Spatial structure of hydrography and flow in a Chilean fjord, Estuario Reloncaví

Valle‐Levinson, Arnoldo; Sarkar, Nandita; Sanay, Rosario; Soto, Doris; Leon, J. De

doi:10.1007/bf02782972

Cited by 78 publications

(79 citation statements)

References 23 publications

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“…The estuarine waters are relatively poor in nutrients, with the oceanic Subantarctic Waters (SAAW) being the main source of nutrients, as documented for the southern Chile shelf margin (Silva and Neshyba 1979). In Chilean fjords, the horizontal buoyancy input resulting from freshwater runoff has an important effect on the primary production (PP) of algae that are isolated from their principal source of nutrients (i.e., the nutrients trapped below the pycnocline), thus, leading to the eventual shutdown of production after short bloom periods (Valle-Levinson et al 2007;Iriarte et al 2007). The highly seasonal variability in PP (1-3 g C m -2 day -1 ; 4) has been associated with efficient export production to the sediments (0.2-0.6 g C m -2 day -1 ; 5), suggesting that the Chilean fjord region is a major ''CO 2 sink'' during the highly productive season.…”

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confidence: 99%

Patagonian Fjord Ecosystems in Southern Chile as a Highly Vulnerable Region: Problems and Needs

Iriarte

González

Nahuelhual

2010

AMBIO

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Southern Chile encompasses one of the most extensive fjord regions of the world, the Patagonia, currently exposed to natural and anthropogenic perturbations. These fjord ecosystems provide important services to humans, which have not been adequately measured and valued. As a consequence, ecosystem services are commonly ignored in public policy design and in the evaluation of development projects. Here we tackle questions that are highly relevant for the nation's development, namely (1) understanding fjord functioning, and (2) developing management strategies based on ecosystem services, in order to secure simultaneous and adequate use of these ecosystems which area influenced by ecological (e.g., biogeochemical) and productive (e.g., aquaculture, fisheries) processes. We also seek to strengthen the analysis of fjord ecosystem value from the economical (including coastal zoning), socio-cultural, institutional, and governmental points of view. In addition, the investigation of current and future effects of climate change on this large region offers a unique opportunity to understand the social and economic consequences of a global phenomenon at local to regional scales. Biogeochemical and socio-economic models will be used to simulate future scenarios under a gamut of management options.

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mentioning

confidence: 99%

Patagonian Fjord Ecosystems in Southern Chile as a Highly Vulnerable Region: Problems and Needs

Iriarte

González

Nahuelhual

2010

AMBIO

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“…In the case of rivers and fjords, if the drag and current conditions are sufficiently high or exceed an order of magnitude of wind (>10 m s −1 in the fjord valley), surface currents must also be considered. In this case, it is not necessary to consider superficial currents, which were reported to be as low as 5 cm s −1 (even at maximum tidal currents; Valle-Levinson et al 2007). Thus, surface current was not included in the estimation of gas transfer velocity (k w ), as was the cases for estimates of N 2 O fluxes (Yevenes et al 2016); however, this may underestimate N 2 O fluxes in the Reloncaví fjord.…”

Section: Discussionmentioning

confidence: 99%

“…In northern Patagonia, water circulation essentially follows a two-layer estuarine flow pattern (Sievers and Silva 2008); brackish water moves out superficially, and marine water enters predominantly through a subsuperficial layer in the Guafo mouth. Occasionally, wind-associated (Cáceres et al 2002) and/or non-linear tidal effects (Valle-Levinson et al 2007) can generate a three-layer circulation pattern, which consists of a thin surface layer flowing ocean-ward, a thick intermediate layer flowing inward, and a narrow bottom layer flowing oceanward.…”

