Paper Reviewed
Knapp, J.L., Bridges, C.R., Krohn, J., Hoffman, L.C. and Auerswald, L. 2015. Acid-base balance and changes in haemolymph properties of the South African rock lobsters, Jasus lalandii, a palinurid decapod, during chronic hypercapnia. Biochemical and Biophysical Research Communications 461: 475-480.

According to Knapp et al. (2015), relatively few studies have examined the effects of ocean acidification on crustaceans, and those that do reveal a wide range of responses, making it difficult to generalize its anticipated impacts. Thus, they say, more research is necessary, especially in the form of long-term studies that persist beyond just a few days; and in an effort to fill this data void, the team of five researchers set out to investigate the impact of ocean acidification on the South African rock lobster (Jasus lalandii), a commercially valuable cold-water species inhabiting shallow waters off the western coast of southern Africa.

To accomplish their objective, Knapp et al. collected juvenile rock lobsters from an offshore oyster farm in Langebaan Lagoon, Western Cape, South Africa, which were then transported to a controlled laboratory setting in Cape Town. After acclimating the juveniles for a period of four months, half were placed in a pH treatment maintained at 7.3 (hypercapnic) and half at a pH treatment of 8.0 (the control). At the end of the experiment (195 days, approximately 28 weeks), differences in lobster weight and carapace length were examined, as well as changes in the lobsters' extracellular fluid (haemolymph).

Results indicated there was no statistical difference in lobster weight or carapace length among the two pH treatments at the end of the experiment. In addition, the authors report the juvenile lobsters were "capable of bicarbonate buffering of their haemolymph to provide optimum pH conditions for oxygen binding," which helped "to ensure functioning of respiration during prolonged hypercapnia." They also state that "modification of the intrinsic structure of the haemocyanin molecule, and possibly the presence of molecular modulators, seems to improve oxygen affinity under conditions of elevated pCO2." Such adaptation, however, may not be all that surprising given that Knapp et al. report frequent upwelling events are common in the marine environment from which the juvenile lobsters were acquired, events in which "the pH can drop to levels as low as 6.6 for several days." Taken together, these observations suggest the South African rock lobster will likely be little impacted by future ocean acidification over the next century and beyond.