Behavioral plasticity of decorations in a polychaete ecosystem engineer in western Atlantic salt marsh systems

Aim Animals inhabiting temperate ecosystems often use behavioral plasticity to adapt to seasonally changing environmental conditions. Behavioral changes by ecosystem engineers in response to regular thermal cycles, extreme thermal events, or increasing average temperatures may also change the ambient environment, exacerbating these thermal events. The predatory marine worm Diopatra cuprea decorates its tube cap with shells, algae, and plant matter in Mid-Atlantic, USA salt marshes. This decoration behavior has assisted in the persistence and spread of the non-native, red macroalga Gracilaria vermiculophylla in soft bottom habitats. Previous work has shown that decoration patterns can vary across biogeographic regions, suggesting that local environmental factors can affect D. cuprea behavior. We investigated the patterns of plasticity of D. cuprea decoration behavior across populations and seasons. Location Coastal marsh systems along the Atlantic coasts of Delaware, Virginia, and North Carolina. Methods We surveyed D. cuprea decoration behavior and available decoration materials in coastal marsh systems of the Mid-Atlantic. We then perform repeated choice experiments in the laboratory to observe if D. cuprea decoration choices varied with site of origin. Results Diopatra cuprea decoration in the field varied among seasons and regions but was similar to the available decorations in the environment. In the laboratory, D. cuprea decorated with materials common to their site of origin. Decoration percentage observed in the field did not match those observed in the laboratory experiments. Main Conclusions Local hydrology and availability of material are likely the greatest influences on D. curpea decoration in the field. In the laboratory, D. cuprea exhibited site-specific preferences possibly due to previous exposure, showing evidence of fixed decoration preferences in the population. These findings underscore the importance of individual variation in mediating behavioral responses to environmental conditions, with implications for how habitat-modifying species like D. cuprea may adapt to shifting ecological conditions.