Microbial degradation of cold-water coral-derived organic matter: potential implication for organic C cycling in the water column above Tisler Reef

Budgets for nitrogen, phosphorus, and organic carbon in Toolik Lake, Alaska, were assembled from data collected during 1977–81. The annual total organic carbon (TOC), total nitrogen (TN), and total phosphorus (TP) loads to the Sake were 8557, 290, and 4.64 mmol∙m−2. Inlet streams were the major source of nutrients to the lake, as direct precipitation provided only 1, 2, and 5%, respectively, of the annual TOC, TN, and TP loads to the lake. Up to 30% of the annual N and P inputs to the lake from riverine sources occurred during the first 10 d of stream flow following breakup when cold water temperatures and snow-covered ice limited primary production. Due to the short water renewal time (0.5 yr), efficiency of nutrient retention was poor and 90, 82, and 70% of the annual TOC, TN, and TP inputs to the lake were discharged at the outlet stream. Regeneration within the water column supplied 40–66% and 68–78% of the N and P necessary for measured primary production. Yearly accumulation rates for C, N, and P in the sediment were about 220, 21.0, and 1.75 mmol∙m−2. Phosphorus remineralized within the sediment was completely retained due to adsorption onto Fe oxide minerals in the oxidizing surface layer. Annual rates of release of C and N to the overlying water column were 110 and 11.5–22.2 mmol∙m2. Mass balance considerations showed no serious errors in estimates of any terms of the annual sediment and water column N, P, and organic C budgets.

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Particulate organic matter fluxes and hydrodynamics at the Tisler cold-water coral reef

Journal of Marine Systems ◽

10.1016/j.jmarsys.2010.11.003 ◽

2011 ◽

Vol 85 (1-2) ◽

pp. 19-29 ◽

Cited By ~ 45

Author(s):

Hannes Wagner ◽

Autun Purser ◽

Laurenz Thomsen ◽

Carlos César Jesus ◽

Tomas Lundälv

Keyword(s):

Organic Matter ◽

Coral Reef ◽

Particulate Organic Matter ◽

Cold Water ◽

Water Coral

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Environmental factors influencing cold-water coral ecosystems in the oxygen minimum zones on the Angolan and Namibian margins

10.5194/bg-2019-52 ◽

2019 ◽

Cited By ~ 1

Author(s):

Ulrike Hanz ◽

Claudia Wienberg ◽

Dierk Hebbeln ◽

Gerard Duineveld ◽

Marc Lavaleye ◽

...

Keyword(s):

Organic Matter ◽

High Temperatures ◽

Environmental Conditions ◽

Cold Water ◽

Tidal Mixing ◽

Low Oxygen ◽

Nepheloid Layer ◽

Oxygen Minimum Zones ◽

Oxygen Minimum ◽

Water Coral

Abstract. Fossil cold-water coral mounds overgrown by sponges and bryozoans were observed in anoxic conditions on the Namibian margin, while mounds colonized by thriving cold-water coral reefs were found in hypoxic conditions on the Angolan margin. These low oxygen conditions do not meet known environmental ranges favoring cold-water corals and hence are expected to provide unsuitable habitats for cold-water coral growth and therefore reef formation. To explain why the living fauna can nevertheless thrive in both areas, present day environmental conditions at the southwestern African margin were assessed. Downslope CTD transects and the deployment of bottom landers were used to investigate spatial and temporal variations of environmental properties. Temporal measurements in the mound areas recorded oscillating low dissolved oxygen concentrations of 0–0.17 ml l−1 (≙ 0–9 % saturation) on the Namibian and 0.5–1.5 ml l−1 (≙ 7–18 % saturation) on the Angolan margin, which were associated with relatively high temperatures (11.8 13.2 °C and 6.4–12.6 °C respectively). Semi-diurnal barotrophic tides were found to interact with the margin topography producing internal waves with excursions of up to 70 and 130 m for the Namibian and Angolan margins, respectively. These tidal movements temporarily deliver water with more suitable characteristics to the coral mounds from below and above the hypoxic zone. Concurrently, the delivery of high quantity and quality of suspended particulate organic matter was observed, which serves as a food source for cold-water corals. On the Namibian slope organic matter indicates a completely marine source and originates directly from the surface productive zone, whereas on the Angolan margin the geochemical signature of organic material suggest an additional mechanisms of food supply. A nepheloid layer observed above the cold-water coral mound area on the Angolan margin may constitutes a reservoir of fresh organic matter, facilitating a constant supply of food particles by tidal mixing. This suggests that the cold-water coral communities as well as the associated fauna may compensate unfavorable conditions induced by low oxygen levels and high temperatures with an enhanced availability of food. With the expected expansion of oxygen minimum zones in the future due to anthropogenic activities, this study provides an example on how ecosystems could cope with such extreme environmental conditions.

