scholarly journals Dissolved organic carbon (DOC) is essential to balance the metabolic demands of North-Atlantic deep-sea sponges

2020 ◽  
Author(s):  
Martijn C. Bart ◽  
Benjamin Mueller ◽  
Titus Rombouts ◽  
Clea van de Ven ◽  
Gabrielle J. Tompkins ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Carbon Cycling ◽  
Deep Sea ◽  
Cold Water ◽  
Dry Weight ◽  
Ex Situ ◽  
Energy Budgets ◽  
Removal Rates ◽  
Species Specific

AbstractSponges are ubiquitous components of various deep-sea habitats, including cold water coral reefs and deep-sea sponge grounds. Despite being surrounded by oligotrophic waters, these ecosystems are known to be hotspots of biodiversity and carbon cycling. To assess the role of sponges in the carbon cycling of deep-sea ecosystems, we studied the energy budgets of six dominant deep-sea sponges (the hexactinellid species Vazella pourtalesi, and demosponge species Geodia barretti, Geodia atlantica, Craniella zetlandica, Hymedesmia paupertas and Acantheurypon spinispinosum) in an ex situ aquarium setup. Additionally, we determined morphological metrics for all species (volume, dry weight (DW), wet weight (WW), carbon (C) content, and ash-free dry weight (AFDW)) and provide species-specific conversion factors. Oxygen (O2) removal rates averaged 3.3 ± 2.8 µmol O2 DWsponge h−1 (all values mean ± SD), live particulate (bacterial and phytoplankton) organic carbon (LPOC) removal rates averaged 0.30 ± 0.39 µmol C DWsponge h−1 and dissolved organic carbon (DOC) removal rates averaged 18.70 ± 25.02 µmol C DWsponge h−1. Carbon mass balances were calculated for four species (V. pourtalesi, G. barretti, G. atlantica and H. paupertas) and revealed that the sponges acquired 1.3–6.6 times the amount of carbon needed to sustain their minimal respiratory demands. These results indicate that irrespective of taxonomic class, growth form, and abundance of microbial symbionts, DOC is responsible for over 90 % of the total net organic carbon removal of deep-sea sponges and allows them to sustain in otherwise food-limited environments on the ocean floor.

scholarly journals Dissolved Organic Carbon Cycling in Forested Watersheds: A Carbon Isotope Approach

1990 ◽  
Vol 26 (12) ◽  
pp. 2949-2957 ◽  
Author(s):  
S. L. Schiff ◽  
R. Aravena ◽  
S. E. Trumbore ◽  
P. J. Dillon
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Carbon Cycling ◽  
Carbon Isotope ◽  
Forested Watersheds ◽  
Organic Carbon Cycling

In situ dissolved organic carbon (DOC) release by submerged macrophyte–epiphyte communities in southern Quebec lakes

2009 ◽  
Vol 66 (9) ◽  
pp. 1522-1531 ◽  
Author(s):  
M. Demarty ◽  
Y. T. Prairie
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Myriophyllum Spicatum ◽  
Dry Weight ◽  
Release Rates ◽  
Doc Production ◽  
Epiphyte Communities ◽  
Benthic Chambers ◽  
Freshwater Macrophyte

We studied the in situ release of dissolved organic carbon (DOC) by growing a submerged freshwater macrophyte–epiphyte complex. Incubations with benthic chambers in five southeastern Quebec lakes show a net DOC production for different communities of Myriophyllum spicatum and Potamogeton spp. Daytime DOC release rates range from undetectable to 9.7 mg C·m–2·h–1. Although DOC release was restricted to daylight hours and thus suggestive of a photosynthesis-related process, we found no strong link between DOC release rates and concurrent illumination or temperature. We found no difference in DOC release rates between the three main colonizing species of the studied region. The overall mean DOC release rate was 4.57 mg C·m–2·h–1 (standard deviation (SD), ±0.65) or 56 µg C·g dry weight–1·h–1 (SD, ±8), which we suggest can be used for extrapolations at the lake scale.

scholarly journals Organic Particles Affect Carbon Cycling in Boreal Waters

Eos ◽  
2019 ◽  
Vol 100 ◽  
Author(s):  
Aaron Sidder
Keyword(s):  
Carbon Dioxide ◽  
Particulate Matter ◽  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Carbon Cycling ◽  
Significant Role ◽  
Carbon Dioxide Emissions ◽  
Organic Particles

Dissolved organic carbon receives much of the focus in aquatic research, but a new study suggests that bulkier particulate matter may play a significant role in regulating carbon dioxide emissions.

scholarly journals Warming and ocean acidification may decrease estuarine dissolved organic carbon export to the ocean

2020 ◽  
Author(s):  
Michelle N. Simone ◽  
Kai G. Schulz ◽  
Joanne M. Oakes ◽  
Bradley D. Eyre
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Ocean Acidification ◽  
Heterotrophic Bacteria ◽  
Temperature Response ◽  
Future Climate ◽  
Estuarine Sediments ◽  
Ex Situ ◽  
Large Contribution ◽  
Labile Organic Matter

Abstract. Estuaries make a disproportionately large contribution of dissolved organic carbon (DOC) to the global carbon cycle, but it is unknown how this will change under a future climate. As such, the response of DOC fluxes from microbially dominated unvegetated sediments to individual and combined future climate stressors of warming (from Δ−3 °C to Δ+5 °C on ambient mean temperatures) and ocean acidification (OA, ~2 times the current partial pressure of CO2, pCO2) was investigated ex situ. Warming alone increased sediment heterotrophy, resulting in a proportional increase in sediment DOC uptake, with sediments becoming net sinks of DOC (3.5 to 8.8 mmol-C m−2 d−1) at warmer temperatures (Δ+3 °C and Δ+5 °C, respectively). This temperature response changed under OA conditions, with sediments becoming more autotrophic and a greater sink of DOC (1 to 4 times greater than under current-pCO2). This response was attributed to the stimulation of heterotrophic bacteria with the autochthonous production of labile organic matter by microphytobenthos. Extrapolating these results to the global area of unvegetated subtidal estuarine sediments, the future climate of warming (Δ+3 °C) and OA may decrease the estuarine export of DOC by ~80 % (~150 Tg-C yr−1) and have a disproportionately large impact on the global DOC budget.

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