The influence of heterotrophy and flow on calcification of the cold-water coral Desmophyllum dianthus


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Stefanie.Sokol [ at ] awi.de

Abstract

The solitary cold-water coral Desmophyllum dianthus, commonly known as deep-sea species, shows an unusual shallow (< 25 m) and dense occurrence (up to 1500 individuals m2) in the northern Patagonian fjord region. This study investigated these shallow-living D. dianthus specimens under exposure to their natural ecoenvironmental gradients and examined the influence of food concentration and flow regime on calcification rates and metabolic activity. Buoyancy weight measurements revealed the highest in situ short-term (~ 2 weeks) calcification rates know for D. dianthus so far with a mass increase of 5.44 ± 3.45 mg CaCO3 cm-2 d-1 and a corresponding weight gain of 0.25 ± 0.18 % d-1. Corals that were simultaneously maintained under flow-through conditions on-site showed significantly lower calcification rates of 1.86 ± 1.37 mg CaCO3 cm-2 d-1 and 0.09 ± 0.08 % d-1. Capture rates and prey-size selectivity were ascertained by incubation experiments under supply of their natural food spectrum. Corals captured most (55 ± 16 prey items cm-2 h-1) under flow speeds of 1.7 cm s-1 and showed declining trends towards stagnant and stronger flow regimes. Prey items greater 1000 µm covered approximately half of their diet. Food availability appeared to significantly influence key physiological processes of D. dianthus. This was examined via laboratory long-term experiments (3 month) with corals maintained in re-circulating flow-chambers. Calcification and respiration rates increased most notably under high food and high flow conditions. The present thesis extended the current knowledge about these shallow-living cold-water corals by investigating their feeding ecology, metabolic fitness and growth behavior under varied environmental parameters.



Item Type
Thesis (Diplom)
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Not peer-reviewed
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Published
Eprint ID
25994
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Sokol, S. (2012): The influence of heterotrophy and flow on calcification of the cold-water coral Desmophyllum dianthus , Diplom thesis, University of Kiel, AWI.


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