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

Abstract

Abstract. The ability of the cold-water coral Lophelia pertusa to exploit different food sources was investigated under standardized conditions in a flume. The tested food sources, dissolved organic matter (DOM, added as dissolved free amino acids), bacteria, algae, and zooplankton (Artemia) were deliberately enriched in 13 C and 15 N. The incorporation of 13 C and 15 N was traced into bulk tissue, fatty acids, hydrolysable amino acids, and the skeleton ( 13 C only) of L. pertusa. Incorporation rates of carbon (ranging from 0.8-2.4 µg C g −1 DW d −1 ) and nitrogen (0.2-0.8 µg N g −1 DW d −1 ) into coral tissue did not differ significantly among food sources indicating an opportunistic feeding strategy. Although total food assimilation was comparable among sources, subsequent food processing was dependent on the type of food source ingested and recovery of assimilated C in tissue compounds ranged from 17 % (algae) to 35 % (Artemia). De novo synthesis of individual fatty acids by L. pertusa occurred in all treatments as indicated by the 13 C enrichment of individual phospholipid-derived fatty acids (PLFAs) in the coral that were absent in the added food sources. This indicates that the coral might be less dependent on its diet as a source of specific fatty acids than expected, with direct consequences for the interpretation of in situ observations on coral nutrition based on lipid profiles.

Food selectivity and processing by the cold-water coral <i>Lophelia pertusa</i>

“…Sand-filtered (1-2 mm particle size) bottom water from 45 m depth out of the adjacent Koster fjord (salinity 31) was continuously flushed through the aquaria (∼ 1 L min −1 ). Experience at the station and our earlier experiments showed that the sand-filtered water still contains sufficient organic particles, so that no extra food was provided during the acclimation period (Mueller et al, 2014). …”

“…Laboratory studies have confirmed the uptake of suspended particles, bacteria, phytoplankton and zooplankton by cold-water corals (Purser et al, 2010; Published by Copernicus Publications on behalf of the European Geosciences Union. 5790 D. van Oevelen et al: Food selectivity and processing by the cold-water coral Lophelia pertusa Mueller et al, 2014;Orejas et al, 2016). Recently, L. pertusa was also shown to take up dissolved organic matter in the form of free amino acids (Gori et al, 2014;Mueller et al, 2014) and to fix inorganic carbon into its biomass, supposedly through chemo-autotrophic activity of associated microbes (Middelburg et al, 2015).…”

“…5790 D. van Oevelen et al: Food selectivity and processing by the cold-water coral Lophelia pertusa Mueller et al, 2014;Orejas et al, 2016). Recently, L. pertusa was also shown to take up dissolved organic matter in the form of free amino acids (Gori et al, 2014;Mueller et al, 2014) and to fix inorganic carbon into its biomass, supposedly through chemo-autotrophic activity of associated microbes (Middelburg et al, 2015). This flexibility in resource utilization clearly indicates an opportunistic feeding strategy (Mueller et al, 2014;Orejas et al, 2016).…”

“…In order to advance our understanding of coldwater coral physiology, we must better understand resource partitioning within the energy budget of the organism. For the cold-water coral Desmophyllum dianthus it was shown that zooplankton contributed to various components of the energy budget, including calcification, respiration and mucus release, following food withdrawal for 1 week (Naumann et al, 2011). The slow (i.e.…”

Larval Behavior and Longevity in the Cold-Water Coral Lophelia pertusa Indicate Potential for Long Distance Dispersal

“…The adult L. pertusa polyps are opportunistic feeders capable of exploiting different food sources including zooplankton, microalgae (in the form of marine snow, POM), bacteria, and dissolved organic carbon and other nutrients (Mueller et al, 2014). It seems as though the planulae share the opportunistic heterotrophic diet of the adults.…”