Elevated pCO2 Affects Feeding Behavior and Acute Physiological Response of the Brown Crab Cancer pagurus

Abstract

Anthropogenic climate change exposes marine organisms to CO2 induced ocean acidification (OA). Marine animals may make physiological and behavioral adaptations to cope with OA. Elevated pCO2 may affect metabolism, feeding, and energy partition of marine crabs, and thereby affect their predator-prey dynamics with mussels. Therefore, we examined the effects of simulated future elevated pCO2 on feeding behavior and energy metabolism of the brown crab Cancer pagurus. Following 54 days of pre-acclimation to control CO2 levels (360 μatm) at 11°C, crabs were exposed to consecutively increased oceanic CO2 levels (2 weeks for 1200 and 2300 μatm, respectively) and subsequently returned to control CO2 level (390 μatm) for 2 weeks in order to study their potential to acclimate elevated pCO2 and recovery performance. Standard metabolic rate (SMR), specific dynamic action (SDA) and feeding behavior of the crabs were investigated during each experimental period. Compared to the initial control CO2 conditions, the SMRs of CO2 exposed crabs were not significantly increased, but increased significantly when the crabs were returned to normal CO2 levels. Conversely, SDA was significantly reduced under high CO2 and did not return to control levels during recovery. Under high CO2, crabs fed on smaller sized mussels than under control CO2; food consumption rates were reduced; foraging parameters such as searching time, time to break the prey, eating time, and handling time were all significantly longer than under control CO2, and prey profitability was significantly lower than that under control conditions. Again, a two-week recovery period was not sufficient for feeding behavior to return to control values. PCA results revealed a positive relationship between feeding/SDA and pH, but negative relationships between the length of foraging periods and pH. In conclusion, elevated pCO2 caused crab metabolic rate to increase at the expense of SDA. Elevated pCO2 affected feeding performance negatively and prolonged foraging periods. These results are discussed in the context of how elevated pCO2 may impair the competitiveness of brown crabs in benthic communities.

Effects of Elevated pCO2 on the Survival and Growth of Portunus trituberculatus

“…Our results showed that OA has a mixed effect on swimming crabs, with increased survival and retarded growth. The negative effect on growth is in line with findings published for other crab species such as larvae of H. araneus ( Walther et al, 2010 ; Schiffer et al, 2013 , 2014 ; Wang et al, 2018 ), Paralithodes camtschaticus , and Chionoecetes bairdi ( Long et al, 2013a , b ), as well as embryos of Petrolisthes cinctipes ( Carter et al, 2013 ; Ceballos-Osuna et al, 2013 ). Such a consensus between studies performed on different species, at different stages of development and with p CO 2 ranging from 710 to 3100 μatm, strongly supports crab sensitivity to OA.…”

“…Ocean acidification has comprehensive effects on the growth and development ( Long et al, 2013a ), physiology and metabolism ( Maus et al, 2018 ), morphology ( Ren et al, 2017 ), and behavior of a variety of marine crabs ( Wang et al, 2018 ). However, the effects of OA have been reported only on the carapace morphology and behavior of juvenile P. trituberculatus ( Ren et al, 2017 , 2018 ).…”

“…Three experimental OA groups were designed with seawater p CO 2 at current or predicted future levels: the ambient p CO 2 was 380 μatm (designated the 380 group), 750 μatm (designated the 750 group) was used to represent the scenario at the end of this century and 1500 μatm (designated the 1500 group) was used to represent the scenario in c. 2200 ( Revi et al, 2014 ; Gattuso et al, 2015 ). To build the experimental systems, a simulated ocean acidification system (CN: ZL201520071087.1) ( Ren et al, 2018 ) and an incubation system that was partially derived from the experimental system of Wang et al (2018) were used. For each group, the incubation system per group consisted of a mixing tank (500 L) and three individual culture tanks (300 L), and seawater was recirculated and purified by using a water purification header tank connected to the culture tanks (200 L).…”

Ocean acidification and hypoxia alter organic carbon fluxes in marine soft sediments

“…Ocean acidification can negatively affect benthic marine invertebrates, either directly, by altering physiological processes (Pan et al, ; Wang, Hu, Wu, Storch, & Poertner, ; Widdicombe & Spicer, ), or indirectly, via modification of food web interactions (Duarte et al, ; Kamya et al, ; Queirós et al, ). Previous studies have shown that elevated CO 2 can result in reduced growth rate, disruption of extracellular acid–base balance, alteration of metabolism, lethargy and modification of individual level trade‐offs in energy consuming processes of invertebrates, across different taxonomic groups (Kroeker, Kordas, Crim, & Singh, ; Portner & Farrell, ; Widdicombe & Spicer, ).…”

Impacts of Global Warming and Elevated CO2 on Sensory Behavior in Predator-Prey Interactions: A Review and Synthesis

“…Elevated CO 2 may cause some indirect physiological effects with behavioral consequences for predator-prey interactions. High CO 2 levels can indirectly decrease foraging success of brown crab predators (Cancer pagurus) through increased resting metabolic rates and thus less energy allocated to foraging behavior (Wang et al, 2018). Thick shell mussels (Mytilus coruscus) also experience reduced excretion rates in elevated CO 2 conditions, which may indirectly affect chemical cues used by predators although this has not been tested (Wang et al, 2015).…”