Highlights
• This is the first known study evaluating combined temperature and pCO2 effects on cercarial life history traits.
• A trade-off between cercarial emergence and survival was observed at high water temperature.
• Combined effects of higher levels of temperature and pCO2 reduce cercarial survival.
• Combined levels of temperature and pCO2 produce species-specific responses in emergence of cercariae.
• It is suggested that infection of these trematode species in upwelling areas could increase in the future.
Abstract
Ocean warming and acidification are general consequences of rising atmospheric CO2 concentrations. In addition to future predictions, highly productive systems such as the Humboldt Current System (HCS) are characterized by important variations in both temperature and pCO2 level, but how these physical-chemical ocean changes might influence the transmission and survival of parasites has not been assessed. This study experimentally evaluated the effects of temperature (14, 18 and 25°C) and the combined effects of temperature (∼15 and 20°C) and pCO2 level (∼500 and 1400 microatmospheres (µatm) on the emergence and survival of two species of marine trematodes—Echinostomatidae gen. sp. and Philophthalmidae gen. sp.— both of which infect the intertidal snail Echinolittorina peruviana. Snails were collected from intertidal rocky pools in a year-round upwelling area of the northern HCS (23°S). Two experiments assessed parasite emergence and survival by simulating emersion-immersion tidal cycles. To assess parasite survival, 2 h old cercariae (on average) were taken from a pool of infected snails incubated at 20–25°C, and their mortality was recorded every 6 h until all the cercariae were dead. For both species, a trade-off between high emergence and low survival of cercariae was observed in the high temperature treatment. Species-specific responses to the combination of temperature and pCO2 levels were also observed: the emergence of Echinostomatidae cercariae was highest at 20°C regardless of the pCO2 levels. By contrast, the emergence of Philophthalmidae cercariae was highest at elevated pCO2 (15 and 20°C), suggesting that CO2 may react synergistically with temperature, increasing transmission success of this parasite in coastal ecosystems of the HCS where water temperature and pH are expected to decrease. In conclusion, our results suggest that integrating temperature-pCO2 interactions in parasite studies is essential for understanding the consequence of climate change in future marine ecosystem health.
Leiva N. V., Manriquez P. H., Aguilera V. M. & Gonzalez M. T., in press. Temperature and pCO2 jointly affect the emergence and survival of cercariae from a snail host: implications for future parasitic infections in the Humboldt Current System. International Journal for Parasitology. Article (subscription required).
