| Biological trait . | RSS . | Justification . | |
|---|---|---|---|
| Acid-sensitive structures | External | 3 | Taxa with chitinous (Long et al., 2019) and calcareous (Byrne and Fitzer, 2020) exoskeletons have been found to exhibit severe deformities when exposed to near-future CO2 concentrations, negatively impacting feeding, reproduction, movement, and mechanical protection. Calcification rates decrease in waters with elevated pCO2, leading to reductions in exoskeleton size by as much as 50% (Díaz-Castañeda et al., 2019). Differences in RSS between external and internal acid-sensitive structures were determined by assessing the likelihood of exposure to increased acidity in the surrounding medium. |
| Internal | 2 | ||
| None | 1 | Theoretical absence of negative effects associated with the absence of acid-sensitive structures. | |
| Adult mobility (Quierós et al. scores) | Sessile (*1 and 2) | 3 | Organisms capable of higher levels of activity are subject to more anaerobic respiration than slow-moving or sessile taxa. Organisms that regularly respire anaerobically are more capable of buffering increased pCO2 to prevent acidosis and are more efficient at removing excess internal CO2 (Melzner et al., 2009), with those displaying a more hypometabolic mode of life between and within taxonomic groups capable of less acid-base regulation (Pörnter, 2008). More active taxa have been found to be broadly more resistant to rapid increases in oceanic pCO2 throughout other mass-extinction events (Knoll et al., 1996), and to be less susceptible to ocean conditions projected by the year 2100 (Kelly and Hofmann, 2012). |
| Slow (*3) | 2 | ||
| Free (*4) | 1 | ||
| Reproduction strategy | Broadcast | 3 | Evidence that increased ocean pCO2 can decrease fertilisation success, as a reduction in sperm velocity and intracellular Ca2+ oscillations decrease the probability of gamete fusion per collision (Shi et al., 2017; Colen et al.,2012). |
| External brooding | 2 | Brooding species have been found to outcompete non-brooding species in environments with elevated pCO2 and show a higher ability to adapt to environmental changes (Lucey et al., 2015). Brooders are often exposed to elevated pCO2 due to a concentration of respiratory waste, with this fluctuating particularly intensely in internal brood chambers, where parental-stress-induced isolation can result in the pH of the chamber falling as low as 7.46 (Cole et al., 2016). The requirement of brooding organisms to withstand high acidity during this stage is thought to allow for greater tolerance to high pCO2 later in life (Gray et al., 2019). | |
| Internal brooding | 1 | ||
| Larval stage | Planktotrophic | 3 | Evidence that taxa with pelagic larval stages are more sensitive to increases in ocean pCO2 than direct developing counterparts (Lucey et al., 2015), with the transition from pelagic larvae to the benthic adult form being energetically taxing and creating a survivability bottleneck (Díaz-Castañeda et al., 2019). Algae exposed to projected levels of ocean pCO2 have less nutritional value, with lower protein and organic contents, requiring compensatory feeding (Duarte et al., 2016). This increases the risk of larval malnutrition, potentially causing severe latent effects (Pechenik and Tyrell, 2015). |
| Lecithotrophic | 2 | Lecithotrophic larvae either derive nutrition from maternal yolk reserves or are non-feeding at this stage (Kempf and Hadfield, 1985), and so are not subject to feeding-related stress. Studies have found lecithotrophs to both benefit (Dupont et al., 2010) and be severely disadvantaged (Verkaik et al., 2016) by exposure to low pH conditions. | |
| Direct development or non-pelagic | 1 | Not subject to the stresses of planktonic development. | |
| Biological trait . | RSS . | Justification . | |
|---|---|---|---|
| Acid-sensitive structures | External | 3 | Taxa with chitinous (Long et al., 2019) and calcareous (Byrne and Fitzer, 2020) exoskeletons have been found to exhibit severe deformities when exposed to near-future CO2 concentrations, negatively impacting feeding, reproduction, movement, and mechanical protection. Calcification rates decrease in waters with elevated pCO2, leading to reductions in exoskeleton size by as much as 50% (Díaz-Castañeda et al., 2019). Differences in RSS between external and internal acid-sensitive structures were determined by assessing the likelihood of exposure to increased acidity in the surrounding medium. |
| Internal | 2 | ||
| None | 1 | Theoretical absence of negative effects associated with the absence of acid-sensitive structures. | |
| Adult mobility (Quierós et al. scores) | Sessile (*1 and 2) | 3 | Organisms capable of higher levels of activity are subject to more anaerobic respiration than slow-moving or sessile taxa. Organisms that regularly respire anaerobically are more capable of buffering increased pCO2 to prevent acidosis and are more efficient at removing excess internal CO2 (Melzner et al., 2009), with those displaying a more hypometabolic mode of life between and within taxonomic groups capable of less acid-base regulation (Pörnter, 2008). More active taxa have been found to be broadly more resistant to rapid increases in oceanic pCO2 throughout other mass-extinction events (Knoll et al., 1996), and to be less susceptible to ocean conditions projected by the year 2100 (Kelly and Hofmann, 2012). |
