Compositional and biogeochemical variations of sediments across the terrestrial-marine continuum of the Baker-Martínez fjord system (Chile, 48°S)

Rebolledo, Lorena; Bertrand, Sébastien; Lange, Carina B.; Tapia, Fabián J.; Quiroga, Eduardo; Troch, Matthias; Silva, Nelson; Cárdenas, Paola; Pantoja, Silvio

doi:10.1016/j.pocean.2018.12.004

Cited by 19 publications

(24 citation statements)

References 67 publications

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“…For example, higher protein-like fluorescence in summer (Figure 3) is consistent with strong meltwater inputs supplying DOM from glacial sources (Barker et al, 2006;Dubnick et al, 2010;Fellman et al, 2010;Kellerman et al, 2020). This is particularly evident downstream of Jorge Montt Glacier and near the mouths of the Baker and Pascua Rivers (Figure 6B), where summer discharge is driven by melting of the NPI and SPI, respectively (Dussaillant et al, 2012;Rebolledo et al, 2019). Protein-like fluorescence intensity decreases as meltwater inputs decline in winter (Figure 3).…”

Section: Seasonality In Dom Composition In Fjord Surface Layermentioning

confidence: 71%

“…The BMF is situated between the Northern and Southern Patagonian Icefields (NPI, SPI) at ∼48 • S (Figure 1) and consists of two largely disconnected sub-basins: the northerly Martinez Channel (typically < 500 m deep) and the deeper (up to ∼1075 m) Baker Channel to the south (Piret et al, 2019). Strong freshwater inputs from several glacier-fed rivers and high annual rainfall maintain a stratified water column typical of fjords, with a freshwater lens sitting above higher salinity waters (Rebolledo et al, 2019). Vertical exchange between the two layers is largely controlled by semidiurnal tides (Ross et al, 2014), whilst the prevailing westerly winds drive the general circulation patterns in the fjord (Aiken, 2012), such as subsurface warm water intrusions from Baker Channel into Jorge Montt Fjord (Moffat, 2014).…”

Section: Study Regionmentioning

confidence: 99%

“…Vertical exchange between the two layers is largely controlled by semidiurnal tides (Ross et al, 2014), whilst the prevailing westerly winds drive the general circulation patterns in the fjord (Aiken, 2012), such as subsurface warm water intrusions from Baker Channel into Jorge Montt Fjord (Moffat, 2014). Freshwater inputs peak with river discharge in the austral summer (December-March) due to seasonal glacier melting rather than with maximum rainfall in the austral winter (May-August) (Rebolledo et al, 2019). The regimes of the largest rivers, the Baker and Pascua, are dominated by melting of the NPI and SPI, respectively (Dirección General de Aguas, 2019).…”

Section: Study Regionmentioning

confidence: 99%

“…Bulk composition is an important factor affecting the fate of riverine OC in BMF. Strong inputs of terrestrial POC drive high rates of carbon burial at the fjord heads (Rebolledo et al, 2019) and supplement available food sources for zooplankton (Meerhoff et al, 2019). However, the larger and more biolabile DOC flux is likely to be critical for bacterial carbon cycling in the fjord (Vargas et al, 2011;Brett et al, 2017).…”

Section: Assessing the Importance Of Riverine Oc Fluxes To Baker-martmentioning

confidence: 99%

“…Accelerated melting is increasing freshwater flux to the coast in this region (Dussaillant et al, 2019), with implications for fjord hydrodynamics and the supply of organic matter (Iriarte et al, 2014). Freshwater flux is driven primarily by summertime melting but, in contrast to fjords in polar regions, heavy precipitation sustains year-round freshwater inputs and above-freezing sea level temperatures support a more limited amount of glacial melting in winter (Rebolledo et al, 2019). Understanding how fjord DOM composition responds to seasonal changes in freshwater source (intense glacial melting in summer and heavier precipitation in winter) is relevant for glacially influenced fjords in other wet, maritime locations, such as New Zealand and the Gulf of Alaska, contrasting with polar fjords where freshwater inputs are driven almost exclusively by melt cycles.…”

