National Committee on Marine Sciences (NCMS)
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- Microscopic stages of North Atlantic Laminaria digitata (Phaeophyceae) exhibit trait-dependent thermal adaptation along latitudesSchimpf, Nele M.; Liesner, Daniel; Franke, Kiara; Roleda, Michael Y.; Bartsch, Inka (Frontiers Media SA, 2022-06-17)Kelp forests in the North Atlantic are at risk of decline at their warm temperature distribution margins due to anthropogenic temperature rise and more frequent marine heat waves. To investigate the thermal adaptation of the cold-temperate kelp Laminaria digitata, we sampled six populations, from the Arctic to Brittany (Spitsbergen, Tromsø, Bodø [all Norway], Helgoland [Germany], Roscoff and Quiberon [both France]), across the species’ entire distribution range, spanning 31.5° latitude and 12-13°C difference in mean summer sea surface temperature. We used pooled vegetative gametophytes derived from several sporophytes to approximate the genetic diversity of each location. Gametophytes were exposed to (sub-) lethal high (20-25°C) and (sub-) optimal low (0-15°C) temperature gradients in two full-factorial, common-garden experiments, subjecting subsets of populations from different origins to the same conditions. We assessed survival of gametophytes, their ability to develop microscopic sporophytes, and subsequent growth. We hypothesized that the thermal performance of gametophytes and microscopic sporophytes corresponds to their local long-term thermal history. Integrated gametophyte survival revealed a uniform upper survival temperature (UST) of 24°C among five tested populations (Tromsø to Quiberon). In contrast, following two weeks of thermal priming of gametophytes at 20-22°C, sporophyte formation at 15°C was significantly higher in southern populations (Quiberon and Roscoff) compared to the high-latitude population of Tromsø. Between 0-15°C, survival of the Arctic population (Spitsbergen) was negatively correlated with increasing temperatures, while the southern-most population (Quiberon) showed the opposite. Thus, responses of survival at low, and sporophyte formation at high temperatures, support the concept of local adaption. On the other hand, sporophyte formation between 0-15°C peaked at 6-9°C in the Quiberon and at 9-12°C in the Spitsbergen population. Sporophyte growth rates (GR) both in length and width were similar for Spitsbergen, Tromsø and Quiberon; all had maximum GRs at 12-15°C and low GRs at 0-6°C. Therefore, responses of sporophyte formation and growth at low temperatures do not reflect ecotypic adaptation. We conclude that L. digitata populations display trait-dependent adaptation, partly corresponding to their local temperature histories and partly manifesting uniform or unpredictable responses. This suggests differential selection pressures on the ontogenetic development of kelps such as L. digitata.We would like to thank A. Wagner for the sampling and clonal isolation of kelp material and technical assistance in the laboratory, C. Daniel for support with the image analysis, L. Foqueau for the SST data, C. Gauci for statistical advice and S. DeAmicis for supervision in this BSc Thesis.
- The complete mitochondrial genome of a wild-collected Kappaphycus malesianus (Solieriaceae, Rhodophyta)Crisostomo, Bea A.; Dumilag, Richard V.; Roleda, Michael Y.; Lluisma, Arturo O. (Taylor & Francis, 2023-03-04)Kappaphycus malesianus is a red seaweed farmed primarily for its carrageenan, a polysaccharide important in the food and pharmaceutical industries. Among the commercially cultivated Kappaphycus species, only K. malesianus has no mitogenome data available. Here, we assembled the mitochondrial genome of K. malesianus from next-generation sequencing data. The circular mitogenome consisted of 25,250 base pairs (bp) with a GC content of 30.25%. These values were comparable to previously sequenced solieriacean mitogenomes. Structural features, such as the stem-loop and hairpin, which were previously reported in other rhodophytes mitochondrial DNA, were also identified. The annotated genes (24 protein-coding genes, 24 tRNA genes, and 2 rRNA genes) were arranged in an order similar to the other available solieriacean mitogenomes. Lastly, phylogenetic analysis using 23 predicted protein domains showed the sister relationship of K. malesianus with other Kappaphycus species.The authors are grateful to Z.-Z. Aguinaldo, S. Damsik, and J. Turong for aiding during laboratory and field works. The authors also acknowledge the LGU of Sitangkai, Tawi-Tawi for granting permission for the collection activities. This is contribution no. 495 from the University of the Philippines the Marine Science Institute (UPMSI), Diliman, Quezon City.
