Seasonal hydrography and surface outflow in a fjord with a deep sill: the Reloncaví fjord, Chile

Castillo, Manuel; Cifuentes, Ursula; Pizarro, Óscar; Djurfeldt, Leif; Cáceres, Mario

doi:10.5194/os-12-533-2016

Cited by 35 publications

(40 citation statements)

References 34 publications

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“…, reaching maximum levels from June to August (Garreaud et al 2013 ) (Castillo et al 2016). The freshwater supply from the river discharges in the RE reached a maximum during June (León-Muñoz et al 2013); thus, our sampling was carried out during periods of maximum freshwater discharge.…”

Section: Discussion Environmental Conditions In the Reloncaví Estuarymentioning

confidence: 99%

“…Indeed, the fjord was well stratified throughout the period and presented a narrow and permanent layer of brackish water. The depth of the upper layer slightly varied between seasons, remaining at about 4.5 m depth (Castillo et al 2016). This suggests that stratification of the upper layer of the fjord is maintained seasonally, despite the occurrence of significant changes in river discharges and winds (Castillo et al 2016).…”

Section: Discussion Environmental Conditions In the Reloncaví Estuarymentioning

confidence: 99%

“…The area is sparsely populated; however, emerging aquaculture, fisheries, and tourism activities are taking place. The region is subject to a marked hydrographic variability, associated with regimes of high rainfall and temperature fluctuations (Castillo et al 2016). The study area receives fresh water inputs from various rivers, including Puelo, Petrohué, and Cochamo (León-Muñoz et al 2013).…”

Section: Methodology Hydrographic Setting Of the Study Sitementioning

confidence: 99%

“…1). The fjord hydrography showed a relatively thin (<5 m depth), continuously stratified, buoyant layer with high stratification (Castillo et al 2016). Below this thin layer, a relatively homogenous water of marine origin occupied the ISC.…”

Section: Methodology Hydrographic Setting Of the Study Sitementioning

confidence: 99%

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Spatial Distribution of Nitrous Oxide (N2O) in the Reloncaví Estuary–Sound and Adjacent Sea (41°–43° S), Chilean Patagonia

Yevenes

Bello

Sanhueza-Guevara

2016

Estuaries and Coasts

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Fjords and estuaries exchange large amounts of solutes, gases, and particulates between fluvial and marine systems. These exchanges and their relative distributions of compounds/particles are partially controlled by stratification and water circulation. The spatial and vertical distributions of N 2 O, an important greenhouse gas, along with other oceanographic variables, are analyzed from the Reloncaví estuary (RE) (~41°30′ S) to the gulf of Corcovado in the interior sea of Chiloé (43°45′ S) during the austral winter. Freshwater runoff into the estuary regulated salinity and stratification of the water column, clearly demarking the surface (<5 m depth) and subsurface layer (>5 m depth) and also separating estuarine and marine influenced areas. N 2 O levels varied between 8.3 and 21 nM (corresponding to 80 and 170 % saturation, respectively), being significantly lower (11.8 ± 1.70) at the surface than in subsurface waters in the Reloncaví estuary (14.5 ± 1.73). Low salinity and NO 3 − , NO 2 − , and PO 4 3− levels, as well as high Si(OH) 4 values were associated with low surface N 2 O levels. Remarkably, an accumulation of N 2 O was observed in the subsurface waters of the Reloncaví sound, associated with a relatively high consumption of O 2 . The sound is exposed to increasing anthropogenic impacts from aquaculture and urban discharge, occurring simultaneously with an internal recirculation, which leads to potential signals of early eutrophication. In contrast, within the interior sea of Chiloé (ISC), most of water column was quasi homohaline and occupied by modified subantarctic water (MSAAW), which was relatively rich in N 2 O (12.6 ± 2.36 nM) and NO 3 − (18.3 ± 1.63 μM). The relationship between salinity, nutrients, and N 2 O revealed that water from the open ocean, entering into ISC (the Gulf of Corcovado) through the Guafo mouth, was the main source of N 2 O (up to 21 nM), as it gradually mixed with estuarine water. In addition, significant relationships between N 2 O excess vs. AOU and N 2 O excess vs. NO 3 − suggest that part of N 2 O is also produced by nitrification. Our results show that the estuarine and marine waters can act as light source or sink of N 2 O to the atmosphere (air-sea N 2 O fluxes ranged from −1.57 to 5.75 μmol m −2 day −1 ), respectively; influxes seem to be associated to brackish water depleted in N 2 O that also caused a strong stratification, creating a barrier to gas exchange.

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Section: Discussion Environmental Conditions In the Reloncaví Estuarymentioning

confidence: 99%

Section: Discussion Environmental Conditions In the Reloncaví Estuarymentioning

confidence: 99%

Section: Methodology Hydrographic Setting Of the Study Sitementioning

confidence: 99%

Section: Methodology Hydrographic Setting Of the Study Sitementioning

confidence: 99%

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Spatial Distribution of Nitrous Oxide (N2O) in the Reloncaví Estuary–Sound and Adjacent Sea (41°–43° S), Chilean Patagonia

Yevenes

Bello

Sanhueza-Guevara

2016

Estuaries and Coasts

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“…1). The Reloncaví fjord is one of the most widely studied fjords in Chile (e.g., Castillo et al 2016). It is 55 km long and 2-3 km wide and receives freshwater discharge from the Petrohué (annual mean ∼ 280 m ) and the Puelo River (annual mean ∼ 650 m 3 s…”

Section: Characteristics Of Study Sitesmentioning

confidence: 99%

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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Neutral and adaptive loci reveal fine‐scale population structure in Eleginops maclovinus from north Patagonia

Canales‐Aguirre

Larson

McKinney

et al. 2022

Ecology and Evolution

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Patagonia is an understudied area, especially when it comes to population genomic studies with relevance to fishery management. However, the dynamic and heterogeneous landscape in this area can harbor an important but cryptic genetic population structure. Once such information is revealed, it can be integrated into the management of infrequently investigated species. Eleginops maclovinus is a protandrous hermaphrodite species with economic importance for local communities that are currently managed as a single genetic unit. In this study, we sampled five locations distributed across a salinity cline from Northern Patagonia to investigate the genetic population structure of E . maclovinus . We used restriction site‐associated DNA (RAD) sequencing and outlier tests to obtain neutral and adaptive loci, using F ST and GEA approaches. We identified a spatial pattern of structuration with gene flow and spatial selection by environmental association. Neutral and adaptive loci showed two and three genetic groups, respectively. The effective population sizes estimated ranged from 572 (Chepu) to 14,454 (Chaitén) and were influenced more by locality than by salinity cline. We found loci putatively associated with salinity suggesting that salinity may act as a selective driver in E . maclovinus populations. These results suggest a complex interaction between genetic drift, gene flow, and natural selection in this area. Our findings also suggest several evolutionary significant units in this area, and the information should be integrated into the management of this species. We discussed the significance of these results for fishery management and suggest future directions to improve our understanding of how E . maclovinus has adapted to the dynamic waters of Northern Patagonia.

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Seasonal hydrography and surface outflow in a fjord with a deep sill: the Reloncaví fjord, Chile

Cited by 35 publications

References 34 publications

Spatial Distribution of Nitrous Oxide (N2O) in the Reloncaví Estuary–Sound and Adjacent Sea (41°–43° S), Chilean Patagonia

Spatial Distribution of Nitrous Oxide (N2O) in the Reloncaví Estuary–Sound and Adjacent Sea (41°–43° S), Chilean Patagonia

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

Neutral and adaptive loci reveal fine‐scale population structure in Eleginops maclovinus from north Patagonia

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