Physiological effects of environmental acidification in the deep-sea urchin <i>Strongylocentrotus fragilis</i>

Abstract

Abstract. Anthropogenic CO 2 is now reaching depths over 1000 m in the Eastern Pacific, overlapping the Oxygen Minimum Zone (OMZ). Deep-sea animals are suspected to be especially sensitive to environmental acidification associated with global climate change. We have investigated the effects of elevated pCO 2 and variable O 2 on the deep-sea urchin Strongylocentrotus fragilis, a species whose range of 200-1200 m depth includes the OMZ and spans a pCO 2 range of approx. 600-1200 µatm (approx. pH 7.6 to 7.8). Individuals were evaluated during two exposure experiments (1-month and 4 month) at control and three levels of elevated pCO 2 at in situ O 2 levels of approx. 10 % air saturation. A treatment of control pCO 2 at 100 % air saturation was also included in experiment two. During the first experiment, perivisceral coelomic fluid (PCF) acid-base balance was investigated during a one-month exposure; results show S. fragilis has limited ability to compensate for the respiratory acidosis brought on by elevated pCO 2 , due in part to low non-bicarbonate PCF buffering capacity. During the second experiment, individuals were separated into fed and fasted experimental groups, and longer-term effects of elevated pCO 2 and variable O 2 on righting time, feeding, growth, and gonadosomatic index (GSI) were investigated for both groups. Results suggest that the acidosis found during experiment one does not directly correlate with adverse effects during exposure to realistic future pCO 2 levels.

Habitat compression and expansion of sea urchins in response to changing climate conditions on the California continental shelf and slope (1994–2013)

“…fragilis (Taylor et al, 2014), and trawl surveys at 5-yr intervals could not reveal the influence of 20 ENSO events on L. pictus populations. To determine the feasibility of urchin migration as a possible mechanism for the observed depth changes, we estimated the average slope of the continental shelf and slope in the SCB using Google Earth.…”

Chasing the Future: How Will Ocean Change Affect Marine Life?

“…Each CT (7.6-liter RubberMaid Model 1530 water cooler) is equipped with a float valve to regulate seawater input, sensors (T, DO, pH), a gas input line connected to a diffuser stone, a 600-watt heater, and a drain with a distribution manifold that connects delivery rates according to pH and DO set points. The GCA has supported several studies evaluating the response of a variety of deep-sea animals to future deep-sea conditions (e.g., Pane and Barry, 2007;Pane et al, 2008;Kim et al, 2013a,b;Taylor et al, 2014;Hamilton et al, 2017).…”

Ocean acidification may alter predator-prey relationships and weaken nonlethal interactions between gastropods and crabs

“…The pH was modified in one of the header tanks via bubbling with a CO 2 /air mixture sufficient to maintain the desired 0.3-unit pH reduction, also based on North Pacific estimates for 2100 under RCP6.0 (Pachauri et al 2015). This headertank system means that CO 2 treatments were not true replicates, but similar systems have been used previously for OA research (Taylor et al 2014, Lord et al 2017, and it was the only feasible way to implement a continuous offset, constantly changing pH system for all 32 elevated CO 2 tanks simultaneously. Flow of the air-gas mixture was controlled by a solenoid valve attached to a MBARI-built control system which utilized LabVIEW™ (National Instruments) software and a proportional-integrative-derivative controller to keep pH 0.3 units below ambient seawater conditions.…”