Section: Introductionmentioning

confidence: 99%

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Seasonal Changes in Dissolved Organic Matter Composition in a Patagonian Fjord Affected by Glacier Melt Inputs

et al. 2021

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Biogeochemical processes in fjords are likely affected by changes in surrounding glacier cover but very little is known about how meltwater directly influences dissolved organic matter (DOM) in fjords. Moreover, the data available are restricted to a handful of northern hemisphere sites. Here we analyze seasonal and spatial variation in dissolved organic carbon (DOC) concentration and DOM composition (spectrofluorescence, ultrahigh resolution mass spectrometry) in Baker-Martinez Fjord, Chilean Patagonia (48°S), to infer the impacts of rapid regional deglaciation on fjord DOM. We show that surface layer DOC concentrations do not vary significantly between seasons, but DOM composition is sensitive to differences in riverine inputs. In summer, higher protein-like fluorescence reflects increased glacial meltwater inputs, whilst molecular level data show weaker influence from marine DOM due to more intense stratification. We postulate that the shifting seasonal balance of riverine and marine waters affects the supply of biolabile peptides and organic nitrogen cycling in the surface layer. Trends in DOM composition with increasing salinity are consistent with patterns in estuaries (i.e. preferential removal of aromatic compounds and increasing relative contribution of unsaturated and heteroatom-rich DOM from marine sources). Preliminary estimates also suggest that at least 10% of the annual organic carbon stock in this fjord is supplied by the four largest, glacially fed rivers and that these inputs are dominated by dissolved (84%) over particulate organic carbon. Riverine DOC may therefore be an important carbon subsidy to bacterial communities in the inner fjord. The overall findings highlight the biogeochemical sensitivity of a Patagonian fjord to changes in glacier melt input, which likely has relevance for other glaciated fjords in a warming climate.

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Section: Seasonality In Dom Composition In Fjord Surface Layermentioning

confidence: 71%

Section: Study Regionmentioning

confidence: 99%

Section: Study Regionmentioning

confidence: 99%

Section: Assessing the Importance Of Riverine Oc Fluxes To Baker-martmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Seasonal Changes in Dissolved Organic Matter Composition in a Patagonian Fjord Affected by Glacier Melt Inputs

et al. 2021

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Environmental and coastline changes controlling Holocene carbon accumulation rates in fjords of the western Strait of Magellan region

Ríos

Kilian

Lange

et al. 2020

Continental Shelf Research

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Organic-rich sediments of the southernmost Chilean Pacific coast and its fjord system constitute an important component of the global marine carbon budget. Sediment records from Trampa and Caribe bays and Churruca fjord in the western Magellan fjord system have been analyzed with the goal of understanding the factors controlling carbon accumulation and its regional fluctuation throughout the Holocene. The individual response in paleoproductivity at the different sites and related variations in accumulation rates document a very complex interplay among local and regional-scale environmental changes, and coastline elevation across the Holocene. Shallow sill basins close to the Pacific coast, as the ones studied here, are particularly sensitive to these processes, having responded with strong productivity changes throughout the Holocene.A Bayesian mixed model approach, using sediment archived provenance proxies, indicates that components of terrestrial plants and soils washed-out into these basins contribute with a variable proportion (20-80 wt%) of the total accumulated organic carbon. Accumulation rates of terrestrial carbon increase with the amount of precipitation in the hyper-humid mountain area, but also reflect distinct Holocene plant successions as well as longterm development of soil and vegetation cover that strongly overprint the direct precipitation impact. Over the Holocene accumulation rates of biogenic carbonate and aquatic-marine organic carbon range between 5 and 118 kg m À 2 kyr À 1 and 0.3-20 kg m À 2 kyr À 1 , respectively. This variability depends on water column structure and conditions, which are regulated by the degree of marine transgression as a function of post glacial sea level rise and isostatic uplift as well as precipitation-related surface water freshening. In the Bahia Trampa record, a significant change in accumulation rates indicates a marine transgression at ca. 12.2 kyr BP, when the global sea level was 60-70 m lower than today and eustatic rise overcame isostatic rebound rates. In Caribe and Trampa records, CaCO 3 accumulation rates were higher at ca. 7 kyr BP. The Churruca record shows organic carbon accumulation rates up to 36.2 kg m À 2 kyr À 1 during the early Holocene.

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Fjords as Aquatic Critical Zones (ACZs)

Bianchi

Arndt

Austin

et al. 2020

Earth-Science Reviews

145

122

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Compositional and biogeochemical variations of sediments across the terrestrial-marine continuum of the Baker-Martínez fjord system (Chile, 48°S)

Cited by 19 publications

References 67 publications

Seasonal Changes in Dissolved Organic Matter Composition in a Patagonian Fjord Affected by Glacier Melt Inputs

Seasonal Changes in Dissolved Organic Matter Composition in a Patagonian Fjord Affected by Glacier Melt Inputs

Environmental and coastline changes controlling Holocene carbon accumulation rates in fjords of the western Strait of Magellan region

Fjords as Aquatic Critical Zones (ACZs)

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