Effects of ocean acidification on the early developmental stages of the horned turban, Turbo cornutus

Abstract

To estimate the impact of CO2-driven ocean acidification on the early life stages of gastropods, the effects of increased partial pressure of seawater carbon dioxide (pCO2) (800–2,000 μatm) on the early developmental stages and larval shell length of the commercially important gastropod, the horned turban snail, Turbo cornutus were investigated. Increase in experimental seawater pCO2 had an increasingly negative impact on the early developmental rate; the proportion of embryos or larvae displaying retarded development increased at higher pCO2. The proportion of embryos that developed to the 4-cell stage at 2 h after fertilization decreased linearly with increasing pCO2. At ~1,000 μatm pCO2, retarded development was observed in ~50 % of larvae. No embryos developed to the 4-cell stage at 2,000 μatm pCO2 within 2 h of fertilization. A similar trend continued until 24–26 h after fertilization; the proportion of larvae attaining veliger stage by 24–26 h also decreased with increasing pCO2. The shell length of T. cornutus veligers decreased gradually as seawater pCO2 increased, but markedly decreased in seawater under nearly unsaturated and unsaturated conditions (≤1.04) of the aragonite saturation state (Ωaragonite). The results indicate that increased pCO2 seawater has a progressive and acute effect on embryonic and larval T. cornutus, and imply that the extended early developmental period and/or the downsized larval shell produced by ocean acidification will have a negative impact on survival, settlement and recruitment well into the future.