Abstract
Changes in coloration enable animals to refine their camouflage to match different visual environments. Such plasticity provides ecological benefits and could potentially be exploited to support conservation or stock enhancement efforts. One application could be ensuring that hatchery-reared animals, reared to stock wild populations, are appropriately matched to their environment on release. European lobster (Homarus gammarus) hatcheries aim to restock or enhance local lobster populations by rearing juveniles through their most vulnerable stages, then releasing them into the wild. However, little consideration has been given to their camouflage and the implications of matching individuals to their release site. This study assesses to what extent juvenile lobsters can change coloration to match their background and whether hatchery practices could be altered to enhance lobster camouflage. We test this by switching individuals between black or white backgrounds in the laboratory and monitoring their coloration over time. Our work demonstrates the capacity of juvenile lobsters to change lightness in response to their surroundings. We show that juvenile lobsters are capable of small changes in luminance (perceived lightness) to better match their background over 2-3 weeks. These changes potentially correspond to improved camouflage, based on a model of predator (European pollack, Pollachius pollachius) vision. However, over a longer period (5 weeks), lobsters maintained on either background converged on the same darker coloration, suggesting that lobsters also experience changes in appearance associated with ontogeny. By refining the approaches used here, there is potential for hatcheries to rear lobsters on backgrounds that better match their release site. However, such manipulations should be considered in the context of ontogenetic changes and release timing (which varies between stocking programmes). This study highlights the potential to use colour change in stocking and aquaculture, as well as gaps that could be addressed through further research in this area.
Footnotes
Abstract has been reduced to 300 words. Introduction now contains more detail on lobster ecology to provide more context to the study. Methods section has been updated to include further information on the moult cycle and the feeding regime to aid replication of the study. All figure and table captions have been revised for clarity. Discussion has been updated to clarify that there is potential for this work to be applied to stocking and that there is scope for the approaches to be refined with further research. Wording on the potential implications for survival has been updated to clarify that this is a possible benefit, not one tested in this study. Manuscript has been reformatted according to journal requirements. Supplemental files updated.
