Providing reliable instrumentation that enables collection of high-quality, comparable data is one of the most challenging aspects of establishing ocean acidification monitoring programs. This is especially true for under-resourced countries, where such data are mostly unavailable. In 2016, The Ocean Foundation (TOF) worked with international bodies, including the International Atomic Energy Agency’s Ocean Acidification International Coordination Centre and the Global Ocean Acidification Observing Network (GOA-ON), and subject matter experts to develop a set of equipment known as the “GOA-ON in a Box” kit (The Ocean Foundation, 2017). This comprehensive kit provides researchers with everything needed—down to specialized rubber bands—to obtain weather-quality carbonate system measurements as defined by GOA-ON (Newton et al., 2015). Data are generated from spectrophotometric measurements of pHT and manual titrations for total alkalinity from discrete samples as well as in situ sensors, the iSAMI-pH and a CTD. The kit’s modular design, composed of nearly 100 unique items, makes it much less expensive than comparable integrated systems and allows for easier troubleshooting and replacement of supplied spare components.
The Ocean Foundation’s Ocean Science Equity Initiative—EquiSea—was founded in 2022 to address systemic inequities in ocean science capacity and opportunities. It provides financial support for projects, coordinates capacity development activities, fosters collaboration and co-financing of ocean science, and supports the development of low-cost ocean science technologies. The EquiSea strategic framework was co-developed with input from more than 200 ocean science practitioners in more than 35 countries. The authors of this article are those who played the most active roles in EquiSea’s development.
Many marine algae occupy habitats that are dark, deep, or encrusted on other organisms and hence are frequently overlooked by natural product chemists. However, exploration of less-studied organisms can lead to new opportunities for drug discovery. Genetic variation at the individual, species, genus, and population levels as well as environmental influences on gene expression enable expansion of the chemical repertoire associated with a taxonomic group, enabling natural product exploration using innovative analytical methods. A nontargeted LC-MS and 1H NMR spectroscopy-based metabolomic study of 32 collections of representatives of the calcareous red algal genus Peyssonnelia from coral reef habitats in Fiji and the Solomon Islands revealed significant correlations between natural products' chemistry, phylogeny, and biomedically relevant biological activity. Hierarchical cluster analysis (HCA) of LC-MS data in conjunction with NMR profiling and MS/MS-based molecular networking revealed the presence of at least four distinct algal chemotypes within the genus Peyssonnelia. Two Fijian collections were prioritized for further analysis, leading to the isolation of three novel sulfated triterpene glycosides with a rearranged isomalabaricane carbon skeleton, guided by the metabolomic data. The discovery of peyssobaricanosides A-C (15-17) from two Fijian Peyssonnelia collections, but not from closely related specimens collected in the Solomon Islands that were otherwise chemically and phylogenetically very similar, alludes to population-level variation in secondary metabolite production. Our study reinforces the significance of exploring unusual ecological niches and showcases marine red algae as a chemically rich treasure trove.
Tuberculosis (TB) is a dreadful infectious disease and a leading cause of mortality and morbidity worldwide, second in 2020 only to severe acute respiratory syndrome 2 (SARS-Cov-2). With limited therapeutic options available and a rise in multidrug-resistant tuberculosis cases, it is critical to develop antibiotic drugs that display novel mechanisms of action. Bioactivity-guided fractionation employing an Alamar blue assay for Mycobacterium tuberculosis strain H37Rv led to the isolation of duryne (13) from a marine sponge Petrosia sp. sampled in the Solomon Islands. Additionally, five new strongylophorine meroditerpene analogues (1–5) along with six known strongylophorines (6–12) were isolated from the bioactive fraction and characterized using MS and NMR spectroscopy, although only 13 exhibited antitubercular activity.
