Will coralline algae reef protect marine biodiversity against climate changes?

Scientific evidence for climate change is unequivocal, but how marine ecosystems will be affected is still an open question. While studies have been focusing on the survival of biogenic reefs, little has been done on the mitigating effects that the biogenic structures can exert on the associated fauna and their functional strategies/traits in future oceans. In this study we used 3D artificial reef proto-types, resembling structures of natural coralline algae to study the mitigation effects of the natural algae reef on its associated fauna under the 2100 future climate scenario. Sixty artificial reefs (5x5 cm2) were created and transplanted within the natural reefs (1 site, 3 areas) in the Gulf of La Spezia (Italy). Natural and artificial reefs (5x5 cm2) were collected after 5 months and a subset of samples (4 artificial and 4 natural reefs) was collected after 4 months to analyse the similarities on their associated fauna. After collection, the reefs were transferred to the lab and cultured at high CO2 (1000 µatm CO2) for 2 months. At the beginning and at the end of the experiment photosynthesis and respiration of the reefs were measured. The fauna assemblages of the artificial reef showed a rather high similarity (over 60%) compared to the natural reefs. The photosynthesis of the high CO2 natural reef was 45 % lower compared to the control after the CO2 acclimatization phase. Fauna assemblages sorted from natural and artificial reefs will be analysed at species level in order to estimate changes in diversity, abundance and relevant functional traits.