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Environmental factors influencing benthic communities in the oxygen minimum zones on the Angolan and Namibian margins

Biogeosciences ◽

10.5194/bg-16-4337-2019 ◽

2019 ◽

Vol 16 (22) ◽

pp. 4337-4356 ◽

Cited By ~ 8

Author(s):

Ulrike Hanz ◽

Claudia Wienberg ◽

Dierk Hebbeln ◽

Gerard Duineveld ◽

Marc Lavaleye ◽

...

Keyword(s):

Organic Matter ◽

High Temperatures ◽

Environmental Conditions ◽

Cold Water ◽

Benthic Communities ◽

Benthic Fauna ◽

Low Oxygen ◽

Oxygen Minimum Zones ◽

Oxygen Minimum ◽

Water Coral

Abstract. Thriving benthic communities were observed in the oxygen minimum zones along the southwestern African margin. On the Namibian margin, fossil cold-water coral mounds were overgrown by sponges and bryozoans, while the Angolan margin was characterized by cold-water coral mounds covered by a living coral reef. To explore why benthic communities differ in both areas, present-day environmental conditions were assessed, using conductivity–temperature–depth (CTD) transects and bottom landers to investigate spatial and temporal variations of environmental properties. Near-bottom measurements recorded low dissolved oxygen concentrations on the Namibian margin of 0–0.15 mL L−1 (≜0 %–9 % saturation) and on the Angolan margin of 0.5–1.5 mL L−1 (≜7 %–18 % saturation), which were associated with relatively high temperatures (11.8–13.2 ∘C and 6.4–12.6 ∘C, respectively). Semidiurnal barotropic tides were found to interact with the margin topography producing internal waves. These tidal movements deliver water with more suitable characteristics to the benthic communities from below and above the zone of low oxygen. Concurrently, the delivery of a high quantity and quality of organic matter was observed, being an important food source for the benthic fauna. On the Namibian margin, organic matter originated directly from the surface productive zone, whereas on the Angolan margin the geochemical signature of organic matter suggested an additional mechanism of food supply. A nepheloid layer observed above the cold-water corals may constitute a reservoir of organic matter, facilitating a constant supply of food particles by tidal mixing. Our data suggest that the benthic fauna on the Namibian margin, as well as the cold-water coral communities on the Angolan margin, may compensate for unfavorable conditions of low oxygen levels and high temperatures with enhanced availability of food, while anoxic conditions on the Namibian margin are at present a limiting factor for cold-water coral growth. This study provides an example of how benthic ecosystems cope with such extreme environmental conditions since it is expected that oxygen minimum zones will expand in the future due to anthropogenic activities.

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Microbial processing of sedimentary organic matter at a shallow LTER site in the northern Adriatic Sea: an 8-year case study

Nature Conservation ◽

10.3897/natureconservation.34.30099 ◽

2019 ◽

Vol 34 ◽

pp. 397-415 ◽

Cited By ~ 1

Author(s):

Annalisa Franzo ◽

Mauro Celussi ◽

Matteo Bazzaro ◽

Federica Relitti ◽

Paola Del Negro

Keyword(s):

Organic Matter ◽

Adriatic Sea ◽

Environmental Variable ◽

Biologically Active ◽

Stepwise Multiple Regression ◽

Northern Adriatic Sea ◽

Northern Adriatic ◽

Organic C ◽

C Cycling ◽

Long Term Ecological Research

Benthic prokaryotes are the key-players in C-cycling at the sediment-seawater interface, one of the largest biologically active interfaces on Earth. Here, microbial-mediated processes, such as the degradation of organic matter and the incorporation of mobilized C into microbial biomass, depend on several factors such as environmental temperature and substrate availability, especially in shallow sediments at mid-high latitudes where seasonal fluctuations of these variables occur. In the present study, four degradative activities (β-glucosidase, lipase, chitinase and aminopeptidase), Heterotrophic C Production (HCP), Total Organic C (TOC), Total Nitrogen (TN) and Biopolymeric C (BPC) were investigated seasonally from April 2010 to April 2018 in the surface sediments of a shallow Long-Term Ecological Research (LTER) station of the northern Adriatic Sea. Significant temperature-dependences were described by Arrhenius-type equations for HCP and each of the degradative activities tested with the exception of aminopeptidase. The relatively low apparent Activation Energies suggested that these microbial-mediated processes were enhanced by the availability of palatable substrates over the study period. Nevertheless, a clear and tight dependence from such substrates was detected only for aminopeptidase, the most pronounced degradative activity observed. TN was identified by the stepwise multiple regression analysis as the environmental variable that mainly drove this exoenzymatic activity. Enhanced aminopeptidase rates mirrored peaks of TN that seemed, in turn, linked to the seasonal proliferation of benthic microalgae. By supplying prokaryotes with promptly available substrates, these autotrophs, represented mainly by diatoms, seemed to play an important role in the C-cycling regulation at the studied LTER station.