Microbes produce natural products that mediate interactions with each other and with their environments, representing a potential source of antibiotics for human use. The biosynthesis of some antibiotics whose constitutive production otherwise remains low has been shown to be induced by competing microbes. Competition among macroorganism hosts may further influence the metabolic outputs of members of their microbiomes, especially near host surfaces where hosts and microbial symbionts come into close contact. At multiple field sites in Fiji, we collected matched samples of corals and algae that were freestanding or in physical contact with each other, cultivated bacteria from their surfaces, and explored growth-inhibitory activities of these bacteria against marine and human pathogens. In the course of the investigation, an interaction was discovered between two coral-associated actinomycetes in which an Agrococcus sp. interfered with the antibiotic output of a Streptomyces sp. Several diketopiperazines identified from the antibiotic-producing bacterium could not, on their own, account for the antibiotic activity indicating that other, as yet unidentified molecule(s) or molecular blends, possibly including diketopiperazines, are likely involved. This observation highlights the complex molecular dynamics at play among microbiome constituents. The mechanisms through which microbial interactions impact the biological activities of specialized metabolites deserve further attention considering the ecological and commercial importance of bacterial natural products.
Since early 2020, disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a global pandemic, causing millions of infections and deaths worldwide. Despite rapid deployment of effective vaccines, it is apparent that the global community lacks multipronged interventions to combat viral infection and disease. A major limitation is the paucity of antiviral drug options representing diverse molecular scaffolds and mechanisms of action. Here we report the antiviral activities of three distinct marine natural products—homofascaplysin A (1), (+)-aureol (2), and bromophycolide A (3)—evidenced by their ability to inhibit SARS-CoV-2 replication at concentrations that are nontoxic toward human airway epithelial cells. These compounds stand as promising candidates for further exploration toward the discovery of novel drug leads against SARS-CoV-2.
Mangrove coverage in Fiji is among the highest of all Pacific island nations. These ecosystems store disproportionate amounts of carbon, provide critically important resources for communities, and protect coastal communities against the impacts of tropical cyclones. They are therefore vital in mitigating and adapting to the impacts of climate change. An improved understanding of both the scale and drivers of mangrove loss in Fiji can underpin sustainable management strategies and achieve climate change mitigation and adaptation goals. In this study we assessed mangrove cover, landcover change, and drivers of landcover change for Fiji between 2001 and 2018, as well as the impacts of landcover change on the structural characteristics of mangroves at selected sites on the Fijian island of Viti Levu. Results were then framed within the context of developing management responses, including the potential to develop forest carbon projects. We found Fiji’s mangrove estate to be 65,243 ha, with a loss of 1135 ha between 2001 and 2018 and an annual rate of loss of 0.11%. Tropical cyclones accounted for 77% of loss (~870 ha), with highest losses along the northern coastlines of Viti Levu and Vanua Levu. Mangrove structural characteristics showed high variability in the level of damage incurred, with taller riverine and hinterland vegetation sustaining greater levels of damage than coastal fringing or scrub mangroves. There was no tropical cyclone damage evident along the southern coastline of Viti Levu, with small-scale harvesting the predominate driver of loss in this region. Because of the large effect of cyclone damage on mangroves in the region, small to medium scale restoration projects may be appropriate interventions to increase mangrove cover and carbon stocks. Where harvesting of mangroves occurs, improved management to avoid deforestation could also provide opportunities to maintain mangrove cover and carbon stocks.
A new cyclic peptide, kakeromamide B (1), and previously described cytotoxic cyanobacterial natural products ulongamide A (2), lyngbyabellin A (3), 18E-lyngbyaloside C (4), and lyngbyaloside (5) were identified from an antimalarial extract of the Fijian marine cyanobacterium Moorea producens. Compound 1 exhibited moderate activity against Plasmodium falciparum blood-stages with an EC50 value of 8.9 µM whereas 2 and 3 were more potent with EC50 values of 0.99 µM and 1.5 nM, respectively. Compounds 1, 4, and 5 displayed moderate liver-stage antimalarial activity against P. berghei liver schizonts with EC50 values of 11, 7.1, and 4.5 µM, respectively. The threading-based computational method FINDSITEcomb2.0 predicted the binding of 1 and 2 to potentially druggable proteins of Plasmodium falciparum, prompting formulation of hypotheses about possible mechanisms of action. Kakeromamide B (1) was predicted to bind to several Plasmodium actin-like proteins and a sortilin protein suggesting possible interference with parasite invasion of host cells. When 1 was tested in a mammalian actin polymerization assay, it stimulated actin polymerization in a dose-dependent manner, suggesting that 1 does, in fact, interact with actin.
