Combined effects of ocean warming and acidification on the larval stages of the European abalone Haliotis tuberculata.

This study examined the physiological responses of the larval stages of Haliotis tuberculata, an economically important abalone, to combined temperature (17 °C and 19 °C) and pH (ambient pH and -0.3 units, i.e., +200% increase in seawater acidity) in a full factorial experiment. Tissue organogenesis, shell formation, and shell length significantly declined due to low pH. High temperature significantly increased the proportion of fully shelled larvae at 24 h post-fertilization (hpf), but increased the proportion of unshelled larvae at 72 hpf. Percentage of swimming larvae at 24 hpf, 72 hpf and 96 hpf significantly declined due to high temperature, but not because of low pH. Larval settlement increased under high temperature, but was not affected by low pH. Despite the fact that no interaction between temperature and pH was observed, the results provide additional evidence on the sensitivity of abalone larvae to both low pH and high temperature. This may have negative consequences for the persistence of abalone populations in natural and aquaculture environments in the near future.

Virulence of Vibrio harveyi ORM4 towards the European abalone Haliotis tuberculata involves both quorum sensing and a type III secretion system.

Environmental Vibrio strains represent a major threat in aquaculture, but the understanding of their virulence mechanisms heavily relies on the transposition of knowledge from human-pathogen vibrios. Here, the genetic bases of the virulence of Vibrio harveyi ORM4 towards the European abalone Haliotis tuberculata were characterized. We demonstrated that luxO, encoding a major regulator of the quorum sensing system, is crucial for the virulence of this strain, and that its deletion leads to a decrease in swimming motility, biofilm formation, and exopolysaccharide production. Furthermore, the biofilm formation by V. harveyi ORM4 was increased by abalone serum, which required LuxO. The absence of LuxO in V. harveyi ORM4 yielded opposite phenotypes compared with other Vibrio species including V. campbellii (still frequently named V. harveyi). In addition, we report a full type III secretion system (T3SS) gene cluster in the V. harveyi ORM4 genome. LuxO was shown to negatively regulate the promoter activity of exsA, encoding the major regulator of the T3SS genes, and the deletion of exsA abolished the virulence of V. harveyi ORM4. These results unveil virulence mechanisms set up by this environmentally important bacterial pathogen and pave the way for a better molecular understanding of the regulation of its pathogenicity.

Conservation needs to evolve to survive in the post-pandemic world.

The conservation of biodiversity-and the vital ecosystem services it generates-is one of the greatest challenges humanity faces, yet the field faces drastic funding cuts as society realigns its priorities in the face of the COVID-19 pandemic. Here, we argue that diverting attention from conservation would, however, increase the risk of further global health crises because the emergence of novel infectious diseases is partially driven by global environmental change. As the discrepancy between conservation needs and society's willingness to pay for them grows, conservation will have to evolve to stay relevant in the age global change-induced human infectious disease.

There is an inverse relationship between the capacity of climate change refugia and species adaptation potential.

There is an inverse relationship between species adaptation potential (green/curved line) and refugial capacity (blue/light triangle). The ability of refugia species to adapt/acclimatize to future stressors (red/dark triangle), assuming this is within their physiological capabilities, depends on the refugial capacity of the refugia in which they live. The more effective a refugium, the lower the chance of its species adapting/acclimatizing. This article is a commentary on Kapsensberg & Cyronak, 25, 3201-3214.

Biological interactions: The overlooked aspects of marine climate change refugia.

This article emphasizes on biological interactions as an important overlooked criterion to better assess the chance of target marine species in potential refugia to survive climate change. It proposes future climate change refugia studies must consider the reciprocal interactions among climate change, biological factor, and conservation strategies.

Colony-specific calcification and mortality under ocean acidification in the branching coral Montipora digitata.

Ocean acidification (OA) threatens calcifying marine organisms including reef-building corals. In this study, we examined the OA responses of individual colonies of the branching scleractinian coral Montipora digitata. We exposed nubbins of unique colonies (n = 15) to ambient or elevated pCO2 under natural light and temperature regimes for 110 days. Although elevated pCO2 exposure on average reduced calcification, individual colonies showed unique responses ranging from declines in positive calcification to negative calcification (decalcification) to no change. Similarly, mortality was greater on average in elevated pCO2, but also showed colony-specific patterns. High variation in colony responses suggests the possibility that ongoing OA may lead to natural selection of OA-tolerant colonies within a coral population.

Colony-specific investigations reveal highly variable responses among individual corals to ocean acidification and warming.

As anthropogenic climate change is an ongoing concern, scientific investigations on its impacts on coral reefs are increasing. Although impacts of combined ocean acidification (OA) and temperature stress (T) on reef-building scleractinian corals have been studied at the genus, species and population levels, there are little data available on how individual corals respond to combined OA and anomalous temperatures. In this study, we exposed individual colonies of Acropora digitifera, Montipora digitata and Porites cylindrica to four pCO2-temperature treatments including 400 µatm-28 °C, 400 µatm-31 °C, 1000 µatm-28 °C and 1000 µatm-31 °C for 26 days. Physiological parameters including calcification, protein content, maximum photosynthetic efficiency, Symbiodinium density, and chlorophyll content along with Symbiodinium type of each colony were examined. Along with intercolonial responses, responses of individual colonies versus pooled data to the treatments were investigated. The main results were: 1) responses to either OA or T or their combination were different between individual colonies when considering physiological functions; 2) tolerance to either OA or T was not synonymous with tolerance to the other parameter; 3) tolerance to both OA and T did not necessarily lead to tolerance of OA and T combined (OAT) at the same time; 4) OAT had negative, positive or no impacts on physiological functions of coral colonies; and 5) pooled data were not representative of responses of all individual colonies. Indeed, the pooled data obscured actual responses of individual colonies or presented a response that was not observed in any individual. From the results of this study we recommend improving experimental designs of studies investigating physiological responses of corals to climate change by complementing them with colony-specific examinations.