Abstract
The feeding biology of deep-sea octocorals remains poorly understood, as attention is more often directed to reef building corals. The present study focused on two common deep-water octocoral species in the Azores Archipelago, Dentomuricea aff. meteor and Viminella flagellum, aiming at determining their ability to exploit different food sources. We adopted an experimental approach, with three different food sources, including live phytoplankton, live zooplankton and dissolved organic matter (DOM), that were artificially enriched with 13C and 15N (C and N tracers). The presence of tracers was subsequently followed in the coral tissue, C respiration and particulate organic C and N (POC and PON) release. In both species, feeding with zooplankton resulted in significantly higher incorporation of tracers in all measured variables, compared to the other food sources, highlighting the importance of zooplankton for major physiological processes. Our results revealed contrasting metabolic strategies between the two species, with D. aff. meteor acquiring higher amounts of prey and allocating higher percentage to respiration and release of POC and PON than V. flagellum. Such metabolic differences can shape species fitness and distributions and have further ecological implications on the ecosystem function of communities formed by different octocoral species.
Highlights
The feeding biology of deep-sea octocorals remains poorly understood, as attention is more often directed to reef building corals
We examined the feeding biology of two common habitat-forming deep octocoral species in the Azores Archipelago: Dentomuricea aff. meteor and Viminella flagellum
Target C concentrations within the aquaria were successfully achieved in the case of the dissolved organic matter (DOM) and zooplankton derived source (ZOO) treatment, they were below the target for the phytoplankton derived source (PHYTO) treatment, by 34% for D. aff. meteor and 44% for V. flagellum respectively (Table 1)
Summary
The feeding biology of deep-sea octocorals remains poorly understood, as attention is more often directed to reef building corals. The presence of tracers was subsequently followed in the coral tissue, C respiration and particulate organic C and N (POC and PON) release In both species, feeding with zooplankton resulted in significantly higher incorporation of tracers in all measured variables, compared to the other food sources, highlighting the importance of zooplankton for major physiological processes. Meteor acquiring higher amounts of prey and allocating higher percentage to respiration and release of POC and PON than V. flagellum Such metabolic differences can shape species fitness and distributions and have further ecological implications on the ecosystem function of communities formed by different octocoral species. We examined the feeding biology of two common habitat-forming deep octocoral species in the Azores Archipelago: Dentomuricea aff. Food sources were artificially enriched with 13C and 15N and food utilization was quantified (a) as the appearance of 13C15N in the coral tissue, indicating tracer carbon (C) and nitrogen (N) incorporation from the provided food, (b) as the production of 13C-enriched dissolved inorganic carbon (DIC) by the coral, indicating tracer C respiration, and (c) as the production of 13C15N-enriched particulate organic carbon and nitrogen (POC, PON) by the coral, indicating tracer POC and PON release
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