Browsing by Author "Huovinen, Pirjo"
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Item Boletín Antártico Chileno(Instituto Antártico Chileno, 2014) Acevedo, Jorge; Gómez, Iván; Huovinen, Pirjo; Cárdenas, Cesar; González, Marcelo; Alcaíno, Jennifer; Barahona, Salvador; Baeza, Marcelo; Cifuentes, Víctor; Hervé, Francisco; Bravo Rebolledo, Elisa; Vega, Edgardo; Jaña, Ricardo; Retamales Espinoza, JoséItem Ilaia(Instituto Antártico Chileno, 2015) Gallardo, Jorge; Espinoza, Pablo; Flores, Patricio; Muñoz, Patricio; Acevedo, Jorge; Barticevic, Elías; Gómez, Iván; Huovinen, Pirjo; Canales, Reiner; Hervé, Francisco; Martinic Beros, Mateo; Salazar, Juan Francisco; Edgardo, Vega; Canales, Reiner; Retamales Espinoza, José; Ruíz, Pablo; Quinán, René; Ojeda, Pamela; Runyard, Robert; Leppe, Marcelo; Barticevic, Elías; Vega, EdgardoItem Photosynthetic UV stress tolerance of the Antarctic snow alga Chlorella sp. modified by enhanced temperature?(Sociedad de Biología de Chile, 2016) Rivas, C.; Navarro, N.; Huovinen, Pirjo; Gómez, L.Background: Photosynthetic characteristics and the effect of UV radiation and elevated temperature measured were studied in Chlorella sp. isolated from a snow microalgal community at King George Island, Maritime Antarctica through the chlorophyll florescence (rapid light curves and maximum quantum yield, respectively). The environmental context was monitored through measurements of spectral depth profiles of solar radiation (down to 40 cm) in the snowpack as well as a through continuous recording of temperature and PAR using dataloggers located at different depths (0–30 cm) within the snow column. Results: The photochemistry of Chlorella sp. was affected by UV radiation in a 12-h laboratory exposure under all studied temperatures (5, 10, 15, 20 °C): the algae exposed to PAR + UV-A radiation were inhibited by 5.8 % whilst PAR + UV-A + UV-B radiation decreased Fv/Fm by 15.8 %. In both treatments the 12-h recovery after UV exposure was almost complete (80–100 %). Electron transport based P-I curve parameters maximal electron transport rate (ETRmax), photosynthetic efficiency (α) and the saturating irradiance (Ek) no varied in response to different temperatures. Conclusions: Results revealed that Chlorella sp. not only shows high photosynthetic efficiency at ambient conditions, but also exhibits tolerance to solar radiation under higher temperatures and possessing a capacity for recovery after inhibition of photosynthesis by UV radiation.Item Stress tolerance of Antarctic macroalgae in the early life stages(Sociedad de Biología de Chile, 2016) Navarro, Nelso P.; Huovinen, Pirjo; Gómez, IvánBackground: Early life stages of macroalgae, especially from polar species, can be highly vulnerable to physical stressors, leading to important consequences for the fate of the whole population in scenarios of changing environmental variability. In the present study, tolerance to UV and temperature stress, as measured by rapid adjustment of photochemistry, Fv/Fm, and photosynthetic characteristics based on P-E curves (ETRmax, α and Ek), was assessed in the early life stages of six Antarctic macroalgal species from eulittoral (Pyropia endiviifolia, Iridaea cordata, Adenocystis utricularis and Monostroma hariotii) and sublittoral (Ascoseira mirabilis and Gigartina skottsbergii). Results: Reproductive cells of eulittoral species showed the highest light demands (Ek >45 μmol photon m−2 s−1) when compared to those from sublittoral species (Ek < 30 μmol photon m−2 s−1). Short-term experiments of 1 h revealed that reproductive cells of P. endiviifolia, A. utricularis and M. hariotii had the highest temperature tolerance with a decrease of Fv/Fm observed only at 30 °C, while carpospores of G. skottsbergii exhibited the highest sensitivity to temperature increase with a decrease of Fv/Fm, which could be observed at 5 °C. UV tolerance was observed in reproductive cells of the eulittoral species with < 20 % inhibition in Fv/Fm from UV after four hours of exposure, while sublittoral species were more sensitive with >30 % inhibition in Fv/Fm in the same condition. Enhanced temperature (7 and 12 °C) improved the tolerance of I. cordata compared to 2 °C, but exacerbated the detrimental effects of UV on A. mirabilis. Conclusion: Results showed that photosynthetic characteristics varied among reproductive cells of different species, reflecting the vertical zonation of parental thalli. Otherwise, these differences appear to underlie biogeographical and evolutionary components. In addition, UV tolerance was modulated by temperature increase, while temperature increase, in turn, ameliorated the detrimental effects of stress treatments in some eulittoral species (I. cordata tetraspores). In sublittoral A. mirabilis gametangia, temperature exacerbated the reduction of