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.
- Marine macroalgal reference culture collection at the University of the Philippines Marine Science Institute (UP-MMARCC): Status and prospects for advancing Philippine phycologySantiañez, Wilfred John E.; Guerta, Christian Ace T.; Lastimoso, John Michael L. (Assocation of Systematic Biologists in the Philippines, 2022-11-16)Seaweeds research in the Philippines-from studies on their diversity, natural products chemistry, and the utilization of their derivatives-is largely based on spot collections of large and conspicuous components of the seaweed flora found along the coasts. Such efforts are often focused on commercially important seaweeds; thus, most of the smaller and even microscopic seaweeds remain understudied, if not completely overlooked. Consequently, little to none is known on many aspects of the biology, ecology, and even biochemistry of these components of the Philippine seaweed flora. To understand aspects of seaweed biology and serve as a facility for preserving the genetic resources of Philippine seaweeds, we established the Marine Macroalgal Reference Culture Collection at the University of the Philippines Marine Science Institute (UP-MMARCC). We are currently maintaining 446 seaweed strains (or isolates) collected from several coastal and offshore areas in the Philippines, the latter including the Kalayaan Island Group in the West Philippine Sea, and 25 isolates from Okinawa, Japan. To our knowledge, the UP-MMARCC is the most diverse and widely sampled culture collection in the Philippines so far. Moreover, our preliminary molecular-assisted biodiversity studies suggest that UP-MMARCC houses several isolates that are either new records to the Philippines or putative new taxa. We anticipate that with continued support, we will be able to sustain and expand our culture collection, not only to facilitate discoveries but also to cater to the needs of the Philippine seaweed industry and in support of its call for diversifying our seaweed commodities and their products.
- Reproductive phenology and morphology of Macrocystis pyrifera (Laminariales, Ochrophyta) from southern New Zealand in relation to wave exposure1Leal, Pablo P.; Roleda, Michael Y.; Fernández, Pamela A.; Nitschke, Udo; Hurd, Catriona L. (Wiley, 2021-07-23)Macrocystis pyrifera is a major habitat forming kelp in coastal ecosystems of temperate regions of the northern and southern hemispheres. We investigated the seasonal occurrence of adult sporophytes, morphological characteristics, and reproductive phenology at two sites within a wave-protected harbour and two wave-exposed sites in southern New Zealand every 3–4 months between 2012 and 2013. Seasonality in reproduction was assessed via the number of sporophylls, the occurrence of sori on sporophylls, and non-sporophyllous laminae (fertile pneumatocyst-bearing blades and fertile apical scimitars), meiospore release, and germination. We found that M. pyrifera was present and reproductive year-round in three of the four sites, and patterns were similar for the wave-exposure conditions. Sori were found on pneumatocyst-bearing blades and apical scimitars in addition to the sporophylls, and viable meiospores were released from all three types of laminae. Morphological variations between sites with different wave exposure indicate that sporophytes from wave-protected sites have bigger blades and holdfasts and are longer than those from wave-exposed sites. We discuss the implications of these biological variables for the ecology of M. pyrifera inhabiting different wave exposure environments in southern New Zealand.Pablo P. Leal was supported by a scholarship from BECAS CHILE-ANID and by Programa Integral de Desarrollo de Acuicultura de Algas para Pescadores Artesanales (Etapa 4), funded by the Subsecretarıa de Economıa y Empresas de Menor Tamano (Convenio 2016). Michael Y. Roleda acknowledges the Philippine’s Department of Science and Technology (DOST) Balik Scientist Program for the fellowship. Udo Nitschke gratefully acknowledges support by Skidmore College, 815 North Broadway, Saratoga Springs, NY 12866, USA. Pamela A. Fernandez was supported by the Chilean National Commission for Scientific and Technological Research (ANID/FONDECYT; Postdoctoral grant 3170225 and grant 1180647) and ANID/Programa Basal (CeBiB, FB-0001). We are grateful to Rocio Suarez for assisting in field sampling.
