Interactive effects of ocean acidification and settlement biofilm on the early development of the European abalone Haliotis tuberculata
Auzoux-Bordenave, S.; Kavousi, J.; Nedelec, K.; Martin, S.; Badou, A.; Dubois, P.; M'Zoudi, S.; Hubas, C.; Huchette, S.; Roussel, S. (2026). Interactive effects of ocean acidification and settlement biofilm on the early development of the European abalone Haliotis tuberculata. Mar. Pollut. Bull. 227: 119412. https://dx.doi.org/10.1016/j.marpolbul.2026.119412
Ocean acidification (OA) and associated shifts in carbonate chemistry represent major threats to marine organisms, particularly calcifiers. OA effects can be influenced by other environmental variables, including the biotic environment. This study investigated the effects of OA and algal density, acting through an Ulvella-conditioned settlement biofilm, on post-larval and juvenile abalone (Haliotis tuberculata). In a three-month full factorial experiment, abalone were exposed from metamorphosis onward to two pH conditions (ambient 8.0 and reduced 7.7) and two initial densities of the green alga Ulvella lens on settlement plates. Biofilm biomass and composition were characterised using spectral reflectance and HPLC pigment analysis. Biological (density, length), physiological (respiration rate), behavioural (hiding response) and shell parameters (colour, surface corrosion, strength) of abalone were measured. Biofilm biomass and composition assessed with pigment proxies remained relatively stable under both pH conditions, though greater variability in algal biomass occurred at low initial Ulvella density. Post-larval density and total length decreased significantly under low pH, while high Ulvella density reduced juvenile length at 80 days, likely due to competition between algal groups. A pH × Ulvella interaction affected shell fracture resistance and colouration, but not metabolism or behaviour, indicating that juvenile abalone maintained vital functions. Overall, the results confirm the sensitivity of early H. tuberculata stages to moderate OA (−0.3 pH unit) and highlight indirect macroalgal effects through changes in diatom cover. In natural environment, the capacity of abalone to cope with future OA will depend on complex trade-offs between direct acidification effects and food-related biotic interactions.
All data in the Integrated Marine Information System (IMIS) is subject to the VLIZ privacy policy
