The Effects of a CO2-Driven Decrease in pH on Aspects of Larval American Lobster, Homarus Americanus H. Milne-Edwards 1837, Development: A Simplified Model of Near-Future Ocean Acidification Effects

Although ocean acidification has continued to garner well deserved attention from the scientific community, a startling lack of research has been committed to its effects on juvenile organisms. As many marine organisms are r-strategists, increasing the stressors on developing individuals could have huge effects on population dynamics; one commercially important species that may be affected in the American Lobster, Homarus americanus. This paper looks at the expression of three immune-related genes and the mineral content of the shells of juvenile H. americanus that were raised in carbon dioxide driven reduced pH seawater from hatch through 42000 degree*hours (°C*hrs) in an attempt to assess the chronic effects on individuals. Gene expression showed the cyclical nature of hormones in crustaceans. Analysis of shell composition showed a significant drop in calcium levels after metamorphosis of the larvae to juvenile form in the low pH group, a result that confirms earlier studies on the closely related European Lobster, H. gammarus. Total lengths and weights were also significantly lower in the low pH group when compared to the control group. In addition to these effects, the presence of intermediate staged larvae in the low pH group indicates that larval development at near-future ocean pH levels is compromised in measurable amounts; though the repercussions of the effects are unknown on the overall population dynamics in the Northeastern region of North America, it clearly demonstrates the importance of continuing research on such a commercially important species.