Ten representative actinobacterial strains isolated from marine sediments collected worldwide were studied to determine their taxonomic status. The strains were previously identified as members of the genus Salinispora and shared >99 % 16S rRNA gene sequence similarity to the three currently recognized Salinispora species. Comparative genomic analyses resulted in the delineation of six new species based on average nucleotide identity and digital DNA–DNA hybridization values below 95 and 70 %, respectively. The species status of the six new groups was supported by a core-genome phylogeny reconstructed from 2106 orthologs detected in 118 publicly available Salinispora genomes. Chemotaxonomic and physiological studies were used to complete the phenotypic characterization of the strains. The fatty acid profiles contained the major components iso-C16 : 0, C15 : 0, iso-17 : 0 and anteiso C17 : 0. Galactose and xylose were common in all whole-sugar patterns but differences were found between the six groups of strains. Polar lipid compositions were also unique for each species. Distinguishable physiological and biochemical characteristics were also recorded. The names proposed are Salinispora cortesiana sp. nov., CNY-202T (=DSM 108615T=CECT 9739T); Salinispora fenicalii sp. nov., CNT-569T (=DSM 108614T=CECT 9740T); Salinispora goodfellowii sp. nov., CNY-666T (=DSM 108616T=CECT 9738T); Salinispora mooreana sp. nov., CNT-150T (=DSM 45549T=CECT 9741T); Salinispora oceanensis sp. nov., CNT-138T (=DSM 45547T=CECT 9742T); and Salinispora vitiensis sp. nov., CNT-148T (=DSM 45548T=CECT 9743T).
Mangrove ecosystems are particularly important for small island developing states of the Pacific, such as Fiji, which are at the forefront of the impacts of climate change. This is because of the ability of mangroves to mitigate storm surges and floods as well as their high carbon sequestration and storage capacity. However, there are few detailed studies on the spatial variation in mangrove structure and carbon stocks in Fiji, and this information is essential to support decision making by government and communities, enabling the development of effective mitigation and adaptation responses. We assessed mangrove forest structure in contrasting regions around Fiji's largest island, Viti Levu, within sites managed by indigenous (iTaukei) Fijians. Mangroves of the Ba, Nadroga-Navosa, and Rewa and Tailevu regions showed high variance in both structural complexity and ecosystem carbon stocks. Levels of variation were similar to that observed globally due to variable geomorphological and biophysical settings related to orographic rainfall, freshwater influx, tidal amplitude and cyclonic disturbances. High biomass, structurally complex forests occur on the wetter south-east coast (e.g. the Rewa Delta), while structurally uniform scrub mangroves dominate large areas of mangroves along the north-west (e.g. the Ba Delta) and west coast (e.g. the Tuva Delta). Mangroves of the Ba region displayed considerable damage from tropical cyclones, particularly in taller vegetation. All mangrove sites assessed were important reservoirs of carbon, with results when scaled to the spatial extent of mangroves in Fiji revealing that ecosystem carbon storage is disproportionate to area and equates to 73.3% of the carbon held within terrestrial rainforests, despite occupying just 7.3% of the total area. This underscores the importance of mangroves as valuable carbon sinks in Fiji and the need to develop incentives for improved conservation and restoration.
Seagrasses provide a wide range of services including food provision, water purification and coastal protection. Pacific small island developing states (PSIDS) have limited natural resources, challenging economies and a need for marine science research. Seagrasses occur in eleven PSIDS and nations are likely to benefit in different ways depending on habitat health, habitat cover and location, and species presence. Globally seagrass habitats are declining as a result of anthropogenic impacts including climate change and in PSIDS pressure on already stressed coastal ecosystems, will likely threaten seagrass survival particularly close to expanding urban settlements. Improved coastal and urban planning at local, national and regional scales is needed to reduce human impacts on vulnerable coastal areas. Research is required to generate knowledge-based solutions to support effective coastal management and protection of the existing seagrass habitats, including strenghened documentation the socio-economic and environmental services they provide. For PSIDS, protection of seagrass service benefits requires six priority actions: seagrass habitat mapping, regulation of coastal and upstream development, identification of specific threats at vulnerable locations, a critique of cost-effective restoration options, research devoted to seagrass studies and more explicit policy development.
