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National Committee on Marine Sciences (NCMS)

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Start date: 2022Ocean Decade Challenge: search.filters.odc.Challenge 5: Unlock ocean-based solutions to climate change

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    Quantifying vertical land motion at tide gauge sites using permanent scatterer interferometric synthetic aperture radar and global navigation satellite system solutions
    Reyes, Rosalie; Bauzon, Ma. Divina Angela; Pasaje, Nikki Alen; Alfante, Rey Mark; De Lara, Pocholo Miguel; Ordillano, Marion; Flores, Paul Caesar; Rediang, Abegail; Nota, Patrick Anthony; Siringan, Fernando; Blanco, Ariel; Bringas, Dennis (Springer, 2022-01-29)
    One of the consequences of climate change is sea level rise (SLR). Near the coast SLR varies at different locations due to the contributions from regional/local climatic and non-climatic factors. Vertical land motion (VLM) can affect the accuracy of sea level observations from tide gauges (TG) that may exacerbate coastal area inundation/flooding. This study investigated the viability of Permanent Scatterer Interferometric Synthetic Aperture Radar (PSInSAR) to quantify the rate of VLM at the TG sites. Measurements from TG co-located GNSS receivers provide the actual VLM rates and ground truth for PSInSAR-derived rates. Based on the results from the 9 study sites, almost all except one are subsiding. Both PSInSAR and GNSS solutions showed the same trend with rates that correlate at 0.89. Analysis from 20 Active GNSS stations showed 95% of the sites are undergoing land subsidence. This should be a cause of concern for communities near the coastal areas.
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    Microscopic stages of North Atlantic Laminaria digitata (Phaeophyceae) exhibit trait-dependent thermal adaptation along latitudes
    Schimpf, 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.
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    Effect of the Intensified Sub‐Thermocline Eddy on strengthening the Mindanao undercurrent in 2019
    Azminuddin, Fuad; Lee, Jae Hak; Jeon, Dongchull; Shin, Chang‐Woong; Villanoy, Cesar; Lee, Seok; Min, Hong Sik; Kim, Dong Guk (American Geophysical Union, 2022-02)
    The northward-flowing Mindanao Undercurrent (MUC) was directly measured by acoustic Doppler current profilers from a subsurface mooring at about 8°N, 127°E during 2 years (November 2017–December 2019). Its depth covers a range from 400 m to deeper than 1,000 m with its core appearing at around 900 m. The mean velocity of MUC's core was approximately 5.8 cm s−1 with a maximum speed of about 47.6 cm s−1. The MUC was observed as a quasi-permanent current with strong intraseasonal variability (ISV) with a period of 70–80 days. Further analyses with an eddy-resolving circulation model output suggest that the ISV is closely related to sub-thermocline eddies (SEs). In this study, two types of SEs near the Philippine coast are disclosed: the westward propagating SE (SE-1) and the quasi-stational SE southeast of Mindanao Island (SE-2). The SE-1 has both cyclonic and anticyclonic polarities with the propagation speed of 7–8 cm s−1, while the SE-2 is an anticyclonic eddy that moves erratically within 4–8°N, 127–130°E with the mean translation speed of about 11 cm s−1. Even though the SE-1 plays an important role in modulating the MUC, our results show that the observed strong MUC event (May–July 2019) is evidently induced by the intensified SE-2 that moves northwestward. This study emphasizes that the SE-2 when intensified, receives more energy from the strengthened New Guinea Coastal Undercurrent and loses the energy northward along the Philippine coast by intensifying the MUC.
    This study was part of the project entitled “study on air–sea interaction and process of rapidly intensifying Typhoon in the northwestern Pacific” (PM61670) funded by the Ministry of Oceans and Fisheries, Rep. of Korea. This study was also partly supported by the project entitled “Influences of the Northwest Pacific circulation and climate variability on the Korean water changes and material cycle I—The role of Jeju warm current and its variability” (PEA0011) funded by Korea Institute of Ocean Science and Technology (KIOST). The mooring data used in this study were provided by KIOST and are available from the KIOST live access server (http://las.kiost.ac.kr/data_adcp/). The model data are freely available from Mercator Ocean (https://resources.marine.copernicus.eu/?option=com_csw&view=details&product_id=GLOBAL_ANALYSIS_FORECAST_PHY_001_024).