- Comparison of photosynthetic responses of healthy and ‘diseased’ Kappaphycus alvarezii (Doty) Doty using P vs I curveGanzon-Fortes, E. T.; Azanza-Corrales, R.; Aliaza, T. (Walter de Gruyter GmbH, 1993)Healthy and 'diseased' thalli of Kappaphycus alvarezii were collected from two different sites in Bolinao, Pangasinan, northern Philippines. Their photosynthetic responses to varying photon fluence levels we reassessed. The healthy branches had higher photosynthetic rates (expressed in mgO2 gdw"1 h'1) at all light levels and did not show photoinhibition at photon fluence levels of up to 800 μπιοί photons m~2s~!. The 'diseased' branches showed a significant decrease in their photosynthetic performance as manifested by their lower Pmax, increased Ic, and lower alpha, and a photoinhibition above 600 μιηοΐ photons m~2 s"1. Examination of the concentration of pigments — chlorophyll a, r-phycoerythrin and r-phycocyanin, revealed a significant drop in the 'diseased' plants, suggesting the major role played by these pigments in the observed differences in their photosynthetic responses.
- Feeding ecology and trophic role of sea urchins in a tropical seagrass communityKlumpp, David W.; Salita-Espinosa, J. T.; Fortes, M. D. (Elsevier BV, 1993-04)The grazing impact of urchins on seagrass and algal resources, and the relative importance of this to the lower-level trophic flux of a tropical seagrass community were investigated. Thalassia hemprichii (Ehrenb.) Aschers. accounted for 80–93% of seagrass frond biomass at Bolinao in the Philippines. Growth rate of seagrass was 6.6 mm per shoot day−1, or 2.3 mg AFDW per shoot day−1. Production of seagrass fronds per unit area of seagrass bed varied with location from 870 to 1850 mg AFDW m−2 day−1. Urchin density ranged from 0.9 to 4.2 m−2, with Tripneustes gratilla (L.) and Salmacis sphaeroides (L.) being the most common species. Tripneustes gratilla fed mostly on attached seagrass fronds (77–89% of diet), especially Thalassia hemprichii, whereas S. sphaeroides was a generalist, consuming Thalassia hemprichii fronds (13–65%), detached seagrass debris (5–39%), the red alga Amphiroa fragilissima (L.) Lamour. (0–30%), algal-coated sediment and rubble (0–51%) in proportions that varied with the availability of preferred food types. Live Thalassia hemprichii fronds were clearly preferred over macroalgae or dead seagrass fronds by Tripneustes gratilla, but S. sphaeroides consumed all three food types without preference. Both urchins avoided the common brown alga, Sargassum crassifolium J. Agardh. Urchins absorbed 73–76% of organic matter in seagrass fronds with epiphytes (75% of DW), and 55% of that in epiphyte-free fronds. Seagrass debris and the macroalgae A. fragilissima were of lower food quality as they were lower in organic matter, and this matter was absorbed less efficiently by urchins. Rates of ingestion (IR in g WW per urchin day−1) were proportional to body weight (W in g WW) according to the functions: IR = 0.56W0.34 (T. gratilla) and IR = 0.17W0.53 (Salmacis sphaeroides). Predicted grazing impact of urchins on seagrass resources varied spatially and temporally. Estimated annual grazing rate at the main study site was 158 g AFDW m−2, equivalent to 24% of annual seagrass production, but owing to large changes in urchin population structure and density, grazing impact is expected to vary from < 5% to > 100% at different times of year. A synthesis of knowledge on the lower-level trophic pathways in this system indicates that seagrass-urchin and periphyton-epifauna grazing interactions are both important in their contribution to overall trophic flux.
