Microbial abundance in the coelenteron and mucus of the cold-water coral Lophelia pertusa and in bottom water of the reef environment

Abstract

Microorganisms play an important role in coral ecology; however, little is known about cold-water coral (CWC) reefs. Microbial abundance in bottom water of Lophelia pertusadominated CWC reefs in the Skagerrak, North Sea, was elevated by ca. 40% for prokaryotes and 70 to 90% for viruses compared to bottom water where no corals were present. This indicates that CWCs influence the microbial food web in bottom water. Furthermore, results suggest that microorganisms contributed significantly to the stock of organic nitrogen (13%) and organic phosphorus (32%) in bottom water. Prokaryotic abundances in the coelenteron of freshly collected corals were (2.0 ± 0.2) × 10 7 cells ml −l and viral abundances were (4.0 ± 0.6) × 10 7 particles ml −l . Prokaryotic abundances in coral mucus were (7.5 ± 0.7) × 10 7 cells ml −l and viral abundances were (1.7 ± 0.3) × 10 8 particles ml −l . Onboard incubations with elevated prokaryotic and viral abundances in the incubation water indicated that (1) corals accumulate microorganisms in the coelenteron as a potential food source and (2) control mechanisms exist for the abundance of prokaryotic cells and viral particles in the mucus. Our data suggest that L. pertusa controls microbial biomass in the CWC reef environment and coral microhabitats. KEY WORDS: Cold-water coral · Microbial abundance · Lophelia pertusa · Viruses · Prokaryotes · Bacteria · ReefsResale or republication not permitted without written consent of the publisher Aquat Biol 16: 209-216, 2012 210 barrier against incoming fowling or pathogenic prokaryotes (Reshef et al. 2006) and as a buffer against environmental change (Rosenberg et al. 2007).Recent research has shown that viral abundance decreases with distance from the coral (Seymour et al. 2005, Patten et al. 2006 and that the mucus contains an astounding morphological diversity of viruses (Davy & Patten 2007). To our knowledge, no data have been published on the abundance of viruses in the mucus or coelenteron of corals, and the viral ecology of the coral holobiont remains largely unstudied.This study had 3 objectives: (1) to quantify prokaryotic and viral abundances (and inorganic and organic nutrients) in a CWC reef environment in the Skagerrak, North Sea, (2) to quantify prokaryotic and viral abundance in 2 major microhabitats of Lophelia pertusa, viz. the coelenteron and the mucus, and (3) to test whether an increase in the abundance of prokaryotes and viruses in ambient water by ca. 1 order of magnitude can change abundances in the coelenteron and mucus. MATERIALS AND METHODSSamples were obtained during the BIOSYS cruise (www. nioz. nl/public/dmg/rpt/crs/64pe263.pdf) on the RV 'Pelagia' in March 2007 to the Skagerrak of Norway at Fjellknausene (59.07°N, 10.74°E) and Soester (59.08°N, 10.76°E), ca. 100 km south of Oslo (Norway). Colonies of Lophelia pertusa and water samples were collected at 78 to 128 m depth from a reef site that was dominated by L. pertusa. The water column was characterized by a conductivity-temperaturedensity (CTD) rosette ...

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

“…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. In the light of the diverse role of mucus, a frequent switch between TOC excretion and uptake might be related to the direction of mucus flow transporting mucus-trapped TOC into (uptake) or out of the coelenteron (excretion), where for corals of the HF the more frequently observed TOC uptake might be a consequence of the more frequent food uptake and inward-directed ciliate and mucus movement.…”

Bacterial Communities in Tissues and Surficial Mucus of the Cold-Water Coral Paragorgia arborea

“…The mucus of shallow-water scleractinian corals is subject to diurnal or hourly replacement cycles, and therefore its bacterial diversity and richness could be constantly changing (Ainsworth et al, 2010;Sweet et al, 2011). In the deep-water scleractinian Lophelia pertusa, bacterial communities within the tissues were more stable than those in mucus, which is continuously being replenished following release in the water column (Wild et al, 2008;Weinbauer et al, 2012). It has been previously documented that P. arborea produces abundant mucus (Etnoyer et al, 2006).…”

“…As only a few cold-water corals have been studied, there is a knowledge gap regarding these organisms' bacterial communities and their functional roles in the host. Previous studies have reported variability in bacterial compositions between octocoral genera (Brück et al, 2007), between congeners (Holm and Heidelberg, 2016;Kellogg et al, 2016), between coral microhabitats (Weinbauer et al, 2012), within species and between sampling locations (Gray et al, 2011). In this study, we characterized the bacterial associates of P. arborea across two compartments: (1) skeletal and polyp tissue, and (2) surface mucus, and examined the degree of similarity in bacterial composition across three study locations in the Gulf of Maine (ranging in depth between 411 and 700 m) to explore the effects of relative sampling location proximity and depth on bacterial composition.…”

Coral-associated viruses and bacteria in the Ha Long Bay, Vietnam

“…However, we have no direct evidence for this to occur in the present study. Another recent study on cold water corals reported that an experimental enrichment of viral and bacterial abundance in surrounding water did increase the abundances in the coelenteron but not in the mucus of corals, indicating some sort of ecological stability of epibiotic microbes (Weinbauer et al 2012). Alternatively, coral-associated bacterial communities have also been recognized for their ecological adaptation, being capable of strong physiological and genetic adjustments to cope with environmental disturban ces and to ultimately ensure coral viability (Reshef et al 2006.…”