Increased temperature but not pCO2 levels affect early developmental and reproductive traits of the economically important habitat-forming kelp Lessonia trabeculata

The effects of ocean warming and ocean acidification on developmental and reproductive traits of Lessonia trabeculata were evaluated. Meiospores were cultured for 35 days in an experimental mesocosm where temperature (similar to 15 and 19 degrees C) and partial CO2 pressure (pCO(2), similar to 400 and 1300 mu atm) were controlled. The results indicate that germination was reduced at 19 degrees C, whereas the increase of pCO(2) only had effects at 15 degrees C. Likewise, the increase in temperature significantly affected the vegetative growth of female gametophytes. Sex ratio was not affected significantly by any of the variables studied. Fertility and reproductive success decreased by about 50% at 19 degrees C. The pCO(2) levels had no significant effects on most early developmental traits. The results suggest that ocean warming or periodic warming events (e.g. an El Nino event) might affect the recruiting capacity of this or other similar species by affecting their early developmental stages.