Meeting Abstract
The phyllosome larvae of spiny lobsters spend months developing in the open-water environment, potentially leaving them vulnerable to the influence of decreasing pH and increasing temperature. Here, we studied the survival and growth of California spiny lobster (Panulirus interruptus) phyllosoma exposed to reduced pH and increased temperature conditions. We hypothesized that warmer temperature alone would accelerate the progression to later larval stages, but reduced pH and combined stressors would increase mortality and slow growth. Two hatches of California spiny lobster phyllosoma (8 replicates/treatment, 20 to 25 larvae/replicate) were exposed to ambient pH and temperature (8.04, 18.5 °C), increased temperature (8.04, 22.2 °C), reduced pH (7.66, 18.4 °C) and combined reduced pH and increased temperature (7.67, 22.4 °C) conditions for 3.5 (hatch 1) or 5 weeks (hatch 2). Larvae were checked for survival every three days, and a subset from each treatment were staged daily starting at 2.5 weeks. By 3.5 weeks of exposure, 33% of hatch 1 and 42% of hatch 2 in both increased temperature treatments reached Stage III of XI, rising to 100% at 5 weeks. In contrast, only 0-4% had reached this stage in the ambient and reduced pH treatments by 5 weeks. After 3.5 weeks, 15% of hatch 1 larvae exposed to increased temperature/reduced pH were alive, significantly more than the 2% of other treatments. At 5 weeks, there was no difference in hatch 2 survival among treatments (p=0.60). These findings indicate that there are no negative effects of early exposure to reduced pH on the growth rate and survival of larval California spiny lobsters, but increased ocean temperature speeds up larval development, potentially reducing larval duration and bolstering settlement.