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    Nitrite regeneration in the oligotrophic Atlantic Ocean
    Clark, Darren R.; Rees, Andrew P.; Ferrera, Charissa M.; Al-Moosawi, Lisa; Somerfield, Paul J.; Harris, Carolyn; Quartly, Graham D.; Goult, Stephen; Tarran, Glen; Lessin, Gennadi (Copernicus GmbH, 2022-03-07)
    The recycling of scarce nutrient resources in the sunlit open ocean is crucial to ecosystem function. Nitrification directs ammonium (NH4+) derived from organic matter decomposition towards the regeneration of nitrate (NO3-), an important resource for photosynthetic primary producers. However, the technical challenge of making nitrification rate measurements in oligotrophic conditions combined with the remote nature of these environments means that data availability, and the understanding that provides, is limited. This study reports nitrite (NO2-) regeneration rate (RNO2 – the first product of nitrification derived from NH4+ oxidation) over a 13 000 km transect within the photic zone of the Atlantic Ocean. These measurements, at relatively high resolution (order 300 km), permit the examination of interactions between RNO2 and environmental conditions that may warrant explicit development in model descriptions. At all locations we report measurable RNO2 with significant variability between and within Atlantic provinces. Statistical analysis indicated significant correlative structure between RNO2 and ecosystem variables, explaining ∼65 % of the data variability. Differences between sampling depths were of the same magnitude as or greater than horizontally resolved differences, identifying distinct biogeochemical niches between depth horizons. The best overall match between RNO2 and environmental variables combined chlorophyll-a concentration, light-phase duration, and silicate concentration (representing a short-term tracer of water column physical instability). On this basis we hypothesize that RNO2 is related to the short-term autotrophic production and heterotrophic decomposition of dissolved organic nitrogen (DON), which regenerates NH4+ and supports NH4+ oxidation. However, this did not explain the observation that RNO2 in the deep euphotic zone was significantly greater in the Southern Hemisphere compared to the Northern Hemisphere. We present the complimentary hypothesis that observations reflect the difference in DON concentration supplied by lateral transport into the gyre interior from the Atlantic's eastern boundary upwelling ecosystems.
    We thank the crew of the AMT19 cruise. MSLA data were obtained and analysed through the NERC Earth Observation Data Acquisition and Analysis Service (NEODAAS), and further data were provided by the European Space Agency's Sea Level CCI. This is contribution number 320 of the AMT program supported by UKRI through the National Capability Long-term Single Centre Science Programme, Climate Linked Atlantic Sector Science program and further from the Natural Environment Research Council funded Microbial Carbon Pump project. We would like to thank Dennis Hansell and two anonymous reviewers for constructive and insightful comments.
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    Clay mineral nanostructures regulate sequestration of organic carbon in typical fluvial sediments
    Song, Hongzhe; Liu, Zhifei; Lin, Baozhi; Zhao, Yulong; Siringan, Fernando P.; You, Chen-Feng (Elsevier, 2024-02-15)
    The association between clay minerals and organic carbon is pivotal for understanding transport, burial, and preservation processes of sedimentary organic carbon. However, fine-scale microscopic studies are still limited in assessing the effect of diverse clay mineral structures and properties on organic carbon sequestration. In this study, we employed X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy coupled with energy dispersive spectroscopy and electron energy loss spectroscopy analyses to investigate the nanoscale interaction between clay minerals and organic carbon of two typical fluvial sediment samples with contrasting clay mineral compositions and organic carbon origins. Sample from Taiwan shows abundant illite and chlorite with petrogenic organic carbon, while sample from Luzon has significant smectite with pedogenic organic carbon. We observed that the nanostructure of the clay minerals controls the distribution of organic carbon. In the Luzon sample, the organic carbon is tightly associated with smectite, occupying expandable interlayer spaces. In the Taiwan sample, however, the organic carbon is primarily confined on the surface and edge of illite. These findings offer valuable insights into the selective association of organic carbon with clay minerals and underscore the role of clay mineral nanolayer structures in governing the occurrence and preservation of organic carbon in sediments. A comprehensive understanding of these interactions is crucial for accurate assessments of carbon cycling and sequestration in the natural environment.
    We sincerely thank Shunai Che and Lu Han for their help in TEM experiments and data processing. We thank Editor Dr. Andrew Hursthouse for handling the manuscript and two anonymous reviewers for their constructive comments on the early version of this paper. This work was supported by the National Natural Science Foundation of China (42130407, 42188102, 42306066) and the Interdisciplinary Project of Tongji University (ZD-22-202102).
