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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 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 Macroalgas marinas antárticas: distribución, abundancia y necromasa en isla Rey Jorge, ShetIand del Sur, Antártica(1992) Westermeier, Renato; Gómez, Iván; Rivera, Pedro; Müller, DieterEl presente trabajo entrega antecedentes sobre la estructura y composición de macroalgas marinas en la isla Rey Jorge, Shetland del Sur. El estudio se llevó a cabo entre 1986 y 1989 en la zona inter-submareal. Al mismo tiempo, se realizaron determinaciones de necromasa de algas en arribazones. Los componentes algales más importantes en la zona intermareal corresponden a algas verdes filamentosas tales como Urospora penicilliformis (Roth) Aresch. y Enteromorpha bulbosa (Suhr) Mont. En el nivel mesomareal superior destaca Porphyra endiviifolium (A. y E.S. Gepp) Chamb., que se encuentra restringida a grietas entre los roqueríos. La presencia de pozas intermareales en el mesomareal inferior extiende el límite superior de distribución de algunas especies submareales tales como Leptosomia simplex (A. y E.S. Gepp) Kylin e lridaea obovata Kutzing. En la zona submareal, en tanto, el sustrato está dominado por Himantothallus grandifolius (A. y E.S. Gepp) Moe y Silva, el cual aporta sobre el 80% de la biomasa total; sin embargo, en las evaluaciones de necromasa, su incidencia es nula. En general, gran parte de la necromasa cuantificada en las arribazones, estuvo constituida por especies que habitan entre 0 y 5 m de profundidad, especialmente L. simplex e I, obovata. El esquema zonacional descrito en isla Rey Jorge, así como los resultados de necromasa, parecen indicar una fuerte relación entre las características morfológicas de las algas y su grado de susceptibilidad ante disturbios ambientales generados ya sea por el oleaje o por los hielos.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 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.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 Consistent richness-biomass relationship across environmental gradients in a marine macroalgal-dominated subtidal community on the western antarctic peninsula(Public Library of Science (PLOS), 2015-09-18) Valdivia, Nelson; Díaz, María José; Garrido, Ignacio; Gómez, Iván; Mahon, Andrew R.Biodiversity loss has spurred the biodiversity-ecosystem functioning research over a range of ecosystems. In Antarctica, however, the relationship of taxonomic and functional diversity with ecosystem properties (e.g., community biomass) has received less attention, despite the presence of sharp and dynamic environmental stress gradients that might modulate these properties. Here, we investigated whether the richness-biomass relationship in macrobenthic subtidal communities is still apparent after accounting for environmental stress gradients in Fildes Bay, King George Island, Antarctica. Measurements of biomass of mobile and sessile macrobenthic taxa were conducted in the austral summer 2013/4 across two environmental stress gradients: distance from nearest glaciers and subtidal depth (from 5 to 30 m). In general, community biomass increased with distance from glaciers and water depth. However, generalised additive models showed that distance from glaciers and depth accounted for negligible proportions of variation in the number of functional groups (i.e., functional richness) and community biomass when compared to taxonomic richness. Functional richness and community biomass were positive and saturating functions of taxonomic richness. Large endemic, canopy-forming brown algae of the order Desmarestiales dominated the community biomass across both gradients. Accordingly, differences in the composition of taxa accounted for a significant and large proportion (51%) of variation in community biomass in comparison with functional richness (10%). Our results suggest that the environmental factors here analysed may be less important than biodiversity in shaping mesoscale (several km) biomass patterns in this Antarctic system. We suggest that further manipulative, hypothesis-driven research should address the role of biodiversity and species' functional traits in the responses of Antarctic subtidal communities to environmental variation.