photosynthetic efficiency.Item Underwater optics in sub-antarctic and antarctic coastal ecosystems(Public Library of Science (PLOS), 2016-05-04) Huovinen, Pirjo; Ramírez, Jaime; Gómez, Iván; Ban, SyuheiUnderstanding underwater optics in natural waters is essential in evaluating aquatic primary production and risk of UV exposure in aquatic habitats. Changing environmental conditions related with global climate change, which imply potential contrasting changes in underwater light climate further emphasize the need to gain insights into patterns related with underwater optics for more accurate future predictions. The present study evaluated penetration of solar radiation in six sub-Antarctic estuaries and fjords in Chilean North Patagonian region (39-44 degrees S) and in an Antarctic bay (62 degrees S). Based on vertical diffuse attenuation coefficients (K-d), derived from measurements with a submersible multichannel radiometer, average summer UV penetration depth (z(1%)) in these water bodies ranged 2-11 m for UV-B (313 nm), 4-27 m for UV-A (395 nm), and 7-30 m for PAR (euphotic zone). UV attenuation was strongest in the shallow Quempillen estuary, while Fildes Bay (Antarctica) exhibited the highest transparency. Optically non-homogeneous water layers and seasonal variation in transparency (lower in winter) characterized Comau Fjord and Puyuhuapi Channel. In general, multivariate analysis based on K-d values of UV and PAR wavelengths discriminated strongly Quempillen estuary and Puyuhuapi Channel from other study sites. Spatial (horizontal) variation within the estuary of Valdivia river reflected stronger attenuation in zones receiving river impact, while within Fildes Bay a lower spatial variation in water transparency could in general be related to closeness of glaciers, likely due to increased turbidity through ice-driven processes. Higher transparency and deeper UV-B penetration in proportion to UV-A/visible wavelengths observed in Fildes Bay suggests a higher risk for Antarctic ecosystems reflected by e.g. altered UV-B damage vs. photorepair under UV-A/PAR. Considering that damage repair processes often slow down under cool temperatures, adverse UV impact could be further exacerbated by cold temperatures in this location, together with episodes of ozone depletion. Overall, the results emphasize the marked spatial (horizontal and vertical) and temporal heterogeneity of optical characteristics, and challenges that these imply for estimations of underwater optics.Item Up, down, and all around: scale-dependent spatial variation in rocky-shore communities of Fildes peninsula, King George island, antarctica(Public Library of Science (PLOS), 2014-06-23) Valdivia, Nelson; Díaz, María José; Holtheuer, Jorge; Garrido, Ignacio; Huovinen, Pirjo; Gómez, IvánUnderstanding the variation of biodiversity along environmental gradients and multiple spatial scales is relevant for theoretical and management purposes. Hereby, we analysed the spatial variability in diversity and structure of intertidal and subtidal macrobenthic Antarctic communities along vertical environmental stress gradients and across multiple horizontal spatial scales. Since biotic interactions and local topographic features are likely major factors for coastal assemblages, we tested the hypothesis that fine-scale processes influence the effects of the vertical environmental stress gradients on the macrobenthic diversity and structure. We used nested sampling designs in the intertidal and subtidal habitats, including horizontal spatial scales ranging from few centimetres to 1000s of metres along the rocky shore of Fildes Peninsula, King George Island. In both intertidal and subtidal habitats, univariate and multivariate analyses showed a marked vertical zonation in taxon richness and community structure. These patterns depended on the horizontal spatial scale of observation, as all analyses showed a significant interaction between height (or depth) and the finer spatial scale analysed. Variance and pseudo-variance components supported our prediction for taxon richness, community structure, and the abundance of dominant species such as the filamentous green alga Urospora penicilliformis (intertidal), the herbivore Nacella concinna (intertidal), the large kelp-like Himantothallus grandifolius (subtidal), and the red crustose red alga Lithothamnion spp. (subtidal). We suggest that in coastal ecosystems strongly governed by physical factors, fine-scale processes (e. g. biotic interactions and refugia availability) are still relevant for the structuring and maintenance of the local communities. The spatial patterns found in this study serve as a necessary benchmark to understand the dynamics and adaptation of natural assemblages in response to observed and predicted environmental changes in Antarctica.