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    Estimation of the vertical phytoplankton distribution in the Philippine Sea: Influence of turbulence following passage of typhoons
    Cordero-Bailey, Kristina S.A.; Almo, Aldwin T.; David, Laura T.; Yñiguez, Aletta T. (Elsevier, 2022-11)
    The subsurface chlorophyll-a maximum (SCM) is a phenomenon that contributes significantly to the total primary production of the open ocean but it is not observable from remote sensing, thus primary production based on satellite information is highly underestimated. In a highly dynamic region such as the Philippine Sea, turbulence caused by tropical storms may exert significant impact on the SCM feature. In this study, we attempt to estimate the vertical phytoplankton profile in the Philippine Sea from remote sensing images by applying a generic quantitative approach. Generalized Additive Models (GAM) followed by Generalized Linear Models (GLMs) were used create predictive equations between response variables (Chl-a profile parameters) and predictor variables (RS parameters). GAM was able to predict integrated Chl-a biomass using photosynthetic active radiation (PAR), wind speed and wind stress, the depth of the Chl-a peak using surface Chl-a, wind speed and wind stress, and the baseline Chl-a concentration using sea surface temperature, sea surface salinity and PAR. GLM found wind stress and wind speed as significant predictors for integrated Chl-a biomass, while surface Chl-a, wind speed and wind stress were significant predictors for depth of the Chl-a peak. When the predictive equations were applied to 2020 monthly satellite images, they were seen to adequately estimate the offshore spatial distribution of the two Chl-a parameters. Increased turbulence due to high wind speed and wind stress during passage of tropical storms was seen to result in shallowing of the SCM and subsequent increase in Chl-a within the water column. These equations could be refined if long-term observational data was available. The capacity to estimate vertical distribution of primary productivity in the Philippines provides a means to better understand fisheries productivity and biogeochemical cycling in the region.
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    Submerged reef features in Apo and Tubbataha Reefs, Philippines, revealed paleo sea-level history during the last deglaciation
    Munar, Jeffrey C.; Aurelio, Mario A.; Dumalagan, Edwin E.; Tinacba, Erin Joy C.; Doctor, Ma. Angelique A.; Siringan, Fernando P. (Springer, 2024-02-27)
    The morphology of coral reefs provides an effective benchmark of past sea levels because of their limited vertical range of formation and good geologic preservation. In this study, we analyze the seafloor morphology around two atolls in the Philippines: Tubbataha Reef, in Palawan, and Apo Reef, in Occidental Mindoro. High-resolution multibeam bathymetry to a depth of 200 m reveals seafloor features including reef ridges and staircase-like terraces and scarps. Depth profiles across the reefs show terraces formed within six and seven depth ranges in Tubbataha Reef and in Apo Reef, respectively. These were further observed through a remotely operated vehicle. The terraces and scarps are interpreted as backstepping reefs that were drowned during an overall rise in sea level from the Last Glacial Maximum (LGM). Terraces are used as indicators of paleo sea level and the separation between terraces as the magnitude of sea-level rises coeval with meltwater pulse events during the last deglaciation. The pattern for both Apo and Tubbataha reefs indicates subsidence, consistent with the absence of Holocene emergent features and their atoll morphologies. Subsidence of up to 17 m since the LGM in Apo Reef is mainly attributed to the downbowing of the crust toward Manila Trench. In Tubbataha Reef, subsidence of up to 14 m is attributed to the continuous cooling of the volcanic crust underlying the atoll. These can be used to fill gaps in the tectonic history of the study sites from the last deglaciation.
    This study was funded by the Department of Science and Technology–Philippine Council for Agriculture, Aquatic and Natural Resources Research Development (DOST-PCARRD) Geophysical Coral Mapping Project and Acquisition of Detailed Bathymetry for Coastal Erosion Management Project both under F. P. Siringan, and National Assessment of Coral Reef Environment (NACRE) Project under Hazel Arceo. We would like to mention, in particular, Dominic Jone Cabactulan, Timothy Quimpo, Ronald Olavides, Mary Ann Calleja, Patrick Cabaitan, and Cesar Villanoy who were members of the project team. We thank the Tubbataha Management Office, Sablayan Local Government Unit, and Department of Environment and Natural Resources for the work permits and logistical help during the surveys.
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    Short-term exposure to independent and combined acidification and warming elicits differential responses from two tropical seagrass-associated invertebrate grazers
    Baure, Jerwin G.; Roleda, Michael Y.; Juinio-Meñez, Marie Antonette (Springer, 2023-08-10)
    Ocean acidification and warming could affect animal physiology, key trophic interactions and ecosystem functioning in the long term. This study investigates the effects of four pH−temperature combination treatments simulating ocean acidification (OA), ocean warming (OW) and combined OA and OW conditions (FUTURE) relative to ambient present-day conditions (PRESENT) on the grazing of the juveniles of two seagrass-associated invertebrates namely the sea cucumber Stichopus cf. horrens and topshell Trochus maculatus over a 5-day exposure period. Diel and feeding activity of both species increased under OW and FUTURE to some extent, while the nighttime activity of Trochus but not Stichopus decreased under OA relative to PRESENT during the first 2 days. Fecal production of Stichopus did not differ among treatments, while the lowest fecal production of Trochus was observed under OA during the first 24 h of grazing. These responses suggest that Trochus may be initially more sensitive to OA compared with Stichopus. Interestingly, fecal production of Trochus in FUTURE was significantly higher than OA, suggesting that warming may ameliorate the negative effect of acidification. Diel activity, feeding and fecal production after 5 days did not differ among treatments for both species, suggesting acclimation to the acute changes in temperature and pH after a few days, although Stichopus acclimated rapidly than Trochus. The ability of the two juvenile invertebrate grazers to rapidly acclimate to increased temperature and lowered pH conditions after short-term exposure may favor their survival under projected changes in ocean conditions.
