High dissolved organic carbon release by benthic cyanobacterial mats in a Caribbean reef ecosystem.
Benthic cyanobacterial mats (BCMs) are increasing in abundance on coral reefs worldwide. However, their impacts on biogeochemical cycling in the surrounding water and sediment are virtually unknown. By measuring chemical fluxes in benthic chambers placed over sediment covered by BCMs and sediment with BCMs removed on coral reefs in Curaçao, Southern Caribbean, we found that sediment covered by BCMs released 1.4 and 3.5 mmol C m(-2) h(-1) of dissolved organic carbon (DOC) during day and night, respectively. Conversely, sediment with BCMs removed took up DOC, with day and night uptake rates of 0.9 and 0.6 mmol C m(-2) h(-1). DOC release by BCMs was higher than reported rates for benthic algae (turf and macroalgae) and was estimated to represent 79% of the total DOC released over a 24 h diel cycle at our study site. The high nocturnal release of DOC by BCMs is most likely the result of anaerobic metabolism and degradation processes, as shown by high respiration rates at the mat surface during nighttime. We conclude that BCMs are significant sources of DOC. Their increased abundance on coral reefs will lead to increased DOC release into the water column, which is likely to have negative implications for reef health.
1] Max Planck Institute for Marine Microbiology (MPI Bremen), Celsiusstr. 1, 28359 Bremen, Germany [2] Leibniz Center for Tropical Marine Ecology (ZMT), Fahrenheitstr. 6, 28359 Bremen, Germany [3] CRIOBE - USR 3278, CNRS-EPHE-UPVD, 58 Avenue Paul Alduy, 66860 Perpignan Cedex, France.
Hannah J
HJ
Brocke
1] Max Planck Institute for Marine Microbiology (MPI Bremen), Celsiusstr. 1, 28359 Bremen, Germany [2] Alfred Wegener Institute, Am Handelshafen 12, 27570 Bremerhaven, Germany.
Frank
F
Wenzhoefer
Max Planck Institute for Marine Microbiology (MPI Bremen), Celsiusstr. 1, 28359 Bremen, Germany.
Dirk
D
de Beer
1] Royal Netherlands Institute for Sea Research (NIOZ), P.O. Box 59, 1790AB Den Burg, Texel, The Netherlands [2] CARMABI Foundation, Piscaderabaai z/n, P.O. Box 2090, Willemstad, Curaçao.
Benjamin
B
Mueller
1] Royal Netherlands Institute for Sea Research (NIOZ), P.O. Box 59, 1790AB Den Burg, Texel, The Netherlands [2] CARMABI Foundation, Piscaderabaai z/n, P.O. Box 2090, Willemstad, Curaçao.
Fleur C
FC
van Duyl
1] CRIOBE - USR 3278, CNRS-EPHE-UPVD, 58 Avenue Paul Alduy, 66860 Perpignan Cedex, France [2] CARMABI Foundation, Piscaderabaai z/n, P.O. Box 2090, Willemstad, Curaçao [3] Laboratoire d'Excellence "CORAIL"
Maggy M
MM
Nugues
D057894:Coral Reefs; D000458:Cyanobacteria / Q000378:metabolism*; D017753:Ecosystem; D019015:Geologic Sediments / Q000737:chemistry*; D009930:Organic Chemicals / Q000032:analysis*; D012623:Seawater / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis*
D009930:Organic Chemicals; D014874:Water Pollutants, Chemical