| Slow (*3) | 2 | ||
| Free (*4) | 1 | ||
| Reproduction strategy | Broadcast | 3 | Evidence that increased ocean pCO2 can decrease fertilisation success, as a reduction in sperm velocity and intracellular Ca2+ oscillations decrease the probability of gamete fusion per collision (Shi et al., 2017; Colen et al.,2012). |
| External brooding | 2 | Brooding species have been found to outcompete non-brooding species in environments with elevated pCO2 and show a higher ability to adapt to environmental changes (Lucey et al., 2015). Brooders are often exposed to elevated pCO2 due to a concentration of respiratory waste, with this fluctuating particularly intensely in internal brood chambers, where parental-stress-induced isolation can result in the pH of the chamber falling as low as 7.46 (Cole et al., 2016). The requirement of brooding organisms to withstand high acidity during this stage is thought to allow for greater tolerance to high pCO2 later in life (Gray et al., 2019). | |
| Internal brooding | 1 | ||
| Larval stage | Planktotrophic | 3 | Evidence that taxa with pelagic larval stages are more sensitive to increases in ocean pCO2 than direct developing counterparts (Lucey et al., 2015), with the transition from pelagic larvae to the benthic adult form being energetically taxing and creating a survivability bottleneck (Díaz-Castañeda et al., 2019). Algae exposed to projected levels of ocean pCO2 have less nutritional value, with lower protein and organic contents, requiring compensatory feeding (Duarte et al., 2016). This increases the risk of larval malnutrition, potentially causing severe latent effects (Pechenik and Tyrell, 2015). |
| Lecithotrophic | 2 | Lecithotrophic larvae either derive nutrition from maternal yolk reserves or are non-feeding at this stage (Kempf and Hadfield, 1985), and so are not subject to feeding-related stress. Studies have found lecithotrophs to both benefit (Dupont et al., 2010) and be severely disadvantaged (Verkaik et al., 2016) by exposure to low pH conditions. | |
| Direct development or non-pelagic | 1 | Not subject to the stresses of planktonic development. | |
RSS = ranging from more sensitive to increased pCO2 (3) to least sensitive to increased pCO2 (1). *The 1–4 scale within the Adult Mobility category refers to the scale used to define movement of benthic invertebrates by Quierós et al. (2013).
| Biological trait . | RSS . | Justification . | |
|---|---|---|---|
| Acid-sensitive structures | External | 3 | Taxa with chitinous (Long et al., 2019) and calcareous (Byrne and Fitzer, 2020) exoskeletons have been found to exhibit severe deformities when exposed to near-future CO2 concentrations, negatively impacting feeding, reproduction, movement, and mechanical protection. Calcification rates decrease in waters with elevated pCO2, leading to reductions in exoskeleton size by as much as 50% (Díaz-Castañeda et al., 2019). Differences in RSS between external and internal acid-sensitive structures were determined by assessing the likelihood of exposure to increased acidity in the surrounding medium. |
| Internal | 2 | ||
| None | 1 | Theoretical absence of negative effects associated with the absence of acid-sensitive structures. | |
| Adult mobility (Quierós et al. scores) | Sessile (*1 and 2) | 3 | Organisms capable of higher levels of activity are subject to more anaerobic respiration than slow-moving or sessile taxa. Organisms that regularly respire anaerobically are more capable of buffering increased pCO2 to prevent acidosis and are more efficient at removing excess internal CO2 (Melzner et al., 2009), with those displaying a more hypometabolic mode of life between and within taxonomic groups capable of less acid-base regulation (Pörnter, 2008). More active taxa have been found to be broadly more resistant to rapid increases in oceanic pCO2 throughout other mass-extinction events (Knoll et al., 1996), and to be less susceptible to ocean conditions projected by the year 2100 (Kelly and Hofmann, 2012). |
| Slow (*3) | 2 | ||
| Free (*4) | 1 | ||
| Reproduction strategy | Broadcast | 3 | Evidence that increased ocean pCO2 can decrease fertilisation success, as a reduction in sperm velocity and intracellular Ca2+ oscillations decrease the probability of gamete fusion per collision (Shi et al., 2017; Colen et al.,2012). |
| External brooding | 2 | Brooding species have been found to outcompete non-brooding species in environments with elevated pCO2 and show a higher ability to adapt to environmental changes (Lucey et al., 2015). Brooders are often exposed to elevated pCO2 due to a concentration of respiratory waste, with this fluctuating particularly intensely in internal brood chambers, where parental-stress-induced isolation can result in the pH of the chamber falling as low as 7.46 (Cole et al., 2016). The requirement of brooding organisms to withstand high acidity during this stage is thought to allow for greater tolerance to high pCO2 later in life (Gray et al., 2019). | |
