Abstract
We investigated microphytobenthic photosynthesis at four stations in the coral reef sediments at Heron Reef, Australia. The microphytobenthos was dominated by diatoms, dinoflagellates and cyanobacteria, as indicated by biomarker pigment analysis. Conspicuous algae firmly attached to the sand grains (ca. 100 μm in diameter, surrounded by a hard transparent wall) were rich in peridinin, a marker pigment for dinoflagellates, but also showed a high diversity based on cyanobacterial 16S rDNA gene sequence analysis. Specimens of these algae that were buried below the photic zone exhibited an unexpected stimulation of respiration by light, resulting in an increase of local oxygen concentrations upon darkening. Net photosynthesis of the sediments varied between 1.9 and 8.5 mmol O2 m-2 h-1 and was strongly correlated with Chl a content, which lay between 31 and 84 mg m-2. An estimate based on our spatially limited dataset indicates that the microphytobenthic production for the entire reef is in the order of magnitude of the production estimated for corals. Photosynthesis stimulated calcification at all investigated sites (0.2-1.0 mmol Ca2+ m-2 h-1). The sediments of at least three stations were net calcifying. Sedimentary N2-fixation rates (measured by acetylene reduction assays at two sites) ranged between 0.9 to 3.9 mmol N2 m-2 h-1 and were highest in the light, indicating the importance of heterocystous cyanobacteria. In coral fingers no N2-fixation was measurable, which stresses the importance of the sediment compartment for reef nitrogen cycling.
| Original language | English |
|---|---|
| Pages (from-to) | 876-888 |
| Number of pages | 13 |
| Journal | Estuarine, Coastal and Shelf Science |
| Volume | 76 |
| Issue number | 4 |
| DOIs | |
| Publication status | Published - Mar 1 2008 |
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Keywords
- Australia
- calcification
- coral reefs
- Heron Island
- light-dark shift method
- microphytobenthic photosynthesis
- N-fixation
- permeable sediments
ASJC Scopus subject areas
- Aquatic Science
- Oceanography
Cite this
Microbial photosynthesis in coral reef sediments (Heron Reef, Australia). / Werner, Ursula; Blazejak, Anna; Bird, Paul; Eickert, Gabriele; Schoon, Raphaela; Abed, Raeid M M; Bissett, Andrew; de Beer, Dirk.
In: Estuarine, Coastal and Shelf Science, Vol. 76, No. 4, 01.03.2008, p. 876-888.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Microbial photosynthesis in coral reef sediments (Heron Reef, Australia)
AU - Werner, Ursula
AU - Blazejak, Anna
AU - Bird, Paul
AU - Eickert, Gabriele
AU - Schoon, Raphaela
AU - Abed, Raeid M M
AU - Bissett, Andrew
AU - de Beer, Dirk
PY - 2008/3/1
Y1 - 2008/3/1
N2 - We investigated microphytobenthic photosynthesis at four stations in the coral reef sediments at Heron Reef, Australia. The microphytobenthos was dominated by diatoms, dinoflagellates and cyanobacteria, as indicated by biomarker pigment analysis. Conspicuous algae firmly attached to the sand grains (ca. 100 μm in diameter, surrounded by a hard transparent wall) were rich in peridinin, a marker pigment for dinoflagellates, but also showed a high diversity based on cyanobacterial 16S rDNA gene sequence analysis. Specimens of these algae that were buried below the photic zone exhibited an unexpected stimulation of respiration by light, resulting in an increase of local oxygen concentrations upon darkening. Net photosynthesis of the sediments varied between 1.9 and 8.5 mmol O2 m-2 h-1 and was strongly correlated with Chl a content, which lay between 31 and 84 mg m-2. An estimate based on our spatially limited dataset indicates that the microphytobenthic production for the entire reef is in the order of magnitude of the production estimated for corals. Photosynthesis stimulated calcification at all investigated sites (0.2-1.0 mmol Ca2+ m-2 h-1). The sediments of at least three stations were net calcifying. Sedimentary N2-fixation rates (measured by acetylene reduction assays at two sites) ranged between 0.9 to 3.9 mmol N2 m-2 h-1 and were highest in the light, indicating the importance of heterocystous cyanobacteria. In coral fingers no N2-fixation was measurable, which stresses the importance of the sediment compartment for reef nitrogen cycling.
AB - We investigated microphytobenthic photosynthesis at four stations in the coral reef sediments at Heron Reef, Australia. The microphytobenthos was dominated by diatoms, dinoflagellates and cyanobacteria, as indicated by biomarker pigment analysis. Conspicuous algae firmly attached to the sand grains (ca. 100 μm in diameter, surrounded by a hard transparent wall) were rich in peridinin, a marker pigment for dinoflagellates, but also showed a high diversity based on cyanobacterial 16S rDNA gene sequence analysis. Specimens of these algae that were buried below the photic zone exhibited an unexpected stimulation of respiration by light, resulting in an increase of local oxygen concentrations upon darkening. Net photosynthesis of the sediments varied between 1.9 and 8.5 mmol O2 m-2 h-1 and was strongly correlated with Chl a content, which lay between 31 and 84 mg m-2. An estimate based on our spatially limited dataset indicates that the microphytobenthic production for the entire reef is in the order of magnitude of the production estimated for corals. Photosynthesis stimulated calcification at all investigated sites (0.2-1.0 mmol Ca2+ m-2 h-1). The sediments of at least three stations were net calcifying. Sedimentary N2-fixation rates (measured by acetylene reduction assays at two sites) ranged between 0.9 to 3.9 mmol N2 m-2 h-1 and were highest in the light, indicating the importance of heterocystous cyanobacteria. In coral fingers no N2-fixation was measurable, which stresses the importance of the sediment compartment for reef nitrogen cycling.
KW - Australia
KW - calcification
KW - coral reefs
KW - Heron Island
KW - light-dark shift method
KW - microphytobenthic photosynthesis
KW - N-fixation
KW - permeable sediments
UR - http://www.scopus.com/inward/record.url?scp=38749134541&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=38749134541&partnerID=8YFLogxK
U2 - 10.1016/j.ecss.2007.08.015
DO - 10.1016/j.ecss.2007.08.015
M3 - Article
VL - 76
SP - 876
EP - 888
JO - Estuarine, Coastal and Shelf Science
JF - Estuarine, Coastal and Shelf Science
SN - 0272-7714
IS - 4
ER -