Two sulfated diterpene glycosides featuring a highly substituted and sterically encumbered cyclopropane ring have been isolated from the marine red alga Peyssonnelia sp. Combination of a wide array of 2D NMR spectroscopic experiments, in a systematic structure elucidation workflow, revealed that peyssonnosides A-B (1-2) represent a new class of diterpene glycosides with a tetracyclo [7.5.0.01,10.05,9] tetradecane architecture. A salient feature of this workflow is the unique application of quantitative interproton distances obtained from the rotating frame Overhauser effect spectroscopy (ROESY) NMR experiment, wherein the β-d-glucose moiety of 1 was used as an internal probe to unequivocally determine the absolute configuration, which was also supported by optical rotatory dispersion (ORD). Peyssonnoside A (1) exhibited promising activity against liver stage Plasmodium berghei and moderate antimethicillin-resistant Staphylococcus aureus (MRSA) activity, with no cytotoxicity against human keratinocytes. Additionally, 1 showed strong growth inhibition of the marine fungus Dendryphiella salina indicating an antifungal ecological role in its natural environment. The high natural abundance and novel carbon skeleton of 1 suggests a rare terpene cyclase machinery, exemplifying the chemical diversity in this phylogenetically distinct marine red alga.
A series of oligomeric phenols including the known natural product 3,4,3′,4′-tetrahydroxy-1,1′-biphenyl (3), the previously synthesized 2,3,8,9-tetrahydroxybenzo[c]chromen-6-one (4), and eight new related natural products, cladophorols B–I (5–12), were isolated from the Fijian green alga Cladophora socialis and identified by a combination of NMR spectroscopy, mass spectrometric analysis, and computational modeling using DFT calculations. J-resolved spectroscopy and line width reduction by picric acid addition aided in resolving the heavily overlapped aromatic signals. A panel of Gram-positive and Gram-negative pathogens used to evaluate pharmacological potential led to the determination that cladophorol C (6) exhibits potent antibiotic activity selective toward methicillin-resistant Staphylococcus aureus (MRSA) with an MIC of 1.4 μg/mL. Cladophorols B (5) and D–H (7–11) had more modest but also selective antibiotic potency. Activities of cladophorols A–I (4–12) were also assessed against the asexual blood stages of Plasmodium falciparum and revealed cladophorols A (4) and B (5) to have modest activity with EC50 values of 0.7 and 1.9 μg/mL, respectively.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Marine invertebrates and algae collected off the coast of Espirito Santo in Vanuatu were investigated for antimicrobial and cytotoxic activities. The combined crude methanol-dichloromethane extracts from 52 sponges, 5 algae, 17 soft corals (cnidaria) and 5 other samples of various marine invertebrates were screened for cytotoxicity, antibacterial and antifungal properties. The cytotoxicity of the samples was determined using a brine shrimp lethality test and, notably, 78% of the invertebrate and algae samples showed cytotoxic activity against brine shrimps with the sponge Crella spinulata displaying the strongest activity. Antimicrobial activity was determined against three resistant bacterial strains and two fungal strains. A total of 42% of the samples tested showed antimicrobial activity against at least one of the five strains. The most potent antibacterial activities were recorded for the sponges Lamellodysidea herbacea, Phyllospongia sp., a sponge in the order Halichondrida and Hippospongia metachromia. A Theonella sp. sponge displayed the strongest antifungal activity.
Over the past 30 years, approximately 140 papers have been published on marine natural products chemistry and related research from the Fiji Islands. These came about from studies starting in the early 1980s by the research groups of Crews at the University of California Santa Cruz, Ireland at the University of Utah, Gerwick from the Scripps Institution of Oceanography, the University of California at San Diego and the more recent groups of Hay at the Georgia Institute of Technology (GIT) and Jaspars from the University of Aberdeen. This review covers both known and novel marine-derived natural products and their biological activities. The marine organisms reviewed include invertebrates, plants and microorganisms, highlighting the vast structural diversity of compounds isolated from these organisms. Increasingly during this period, natural products chemists at the University of the South Pacific have been partners in this research, leading in 2006 to the development of a Centre for Drug Discovery and Conservation (CDDC).