| Internal brooding | 1 | ||
| Larval stage | Planktotrophic | 3 | Evidence that taxa with pelagic larval stages are more sensitive to increases in ocean pCO2 than direct developing counterparts (Lucey et al., 2015), with the transition from pelagic larvae to the benthic adult form being energetically taxing and creating a survivability bottleneck (Díaz-Castañeda et al., 2019). Algae exposed to projected levels of ocean pCO2 have less nutritional value, with lower protein and organic contents, requiring compensatory feeding (Duarte et al., 2016). This increases the risk of larval malnutrition, potentially causing severe latent effects (Pechenik and Tyrell, 2015). |
| Lecithotrophic | 2 | Lecithotrophic larvae either derive nutrition from maternal yolk reserves or are non-feeding at this stage (Kempf and Hadfield, 1985), and so are not subject to feeding-related stress. Studies have found lecithotrophs to both benefit (Dupont et al., 2010) and be severely disadvantaged (Verkaik et al., 2016) by exposure to low pH conditions. | |
| Direct development or non-pelagic | 1 | Not subject to the stresses of planktonic development. | |
| Biological trait . | RSS . | Justification . | |
|---|---|---|---|
| Acid-sensitive structures | External | 3 | Taxa with chitinous (Long et al., 2019) and calcareous (Byrne and Fitzer, 2020) exoskeletons have been found to exhibit severe deformities when exposed to near-future CO2 concentrations, negatively impacting feeding, reproduction, movement, and mechanical protection. Calcification rates decrease in waters with elevated pCO2, leading to reductions in exoskeleton size by as much as 50% (Díaz-Castañeda et al., 2019). Differences in RSS between external and internal acid-sensitive structures were determined by assessing the likelihood of exposure to increased acidity in the surrounding medium. |
| Internal | 2 | ||
| None | 1 | Theoretical absence of negative effects associated with the absence of acid-sensitive structures. | |
| Adult mobility (Quierós et al. scores) | Sessile (*1 and 2) | 3 | Organisms capable of higher levels of activity are subject to more anaerobic respiration than slow-moving or sessile taxa. Organisms that regularly respire anaerobically are more capable of buffering increased pCO2 to prevent acidosis and are more efficient at removing excess internal CO2 (Melzner et al., 2009), with those displaying a more hypometabolic mode of life between and within taxonomic groups capable of less acid-base regulation (Pörnter, 2008). More active taxa have been found to be broadly more resistant to rapid increases in oceanic pCO2 throughout other mass-extinction events (Knoll et al., 1996), and to be less susceptible to ocean conditions projected by the year 2100 (Kelly and Hofmann, 2012). |
| Slow (*3) | 2 | ||
| Free (*4) | 1 | ||
| Reproduction strategy | Broadcast | 3 | Evidence that increased ocean pCO2 can decrease fertilisation success, as a reduction in sperm velocity and intracellular Ca2+ oscillations decrease the probability of gamete fusion per collision (Shi et al., 2017; Colen et al.,2012). |
| External brooding | 2 | Brooding species have been found to outcompete non-brooding species in environments with elevated pCO2 and show a higher ability to adapt to environmental changes (Lucey et al., 2015). Brooders are often exposed to elevated pCO2 due to a concentration of respiratory waste, with this fluctuating particularly intensely in internal brood chambers, where parental-stress-induced isolation can result in the pH of the chamber falling as low as 7.46 (Cole et al., 2016). The requirement of brooding organisms to withstand high acidity during this stage is thought to allow for greater tolerance to high pCO2 later in life (Gray et al., 2019). | |
| Internal brooding | 1 | ||
| Larval stage | Planktotrophic | 3 | Evidence that taxa with pelagic larval stages are more sensitive to increases in ocean pCO2 than direct developing counterparts (Lucey et al., 2015), with the transition from pelagic larvae to the benthic adult form being energetically taxing and creating a survivability bottleneck (Díaz-Castañeda et al., 2019). Algae exposed to projected levels of ocean pCO2 have less nutritional value, with lower protein and organic contents, requiring compensatory feeding (Duarte et al., 2016). This increases the risk of larval malnutrition, potentially causing severe latent effects (Pechenik and Tyrell, 2015). |
| Lecithotrophic | 2 | Lecithotrophic larvae either derive nutrition from maternal yolk reserves or are non-feeding at this stage (Kempf and Hadfield, 1985), and so are not subject to feeding-related stress. Studies have found lecithotrophs to both benefit (Dupont et al., 2010) and be severely disadvantaged (Verkaik et al., 2016) by exposure to low pH conditions. | |
| Direct development or non-pelagic | 1 | Not subject to the stresses of planktonic development. | |
RSS = ranging from more sensitive to increased pCO2 (3) to least sensitive to increased pCO2 (1). *The 1–4 scale within the Adult Mobility category refers to the scale used to define movement of benthic invertebrates by Quierós et al. (2013).
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