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Bacterial degradation activity in the eastern tropical South Pacific oxygen minimum zone

Biogeosciences ◽

10.5194/bg-17-215-2020 ◽

2020 ◽

Vol 17 (1) ◽

pp. 215-230 ◽

Cited By ~ 3

Author(s):

Marie Maßmig ◽

Jan Lüdke ◽

Gerd Krahmann ◽

Anja Engel

Keyword(s):

Organic Matter ◽

Water Column ◽

Microbial Degradation ◽

Bacterial Production ◽

Leucine Aminopeptidase ◽

Extracellular Enzyme ◽

Bacterial Degradation ◽

Oxygen Loss ◽

Oxygen Minimum

Abstract. Oxygen minimum zones (OMZs) show distinct biogeochemical processes that relate to microorganisms being able to thrive under low or even absent oxygen. Microbial degradation of organic matter is expected to be reduced in OMZs, although quantitative evidence is low. Here, we present heterotrophic bacterial production (3H leucine incorporation), extracellular enzyme rates (leucine aminopeptidase/β-glucosidase) and bacterial cell abundance for various in situ oxygen concentrations in the water column, including the upper and lower oxycline, of the eastern tropical South Pacific off Peru. Bacterial heterotrophic activity in the suboxic core of the OMZ (at in situ ≤ 5 µmol O2 kg−1) ranged from 0.3 to 281 µmol C m−3 d−1 and was not significantly lower than in waters of 5–60 µmol O2 kg−1. Moreover, bacterial abundance in the OMZ and leucine aminopeptidase activity were significantly higher in suboxic waters compared to waters of 5–60 µmol O2 kg−1, suggesting no impairment of bacterial organic-matter degradation in the core of the OMZ. Nevertheless, high cell-specific bacterial production was observed in samples from oxyclines, and cell-specific extracellular enzyme rates were especially high at the lower oxycline, corroborating earlier findings of highly active and distinct micro-aerobic bacterial communities. To assess the impact of bacterial degradation of dissolved organic matter (DOM) for oxygen loss in the Peruvian OMZ, we compared diapycnal fluxes of oxygen and dissolved organic carbon (DOC) and their microbial uptake within the upper 60 m of the water column. Our data indicate low bacterial growth efficiencies of 1 %–21 % at the upper oxycline, resulting in a high bacterial oxygen demand that can explain up to 33 % of the observed average oxygen loss over depth. Our study therewith shows that microbial degradation of DOM has a considerable share in sustaining the OMZ off Peru.

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Early diagenesis of organic matter in the water column and sediments: Microbial degradation and resynthesis of lipids in Lake Haruna

Organic Geochemistry ◽

10.1016/0146-6380(87)90036-2 ◽

1987 ◽

Vol 11 (4) ◽

pp. 251-264 ◽

Cited By ~ 63

Author(s):

Kimitaka Kawamura ◽

Ryoshi Ishiwatari ◽

Kazuko Ogura

Keyword(s):

Organic Matter ◽

Water Column ◽

Microbial Degradation ◽

Early Diagenesis

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High bacterial organic carbon uptake in the Eastern Tropical South Pacific oxygen minimum zone

10.5194/bg-2019-237 ◽

2019 ◽

Author(s):

Marie Maßmig ◽

Jan Lüdke ◽

Gerd Krahmann ◽

Anja Engel

Keyword(s):

Organic Matter ◽

Organic Carbon ◽

Water Column ◽

Microbial Degradation ◽

Bacterial Production ◽

Leucine Aminopeptidase ◽

Extracellular Enzyme ◽

Oxygen Loss ◽

Oxygen Minimum

Abstract. Oxygen minimum zones (OMZs) show distinct biogeochemical processes that relate to microorganisms being able to thrive under low or even absent oxygen. Microbial degradation of organic matter is expected to be reduced in OMZs, although quantitative evidence is low. Here, we present heterotrophic bacterial production (3H leucine-incorporation), extracellular enzyme rates (leucine aminopeptidase/ß-glucosidase) and bacterial cell abundance for various in situ oxygen concentrations in the water column of the Eastern Tropical South Pacific off Peru. Bacterial heterotrophic activity in the suboxic core of the OMZ (at in situ ≤ 5 µmol O2 kg−1) ranged from 0.6 to 160 µmol C m−3 d−1 and was not significantly lower than in waters of 5–60 µmol O2 kg−1. Moreover, bacterial abundance in the OMZ was slightly and leucine aminopeptidase activity even significantly higher in suboxic waters compared to the upper oxycline suggesting no impairment of bacterial organic matter degradation in the core of the OMZ. Nevertheless, high cell-specific bacterial production and extracellular enzyme rates were observed in samples from the upper or lower oxyclines corroborating earlier findings of highly active and distinct micro-aerobic bacterial communities. To assess the impact of bacterial degradation of dissolved organic matter for oxygen loss in the Peruvian OMZ, we compared diapycnal fluxes of oxygen and dissolved organic carbon (DOC) and their microbial uptake within the upper 60 m of the water column. Our data indicate bacterial growth efficiencies of 0.5–8.6 % at the upper oxycline, resulting in a high bacterial oxygen demand that can explain up to 33 % of the observed average oxygen loss over depth. Our study therewith shows that microbial degradation of DOM has a considerable share in sustaining the OMZ off Peru.

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