Seasonal benthic patterns in a glacial Patagonian fjord: the role of suspended sediment and terrestrial organic matter

Quiroga, Eduardo; Ortiz, Paula; González-Saldías, Rodrigo; Reid, Brian; Tapia, Fabián J.; Peréz-Santos, Iván; Rebolledo, Lorena; Mansilla, Ricardo; Pineda, C.A.; Cari, Ilia; Salinas, Nicole; Montiel, Américo; Gerdes, D. W.

doi:10.3354/meps11903

Cited by 35 publications

(20 citation statements)

References 80 publications

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“…Both terrestrial and aquatic ecosystems have high species richness, with birds, amphibians, and marine vertebrates and invertebrates, including several recently described coldwater hydrocoral species growing on vertical walls submerged at depths of 20 to 200 m (Häussermann and Försterra, 2007). Moreover, evidence of active geological processes (e.g., surface hydrothermal vents; Försterra et al, 2014) in Comau Fjord is relevant ecologically and biogeochemically (high methane and sulfide-enriched water), as these processes support trophic webs sustained by giant methanogenic bacteria (chemosynthetic communities) and diverse benthic species (Muñoz et al, 2014;Quiroga et al, 2016). Although the number of cold seeps in the fjord system remains unknown, patches of microbial mats, which obtain energy from the reduction of nitrate and sulfate, may play a key role in supporting a trophic link to invertebrate grazers (chitons, gastropods, mussels, and coldwater scleractinian corals) (Ugalde et al, 2013;Muñoz et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Natural and Human Influences on Marine Processes in Patagonian Subantarctic Coastal Waters

Iriarte

2018

Front. Mar. Sci.

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Some of the largest climate changes on Earth are projected for high-latitude polar and subpolar environments in the coming decades (IPCC, 2014). A number of simultaneous socio-environmental perturbations are affecting Patagonia (41-55 • S), a vast and complex ecosystem whose economic and societal well-being depends on coastal resources (∼80% of people live near-shore; the coastal economy provides>40,000 jobs). In this new scenario, overlapping natural variability (interannual-seasonal dynamics) and human-induced environmental changes (global change) are major drivers influencing the marine food web structure and functions. Evidence of large environmental changes has been detected in the Patagonia marine system through (a) regional-scale, climatic-oceanographic coupled anomalous events, (b) interannual hydrological changes (decreasing pattern) in freshwater river inputs (watersheds into fjords), and (c) more frequent coastal and oceanic microbial outbreaks (Harmful Algal Blooms). Those changes have highly uncertain effects for the basic functionalities, structure, and feedback responses of coastal systems and their coupling with hydrological (e.g., river streamflow) or biogeochemical (e.g., biological carbon pump) processes. The northern Patagonian fjords system is hypothesized to act as an indicator of large-scale climate change given strong environmental variability. This, combined with regional climatic-oceanographic events (e.g., El Niño Southern Oscillation, Southern Annular Mode) and effects of local anthropogenic activities (e.g., nutrient fluxes from extensive aquaculture, land change due to forestry) may impact the chemical and physical properties of the surface water, destabilizing biological productivity and chemical coastal processes. The present synthesis, which gives the results of systemicsensitive chemical and biological variables, may be useful to managers and in preventing socio-environmental impacts from increasing natural and anthropogenic phenomena in Chile's southern coastal system.

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Section: Introductionmentioning

confidence: 99%

Natural and Human Influences on Marine Processes in Patagonian Subantarctic Coastal Waters

Iriarte

2018

Front. Mar. Sci.

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“…The often dramatic retreat of the vast majority of the >70 outlet glaciers in the PIF has been well documented over the last few decades; they are losing mass at a rate equivalent to an estimated 0.067 ± 0.004 mm/yr of sea level rise (Willis et al, ), which is disproportionally large in view of the size of the PIF. Moreover, the increased glacier discharge to the surrounding fjord and shelf systems can strongly modulate salt and heat budgets, sediment dynamics, and local biological communities (Gonzalez et al, ; Gutiérrez et al, ; Quiroga et al, ).…”

