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Michael Y. Roleda

Bio: Michael Y. Roleda is an academic researcher from University of the Philippines Diliman. The author has contributed to research in topics: Alaria esculenta & Photoinhibition. The author has an hindex of 38, co-authored 103 publications receiving 4156 citations. Previous affiliations of Michael Y. Roleda include Alfred Wegener Institute for Polar and Marine Research & University of Kiel.


Papers
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Journal ArticleDOI
TL;DR: This review about the genus Laminaria sensu lato summarizes the extensive literature that has been published since the overview of the genus given by Kain in 1979, and covers recent insights into phylogeny and taxonomy, and discusses morphotypes, ecotypes, population genetics and demography.
Abstract: This review about the genus Laminaria sensu lato summarizes the extensive literature that has been published since the overview of the genus given by Kain in 1979. The recent proposal to divide the genus into the two genera Laminaria and Saccharina is acknowledged, but the published data are discussed under a 'sensu lato' concept, introduced here. This includes all species which have been considered to be 'Laminaria' before the division of the genus. In detail, after an introduction the review covers recent insights into phylogeny and taxonomy, and discusses morphotypes, ecotypes, population genetics and demography. It describes growth and photosynthetic performance of sporophytes with special paragraphs on the regulation of sporogenesis, regulation by endogenous rhythms, nutrient metabolism, storage products, and salinity tolerance. The biology of microstages is discussed separately. The ecology of these kelps is described with a focus on stress defence against abiotic and biotic factors and the role of Laminaria as habitat, its trophic interactions and its competition is discussed. Finally, recent developments in aquaculture are summarized. In conclusion to each section, as a perspective and guide to future research, we draw attention to the remaining gaps in the knowledge about the genus and kelps in general.

409 citations

Journal ArticleDOI
TL;DR: In this paper, the authors present a view on how UVB radiation affects seaweed physiology and ecology and thus shapes the coastal environment by affecting the spatial, species and functional structure of seaweed communities.
Abstract: Stratospheric ozone depletion and the concomitant increase in irradiance of ultraviolet-B radiation (UVB) at the earth’s surface represent major threats to terrestrial and aquatic ecosystems. In costal rocky shore environments, seaweeds constitute a group of organisms of particular significance to ecosystem function. Thus, impairment of seaweed performance by UVB-exposure may result in severe changes in the functioning of coastal ecosystems. Here we present our view on how UVB radiation affects seaweed physiology and ecology and, thus, shapes the coastal environment by affecting the spatial, species and functional structure of seaweed communities.

234 citations

Journal ArticleDOI
TL;DR: In response to nutrient stress, N. oculata emerged as the most robust species with an increase in lipid accumulation of up to three to four-fold compared to the accumulation under nutrient sufficient conditions.

205 citations

Journal ArticleDOI
TL;DR: In this article, the authors investigated multiple stressors on a subantarctic diatom and found that temperature and iron enrichment enhanced growth and helped to overcome nutrient depletion, while considering individual and interactive effects.
Abstract: Investigation of multiple stressors on a subantarctic diatom reveals the importance of considering individual and interactive effects. Experiments show that temperature and iron enrichment enhance growth and help overcome nutrient depletion.

148 citations

Journal ArticleDOI
TL;DR: The effects of pH on meiospore germination and sex determination for the giant kelp, Macrocystis pyrifera, in the presence and absence of additional dissolved inorganic carbon are reported, suggesting that metabolically active cells can compensate for the acidification of seawater.
Abstract: The worldwide effects of ocean acidification (OA) on marine species are a growing concern In temperate coastal seas, seaweeds are dominant primary producers that create complex habitats and supply energy to higher trophic levels Studies on OA and macroalgae have focused on calcifying species and adult stages, but critically, they have overlooked the microscopic stages of the reproductive life cycle, which, for other anthropogenic stressors, eg, UV-B radiation, are the most susceptible life-history phase Also, environmental cues and stressors can cause changes in the sex ratio, which has implications for the mating system and recruitment success Here, we report the effects of pH (759–850) on meiospore germination and sex determination for the giant kelp, Macrocystis pyrifera (Laminariales), in the presence and absence of additional dissolved inorganic carbon (DIC) Lowered pH (759–760, using HCl-only) caused a significant reduction in germination, whereas added DIC had the opposite effect, indicating that increased CO2 at lower pH ameliorates physiological stress This finding also highlights the importance of appropriate manipulation of seawater carbonate chemistry when testing the effects of OA on photosynthetic organisms The proportion of male to female gametophytes did not vary significantly between treatments, suggesting that pH was not a primary environmental modulator of sex Relative to the baseline (pH 819), gametophytes were 32% larger under moderate OA (pH 786) and 10% larger under extreme OA (pH 761) We suggest that metabolically active cells can compensate for the acidification of seawater This homeostatic function minimizes the negative effects of lower pH (high H+ ions) on cellular activity The 6–9% reduction in germination success under extreme OA suggests that meiospores of M pyrifera may be resistant to future OA

133 citations


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Book ChapterDOI
01 Jan 1976
TL;DR: A positive temperature coefficient is the term which has been used to indicate that an increase in solubility occurs as the temperature is raised, whereas a negative coefficient indicates a decrease in Solubility with rise in temperature.
Abstract: A positive temperature coefficient is the term which has been used to indicate that an increase in solubility occurs as the temperature is raised, whereas a negative coefficient indicates a decrease in solubility with rise in temperature.