- Manzaea minuta gen. & comb. nov. (Scytosiphonaceae, Phaeophyceae) from the tropical Northwestern Pacific OceanSantiañez, Wilfred John E.; Kogame, Kazuhiro (Philippine Journal of Systematic Biology, 2022-07-11)Recent molecular-assisted taxonomic studies on the brown algal genus Hydroclathrus has resulted in discoveries of new taxa in the family Scytosiphonaceae, both at the genus and species level. However, phylogenetic studies on Hydroclathrus based on wide geographical sampling also suggested that the genus is not monophyletic. That is, one of the recently described species Hydroclathrus minutus is consistently segregated from the Hydroclathrus main clade. We propose here to segregate H. minutus from the brown algal genus Hydroclathrus and establish the new monotypic genus Manzaea (i.e., Manzaea minuta gen. & comb. nov.) based on information on molecular phylogenetics and morpho-anatomy. Morphologically, M. minuta is similar to Hydroclathrus and Tronoella in having clathrate (net-like) and spreading thalli but is differentiated from the latter two genera in having membranous thalli that are sometimes interadhesive resulting in portions of the thallus forming amorphous clumps. Additionally, Manzaea is distinguished from both clathrate genera in having thick-walled medullary cells and short closely arranged quadriseriate plurangia. Phylogenetic analyses (Maximum Likelihood and Bayesian Inference) based on single (plastidial psaA and rbcL genes) and concatenated (cox3 + psaA + rbcL) genes showed that M. minuta is consistently segregated from the highly supported clade of Hydroclathrus species and often clustering with Tronoella and/or Rosenvingea. Our proposal further increases the diversity of monotypic genera in the Scytosiphonaceae and underscores the need to conduct further studies on tropical seaweed biodiversity.WJES thanks Dr. Gavino C. Trono, Jr. and Dr. Edna T. Ganzon-Fortes for the inspiration and encouragement to conduct seaweed biodiversity and systematics research. WJES is funded by the University of the Philippines through the Balik PhD Program of the Office of the Vice President for Academic Affairs (OVPAA-BPhD-2018-05), the University of the Philippines Diliman through the In-house research grant of the Marine Science Institute, and the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of the Government of Japan under the Monbukagakusho Scholarship Grant. WJES also acknowledges the support of the Department of Science and Technology (DOST)-Philippine Council for Agriculture, Aquatic and Natural Resources Research and Development (PCAARRD) of the Government of the Philippines through the DOST Balik Scientist Program.
- 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.
- Seasonality of standing crop of a Sargassum (Fucales, Phaeophyta) bed in Bolinao, Pangasinan, PhilippinesTrono, Gavino C.; Lluisma, Arturo O. (Springer, 1990-09)The seasonality of standing crop of a Sargassum bed was investigated by conducting monthly sampling from February 1988 to July 1989. Environmental parameters of water movement, salinity, number of daytime minus tides, and water temperature were also measured. An intra-annual pattern of variation in standing crop of Sargassum crassifolium, S. cristaefolium, S. oligocystum, and S. polycystum was observed. Standing crop was generally lowest in February, March, April, or May, and highest in November through January. Sargassum accounted for about 35 to 85% of the monthly algal standing crop of the bed, and the observed variation in overall standing crop of the bed generally reflected the standing crop of Sargassum. The seasonality of the standing crops of the associated algal divisions also followed an annual cycle, but their maximum and minimum standing crops did not coincide with those of Sargassum. Individually, as well as collectively, the standing crops of the Sargassum spp. were poorly correlated with the environmental factors observed.
- Genetic diversity of Kappaphycus malesianus (Solieriaceae, Rhodophyta) from the PhilippinesDumilag, Richard V.; Crisostomo, Bea A.; Aguinaldo, Zae-Zae A.; Lluisma, Arturo O.; Gachon, Claire M.M.; Roleda, Michael Y. (Elsevier, 2023-07)Kappaphycus farming for carrageenan production is characterized by a strong selective pressure at the genetic level. Traits of agronomic importance are compromised due to domestication bottlenecks and the subsequent events of possible selective breeding of founding cultivars. Kappaphycus malesianus is farmed in Malaysia and the Philippines, and is distributed within the Malesian region. While the majority of genetically characterized specimens of this species are from Malaysia, those from the Philippines are poorly explored. Here, we assessed the genetic diversity of K. malesianus from the Philippines based on cox1 sequences. Of the 15 identified haplotypes, 14 specimens represent three novel haplotypes (wild specimens) that form a group distinct from the main clade comprising most K. malesianus haplotypes known to date. An additional haplotype from a cultivated specimen was identical to that of the most widely distributed haplotype. Our findings demonstrate that the K. malesianus is genetically more diverse than previously recognized. It is expected that higher genetic diversity may be revealed through additional sampling from a wider geographic range and careful application of integrative approaches. Future selective breeding programs in Kappaphycus would benefit from the incorporation of the genetic resources, as provided in this study.