Trends in Parasitology
OpinionHost–parasite interactions: a litmus test for ocean acidification?
Section snippets
Increased CO2, seawater chemistry, and marine life
Anthropogenic emissions of carbon dioxide (CO2) since the beginning of the industrial revolution (ca. 1780) have caused atmospheric CO2 to increase at an unprecedented rate and have resulted in a corresponding increase in dissolved CO2 in the global ocean [1]. This addition of CO2 has altered the carbonate chemistry of seawater, increasing hydrogen ion (H+) and bicarbonate ion (HCO3–) concentrations, and reducing the concentration of carbonate ions (CO32–) (Box 1). The predominant consequences
Physiological consequences of OA
As described in Box 1, the addition of CO2 to seawater alters the concentrations of hydrogen (H+), bicarbonate (HCO3–), and carbonate (CO32–) ions. These chemical species play important roles in fundamental physiological processes such as protein function, enzyme activity, ion transport, and calcification. Protein function and enzyme activity are responsible for many important physiological processes, including growth and the generation of metabolic energy. A change in the electrochemical state
Current OA research
The effect of altered environmental pH on marine systems and organisms has been investigated as a basic biological and biogeochemical parameter since the early 20th century (reviewed in [15]). Recently, however, investigations into decreased pH in the context of OA have become the focus of increased scientific attention. Other than a few isolated studies, the majority of research on OA has been conducted since the late 1980s, with 79% of OA articles published since 2004 (see bibliometric
Ecological role of parasites
Undoubtedly, pH is an important regulatory factor in parasite physiology and population dynamics, as demonstrated by research into the effects of pH on parasites in culture [27], in the internal environment of the host [28], and, perhaps most importantly, in freshwater habitats 29, 30, 31, 32. Accordingly, it is likely that changing oceanic pH will have an effect on marine parasite survival or infectivity, especially for species that produce free-living developmental stages (reviewed in [33]).
Parasites as bioindicators
The use of host–parasite interactions as an effective bioindicator of anthropogenic perturbation of community biodiversity and ecosystem structure has been frequently encouraged since 1997 38, 39, 40, 41. Parasites are a ubiquitous component of all ecosystems and, due to their complex life cycles, experience a wide range of environments which represent most biological niches possibly affected by abiotic stressors, for example, the internal compartments of host species (endoparasites), the
Concluding remarks
Despite the abundance of evidence which suggests that the overall effects of OA will be negative, a significant number of marine organisms either benefit from, or are unaffected by, the associated changes to seawater chemistry [1]. For example, some pteropod species which naturally migrate through oxygen minimum zones are unaffected by elevated CO2 levels [54], whereas certain coccolithophore species increase calcification rates under simulated OA conditions [55]. These positive or neutral
Acknowledgements
We wish to thank A. Studer and H. Randhawa for their constructive comments on an earlier draft of this article. This research was funded by the University of Otago, New Zealand.
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Cited by (33)
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2023, Trends in ParasitologyParasitism by metacercariae modulates the morphological, organic and mechanical responses of the shell of an intertidal bivalve to environmental drivers
2022, Science of the Total EnvironmentThe rise of ecological parasitology: twelve landmark advances that changed its history
2021, International Journal for ParasitologyCitation Excerpt :The findings from these studies reveal that some parasite taxa may be particularly sensitive to abiotic conditions; their abundance may drop in the early stages of local environmental changes well before the host population shows any signs of being affected. The emerging field of ‘environmental parasitology’ focuses on the role of parasites as sentinels of environmental change and reliable early-warning indicators of environmental degradation (Vidal-Martinez et al., 2010; MacLeod and Poulin, 2012; Sures et al., 2017). Overall, whether in the context of biological invasions or as potential canaries in the coal mine for environmental change, studies on parasites in the face of anthropogenic impacts have become a major research direction in ecological parasitology.
Monogeneans as bioindicators: A meta-analysis of effect size of contaminant exposure toward Monogenea (Platyhelminthes)
2021, Ecological IndicatorsCitation Excerpt :The effects of pollution on parasites have been reviewed and suggested using parasites as bioindicators for monitoring environmental health (eg. MacLeod and Poulin, 2012; Sures, 2001; Sures et al., 2017; Vidal-Martínez et al., 2010). Parasites are indirectly impacted when pollution affects the physiology or population biology of the host, which may result in naïve hosts becoming more prone infection.
Temperature and pCO<inf>2</inf> jointly affect the emergence and survival of cercariae from a snail host: implications for future parasitic infections in the Humboldt Current system
2019, International Journal for ParasitologyCitation Excerpt :Nonetheless, reductions in survival and other physiological aspects of parasites can vary distinctly between taxa (MacLeod and Poulin, 2015). The free-living stages of trematodes are exposed to a highly variable environment in the intertidal zone, one that entails desiccation risks and fluctuations in the temperature, pH and oxygen conditions (Pietrock and Marcogliese, 2003; MacLeod and Poulin, 2012). The tolerance of these parasites to such environmental stresses may indicate sufficient phenotypic plasticity in certain species that enables them to survive in changing oceanic conditions (MacLeod and Poulin, 2015).
Integrating parasitology and marine ecology: Seven challenges towards greater synergy
2016, Journal of Sea ResearchCitation Excerpt :This suggests a remarkable lack of awareness by parasitologists, including the many working on marine parasites, of the main concerns of their fellow biologists studying ocean ecosystems. There are numerous ways in which ocean acidification can modify host–parasite interactions and parasites could serve as ideal sentinel species for the effects of acidification (MacLeod and Poulin, 2012), making the neglect of this phenomenon by parasitologists even more baffling. As another example, take the concept of facilitation, which has also caught on in marine ecology (Bulleri, 2009).