Abstract
Early life stages of marine calcifiers are particularly vulnerable to climate change. In the Southern Ocean aragonite undersaturation events and areas of rapid warming already occur and are predicted to increase in extent. Here, we present the first study to successfully hatch the polar pteropod Limacina helicina antarctica and observe the potential impact of exposure to increased temperature and aragonite undersaturation resulting from ocean acidification (OA) on the early life stage survival and shell morphology. High larval mortality (up to 39%) was observed in individuals exposed to perturbed conditions. Warming and OA induced extensive shell malformation and dissolution, respectively, increasing shell fragility. Furthermore, shell growth decreased, with variation between treatments and exposure time. Our results demonstrate that short-term exposure through passing through hotspots of OA and warming poses a serious threat to pteropod recruitment and long-term population viability.
Highlights
A multitude of concurrent drivers poses a pernicious, global threat to marine ecosystems and their services (Bijma et al 2013)
A factorial analysis indicated that acidification (p < 0.001), rather than warming (p > 0.05), increases larval mortality
We demonstrate that veligers of L. helicina antarctica are sensitive to warm, acidified, and acidified-warm oceanic conditions predicted for 2100 in the Scotia Sea (IPCC 2013; McNeil and Matear 2008), given that there was a high level of larval mortality on exposure to these conditions
Summary
A multitude of concurrent drivers poses a pernicious, global threat to marine ecosystems and their services (Bijma et al 2013). With increases in temperature of 0.6–2.0 °C, decreases in pH of 0.1–0.4 units and shoaling of the carbonate compensation depth forecasted to occur by 2100 (RCP 2.6–8.5), ocean acidification (OA), and warming pose an acute threat to marine organisms (IPCC 2013; Heinze et al 2015). Understanding the impact of these environmental perturbations on marine biota remains a major challenge (Kroeker et al 2013), since a range of intra- and inter-specific responses to multi-stressors have been observed (Wernberg et al 2012). Early exposure to environmental stressors could alter vulnerability of later developmental stages through latent effects (such as mortality and shell size), adding to the overall impact (Kroeker et al 2013; Suckling et al 2014)
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