Sensory Qualities of Oysters Unaltered by a Short Exposure to Combined Elevated pCO2 and Temperature

Abstract

Reliance on the marine environment for the provision of food is ever-increasing, but future climate change threatens production. Despite this concern, the impact on seafood quality and success of the seafood industry is unknown. Using a short-term study, we test these concerns using a major aquaculture species-Crassostrea gigas-exposing them to three acidification and warming scenarios: (1) ambient pCO 2 (∼400 ppm) & control temperature (15 • C), (2) ambient pCO 2 (∼400 ppm) & elevated temperature (20 • C), (3) elevated pCO 2 (∼1,000 ppm) & elevated temperature (20 • C). Oyster quality was assessed by scoring appearance, aroma, taste, and overall acceptability. A panel of five experts was asked to score nine oysters-three from each treatment-according to agreed criteria. Results indicate that these levels of acidification and warming did not significantly alter the sensory properties of C. gigas, and notably the overall acceptability remained unchanged. Non-statistically supported trends suggest that several sensory attributes-opacity, mouthfeel, aspect of meat, shininess, meat resistance, meat texture, and creaminess-may improve under acidification and warming scenarios. These findings can be considered positive for the future of the aquaculture and food sectors. Crassostrea gigas therefore is expected to remain a key species for food security that is resilient to climate change, whilst retaining its valuable attributes.

Changes in the biochemical and nutrient composition of seafood due to ocean acidification and warming

“…In the UK, oysters are one of the major aquaculture species (Pinnegar et al, 2017) with ~1600 tonnes produced in 2015, and worth more than US$6.4 million. Yet there is increasing concern over the long-term future of shellfish production due to the effects of environmental stressors associated with rising atmospheric CO 2 levels such as warming and marine heat waves, falling levels of seawater carbonate and oxygen plus rising sea levels and increased storminess (Branch et al, 2013;Cooley et al, 2015;Dupont et al, 2014;Ekstrom et al, 2015;Lemasson et al, 2017b). Ocean acidification and sea-surface warming are changing animal physiology and affecting the quality of seafood (Dupont et al, 2014 al., 2017).…”

“…This component is linked to juiciness, which is an important sensory trait of oysters and influences their marketability (Cruz-Romero et al, 2004). Sensory traits, such as juiciness, texture, appearance, odour or taste, are linked to biochemical composition, and have recently been shown to be unchanged in oysters under ocean acidification and warming (Lemasson et al, 2017b). As was also observed in Turbo militaris (Ab Lah, 2018), here the moisture content of either M. gigas or O. edulis did not change when exposed to ocean acidification and warming conditions.…”

“…In the UK, a reduction in the nutritional quality of oysters may not quickly be recognised by consumers, but lower energetic reserves and condition of M. gigas may hold an economic relevance to the aquaculture industry, since this species currently represents >90% of the production (Humphreys et al, 2014). Additionally, the biochemical composition can dictate meat appearance, aroma, taste and texture (Cochet et al, 2015;Fratini et al, 2013), and any changes in biochemical composition occurring because of ocean acidification and warming can impact on the sensory quality (Lemasson et al, 2017b). Therefore changes in biochemical composition under ocean acidification and warming can influence the consumer appeal for the product, reducing the demand for it and depressing its economic value (Cooley et al, 2012).…”

The effects of elevated CO2 on shell properties and susceptibility to predation in mussels Mytilus edulis

“…A mesocosm system was used to reach relevant CO 2 concentrations. Full details are described in Lemasson et al (2017b) to allow for brevity here. For 400 ppm, each tank contained an air stone, and atmospheric air was bubbled gently into each replicate tank.…”

“…Calosi et al, 2017). But wide-ranging negative effects of OAW have also been shown or are predicted to alter ecology, behaviour and physiology (Gazeau et al, 2013;Hughes, 2000;Lemasson et al, 2017a;Lemasson et al, 2017b). For instance, OA has been shown to alter predator-prey dynamics (Dixson et al, 2010;Harvey and Moore, 2017), intracellular pH, biological functioning (Pörtner et al, 2004), metabolism (Thomsen and Melzner, 2010), and individual energetic needs (Gray et al, 2017;Leung et al, 2017).…”