How do warmer, more acidic waters affect newly hatched cuttlefish’s camouflage and movement?

Details

Researchers tested common cuttlefish hatchlings in water warmed by 3 °C, water made more acidic, and water with both changes. The treatments represented projected end-of-century conditions. They observed the animals on sand and black-and-white gravel, using recordings and photographs to assess movement, the time taken to camouflage and body patterns.

Movement-related behavior was not detectably affected by the treatments. On gravel, however, hatchlings exposed to both warming and acidification took longer to camouflage than those exposed to warming alone. Under warming, the animals showed stronger light-and-dark contrasts in patterns that break up their outline. Their degree of background matching did not change. The results therefore suggest changes in particular camouflage responses rather than an overall breakdown of camouflage.

The behavioral findings do not mean the conditions were harmless. Hatching success was 72.7% under combined warming and acidification, compared with 98.8% under control conditions. This experiment describes responses under the tested conditions; it does not establish how cuttlefish will fare across all future ocean environments.