    This work was supported by the Department of Science and Technology–Philippine Council for Agriculture, Aquatic, and Natural Resources Research and Development under Grant QMSR-MRRD-MEC-295-1449. The authors would like to thank Dr. Ian Enochs for his invaluable help in improving this paper. We also thank Tirso Catbagan, Garry Bucol, Rona Soy and Tomilyn Jan Garpa for their assistance during the conduct of this study. We would also like to thank the Marine Biogeochemistry Laboratory of the UP Marine Science Institute for their assistance in analyzing our water samples as well as the DNA Barcoding Laboratory of the UP Institute of Biology for the species identification of our animals.
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    Reproductive consequences of thermal stress-induced bleaching in the giant clam Tridacna crocea
    Sayco, Sherry Lyn G.; Alabort Pomares, Ana; Cabaitan, Patrick C.; Kurihara, Haruko (Elsevier, 2024-01)
    Reproduction is a fundamental process necessary for maintaining a population. However, reproductive processes are sensitive to thermal stress which can cause bleaching in reef organisms such as corals and giant clams. Here we examined the phototrophic and physiological performances, particularly the reproductive processes, in Tridacna crocea during bleaching and recovery periods. Giant clam individuals were induced to bleach at heated treatment (32-33 °C) for 16 days and allowed to recover at 28-29 °C for 35 days. The control giant clams were kept at 28-29 °C. Heated giant clams showed lower phototrophic performances (Fv/Fm and photosynthesis), but their respiration and survival were similar to control giant clams. The gonadosomatic index (GSI) was lower, and the proportion of regressive eggs (i.e., eggs that are no longer viable) was higher in heated than in control giant clams. However, heated giant clams were able to maintain their egg size. In addition, T. crocea showed recovery of phototrophic potential and color of mantle but not of their reproductive output after a month of recovery. Our results indicate that bleaching reduces the reproductive output in giant clams by disrupting their gametogenesis, such as through egg resorption, but giant clams showed potential reproductive strategy, through maintenance of their egg size, to ensure the quality of their offspring. Furthermore, one month of recovery is not sufficient to restore the normal reproductive processes in T. crocea, which may delay their population recovery after a bleaching disturbance.
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    Contrasting reproductive strategies between stress-tolerant and competitive coral taxa
    Bonilla, K. G.; Guest, J. R.; Baria-Rodriguez, M. V. (Springer, 2023-04-19)
    Reproductive traits such as fecundity (i.e., the number of gametes produced) and the size and age of coral colonies at reproductive onset can vary in predictable ways among life history strategies. However, most studies on the onset of reproductive maturity in corals only report the presence or absence of oocytes with little known about variation in fecundity across size and age classes. This study aimed to determine the colony size and fecundity at the onset of reproductive maturity across size classes of two scleractinian corals with contrasting life history strategies, Acropora millepora (competitive) and Favites colemani (stress-tolerant). Colonies at a site in northwestern Philippines were sampled to determine the smallest colony size class with mature oocytes and to estimate fecundity across size classes. Histological slides were also prepared to verify the presence of mature gametes. Colonies were able to produce mature oocytes when they had attained colony diameters of 4.7 cm for A. millepora and 1.5 cm for F. colemani. A. millepora had lower fecundity, but larger oocytes compared to F. colemani. Although small colonies can contribute to the larval pool, the proportion of mature colonies increased for larger size classes, suggesting that larger colonies make a disproportionately greater contribution to population reproductive output. These findings contribute to our understanding of coral population dynamics, particularly in parameterizing population and demographic models for different coral life histories.
    We are grateful to Christine Baran, Jue Alef Lalas, Jerry Arboleda, Gabriel de Guzman, the students and research assistants of Community and Ecology and Interactions of Marine Bionts and Benthic Ecosystems Laboratories for their valuable assistance during field and laboratory works, Darryl Valino for the site map, and Liam Lachs for the assistance on the statistical analyses. This research was supported by the University of the Philippines Marine Science Institute’s In-house project, Department of Science and Technology – ASTHRDP Thesis Grant, and University of the Philippines – Office of the Vice President for Academic Affairs’ Balik Ph.D. project (OVPAA-BPhD-2018-02).