Cleaning determine physiological acclimation capacity to the ocean of tomorrow

Chair: Elvira Poloczanska

José Ricardo Paula (1)*, Miguel Baptista (1), Alexandra S. Grutter (2), Rui Rosa (1)

1 MARE – Marine and Environmental Sciences Centre, Laboratório Marítimo da Guia, Faculdade de Ciências da Universidade de Lisboa, Av. Nossa Senhora do Cabo, 939, 2750-374 Cascais, Portugal
2 School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia

Background
Climate change represents the greatest threat to global diversity as CO2 atmospheric concentration is expected to rise up to 940 ppm by 2100. Recent models predict that this will lead to an increase of 2.7°C in sea surface temperature and a decrease of 0.14-0.42 units in seawater pH. Cleaning mutualisms are key ecological components in coral reef ecosystems. These mutualisms are one of the most common interspecific interactions and involve a cleaner organism that removes and eats ectoparasites from their client fish. Nevertheless, there’s still little knowledge on how multispecies interactions are affected by effects of climate change. In order to understand how cleaning interactions might affect physiological acclimation of clients we tested their physiological responses accounting with cleaner fish presence in each reef.

Methods
In this experiment we collected resident client fish Pomacanthus amboinensis from patch reefs around Lizard Island. These patch reefs have the longest running experiment of cleaner fish removal, used to understand the ecological effects of cleaning, where selected treatment reefs are kept without cleaners since 2000. We’ve collected fish from reefs with and without clients and exposed them to future oceanic conditions. Following exposure fish physiological responses were analysed to characterize their acclimation capacity.

Findings
All fitness measures indicate that cleaner fish absence, possible higher parasite loads and lack of interactions through fish life intensify the negative effects of ocean acidification and ocean warming, making harder to acclimate to future oceanic conditions.

Conclusions
In this study we’ve shown for the first time that under near future oceanic conditions cleaning interactions (in tropical coral reefs) might dictate client fish acclimation potential. Our results provide the first evidence that multispecies interactions need to be analysed together to better determine each species acclimation potential.