Meeting Abstract
The European green crab, Carcinus maenas, is variable in ventral sternite coloration, green after molting and often dark red after prolonged intermolt. Previous studies reported that red morphs are less stress tolerant than green morphs. We tested this previously by exposing crabs of both colors to 2h anoxia and assessed their subsequent motor activity as righting time after flipping them on their back. Green morphs maintained constantly fast while red morphs slowed down from 1 to 6 sec with corresponding differences in lactate accumulation, AMPK activity and HSP70 protein expression. To test how this differential stress tolerance changes throughout the molt cycle from green to red, we used freshly molted juvenile green crabs and assessed weekly their coloration, and tolerance to severe hypoxia. For accelerating the molt cycle and the associated color change we performed eyestalk ablation (ESA) on half of the animals, as ESA has been shown to accelerate molting in crabs. Unexpectedly, the duration of the molt cycle in controls and the ESA group was equal (54-64 days). Additionally, animals did not progress through all of the colors before molting. ESA animals increased in red/green ratio 2 fold, while controls’ color did not change. Despite the lack of color change, some of these animals molted. However, stress tolerance to hypoxia in the ESA animals decreased gradually from 2.1±2.3 to 6.2±3.1 sec, while remaining constant at 1.5±0.9 for controls. This change was only correlated to time in the molt cycle, but not to ventral sternite coloration. Our data show gradual change in stress tolerance through a full molt cycle and indicate that ventral sternite coloration is most likely not mechanistically linked to the respective stress tolerance. Funded by a Maine Space Grant Consortium award to G.P.
