Physiological basis for high CO2 tolerance in marine ectothermic animals: pre-adaptation through lifestyle and ontogeny?
By F. Melzner, M. Gutowska, M. Langenbuch, S. Dupont, M. Lucassen, M. Thorndyke, M. Bleich, H. Pörtner. 2009
747 citations recorded by the source corpus.
Abstract. Future ocean acidification has the potential to adversely affect many marine organisms. A growing body of evidence suggests that many species could suffer from reduced fertilization success, decreases in larval- and adult growth rates, reduced calcification rates, and even mortality when being exposed to near-future levels (year 2100 scenarios) of ocean acidification. Little research focus is currently placed on those organisms/taxa that might be less vulnerable to the anticipated changes in ocean chemistry; this is unfortunate, as the comparison of more vulnerable to more tolerant physiotypes could provide us with those physiological traits that are crucial for ecological success in a future ocean. Here, we attempt to summarize some ontogenetic and lifestyle traits that lead to an increased tolerance towards high environmental pCO2. In general, marine ectothermic metazoans with an extensive extracellular fluid volume may be less vulnerable to future acidification as their cells are already exposed to much higher pCO2 values (0.1 to 0.4 kPa, ca. 1000 to 3900 μatm) than those of unicellular organisms and gametes, for which the ocean (0.04 kPa, ca. 400 μatm) is the extracellular space. A doubling in environmental pCO2 therefore only represents a 10% change in extracellular pCO2 in some marine teleosts. High extracellular pCO2 values are to some degree related to high metabolic rates, as diffusion gradients need to be high in order to excrete an amount of CO2 that is directly proportional to the amount of O2 consumed. In active metazoans, such as teleost fish, cephalopods and many brachyuran crustaceans, exercise induced increases in metabolic rate require an efficient ion-regulatory machinery for CO2 excretion and acid-base regulation, especially when anaerobic metabolism is involved and metabolic protons leak into the extracellular space. These ion-transport systems, which are located in highly developed gill epithelia, form the basis for efficient compensation of pH disturbances during exposure to elevated environmental pCO2. Compensation of extracellular acid-base status in turn may be important in avoiding metabolic depression. So far, maintained "performance" at higher seawater pCO2 (>0.3 to 0.6 kPa) has only been observed in adults/juveniles of active, high metabolic species with a powerful ion regulatory apparatus. However, while some of these taxa are adapted to cope with elevated pCO2 during their regular embryonic development, gametes, zygotes and early embryonic stages, which lack specialized ion-regulatory epithelia, may be the true bottleneck for ecological success – even of the more tolerant taxa. Our current understanding of which marine animal taxa will be affected adversely in their physiological and ecological fitness by projected scenarios of anthropogenic ocean acidification is quite incomplete. While a growing amount of empirical evidence from CO2 perturbation experiments suggests that several taxa might react quite sensitively to ocean acidification, others seem to be surprisingly tolerant. However, there is little mechanistic understanding on what physiological traits are responsible for the observed differential sensitivities (see reviews of Seibel and Walsh, 2003; Portner et al., 2004; Fabry et al., 2008; Portner, 2008). This leads us to the first very basic question of how to define general CO2 tolerance on the species level.
Subfields: Ecology, Global and Planetary Change, Oceanography
View Paper: https://www.semanticscholar.org/paper/61cc5c1c1a5c7cec8109a81cf7dc8c7b58cd26f4
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Citations in the corpus
- Intrageneric variation in antipredator responses of coral reef fishes affected by ocean acidification: implications for climate change projections on marine communities (2011, background): “…elevated CO2 than many invertebrates (Portner et al., 2004; Ishimatsu et al., 2008; Melzner et al., 2009), recent studies have shown that some reef fish suffer olfactory impairment when exposed to elevated CO2 (Portner et al., 2005; Melzner et al., 2009; Munday et al., 2009a; Dixson et al., 2010).”
- Tolerance of juvenile Mytilus galloprovincialis to experimental seawater acidification (2012, background): “Considering the scarcity of that type of study, an alternative approach is to look at indicators for animal performance during long-term CO2 perturbation experiments (Melzner et al 2009).”
- Adaptation and the physiology of ocean acidification (2013, positive): “In a recent review, Melzner and colleagues point out that many organisms with higher metabolic rates (fish, cephalopods, decapod crustaceans) appear to be less affected by elevated pCO2 (Melzner et al. 2009).”
- Physiological and ecological responses of crustaceans to ocean acidification (2011, positive): “…to be the most vulnerable to ocean acidification because they are poor iono-regulators and show little ability to buffer the acidifying effects of elevated CO2 in their body compartments (Fabry et al. 2008, Widdicombe & Spicer 2008, Doney et al. 2009, Melzner et al. 2009, Dupont et al. 2010).”
- Effects of climate change on fish reproduction and early life history stages (2011, background): “…elevated pCO2 than adults because they have a larger surface areato-volume ratio, and thus are more susceptible to changes in ambient conditions, and because they might have lessdeveloped mechanisms for acid–base balance compensation (Fabry et al. 2008; Ishimatsu et al. 2008; Melzner et al. 2009).”
- Ocean acidification does not affect the early life history development of a tropical marine fish. (2011, background): “Fish actively regulate their acid–base balance through bicarbonate accumulation and ion exchange across the gills (Claiborne et al. 2002, Evans et al. 2005, Melzner et al. 2009), and small changes in tissue pH associated with elevated CO2 can usually be compensated by these mechanisms.”
- The physiological and molecular responses of larvae from the reef-building coral Pocillopora damicornis exposed to near-future increases in temperature and pCO2 (2012, background): “Another promising area of research includes the examination of acclimatization to OA (Melzner et al. 2009) and increased temperature (Brown et al. 2002).”
- Sour times: seawater acidification effects on growth, feeding behaviour and acid-base status of Asterias rubens and Carcinus maenas (2012, background): “Melzner et al. (2009) proposed that organisms with high and highly fluctu- 94 Fig.”