Abstract

Understanding the impact of increases in pCO(2) (OA) and extreme changes in temperature on marine organisms is critical to predicting how they will cope with climate change. We evaluated the effects of OA as well as warming and cooling trend temperature on early reproductive traits of Lessonia trabeculata, a bio-engineer kelp species. Son discs were maintained for an exposure time (ET) of 3 (T3) and 7 (T7) days to one of two contrasting pCO(2) levels (450 and 1100 mu atm). In addition, at each pCO(2) level, they were subjected to three temperature treatments: 15 degrees C (control), 10 degrees C (cool) and 19 degrees C (warm). Subsequently, we compared sorus photosynthetic performance (Fv/Fm), the number of meiospores released (MR) and their germination rate (GR) after 48 h of settlement, with values obtained from sore discs not exposed (DNE) to the treatments. The Fv/Fm measured for DNE was lower than at T3 and T7 at 10 and 15 degrees C but not at 19 degrees C. Regardless of temperature, we found no significant differences between MR measured at TO and T3. MR at T7 was significantly lower at 19 degrees C than at 10 and 15 degrees C. We found only a significant reduction in MR in response to elevated pCO(2) at T3. The GR of meiospores released by DNE and then maintained for 48 h to 19 degrees C decreased significantly by similar to 33% when compared with those maintained for the same time at 10 and 15 degrees C. A similar, but more drastic reduction (similar to 54%) in the GR was found in meiospores released by son discs exposed for T3 and maintained for 48 h to 19 degrees C. We suggest that OA and warming trend will threaten the early establishment of this species with further consequences for the functioning of the associated ecosystem.