Regional adaptation defines sensitivity to future ocean acidification

Physiological responses to temperature are known to be a major determinant of species distributions and can dictate the sensitivity of populations to global warming. In contrast, little is known about how other major global change drivers, such as ocean acidification (OA), will shape species distributions in the future. Here, by integrating population genetics with experimental data for growth and mineralization, physiology and metabolomics, we demonstrate that the sensitivity of populations of the gastropod Littorina littorea to future OA is shaped by regional adaptation. Individuals from populations towards the edges of the natural latitudinal range in the Northeast Atlantic exhibit greater shell dissolution and the inability to upregulate their metabolism when exposed to low pH, thus appearing most sensitive to low seawater pH. Our results suggest that future levels of OA could mediate temperature-driven shifts in species distributions, thereby influencing future biogeography and the functioning of marine ecosystems

Tipping points in the dynamics of speciation.

Speciation can be gradual or sudden and involve few or many genetic changes. Inferring the processes generating such patterns is difficult, and may require consideration of emergent and non-linear properties of speciation, such as when small changes at tipping points have large effects on differentiation. Tipping points involve positive feedback and indirect selection stemming from associations between genomic regions, bi-stability due to effects of initial conditions and evolutionary history, and dependence on modularity of system components. These features are associated with sudden 'regime shifts' in other cellular, ecological, and societal systems. Thus, tools used to understand other complex systems could be fruitfully applied in speciation research

Multi-model seascape genomics identifies distinct environmental drivers of selection among sympatric marine species

Background As global change and anthropogenic pressures continue to increase, conservation and management increasingly needs to consider species’ potential to adapt to novel environmental conditions. Therefore, it is imperative to characterise the main selective forces acting on ecosystems, and how these may influence the evolutionary potential of populations and species. Using a multi-model seascape genomics approach, we compare putative environmental drivers of selection in three sympatric southern African marine invertebrates with contrasting ecology and life histories: Cape urchin (Parechinus angulosus), Common shore crab (Cyclograpsus punctatus), and Granular limpet (Scutellastra granularis). Results Using pooled (Pool-seq), restriction-site associated DNA sequencing (RAD-seq), and seven outlier detection methods, we characterise genomic variation between populations along a strong biogeographical gradient. Of the three species, only S. granularis showed significant isolation-by-distance, and isolation-by-environment driven by sea surface temperatures (SST). In contrast, sea surface salinity (SSS) and range in air temperature correlated more strongly with genomic variation in C. punctatus and P. angulosus. Differences were also found in genomic structuring between the three species, with outlier loci contributing to two clusters in the East and West Coasts for S. granularis and P. angulosus, but not for C. punctatus. Conclusion The findings illustrate distinct evolutionary potential across species, suggesting that species-specific habitat requirements and responses to environmental stresses may be better predictors of evolutionary patterns than the strong environmental gradients within the region. We also found large discrepancies between outlier detection methodologies, and thus offer a novel multi-model approach to identifying the principal environmental selection forces acting on species. Overall, this work highlights how adding a comparative approach to seascape genomics (both with multiple models and species) can elucidate the intricate evolutionary responses of ecosystems to global change

Overwintering individuals of the Arctic krill Thysanoessa inermis appear tolerant to short-term exposure to low pH conditions

Areas of the Arctic Ocean are already experiencing seasonal variation in low pH/elevated pCO2 and are predicted to be the most affected by future ocean acidification (OA). Krill play a fundamental ecological role within Arctic ecosystems, serving as a vital link in the transfer of energy from phytoplankton to higher trophic levels. However, little is known of the chemical habitat occupied by Arctic invertebrate species, and of their responses to changes in seawater pH. Therefore, understanding krill’s responses to low pH conditions has important implications for the prediction of how Arctic marine communities may respond to future ocean change. Here, we present natural seawater carbonate chemistry conditions found in the late polar winter (April) in Kongsfjord, Svalbard (79°North) as well as the response of the Arctic krill, Thysanoessa inermis, exposed to a range of low pH conditions. Standard metabolic rate (measured as oxygen consumption) and energy metabolism markers (incl. adenosine triphosphate (ATP) and l-lactate) of T. inermis were examined. We show that after a 7 days experiment with T. inermis, no significant effects of low pH on MO2, ATP and l-lactate were observed. Additionally, we report carbonate chemistry from within Kongsfjord, which showed that the more stratified inner fjord had lower total alkalinity, higher dissolved inorganic carbon, pCO2 and lower pH than the well-mixed outer fjord. Consequently, our results suggest that overwintering individuals of T. inermis may possess sufficient ability to tolerate short-term low pH conditions due to their migratory behaviour, which exposes T. inermis to the naturally varying carbonate chemistry observed within Kongsfjord, potentially allowing T. inermis to tolerate future OA scenarios

Nucleation and Growth from a Biomineralization Perspective

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Vulnerability and adaptation of US shellfisheries to ocean acidification

Ocean acidification is a global, long-term problem whose ultimate solution requires carbon dioxide reduction at a scope and scale that will take decades to accomplish successfully. Until that is achieved, feasible and locally relevant adaptation and mitigation measures are needed. To help to prioritize societal responses to ocean acidification, we present a spatially explicit, multi-disciplinary vulnerability analysis of coastal human communities in the United States. We focus our analysis on shelled mollusc harvests, which are likely to be harmed by ocean acidification. Our results highlight US regions most vulnerable to ocean acidification (and why), important knowledge and information gaps, and opportunities to adapt through local actions. The research illustrates the benefits of integrating natural and social sciences to identify actions and other opportunities while policy, stakeholders and scientists are still in relatively early stages of developing research plans and responses to ocean acidification

Forensic genomics as a novel tool for identifying the causes of mass mortality events

Toxic spills, hypoxia, disease outbreaks and toxin-producing algal blooms are all possible causes of mass mortality events, but in many cases it can be difficult to pinpoint the cause of death. Here we present a new approach that we name 'forensic genomics', combining field surveys, toxin testing and genomic scans. Forensic genomics queries allele frequencies of surviving animals for signatures of agents causing mass mortality and, where genetic diversity is high, is uniquely suited to identify natural selection in action. As a proof of concept, we use this approach to investigate the causes of an invertebrate mass mortality event, and its genetic effects on an abalone population. Our results support that a harmful algal bloom producing a yessotoxin was a major causative agent to the event