Extracoelenteric zooplankton feeding is a key mechanism of nutrient acquisition for the scleractinian coral Galaxea fascicularis

Abstract

SUMMARYInternal and external feeding on zooplankton may provide scleractinian corals with important nutrients. However, the latter process has never been properly quantified. To quantify the dynamics of zooplankton capture, digestion and release for a scleractinian coral, we performed detailed video analyses of Galaxea fascicularis feeding on Artemia nauplii. A highly dynamic process of prey capture, digestion and release was observed. A single G. fascicularis polyp (N3) captured 558±67 and released 383±75 Artemia nauplii over a 6h interval. On average, 98.6% of prey captured was not ingested. Instead, prey items were clustered into aggregates that were digested externally by mesenterial filaments. In addition, we employed carbon, nitrogen and phosphorus analysis of zooplankton before and after digestion by G. fascicularis colonies (N6). For total organic carbon, 43.1% (0.298±0.148gArtemia ), respectively. For extracoelenteric zooplankton feeding alone, total estimated nutrient inputs for G. fascicularis colonies were 76.5±0.0g organic carbon, 15.2±0.0g organic nitrogen, 2.3±0.2g organic phosphorus and 0.5±0.8g inorganic phosphorus per cm 2 coral tissue per day. These values exceed calculations based on intracoelenteric feeding by up to two orders of magnitude. Our results demonstrate that extracoelenteric zooplankton feeding is a key mechanism of nutrient acquisition for a scleractinian coral. These results are of importance to coral aquaculture and our understanding of benthic-pelagic coupling on coral reefs. Supplementary material available online at

Among-species variation in the energy budgets of reef-building corals: scaling from coral polyps to communities

“…, Wijgerde et al, 2011) by the duration of the feeding period (2 h) and then dividing this rate by the measured respiration rate converted to carbon equivalents with values normalized to tissue surface area (as per Hoogenboom et al, 2010). Energy allocation to skeleton growth was calculated from the measured total calcification across the experiment (g) multiplied by the energy cost of calcification (0.152 J mg −1 , Anthony et al, 2002).…”

Oxygen and Heterotrophy Affect Calcification of the Scleractinian Coral Galaxea fascicularis

“…Another issue which should be addressed is how long the inhibitory effect of heterotrophy lasts, which is likely to be only several hours when taking feeding and digestion rates of G. fascicularis into account [31], [32]. A temporal effect would explain the discrepancy between the inhibitory short-term [11,12, this paper] and enhancing long-term [1] effects of heterotrophy on coral calcification.…”

Epizoic acoelomorph flatworms impair zooplankton feeding by the scleractinian coral Galaxea fascicularis

“…This suggests that the observed impairment of prey capture and retention at 1,000 nauplii L −1 was due to mucus grazing by flatworms, limiting the capacity of polyps to capture and retain more nauplii at higher prey concentrations. Indeed, Hii et al and Wijgerde et al found that, at high zooplankton concentrations in particular, G. fascicularis produces copious amounts of mucus, which is likely to facilitate the capture of higher amounts of prey (Hii et al, 2009; Wijgerde et al, 2011a). Finally, kleptoparasitism clearly contributed to a reduction of coral feeding by decreasing prey retention rates of the coral host (also see next section).…”

“…Reduced resistance may result from feeding on coral mucus by flatworms, thereby removing (part of) the layer that protects the coral against sedimentation, dehydration, UV-radiation and pathogens (Barneah et al, 2007b; Brown and Bythell, 2005; Naumann et al, 2010). Moreover, prey capture may be impaired as mucus serves as an effective adhesive layer for capturing prey (Sorokin, 1990; Wijgerde et al, 2011a). …”