1,573 citations

Journal ArticleDOI
TL;DR: Worldwide research on bioactive compounds in seaweed is reviewed, mainly of nine genera or species of seaweed, which are also available in European temperate Atlantic waters, i.e. Laminaria sp.
Abstract: Seaweed is more than the wrap that keeps rice together in sushi. Seaweed biomass is already used for a wide range of other products in food, including stabilising agents. Biorefineries with seaweed as feedstock are attracting worldwide interest and include low-volume, high value-added products and vice versa. Scientific research on bioactive compounds in seaweed usually takes place on just a few species and compounds. This paper reviews worldwide research on bioactive compounds, mainly of nine genera or species of seaweed, which are also available in European temperate Atlantic waters, i.e. Laminaria sp., Fucus sp., Ascophyllum nodosum, Chondrus crispus, Porphyra sp., Ulva sp., Sargassum sp., Gracilaria sp. and Palmaria palmata. In addition, Undaria pinnatifida is included in this review as this is globally one of the most commonly produced, investigated and available species. Fewer examples of other species abundant worldwide have also been included. This review will supply fundamental information for biorefineries in Atlantic Europe using seaweed as feedstock. Preliminary selection of one or several candidate seaweed species will be possible based on the summary tables and previous research described in this review. This applies either to the choice of high value-added bioactive products to be exploited in an available species or to the choice of seaweed species when a bioactive compound is desired. Data are presented in tables with species, effect and test organism (if present) with examples of uses to enhance comparisons. In addition, scientific experiments performed on seaweed used as animal feed are presented, and EU, US and Japanese legislation on functional foods is reviewed.

1,488 citations

01 Jan 2010
TL;DR: A 23-year database of calibrated and validated satellite altimeter measurements is used to investigate global changes in oceanic wind speed and wave height over this period and finds a general global trend of increasing values of windspeed and, to a lesser degree, wave height.
Abstract: Wind speeds over the world’s oceans have increased over the past two decades, as have wave heights. Studies of climate change typically consider measurements or predictions of temperature over extended periods of time. Climate, however, is much more than temperature. Over the oceans, changes in wind speed and the surface gravity waves generated by such winds play an important role. We used a 23-year database of calibrated and validated satellite altimeter measurements to investigate global changes in oceanic wind speed and wave height over this period. We find a general global trend of increasing values of wind speed and, to a lesser degree, wave height, over this period. The rate of increase is greater for extreme events as compared to the mean condition.

737 citations

Journal ArticleDOI
TL;DR: There remains the question as to whether a decrease in population size of the more sensitive primary producers would be compensated for by an increase in the population sizes of more tolerant species, and therefore whether there would be a net negative impact on the absorption of atmospheric carbon dioxide by these ecosystems.
Abstract: Recent results continue to show the general consensus that ozone-related increases in UV-B radiation can negatively influence many aquatic species and aquatic ecosystems (e.g., lakes, rivers, marshes, oceans). Solar UV radiation penetrates to ecological significant depths in aquatic systems and can affect both marine and freshwater systems from major biomass producers (phytoplankton) to consumers (e.g., zooplankton, fish, etc.) higher in the food web. Many factors influence the depth of penetration of radiation into natural waters including dissolved organic compounds whose concentration and chemical composition are likely to be influenced by future climate and UV radiation variability. There is also considerable evidence that aquatic species utilize many mechanisms for photoprotection against excessive radiation. Often, these protective mechanisms pose conflicting selection pressures on species making UV radiation an additional stressor on the organism. It is at the ecosystem level where assessments of anthropogenic climate change and UV-related effects are interrelated and where much recent research has been directed. Several studies suggest that the influence of UV-B at the ecosystem level may be more pronounced on community and trophic level structure, and hence on subsequent biogeochemical cycles, than on biomass levels per se.

729 citations

Journal ArticleDOI
TL;DR: Photosynthetic and growth rates of marine macro-autotrophs are likely to increase under elevated [CO2 ] similar to terrestrial C3 species, and fluxes control micro-environments that promote calcification over dissolution and may be more important than CaCO3 mineralogy in predicting macroalgal responses to OA.
Abstract: Although seagrasses and marine macroalgae (macro-autotrophs) play critical ecological roles in reef, lagoon, coastal and open-water ecosystems, their response to ocean acidification (OA) and climate change is not well understood. In this review, we examine marine macro-autotroph biochemistry and physiology relevant to their response to elevated dissolved inorganic carbon [DIC], carbon dioxide [CO2 ], and lower carbonate [CO3 (2-) ] and pH. We also explore the effects of increasing temperature under climate change and the interactions of elevated temperature and [CO2 ]. Finally, recommendations are made for future research based on this synthesis. A literature review of >100 species revealed that marine macro-autotroph photosynthesis is overwhelmingly C3 (≥ 85%) with most species capable of utilizing HCO3 (-) ; however, most are not saturated at current ocean [DIC]. These results, and the presence of CO2 -only users, lead us to conclude that photosynthetic and growth rates of marine macro-autotrophs are likely to increase under elevated [CO2 ] similar to terrestrial C3 species. In the tropics, many species live close to their thermal limits and will have to up-regulate stress-response systems to tolerate sublethal temperature exposures with climate change, whereas elevated [CO2 ] effects on thermal acclimation are unknown. Fundamental linkages between elevated [CO2 ] and temperature on photorespiration, enzyme systems, carbohydrate production, and calcification dictate the need to consider these two parameters simultaneously. Relevant to calcifiers, elevated [CO2 ] lowers net calcification and this effect is amplified by high temperature. Although the mechanisms are not clear, OA likely disrupts diffusion and transport systems of H(+) and DIC. These fluxes control micro-environments that promote calcification over dissolution and may be more important than CaCO3 mineralogy in predicting macroalgal responses to OA. Calcareous macroalgae are highly vulnerable to OA, and it is likely that fleshy macroalgae will dominate in a higher CO2 ocean; therefore, it is critical to elucidate the research gaps identified in this review.

675 citations