and biology, particularly in the context of newly discovered and largely uncultured major groups (DPL lineages and Rappemonads), and current gaps in our knowledge of genomic content and niche adaptation across the haptophyte tree.

ABSTRACT Seaweed surface provides a suitable substratum for the settlement of microorganisms (bacteria, viruses, and plankton). These microbial partners may have either beneficial or detrimental effects on the host since surface microbiota can act either as a protective layer to the macroalgae (symbiotic beneficial relations) or, under changing environmental conditions, the microbial equilibrium may shift to a detrimental, pathogenic state thus inducing diseases in the host. In commercial aquaculture, seaweed diseases feature a growing concern. Pathogenicity of microorganisms that infect algal hosts is closely related to the release of virulence factors and the formation of biofilms, both of which are regulated by Quorum Sensing (QS). The main focus of this study is to determine the pathogenicity of the surface-associated bacteria of Halymenia floresii, a carrageenophyte that originated from distinct habitats. Twenty-five bacterial species isolated from the surface of H. floresii were individually tested for tip bleaching assay to evaluate their potential pathogenicity. Ten isolates significantly reduced the risk of tip bleaching in H. floresii and were designated as “significantly non-pathogenic”. Vibrio owensii was identified as a “significant pathogen” inducing bleaching disease in H. floresii. By using LC-MS, we here identified its HomoSerine Lactones (HSL) QS signal, as a C4-HSL (short-chain). This study thus suggests a possible involvement of QS signal (short-chain) in the disease-inducing bacterium from the aquaculture ponds (an integrated multitrophic aquaculture system). This study firstly reports on the surface-associated bacteria of a lambda-carrageenophyte. This study must contribute to the development of dedicated strategies for disease control based on HSL disruption in aquaculture.

ABSTRACT The Northern Periphery and Arctic region faces unique economic and food security challenges that may be partly answered by commercial seaweed production. Alaria esculenta and Palmaria palmata are two seaweeds commonly found in the region and suitable for cultivation and processing for food and other commercial products. The drying kinetics for both species were obtained, and the Page and Weibull models best described the data. A drying air temperature increase from 40 to 70°C decreased drying time by 62.4% and 61.7% for A. esculenta and P. palmata, respectively. Desorption isotherms were obtained between 25 and 70°C and showed Brunauer Category III shapes, with water activity increasing with temperature for a fixed moisture content. Net heats of desorption were obtained, with drying to an equilibrium moisture content of 0.01 kgwater kgd.b.–1 requiring 18.1 and 3.94 kJ mol–1 K–1 for A. esculenta and P. palmata, respectively.

ABSTRACT In traditional medicine marine extracts are extensively used as therapies for diabetes. With the increasing rate of incidence of type 2 diabetes mellitus and rising cost of treatments, we investigated the anti-diabetic properties of extracts of common edible seaweeds in Europe including their ability to inhibit alpha-glucosidase and dipeptidyl peptidase 4 (DPP-4) enzymatic activity, block sodium glucose transporter-2 (SGLT-2) activity and stimulate glucagon-like peptide-1 (GLP-1) secretion and synthesis. The most promising seaweed extracts were tested for anti-hyperglycaemic activity in vivo. Some brown seaweed (Phaeophyceae) extracts had inhibitory effects on alpha-glucosidase ranging from 13.9 ± 0.2% to 89.5 ± 0.4% (p < 0.001). However, none of the seaweed extracts was able to block SGLT-2 activity. Ethanol extracts of the kelp Alaria esculenta and water extracts of Laminaria digitata strongly inhibited DPP-4 activity by 91.3 ± 0.1% and 90.0 ± 0.2%, respectively (p < 0.001), while ethanol extracts of Ulva rigida (Chlorophyta) had the greatest potential to stimulate GLP-1 secretion and GLP-1 synthesis (p < 0.001). A water extract of Porphyra linearis (Rhodophyta) significantly reduced the overall glycaemic excursion during an oral glucose tolerance test in normal mice (p < 0.05). These results demonstrate future potential for common edible seaweeds to be used as medicinal foods or bio-therapeutics to tackle type 2 diabetes mellitus by targeting GLP-1 secretion, DPP-4 activity or alpha-glucosidase activity.

ABSTRACT Corallina officinalis is a calcifying red alga, common in tide pools in the North Atlantic with occasional reports from the north-east Pacific. It is an important habitat-forming alga, providing shelter and substrata to many other organisms. To date there are only five published organellar genomes for Corallina, including C. chilensis and C. ferreyrae. This study reports the first four published plastid genomes for C. officinalis, along with three new mitogenomes from samples in the United Kingdom, Spain and Iceland. The plastid genome is 178 kbp and 99.9% of bases are identical for all samples. The mitogenomes are more variable than the plastid genomes, with lengths varying from 26.2 to 26.7 kbp and 99.0% base identity. Structure and length of both of the genomes are consistent with other published Corallina genomes. The most variable mitochondrial gene is sdhD (3.3% variability), while all plastid genes have <1% base variability, with the most variable being psb30 (0.95% variability). The stability of the plastid genome means it is not useful for examining intra-specific variability within Corallina. We discuss whether the ratio of mitogenome and plastome sequences recovered in the readpool of NGS sequencing is indicative of relative copy number.