Meeting Abstract
Spiny lobsters boast predator defenses that function at far and near ranges to comprise multi-tiered protection. These include antennule flicking to detect distant sources of chemical cues, long antennae that push away interlopers, and a spiny exoskeleton to act as armor. Due to incorporating external elements in the exoskeleton and relying on external chemical cues, changes to ocean chemistry (ocean acidification) have the potential to disrupt these multiple modes of defense. We exposed 64 juvenile California spiny lobsters (Panulirus interruptus) to either ambient pH (7.97) or one of three reduced pH treatments (stable pH, 7.67; two levels of diurnal fluctuating pH, 7.67 ±0.05 and ±0.10) for three months. We then introduced a chemical cue (mussel slurry) to lobster tanks and recorded antennule flicking rate. We also examined the structure and mechanical properties of three exoskeleton regions (carapace, horn, and antenna) using SEM and nanoindentation. Preliminary results indicate that lobsters in ambient conditions responded to chemical cues with increased antennule flicking, but this response was significantly depressed in lobsters in reduced-pH water, indicating potential changes to either the cue molecules or sensory cells. Exposure to fluctuating reduced pH decreased the hardness of the horn and carapace in comparison to those in ambient and stable reduced pH, although there were no detectable changes in exoskeleton structure. These results demonstrate the importance of implementing natural environmental variation while also revealing that the defenses allowing spiny lobsters to detect threats from a distance and defend themselves at close range may be compromised under ocean acidification conditions.
