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Digitale Medien

Activity and distribution of bacterial populations in Middle Atlantic Bight shelf sands (2003)

Rusch, Antje ; Huettel, Markus ; Reimers, Clare E ; [weitere]

Oxford, UK : Blackwell Publishing Ltd

FEMS microbiology ecology 44 (2003), S. 0

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ISSN: 1574-6941

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Biologie

Notizen: Spatiotemporal variation and metabolic activity of the microbial community were studied in coarse-grained Middle Atlantic Bight shelf sediments in relation to pools of dissolved and particulate carbon. Algal cells were present 8–〉70 μm) fraction of the sediment held the major share (61–98%) of benthic bacteria. Bacterial and algal cell abundances, exoenzymatic activity, and [DOC] generally showed higher values in May/July 2001 than in August/December 2000. Carbohydrates and proteins were hydrolyzed at potential rates of 1–12 nmol cm−3 h−1 (β-glucosidase) and 3–70 nmol cm−3 h−1 (aminopeptidase), respectively. Fluorescence in situ hybridization analyses of the benthic microbes assigned 45–56% of DAPI-stained cells to Eubacteria and less than 2% to Eukarya. The prokaryotic community was dominated by planctomycetes and members of the Cytophaga/Flavobacterium cluster. Near the sediment surface, iodonitrotetrazolium violet reducing cells, that are considered actively respiring, amounted to 15–29% of total bacteria. Despite a low organic content (particulate organic carbon 〈0.03%) and relatively low bacterial abundances (〈109 cm−3), the Middle Atlantic Bight shelf sediments showed organic matter turnover rates that are comparable to those found in organic-rich finer-grained deposits. Our findings suggest a high biocatalytic filtration activity in these coarse permeable sediments.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1574-6941.2003.tb01093.x

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Digitale Medien

Coral mucus functions as an energy carrier and particle trap in the reef ecosystem (2004)

Huettel, Markus ; Klueter, Anke ; Kremb, Stephan G. ; [weitere]

[s.l.] : Macmillian Magazines Ltd.

Nature 428 (2004), S. 66-70

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ISSN: 1476-4687

Quelle: Nature Archives 1869 - 2009

Thema: Biologie , Chemie und Pharmazie , Medizin , Allgemeine Naturwissenschaft , Physik

Notizen: [Auszug] Zooxanthellae, endosymbiotic algae of reef-building corals, substantially contribute to the high gross primary production of coral reefs, but corals exude up to half of the carbon assimilated by their zooxanthellae as mucus. Here we show that released coral mucus efficiently traps organic ...

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1038/nature02344

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Decomposition of diatoms and nutrient dynamics in permeable North Sea sediments (2004)

Ehrenhauss, Sandra ; Witte, Ursula ; Janssen, Felix ; [weitere]

In: EPIC3Continental Shelf Research, 24(6), pp. 721-737, ISSN: 02784343

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Publikationsdatum: 2017-03-06

Beschreibung: This study addresses the decomposition of diatoms in different permeable North Sea sand beds. During three cruises in 2001 to the southern German Bight, the regeneration of nutrients was assessed after the experimental deposition of organic matter corresponding to a typical spring diatom bloom in in situ and on-board chamber experiments. The diatom pulse was followed by a high regeneration of nutrients during the first day: 5–10% d−1 of the added nitrogen was converted to NH4+ and up to 0.67% d−1 of the added biogenic silica was dissolved to Si(OH)4. These results are used to interpret the response of pore water nutrient concentrations in permeable North Sea sands to seasonal nutrient and phytoplankton dynamics in the water column. The rapid advective solute exchange in these permeable sediments reduces the accumulation of regenerated nutrients, and, thus pore water concentrations of Si(OH)4, PO43− and NH4+ decreased with increasing permeability. All sands were characterized by relatively high NO3− concentrations down to 10 cm sediment depth, indicating that the upper sediment layers are oxidized by advective flushing of the bed. Our results demonstrate that biogenic silica and organic matter are rapidly degraded in permeable coastal sands, revealing that these sediments are very active sites of nutrient recycling.

Repository-Name: EPIC Alfred Wegener Institut

Materialart: Article , isiRev

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