Larval responses of a prey and a predator to ocean acidification

Chair: Peter Thor

Camilla Campanati1, Sam Dupont2, Gray A. Williams1, Vengatesen Thiyagarajan1

 

1 The Swire Institute of Marine Science and School of Biological Sciences, The

University of Hong Kong, Hong Kong SAR, China

2 Department of Biological and Environmental Sciences, University of Gothenburg,

566 Kristineberg, Fiskebäckskil 45178, Sweden

 

Background:

In future climate change scenarios, the survival and responses of key coastal foundation species are critical for the persistence of biodiversity in near-shore ecosystems. Intertidal organisms, by being naturally exposed to large environmental fluctuations, have often been considered more resilient towards future conditions than sub-tidal ones, although with contrasting evidences. Under near-future acidified waters the most vulnerable early life stages could act as population “bottlenecks”. Moreover, organismal fitness in a high-CO2 world is not absolute, as eventually the individuals’ success would also depend on the responses of co-interacting species (e.g. predators). Differential dispersal capacities and growth rates between a prey and a predator at the early-life stages could alter their interspecific dynamics at the adult stage. Future acidification responses of the rock oyster Saccostrea cucullata, a dominant ecosystem engineer in the Indo-Pacific region, and its predator, the muricid gastropod Reishia clavigera, were evaluated in their planktonic early-life stages.

Methods:

Considering the natural range of pH experienced and future conditions from the IPCC projections, we exposed newly hatched larvae of S.cucullata and R. clavigera to 3 different levels of pH ranging from ΔpH =-0.3 to -0.7 pH units for 12 and 15 days of development respectively. The larvae were cultured during the same season, under the same temperature and salinity regimes, and fed with microalgae. Several endpoints, such as larval survival, growth, respiration rate, shell accretion and dissolution were measured for the species throughout their developmental exposure to low pH.

Findings:

Under the same pH exposure, the larvae of the two species showed different sensitivities and growth patterns, with more obvious shell dissolution at the lowest pH conditions.

Conclusions:

Although naturally experiencing the same environment at the hatching time, the early-phases of the two intertidal species present differential tolerances and acclimation capacities under elevated pCO2. I will discuss the causes and infer potential functional consequences for their interaction at the adult stage.