Meeting Abstract
The coloration of many caridean shrimp allows them to blend into their environment but with a degree of success that can depend on both physiology and cuticle structure. While decreased ocean pH and increased temperature—consequences of increased atmospheric pCO2—may affect both animal characteristics, their impact on color change has yet to be explored. Here, we exposed the grass shrimp Hippolyte californiensis to low pH and increased temperature to determine the effect on growth, calcification, and the ability to match environmental color cues of their eelgrass habitat. For seven weeks, solitary shrimp experienced ambient pH and temperature (7.98, 17°C), low pH and ambient temperature (7.53, 17°C), or low pH and increased temperature (7.48, 20°C). After five weeks, the ambient light color was changed from white to green. Carapace length and mass were measured for growth, cuticle mineral ratios were analyzed via inductively-coupled plasma mass spectrometry, and coloration was determined from digital imaging taken under controlled settings and analyzed as red, green, and blue channels in Photoshop. Shrimp showed no significant differences in growth or coloration. However, shrimp in low pH, high temperature conditions had significantly higher ratios of 26Mg/48Ca and 86Sr/25Mg than those in ambient conditions. These findings indicate that these shrimp have sufficient capabilities to compensate for pH changes in their environment in order to maintain growth, mineralization, and coloration, which are perhaps derived from living in eelgrass with diurnal pH changes. Yet, the combined effect of increased temperature and low pH seems to alter the calcification process and change the composition of the cuticle.
