Skeletal growth, respiration rate and fatty acid composition in the cold-water coral Lophelia pertusa under varying food conditions

Abstract

Reefs of the cold-water coral Lophelia pertusa form biodiversity-rich habitats in the deep ocean, but physiology, reproduction, feeding and growth in this species remain poorly investigated. Food supply to reef sites varies considerably both spatially and temporarily. In this study we investigated the effects of starvation and zooplankton feeding on respiration and growth of L. pertusa. In our first experiment, corals were starved for 6 mo, resulting in a 40% decrease in respiration but no visible effects on coral condition or survival. In a second experiment, corals were fed nauplii of Artemia salina for 15 wk at 4 different densities; the organic carbon provided corresponded to between 20 and 300% of the carbon turned over by initial respiration. Respiration rate increased with zooplankton food density, but no effect on skeletal growth could be detected. Skeletal growth remained positive even at low food density. Compared to initial conditions, there was a general decrease in the total concentrations of both structural and storage fatty acids independent of food treatment, but no significant effect among the treatments was discovered. The amount of organic carbon and nitrogen also decreased during the experiment, although significantly less in the highest food density compared to the lowest. The results indicate that L. pertusa is highly tolerant to living on minimal resources for periods of several months. Response-times to varying food conditions were slow, but results suggest that tissue content and composition is a better indicator of food conditions in L. pertusa compared to calcification rates.

Opportunistic feeding on various organic food sources by the cold-water coral <i>Lophelia pertusa</i>

“…The concentration of total fatty acids (20 mg g −1 DW tissue with tissue DW contributing 5 % to total DW, as observed in this study), however, was below the range of 55-124 mg g −1 DW tissue reported by Dodds et al (2009) for L. pertusa from Rockall Bank, Mingulay Reef and New England Seamounts. Local differences can be responsible for this discrepancy as Larsson et al (2013a) reported storage fatty acids concentrations of 15 to 19 mg g −1 DW tissue from L. pertusa collected at the Tisler Reef but also the maintenance in aquaria (3 month in this study) might have altered the lipid content (Larsson et al, 2013b).…”

Effects of elevated pCO2 and feeding on net calcification and energy budget of the Mediterranean cold-water coral Madrepora oculata

“…Calculations (Eqns 16-18) revealed that less than 0.5% of energy would be required for calcification in relation to overall respiration in M. oculata (Table 2). Also, for L. pertusa only 3-5% of the available energy is allocated to calcification in comparison to respiration (Larsson et al, 2013), and metabolic carbon contribution to calcification was 1% in relation to that of the tissue pool and respiration for the CWC L. pertusa (Mueller et al, 2014). The relatively low energy requirement for upregulation of Ω a in the calcifying fluid and the maintenance of relatively high calcification rates might explain the observed resistance to ocean acidification.…”

“…Starvation of D. dianthus caused an initial and significant decrease in calcification after 1 week, while starvation for another 2 weeks did not result in further significant reduction of calcification rates (Naumann et al, 2013b). When L. pertusa was provided with various concentrations of food over 15 weeks, only small and non-significant changes in respiration were measured, and no effect on calcification occurred, despite the fact that food supply varied by a factor of 7.5 (Larsson et al, 2013). Also, for M. oculata (this study) the HF regime only affected the first measurements on calcification, which were taken 2 weeks after the respective feeding regimes had been applied, while during later measurements (4-10 weeks), calcification was independent of feeding regime.…”

“…Starvation triggers a continuous decline in respiration rates of L. pertusa and D. dianthus (Larsson et al, 2013;Naumann et al, 2013a). Starvation of D. dianthus caused an initial and significant decrease in calcification after 1 week, while starvation for another 2 weeks did not result in further significant reduction of calcification rates (Naumann et al, 2013b).…”

“…This is an important mechanism which allows a switch from food ingestion to a removal of undesired components, such as food remnants, metabolites with high N content (Wild et al, 2008), sediment or other particles (Larsson et al, 2013;Larsson and Purser, 2011;Zetsche et al, 2016). Also, mucus has an important role in fuelling bacterial growth in the coelenteron (Herndl and Velimirov, 1986;Weinbauer et al, 2012) and the close vicinity of the coral environment (Wild et al, 2004a(Wild et al, ,b, 2008(Wild et al, , 2009(Wild et al, , 2005.…”