Growth and feeding of deep-sea coral Lophelia pertusa from the California margin under simulated ocean acidification conditions

Abstract

The global decrease in seawater pH known as ocean acidification has important ecological consequences and is an imminent threat for numerous marine organisms. Even though the deep sea is generally considered to be a stable environment, it can be dynamic and vulnerable to anthropogenic disturbances including increasing temperature, deoxygenation, ocean acidification and pollution. Lophelia pertusa is among the better-studied cold-water corals but was only recently documented along the US West Coast, growing in acidified conditions. In the present study, coral fragments were collected at ∼300 m depth along the southern California margin and kept in recirculating tanks simulating conditions normally found in the natural environment for this species. At the collection site, waters exhibited persistently low pH and aragonite saturation states (Ωarag) with average values for pH of 7.66 ± 0.01 and Ωarag of 0.81 ± 0.07. In the laboratory, fragments were grown for three weeks in “favorable” pH/Ωarag of 7.9/1.47 (aragonite saturated) and “unfavorable” pH/Ωarag of 7.6/0.84 (aragonite undersaturated) conditions. There was a highly significant treatment effect (P < 0.001) with an average% net calcification for favorable conditions of 0.023 ± 0.009% d−1 and net dissolution of −0.010 ± 0.014% d-1 for unfavorable conditions. We did not find any treatment effect on feeding rates, which suggests that corals did not depress feeding in low pH/ Ωarag in an attempt to conserve energy. However, these results suggest that the suboptimal conditions for L. pertusa from the California margin could potentially threaten the persistence of this cold-water coral with negative consequences for the future stability of this already fragile ecosystem.

Climate‐induced changes in the suitable habitat of cold‐water corals and commercially important deep‐sea fishes in the North Atlantic

“…In contrast, the direct link between POC flux and deep‐sea fish abundances has proven difficult to demonstrate (Bailey, Ruhl, & Smith, ), despite some evidence that increased surface production may fuel key fish prey taxa such as benthic invertebrates (Bailey et al, ; Drazen, Bailey, Ruhl, & Smith, ; Ruhl & Smith, ). Therefore, the projected decrease in food availability by 2100 in the North Atlantic (Gehlen et al, ; Gomez et al, ; Sweetman et al, ) may exacerbate the likely negative effects of other environmental changes.…”

“…Indeed, multiple studies link reduced food availability to reduced physiological performance (e.g. calcification and respiratory metabolism) and condition of cold-water corals (Büscher et al, 2017;Larsson, Lundälv, & van Oevelen, 2013;Naumann, Orejas, Wild, & Ferrier-Pagès, 2011), as well as their ability to cope with ocean change (Büscher et al, 2017;Georgian et al, 2016;Gomez et al, 2019;Maier et al, 2016;Wood, Spicer, & Widdicombe, 2008). In contrast, the direct link between POC flux and deep-sea fish abundances has proven difficult to demonstrate (Bailey, Ruhl, & Smith, 2006), despite some evidence that increased surface production may fuel key fish prey taxa such as benthic invertebrates (Bailey et al, 2006;Drazen, Bailey, Ruhl, & Smith, 2012;Ruhl & Smith, 2004).…”

“…& Gattuso, 2019; Movilla et al, 2014), the projected shoaling of the calcite and aragonite saturation horizons along with warming is expected to lead to the loss of suitable habitat (Davies & Guinotte, 2011;Perez et al, 2018;Sulpis et al, 2018;Tittensor et al, 2010;Yesson et al, 2012), weakening of the reef frameworks that may result in structural collapse of slow-growing scleractinian corals (Büscher et al, 2019;Gomez, Wickes, Deegan, Etnoyer, & Cordes, 2019;Hennige et al, 2015), and increased mortality of octocorals that form coral gardens (Cerrano et al, 2013;Gugliotti, DeLorenzo, & Etnoyer, 2019). Notwithstanding genotypic variability in cold-water corals' response to ocean acidification (Kurman, Gómez, Georgian, Lunden, & Cordes, 2017;Lunden, McNicholl, Sears, Morrison, & Cordes, 2014), these changes may result in the loss of biodiversity and provision of ecosystem services associated with these ecosystems .…”

Effects of low pH and feeding on calcification rates of the cold-water coralDesmophyllum dianthus

“…Indeed, many studies showed no significant response in calcification rate under high pCO 2 (Maier et al, 2012(Maier et al, , 2013Form & Riebesell, 2012), but the conclusions were based on incubations shorter than in the present study. More recent literature shows, however, a decrease in net calcification of these species under acidified conditions (Maier et al, 2016;Gómez et al, 2018). The response of solitary species such as D. dianthus has been less explored, but some of the few experiments exhibited signs of physiological stress (Carreiro-Silva et al, 2014), especially at certain life stages (Movilla et al, 2014).…”

“…The response of solitary species such as D. dianthus has been less explored, but some of the few experiments exhibited signs of physiological stress (Carreiro-Silva et al, 2014), especially at certain life stages (Movilla et al, 2014). Regarding other stressors in addition to OA, few studies have been carried out with CWCs, but several examined their response to low pH and food availability (Maier et al, 2016;Georgian et al, 2016;Büscher, Form & Riebesell, 2017;Gómez et al, 2018). Being sessile suspension feeders, CWCs strongly depend on food resources from the water column, which are often scarce (Roberts, Wheeler & Freiwald, 2006), so food availability is very likely a key constraint that modulates the effects of environmental stressors such as OA in these species.…”