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1. Contrasting responses of commercially important Northwest Atlantic bivalve species to ocean acidification and temperature conditions

   https://doi.org/10.1371/journal.pclm.0000509  

   McMahon, Teagan; Thatcher, Diana; Williams, Branwen; Wanamaker, Alan; Jellison, Brittany; Franklin, Heidi; Guay, Katherine; Whitney, Nina M; Stewart, Joseph A; LaVigne, Michèle (November 2024, PLOS Climate)

   Cyr, Frédéric (Ed.)

   Modern calcifying marine organisms face numerous environmental stressors, including overfishing, deoxygenation, increasing ocean temperatures, and ocean acidification (OA). Coastal marine settings are predicted to become warmer and more acidic in coming decades, heightening the risks of extreme events such as marine heat waves. Given these threats, it is important to understand the vulnerabilities of marine organisms that construct their shells from calcium carbonate, which are particularly susceptible to warming and decreasing pH levels. To investigate the response of four commercially relevant bivalve species to OA and differing temperatures, juvenileMercenaria mercenaria(hard shell clams), juvenileMya arenaria(soft shell clams), adult and juvenileArctica islandica(ocean quahog), and juvenilePlacopecten magellanicus(Atlantic sea scallops) were grown in varying pH and temperature conditions. Species were exposed to four controlled pH conditions (7.4, 7.6, 7.8, and ambient/8.0) and three controlled temperature conditions (6, 9, and 12°C) for 20.5 weeks and then shell growth and coloration were analyzed. This research marks the first direct comparison of these species’ biological responses to both temperature and OA conditions within the same experiment. The four species exhibited varying responses to temperature and OA conditions. Mortality rates were not significantly associated with pH or temperature conditions for any of the species studied. Growth (measured as change in maximum shell height) was observed to be higher in warmer tanks for all species and was not significantly impacted by pH. Two groups (juvenileM.arenariaand juvenileM.mercenaria) exhibited lightening in the color of their shells at lower pH levels at all temperatures, attributed to a loss of shell periostracum. The variable responses of the studied bivalve species, despite belonging to the same phylogenetic class and geographic region, highlights the need for further study into implications for health and management of bivalves in the face of variable stressors. 

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2. Contrasting responses of photosynthesis and photochemical efficiency to ocean acidification under different light environments in a calcifying alga

   https://doi.org/10.1038/s41598-019-40620-8  

   Briggs, Amy A.; Carpenter, Robert C. (March 2019, Scientific Reports)

   Abstract Ocean acidification (OA) is predicted to enhance photosynthesis in many marine taxa. However, photophysiology has multiple components that OA may affect differently, especially under different light environments, with potentially contrasting consequences for photosynthetic performance. Furthermore, because photosynthesis affects energetic budgets and internal acid-base dynamics, changes in it due to OA or light could mediate the sensitivity of other biological processes to OA (e.g. respiration and calcification). To better understand these effects, we conducted experiments onPorolithon onkodes, a common crustose coralline alga in Pacific coral reefs, crossing pCO₂and light treatments. Results indicate OA inhibited some aspects of photophysiology (maximum photochemical efficiency), facilitated others (α, the responsiveness of photosynthesis to sub-saturating light), and had no effect on others (maximum gross photosynthesis), with the first two effects depending on treatment light level. Light also exacerbated the increase in dark-adapted respiration under OA, but did not alter the decline in calcification. Light-adapted respiration did not respond to OA, potentially due to indirect effects of photosynthesis. Combined, results indicate OA will interact with light to alter energetic budgets and potentially resource allocation among photosynthetic processes inP. onkodes, likely shifting its light tolerance, and constraining it to a narrower range of light environments. 

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3. Contrasting transcriptional responses to Fusarium virguliforme colonization in symptomatic and asymptomatic hosts

   https://doi.org/10.1093/plcell/koaa021  

   Baetsen-Young, Amy; Chen, Huan; Shiu, Shin-Han; Day, Brad (December 2020, The Plant Cell)

   null (Ed.)

   Abstract The broad host range of Fusarium virguliforme represents a unique comparative system to identify and define differentially induced responses between an asymptomatic monocot host, maize (Zea mays), and a symptomatic eudicot host, soybean (Glycine max). Using a temporal, comparative transcriptome-based approach, we observed that early gene expression profiles of root tissue from infected maize suggest that pathogen tolerance coincides with the rapid induction of senescence dampening transcriptional regulators, including ANACs (Arabidopsis thaliana NAM/ATAF/CUC protein) and Ethylene-Responsive Factors. In contrast, the expression of senescence-associated processes in soybean was coincident with the appearance of disease symptom development, suggesting pathogen-induced senescence as a key pathway driving pathogen susceptibility in soybean. Based on the analyses described herein, we posit that root senescence is a primary contributing factor underlying colonization and disease progression in symptomatic versus asymptomatic host–fungal interactions. This process also supports the lifestyle and virulence of F. virguliforme during biotrophy to necrotrophy transitions. Further support for this hypothesis lies in comprehensive co-expression and comparative transcriptome analyses, and in total, supports the emerging concept of necrotrophy-activated senescence. We propose that F. virguliforme conditions an environment within symptomatic hosts, which favors susceptibility through transcriptomic reprogramming, and as described herein, the induction of pathways associated with senescence during the necrotrophic stage of fungal development. 

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4. Plastic responses of bryozoans to ocean acidification

   https://doi.org/10.1242/jeb.163436  

   Swezey, Daniel S.; Bean, Jessica R.; Hill, Tessa M.; Gaylord, Brian; Ninokawa, Aaron T.; Sanford, Eric (December 2017, The Journal of Experimental Biology)
5. Contrasting shrub and grass hydraulic responses to experimental drought

   https://doi.org/10.1007/s00442-024-05543-w  

   O’Keefe, Kimberly; Nippert, Jesse B; Keen, Rachel M; McCulloh, Katherine A (April 2024, Oecologia)