Section: −1mentioning

confidence: 99%

“…However, due to the expansion of intense aquaculture activities, some signals of perturbations have been observed in aquatic systems in the region . Oceanographically, this region could be considered as a transitional marine system, influenced by nutrient-rich and highsalinity oceanic subsurface waters, and nutrient-poor and lowsalinity surface freshwater (Valle-Levinson et al 2007). The main objective of the present study is to describe for the first time the CH 4 distribution in the region, and to determine the relative contribution of estuarine and marine sources of CH 4 under the influence of a strong freshwater runoff, during the winter season in northern Chilean Patagonia.…”

Section: Introductionmentioning

confidence: 99%

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Dissolved Methane Distribution in the Reloncaví Fjord and Adjacent Marine System During Austral Winter (41°–43° S)

Sanzana

Sanhueza-Guevara

Yevenes

2017

Estuaries and Coasts

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Within the earth's atmosphere, methane (CH 4 ) is one of the most important absorbers of infrared energy. It is recognized that coastal areas contribute higher amounts of CH 4 emission; however, there is a lack of accurate estimates for these areas. This is particularly evident within the extensive northern fjord region of Chilean Patagonia, which has one of the highest freshwater runoffs in the world. Oceanographic and biogeochemical variables were analyzed between the Reloncaví fjord (41°S) and the Interior Sea of Chiloé (ISC) (43°S), during the 2013 austral winter. Freshwater runoff into the fjord influences salinity distribution, which clearly delimits the surface (<5 m depth) and subsurface layers (>5 m depth), and also separates the estuarine area from the marine area. In the estuary, the highest CH 4 levels are generally observed in the cold and brackish nutrient-depleted surface waters (N-and P-depleted), ranging from 16.97 to 151.4 nM (mean ± SD 52.20 ± 46.49), equivalent to 640-4537% saturation except for the case of Si(OH) 4 . Conversely, subsurface waters have lower CH 4 levels, fluctuating from 14.3 to 29.6 nM (mean ± SD 22.75 ± 4.36 nM) or 552-1087% saturation. A significant negative correlation was observed between salinity and CH 4 , and a positive correlation between Si(OH) 4 and CH 4 , suggesting that some of the CH 4 in estuarine water is due to continental runoff. Furthermore, the accumulation of seston and/or plankton at the pycnocline may potentially generate the accumulation of CH 4 via microbial processes, as observed in estuarine waters. By contrast, the marine area (the ISC), which is predominantly made up of modified subantarctic water, has a relatively homogenous CH 4 distribution (mean ± SD 9.84 ± 6.20 nM). In comparison with other estuaries, the Reloncaví fjord is a moderate source of CH 4 to the atmosphere, with effluxes ranging from 23.9 to 136 μmol m. This is almost double the levels obs e r v e d i n t h e I S C , w h i c h r a n g e s f r o m 2 2 . 2 t o 46.6 μmol m −2 day −1. Considering that Chilean Patagonia has numerous other fjord systems that are geomorphologically alike, and in some cases have much greater freshwater discharge, this study highlights their potential to be a significant natural source of this greenhouse gas.

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“…Estas áreas se caracterizan océano-gráficamente, por presentar una estructura de dos capas moduladas principalmente por una fuerte haloclina en los primeros 20 m de profundidad (Iriarte et al, 2007), la cual está influenciada por fuertes precipitaciones de 2-5 m año -1 (Strub et al, 1998), y entradas de agua dulce de los ríos que escurren desde la cordillera de los Andes, produciendo un circulación de tipo estuarina en el océano costero (Silva et al, 1998;Dávila et al, 2002;Bustos et al, 2008). En el estuario de Reloncaví propiamente tal, Valle-Levinson et al (2007) han señalado la existencia de un patrón de corrientes de tres capas, formadas por una delgada capa superficial no mayor de 8 m de profundidad, que se desplaza desde la cabeza a la boca del estuario, permitiendo la retención de partículas en su interior, por períodos de 12 a 13 días; una capa intermedia aportando agua de entrada, que alcanzaría los 70 m de profundidad, y bajo ésta una tercera capa de salida bajo los 80 m de profundidad. La producción primaria y clorofila-a, aumenta en estos lugares durante las estaciones de primavera y otoño (Iriarte et al, 2007), observándose en los sectores del seno del Reloncaví, así como Calbuco y Chiloé norte, una sucesión de fitoplancton, debido a floraciones intensas de Gymnodinium aff.…”