- Trans-Arctic asymmetries, melting pots and weak species cohesion in the low-dispersal amphiboreal seaweed Fucus distichusNeiva, João; Assis, Jorge; Fragkopoulou, Eliza; Pearson, Gareth A.; Raimondi, Peter T.; Anderson, Laura; Krause-Jensen, Dorte; Marbà, Núria; Want, Andrew; Selivanova, Olga; Nakaoka, Masahiro; Grant, W. Stewart; Konar, Brenda; Roleda, Michael Y.; Sejr, Mikael K.; Paulino, Cristina; Serrão, Ester A. (Frontiers Media SA, 2024-04-18)Amphiboreal taxa are often composed of vicariant phylogroups and species complexes whose divergence and phylogeographic affinities reflect a shared history of chronic isolation and episodic trans-Arctic dispersal. Ecological filters and shifting selective pressures may also promote selective sweeps, niche shifts and ecological speciation during colonization, but these are seldom considered at biogeographical scales. Here we integrate genetic data and Ecologic Niche Models (ENMs) to investigate the historical biogeography and cohesion of the polymorphic rockweed Fucus distichus throughout its immense amphiboreal range, focusing on trans-Arctic asymmetries, glacial/interglacial dynamics, and integrity of sympatric eco-morphotypes. Populations were sampled throughout the Pacific and the Atlantic, from southern rear-edges to the high-Arctic. They were genotyped for seven microsatellites and an mtDNA spacer, and genetic diversity and structure were assessed from global to local scales. ENMs were used to compare niche divergence and magnitude of post-glacial range shifts in Pacific versus Atlantic sub-ranges. Haplotypic and genotypic data revealed distinct and seemingly isolated Pacific vs Arctic/Atlantic gene-pools, with finer-scale regional sub-structuring pervasive in the Pacific. MtDNA diversity was highly structured and overwhelmingly concentrated in the Pacific. Regionally, Alaska showed the highest intra-population diversity but the lowest levels of endemism. Some sympatric/parapatric ecotypes exhibited distinct genotypic/haplotypic compositions. Strikingly, niche models revealed higher Pacific tolerance to maximum temperatures and predicted a much more consolidated presence in the NE Atlantic. Glacial and modern ranges overlapped extensively in the Pacific, whereas the modern Atlantic range was largely glaciated or emerged during the Last Glacial Maximum. Higher genetic and ecogeographic diversity supports a primary Pacific diversification and secondary Atlantic colonization, also likely reflecting the much larger and more stable climatic refugia in the Pacific. The relic distribution and reduced ecological/morphological plasticity in the NE Atlantic are hypothesized to reflect functional trans-Arctic bottlenecks, recent colonization or competition with congeners. Within the Pacific, Alaska showed signatures of a post-glacial melting pot of eastern and southern populations. Genetic/ecotypic variation was generally not sufficiently discontinuous or consistent to justify recognizing multiple taxonomic entities, but support a separate species in the eastern Pacific, at the southern rear-edge. We predict that layered patterns of phylogeographic structure, incipient speciation and niche differences might be common among widespread low-dispersal amphiboreal taxa.The authors thank Marta Valente (CCMAR), André Silva and Diogo Brito for sequencing and genotyping work and all the people involved in sample collection. Samples from Logy Bay were kindly collected by Kyle R. Millar. DK-J and NM thank Hurtigruten’s FRAM cruise for help with sampling along the Greenland west coast. Greenland sampling was also connected with campaigns for the MarineBasis component of the Greenland Ecosystem Monitoring (GEM) Programme in Nuuk and Young Sound, which is acknowledged.
