Science Source

Rising pCO2 in Freshwater Ecosystems Has the Potential to Negatively Affect Predator-Induced Defenses in Daphnia

States that surprisingly little is known about the impact of anthropogenically caused CO2 on freshwater systems due to their more complex biogeochemistry
Analyzes long-term data from four freshwater reservoirs and observed a continuous pCO2 increase associated with a decrease in pH, indicating that not only the oceans but also inland waters are accumulating CO2
Tests the effect of pCO2-dependent freshwater acidification using the cosmopolite crustacean Daphnia
Bases control pCO2-levels on the present global pCO2average for general validity
Selects treatments with very high pCO2 levels, assuming a continuous non-linear increase of pCO2, reflecting worst-case-scenario future pCO2levels
Finds that such levels of elevated pCO2 reduce the ability of Daphnia to sense its predators and form adequate inducible defenses
Determines that pCO2 and not the resulting reduction in pH impairs predator perception
Concludes that if pCO2alters chemical communication between freshwater species, this perturbs intra- and interspecific information transfer, which may affect all trophic levels