Linking Seasonal Reduction of Microbial Diversity to Increase in Winter Temperature of Waters of a Chilean Patagonia Fjord

Since microorganisms play a major role in the biogeochemistry of the ocean, understanding structure and dynamics of natural microbial communities is crucial in assessing the impact of environmental changes on marine ecosystems. In order to identify key environmental drivers of microbial community structure in Chilean Patagonian fjords, we analyzed composition of the prokaryotic community over an annual cycle at a single sampling site in Puyuhuapi Fjord. Distinctive communities represented mainly by Actinomycetales, Rhodobacteraceae, Cryomorphaceae, and Flavobacteriaceae were associated with Estuarine Fresh Waters, whereas Cenarchaeaceae and Oceanospirillales were representative of Modified Sub Antarctic Waters present in the fjord. Salinity and oxygen were first-order factors explaining segregation of microbial communities in these contrasting water masses. Positive correlations of members of Flavobacteriaceae, Alteromonadales, and Verrucomicrobiales with diatoms in subsurface waters and of Flavobacteriales (Cryomorphaceae and Flavobacteriaceae), Rhodobacteraceae, and Pelagibacteraceae with dinoflagellates in surface waters suggest that phytoplankton composition could define specific niches for microorganisms in Puyuhuapi fjord waters. A dramatic reduction of richness and individual abundances within Flavobacteriaceae, Rhodobacteraceae, and Cenarchaeaceae families was principally explained by seasonal increase of surface water temperature, with major reduction associated with changes in temperature during winter conditions. Taxa that are sensitive to increased temperature are key components of organic matter and element cycling, and we therefore suggest that potential decrease in diversity associated with rising of surface water temperature could impact current biogeochemical status of Patagonian fjord ecosystems

Soothsaying DOM: A Current Perspective on the Future of Oceanic Dissolved Organic Carbon

The vast majority of freshly produced oceanic dissolved organic carbon (DOC) is derived from marine phytoplankton, then rapidly recycled by heterotrophic microbes. A small fraction of this DOC survives long enough to be routed to the interior ocean, which houses the largest and oldest DOC reservoir. DOC reactivity depends upon its intrinsic chemical composition and extrinsic environmental conditions. Therefore, recalcitrance is an emergent property of DOC that is analytically difficult to constrain. New isotopic techniques that track the flow of carbon through individual organic molecules show promise in unveiling specific biosynthetic or degradation pathways that control the metabolic turnover of DOC and its accumulation in the deep ocean. However, a multivariate approach is required to constrain current carbon fluxes so that we may better predict how the cycling of oceanic DOC will be altered with continued climate change. Ocean warming, acidification, and oxygen depletion may upset the balance between the primary production and heterotrophic reworking of DOC, thus modifying the amount and/or composition of recalcitrant DOC. Climate change and anthropogenic activities may enhance mobilization of terrestrial DOC and/or stimulate DOC production in coastal waters, but it is unclear how this would affect the flux of DOC to the open ocean. Here, we assess current knowledge on the oceanic DOC cycle and identify research gaps that must be addressed to successfully implement its use in global scale carbon models

First record of flamentous fungi in the coastal upwelling ecosystem off central Chile Primer registro de hongos flamentosos en el ecosistema de surgencia costero frente a Chile central

We report for the frst time the presence of flamentous fungi in the water column and sediment in the coastal upwelling ecosystem off central Chile, using molecular tools and epifuorescence microscopy. Positive amplifcations of SSU 18s rDNA with specifc fungal primers were obtained for surface waters and sediments of this coastal ecosystem. Molecular richness obtained from denaturing gradient gel electrophoresis showed a higher number of fungal genotypes in nearshore than offshore sites and in summer than winter. Fungal structures identifed by epifuorescence microscopy in the water column were present as individual flaments or as aggregates of hyphae. We show for the frst time vertical water column profles of fungal biomass in the marine ecosystem. Fungal biomass reached up to 5 µg CL-1 in surface waters during summer and their vertical patterns agreed with those of chlorophyll-a and with the general distribution of microplankton biomass in the ocean. The presence of viable fungi in the coastal ocean encourages us to decipher their role in the processing of marine organic matter and to evalúate their inclusión in the actual paradigm of the microbial loop and in the biogeochemistry of the oceans.<br>Este estudio reporta por primera vez la presencia de hongos flamentosos en la columna de agua y sedimentos del ecosistema de surgencia costero de Chile central. La detección de hongos fue realizada utilizando herramientas moleculares y microscopía de epifuorescencia. Productos de amplifcación positivos del gen 18s rADN fueron obtenidos para muestras de agua y sedimento superfcial de este ecosistema costero. El análisis de riqueza molecular de los productos de PCR, realizado por electroforesis en gel con gradiente denaturante, mostró un mayor número de genotipos de hongos en las estaciones más cercanas a la costa y durante el verano. Estructuras de hongos fueron identifcadas por microscopía de epifuorescencia y fueron observadas como flamentos individuales o como agregados de hifas. Nuestros resultados muestran los primeros perfles verticales de biomasa de hongos en el ecosistema marino. La biomasa de hongos alcanzó valores de hasta 5 µg C L-1 en aguas superfciales durante el verano y su estructura vertical fue similar a la observada para clorofla-a y consistente con la distribución vertical general descrita para la biomasa microplactónica en el océano. La presencia de hongos viables en el océano costero plantea la necesidad de descifrar su rol en el procesamiento materia orgánica y evaluar su incorporación en el paradigma actual del anillo microbiano y en los ciclos biogeoquímicos del océano

Actividad citotóxica del aceite esencial presente en la hoja de Ocimmun basilicum (albahaca) mediante el bioensayo de artemia salina, marzo 2010

Tesis (Lic. en Farmacia y Química)-Universidad Nacional Autónoma de Nicaragua, LeónUNAN-Leó

Water-sediment partitioning of flumequine and florfenicol, two antibiotics used in salmon aquaculture in Chile

International audienc

Water column circulation drives microplastic distribution in the Martínez-Baker channels; A large fjord ecosystem in Chilean Patagonia

International audienc

Residual additives in marine microplastics and their risk assessment – A critical review

International audienc

Antibiotics florfenicol and flumequine in the water column and sediments of Puyuhuapi Fjord, Chilean Patagonia

International audienc