- Seaweed as a resilient food solution after a nuclear warJehn, Florian Ulrich; Dingal, Farrah Jasmine; Mill, Aron; Harrison, Cheryl; Ilin, Ekaterina; Roleda, Michael Y.; James, Scott C.; Denkenberger, David (American Geophysical Union, 2024-01-09)Abrupt sunlight reduction scenarios such as a nuclear winter caused by the burning of cities in a nuclear war, an asteroid/comet impact or an eruption of a large volcano inject large amounts of particles in the atmosphere, which limit sunlight. This could decimate agriculture as it is practiced today. We therefore need resilient food sources for such an event. One promising candidate is seaweed, as it can grow quickly in a wide range of environmental conditions. To explore the feasibility of seaweed after nuclear war, we simulate the growth of seaweed on a global scale using an empirical model based on Gracilaria tikvahiae forced by nuclear winter climate simulations. We assess how quickly global seaweed production could be scaled to provide a significant fraction of global food demand. We find seaweed can be grown in tropical oceans, even after nuclear war. The simulated growth is high enough to allow a scale up to an equivalent of 45% of the global human food demand (spread among food, animal feed, and biofuels) in around 9–14 months, while only using a small fraction of the global ocean area. The main limiting factor being the speed at which new seaweed farms can be built. The results also show that the growth of seaweed increases with the severity of the nuclear war, as more nutrients become available due to increased vertical mixing. This means that seaweed has the potential to be a viable resilient food source for abrupt sunlight reduction scenarios.
- Physiological and biochemical characterization of new wild strains of Kappaphycus alvarezii (Gigartinales, Rhodophyta) cultivated under land-based hatchery conditionsNarvarte, Bienson Ceasar V.; Hinaloc, Lourie Ann R.; Genovia, Tom Gerald T.; Gonzaga, Shienna Mae C.; Tabonda-Nabor, April Mae; Roleda, Michael Y. (Elsevier, 2022-12)The red alga Kappaphycus alvarezii is globally cultivated as a major source of k-carrageenan. Farming of this species through clonal propagation has been confined to a few good-quality commercial strains. After more than 50 years of successful cultivation and high productivity, the production of K. alvarezii in most “cottonii”-producing countries like the Philippines had declined in recent decades. This can be attributed to low genetic variability, making “old” cultivars more susceptible to environmental stressors, pests (epi- and endophytes) and diseases (e.g., ice-ice). Hence, the establishment of new cultivars from wild strains with desirable traits may provide alternative seedstocks with different genetic makeup from the currently farmed cultivars. Here, we examined the physiological and biochemical properties of 10 new wild strains of K. alvarezii, belonging to four non-commercially cultivated haplotypes, collected from Eastern Samar, Philippines. These strains were cultivated in an outdoor, land-based hatchery with ambient light and flow-through, nutrient replete seawater. Growth rates, ranging from 0.44 % to 3.74 % d-1, significantly varied among the strains but did not significantly vary among haplotypes. The cultivars also showed a notable change in color and morphology as they adapted to hatchery conditions. Pigments and total phenolic content did not significantly vary among cultivars. Proximate analysis showed that the dry biomass of all K. alvarezii strains was composed mainly of ash (ranging from 39.2 % to 51.0 %), followed by carbohydrate (ranging from 26.0 % to 35.3 %), and with trace amounts of proteins (ranging from 1.02 % to 4.61 %). Moreover, tissue stoichiometry (C, N and P) was comparable among the 10 strains. Considering the promising growth performance of strain SamW-014 under hatchery condition, we recommend its cultivation at sea and conduct corresponding carrageenan yield and quality analyses on its raw dried biomass. Among the 10 strains, five others are also of interest and for consideration. Thereafter, selected strain(s) will be introduced to seaweed farmers for future cultivation to increase biomass production, harvest yields, and income.This is contribution no. 492 from the University of the Philippines- the Marine Science Institute (UPMSI), Diliman, Quezon City. We thank the BFAR 8 Regional Director Juan D. Albaladejo, Vicenta Z. Projimo, and the staff for their hospitality in facilitating the collection of wild Kappaphycus samples in Guiuan, Eastern Samar, and the Bolinao Marine Laboratory (BML) and the Marine Biogeochemistry Laboratory of UPMSI for providing a venue to conduct hatchery and laboratory experiments. We also thank Guillermo Valenzuela and Jerry Arboleda for maintaining our cultures at the BML hatchery. MYR acknowledges the Philippines Department of Science and Technology (DOST) Balik Scientist Program (BSP) fellowship.