Section: áReas De Estudiounclassified

Distribucion temporal de larvas de Mytilus chilensis (Hupe, 1954) (Mollusca: Mytilidae), en el mar interior de Chiloe, sur de Chile

Avendaño

Cantillánez

Pennec

et al. 2011

lajar

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RESUMEN.Entre septiembre 2007 y marzo 2008, en Quillaipe, Metri, Sotomo, Canutillar y Pichicolo (mar interior de Chiloé), se determinó mensualmente la presencia larval de M. chilensis, mediante arrastres verticales de plancton, en una columna de 0-7,5 m y paralelamente se determinó histológicamente el estado reproductivo de ejemplares adultos. Se detectó permanentemente la presencia de larvas en los cinco sitios estudiados, con un significativo incremento entre octubre y diciembre, superando en Canutillar 49 mil larvas por m -3 , sitio que junto a Sotomo registraron las mayores densidades. El análisis de cohortes mostró una similitud de los grupos larvales presentes en los diferentes sitios a partir de septiembre, acentuándose durante noviembre y diciembre, así como una permanente aparición de cohortes en estadios iniciales. En contraste con estos resultados, el proceso reproductivo de M. chilensis en estos sitios, se manifestó de enero a marzo. Se discute que los desoves registrados en estos sitios, no serían responsables de la presencia de las larvas, actuando en consecuencia como áreas receptoras, y de retención de larvas provenientes de otros sitios. Estos resultados sugieren la necesidad de profundizar conocimientos biológicos y ecológicos en áreas de distribución de la especie, así como de dinámica larval y post-larval para identificar áreas exportadoras y de retención, para contribuir a un manejo eficiente y optimizar la captación de semilla. Palabras clave: larvas, Mytilus chilensis, distribución, bivalvo, aguas interiores, sur de Chile.Temporal distribution of larvae of Mytilus chilensis (Hupé, 1854) (Mollusca: Mytilidae), in the interior sea of Chiloé, southern Chile ABSTRACT. The larval presence of M. chilensis was determined monthly from September 2007 to March 2008, in Quillaipe, Metri, Sotomo, Canutillar, and Pichicolo (interior sea of Chiloé) using vertical plankton trawls through a water column from 0 to 7.5 m. At the same time, the reproductive stage of adult individuals was determined histologically. Larvae were detected continuously at the five study sites, with a significant increase from October to December, exceeding 49 thousand per m -3 at Canutillar where, along with Sotomo, the greatest densities were recorded during the study. Cohort analysis showed a similarity in the larval cohorts present at the different sites from September onwards; this was accentuated in November and December, as was the constant appearance of cohorts in the initial stages. In contrast with these results, the reproductive process of M. chilensis at these sites occurred from January to March. Whether or not the spawning recorded at these sites is responsible for the observed larvae is a matter of debate, as the sites may receive and retain larvae exported from other sites. These results suggest a need to compile further biological and ecological knowledge on the areas where this species is distributed and its larval and post-larval dynamics in order to identify exporting and retention areas and thereby contribute ...

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Spatial structure of hydrography and flow in a Chilean fjord, Estuario Reloncaví

Cited by 78 publications

References 23 publications

Patagonian Fjord Ecosystems in Southern Chile as a Highly Vulnerable Region: Problems and Needs

Patagonian Fjord Ecosystems in Southern Chile as a Highly Vulnerable Region: Problems and Needs

Dissolved Methane Distribution in the Reloncaví Fjord and Adjacent Marine System During Austral Winter (41°–43° S)

Distribucion temporal de larvas de Mytilus chilensis (Hupe, 1954) (Mollusca: Mytilidae), en el mar interior de Chiloe, sur de Chile

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