Meeting Abstract
Eastern boundary upwelling systems (EBUS) are productive ecosystems that support as much as one-fifth of global fish harvest and are highly vulnerable to climate change. As a result of naturally-high CO2 (low pH) conditions, EBUS have a reduced capacity to buffer against changes induced by the uptake of anthropogenic CO2. The California market squid, Doryteuthis opalescens, represents one of the most ecologically and economically important species in the California Current system. While adults are highly mobile, developing D. opalescens embryos are attached to the substrate and must be able to survive fluctuations in environmental conditions during development. To investigate the effects of low pH and low oxygen on squid development, embryos were harvested in La Jolla, CA and reared in replicate flow-through seawater tanks of ambient (control; 240 µmol/kg O2, pH 7.95) and low-pH, low-O2 (low pHOx; 90 µmol/kg O2, pH 7.55) until hatching. These conditions represent the limits of pHOx observed in squid spawning habitat. Embryos exposed to low pHOx upregulated stress-response and oxygen-sensitive genes, and altered expression of genes associated with cell-cycle regulation, development and lipid utilization. Embryos exposed to low pHOx conditions also experienced an 11% increase in incubation time and 4% decrease in hatching success. These results suggest that exposure to chronic low pHOx, even within ranges typically found in the environment, represents a physiological stress for D. opalescens embryos. Understanding the mechanisms that enable developmental resilience to variable environmental conditions, and their limitations, will be important for predicting EBUS organismal response to future climate change.
