Water Flow Affects Zooplankton Feeding by the Scleractinian CoralGalaxea fascicularison a Polyp and Colony Level

Abstract

Several factors may affect heterotrophic feeding of benthic marine invertebrates, including water flow rate and polyp context (i.e., the presence of neighbouring polyps). We tested the interactive effects of water flow rate and polyp context on zooplankton feeding by the scleractinian coralGalaxea fascicularis. Single polyps and colonies were incubated in a flow cell for 30 minutes with an ambientArtemianauplii concentration of 10,000 L−1and water flow rates ranging from 1.25 to 40 cm s−1. Water flow rate and polyp context showed significant main and interactive effects on feeding rates ofG. fascicularispolyps. More specifically, feeding rates were optimal at flow rates of 1.25 cm s−1for single polyps and 5 to 10 cm s−1for polyps inhabiting colonies. The presence of epizoic acoelomorph flatworms may have negatively affected the observed feeding rates, especially at high flow. Our results demonstrate that water flow affects coral feeding and thus heterotrophic nutrient input at both a polyp and colony level. These findings are of relevance to our understanding of how biotic and abiotic factors interact on coral heterotrophy and may serve to optimise coral aquaculture.

Coral aquaculture: applying scientific knowledge to ex situ production

“…Fed corals have a twofold faster organic matrix synthesis, calcification, protein and lipid content than starved corals (Houlbr eque & Ferrier-Pag es 2009). Skeletal growth increases in fed corals, as was verified for Stylophora pistillata, Turbinaria reniformis, Pocillopora damicornis, Seriato-pora caliendrum and Galaxea fascicularis Treignier et al 2009;Wijgerde et al 2012a). Heterotrophic feeding also improves coral quality as it contributes to maximize resilience to stress and potential for recovery (Grottoli et al 2006).…”

“…Light endorses the production of photosynthates by the photosynthetic endosymbionts and consequently their translocation to the cnidarian host (Muscatine et al 1981;Bachar et al 2007;Leal et al 2013b). This process largely contributes to coral calcification and growth Wijgerde et al 2012a). Light also affects coral quality-related aspects such as physiological condition, shape, colour and metabolite content (Titlyanov & Titlyanova 2002;Todd 2008;Khalesi et al 2009).…”

Biogeographic variability in the physiological response of the cold‐water coral Lophelia pertusa to ocean acidification

“…), and others finding that denser polyp spacing within colonies enhanced feeding rates (McFadden ; Wijgerde et al . ). Inter‐polyp competition has not yet been observed in cold‐water corals, and as L. pertusa is capable of self‐recognition to avoid intra‐specific competition (Hennige et al .…”

“…It is possible that the considerably lower baseline feeding rate in the Gulf of Mexico corals was due in part to inter-polyp competition for prey, as the Gulf of Mexico corals had a higher number of polyps (10.8 AE 3.2 polypsÁcolony À1 ) compared to the Tisler Reef corals (5.5 AE 1.5 polypsÁcolony À1 ) but the same prey concentration was used in both experiments. Previous research on the effects of intra-specific, interpolyp competition in scleractinian corals has had mixed results, with some studies demonstrating that competition reduced feeding rates and resource acquisition (Merks et al 2004;Einbinder et al 2009;Wijgerde et al 2011), and others finding that denser polyp spacing within colonies enhanced feeding rates (McFadden 1986;Wijgerde et al 2012). Inter-polyp competition has not yet been observed in cold-water corals, and as L. pertusa is capable of self-recognition to avoid intra-specific competition (Hennige et al 2014), it is possible that even closely spaced polyps do not actively compete for food.…”

The Diversity and Ecological Role of Non-scleractinian Corals (Antipatharia and Alcyonacea) on Scleractinian Cold-Water Coral Mounds

“…The food capture rates for different species can strongly depend on current velocity, seawater temperature and polyp size. High flow velocities can deform coral polyps reducing the exposed feeding surface area (Dai and Lin, 1993;Purser et al, 2010;Wijgerde et al, 2012;Gori et al, 2015). Higher flow speeds may also make the polyps less efficient at holding prey (Sebens et al, 1998;Orejas et al, 2011).…”