Developmental performance of ascidian populations to an extreme warming event.

MORGAN ELIZABETH; REPOLHO TIAGO; ALURRALDE GASTÓN

Peniche

Encuentro; International Meeting on Marine Research.; 2018

Coastal environments are increasingly experiencing an upsurge of anomalouslyhigh seawater temperature events, with unpredictable effects over marine biota.Marine heat wave episodes have been identified as a major climate change driver,which can prompt, to a more or less extent, detrimental outcomes to marine species. As a result of an increase in the frequency and timespan of short-term acute warming events, invasive species proliferation is expected to intensify, thus resulting in a loss of native biodiversity, within invaded ecosystems. Under this perspective, we investigated the effect of an acute temperature increase (simulating a marine heat wave), on the developmental performance of Ciona intestinalis early life stages (ELS), derived from populations of anthropogenically-modified and undisturbed environments. Fertilisationrate, embryo and larvae development, settlement and metamorphosis success, andjuvenile heart beat rate were assessed. With the exception for fertilization rate and heart beat rates, temperature had a significant overall effect over analysed endpoints. Ciona intestinalis ELS, derived from undisturbed environments, were the most negatively affected by increased temperature conditions. Opposingly,anthropogenically impacted populations showed an overall consistency in their positive response to thermal stress. Interaction between temperature and population origin (i.e. anthropogenically impacted or undisturbed environments), was statistically significant for three of the ELS analysed endpoints, namely: embryo and larvae development, and metamorphosis. A higher proportion of larvae development and settlement success was observed under increased temperature conditions. Additionally, a higher metamorphosis success rate was observed in individuals exposed to increased temperature conditions, derived from populations from anthropogenically impacted locations. Considering heart beat rates, no differences were observed between sampled populations and experimental temperature conditions. Our findings suggest that future marine heat wave events, together with stress resilience attained by C. intestinalis populations as a result of anthropogenic forcing exposure, could provide favourable breeding conditions towards their environmental proliferation, with unpredictable effects within invaded ecosystems