Section: Introductionmentioning

confidence: 99%

Seasonal Evolution of Ocean Heat Supply and Freshwater Discharge From a Rapidly Retreating Tidewater Glacier: Jorge Montt, Patagonia

et al. 2018

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Proglacial fjords are critical conduits for the exchange of heat and freshwater between the ocean and land ice, and their dynamics heavily modulate the rate of retreat of tidewater glaciers. Here the magnitude, spatial structure, and seasonal evolution of the ocean forcing on the proglacial fjord off a rapidly retreating glacier (Jorge Montt, Patagonia) are characterized using data from multiple shipboard surveys from 2010 to 2016, a multiyear mooring array, and a weather station. The melting of the glacier is forced by relatively warm (8–11°C) waters entering the fjord over a shallow (45 m deep) sill ≈20 km from the terminus. This warm subsurface water is renewed every summer from the surface layer of Gulf of Penas., is transported along the 100‐km long Baker Channel, and reaches the proglacial fjord in the late austral summer to early fall, where it remains relatively warm until late austral spring. Analysis of the freshwater fractions in the fjord reveals that the total freshwater content has a strong seasonal signal with maximum fractional values in the summer, mostly explained by the seasonality of subglacial discharge from the glacier. The submarine melting fraction has no strong seasonal signal, but is a first‐order contributor to the freshwater content of the fjord in winter. This seasonal evolution is consistent with idealized theories of meltwater production, and suggests that the seasonal supply of heat is critical to sustain a high mean temperature for melting, but does not directly control the melting rate variability.

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“…However, it must be noted that comparisons of intercept (treated as a proxy of total biomass) are only possible when spectra represent similar size class range (Hua et al 2013). The intercepts of NBSS plotted for Kongsfjorden fauna were higher than those reported by most other studies (Saiz-Salinas and Ramos 1999;Quiroga et al 2005Quiroga et al , 2012Quiroga et al , 2016, but similar to those of the communities inhabiting highly productive regions and sediments with high organic matter content (Akoumianaki et al 2006;Hua et al 2013). But it must be noted that these differences in intercepts may result from various sampling gears used and not overlapping size classes with our studies.…”

Section: Benthic Size Spectra Of An Arctic Fjordmentioning

confidence: 74%

“…Despite the strong seasonality in pelagic processes and organic matter supply to the sea bottom in Kongsfjorden (Lalande et al 2016), the abundance and biomass size spectra showed little variability between the two studied seasons. Quiroga et al (2016) stated that benthic biomass size spectra may be useful as indicators of short-term local dynamics of environmental factors since slopes, and intercepts of estuarine NBSS varied in response to seasonal variability in organic and mineral matter supply to the sea bottom. Effects of high summer supply of inorganic matter (decrease in meiofauna and macrofauna abundancies) were also detected by (Pawłowska et al 2011) in Adventfjorden near Adventelva and Longyearelva rivers mouth.…”

Section: Benthic Response To Seasonal Variability In Kongsfjorden Ecomentioning

confidence: 99%

Seasonal constancy (summer vs. winter) of benthic size spectra in an Arctic fjord

et al. 2019

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Size spectra are important descriptors of community structure and can indicate changes in community functioning in response to shifts in environmental conditions. There are relatively few assessments of benthic size spectra, and most are based on summer samples alone. Processes influencing size spectra, such as recruitment and predation pressure, vary seasonally, and understanding this variation is necessary to interpret patterns in time or space. Here we compare summer and winter biomass size spectra in the central basin of Kongsfjorden (west Spitsbergen). We recorded seasonal changes in the quality of organic matter available to the benthos, indicated by higher chloroplastic pigments concentrations in surface sediments in summer, as well as in differences in total abundance and biomass of both macrofauna and meiofauna. No significant seasonal differences were documented by multiple regression models for the normalized biomass and size classes. The slope of a linear relationship between normalized biomass and size classes was − 0.54 ± 0.02 indicating a productive system, compared to ecosystems like estuaries. Summer-winter invariability of size spectra suggests that benthic community functioning in this Arctic fjordic system is relatively independent from the seasonality in the supply of organic matter produced in water column.Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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Seasonal benthic patterns in a glacial Patagonian fjord: the role of suspended sediment and terrestrial organic matter

Cited by 35 publications

References 80 publications

Natural and Human Influences on Marine Processes in Patagonian Subantarctic Coastal Waters

Natural and Human Influences on Marine Processes in Patagonian Subantarctic Coastal Waters

Seasonal Evolution of Ocean Heat Supply and Freshwater Discharge From a Rapidly Retreating Tidewater Glacier: Jorge Montt, Patagonia

Seasonal constancy (summer vs. winter) of benthic size spectra in an Arctic fjord

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