Examining the Effects of Ocean Acidification on the Sensory Perception and Behavior of Marine Organisms

Posted: June 18th, 2022

Examining the Effects of Ocean Acidification on the Sensory Perception and Behavior of Marine Organisms

Ocean acidification, a consequence of rising atmospheric carbon dioxide (CO2) levels, has emerged as a significant threat to marine ecosystems worldwide. As CO2 dissolves in seawater, it alters the ocean’s chemistry, lowering its pH and causing a cascade of effects on marine life (Kroeker et al., 2013). While the impact of ocean acidification on the physiology and survival of marine organisms has been extensively studied, its effects on their sensory perception and behavior have received less attention. This paper aims to examine the current state of knowledge regarding the influence of ocean acidification on the sensory capabilities and behavioral responses of marine organisms, highlighting the potential ecological implications and identifying areas for future research.

Sensory Perception in a Changing Ocean
Marine organisms rely on a variety of sensory modalities to navigate their environment, locate food, avoid predators, and communicate with conspecifics. However, the changing chemistry of the ocean due to acidification may disrupt these critical sensory processes. Studies have shown that ocean acidification can impair the olfactory abilities of fish, affecting their ability to detect chemical cues associated with predators, prey, and suitable habitats (Dixson et al., 2010; Munday et al., 2009). For example, clownfish (Amphiprion percula) reared in acidified conditions exhibited reduced avoidance of predator odors and a diminished ability to distinguish between olfactory cues (Dixson et al., 2010).

In addition to olfaction, ocean acidification may also impact the auditory and visual perception of marine organisms. Elevated CO2 levels have been found to alter the hearing sensitivity and behavior of some fish species, potentially affecting their ability to detect and respond to acoustic signals (Simpson et al., 2011). Furthermore, changes in seawater chemistry can influence the transmission and reception of visual cues, particularly in organisms that rely on bioluminescence or color vision for communication and mate selection (Roggatz et al., 2016).

Behavioral Responses to Ocean Acidification
The disruption of sensory perception caused by ocean acidification can lead to altered behavioral responses in marine organisms. Many species rely on chemical cues to locate suitable settlement sites, and the impairment of this ability may result in maladaptive habitat selection (Munday et al., 2009). For instance, coral reef fish exposed to acidified conditions have been observed to settle in suboptimal habitats, potentially increasing their vulnerability to predation and reducing their overall fitness (Devine et al., 2012).

Ocean acidification can also affect the social behavior and interactions of marine organisms. Studies have reported changes in aggression, boldness, and activity levels in fish exposed to elevated CO2 levels (Näslund et al., 2015; Spady et al., 2018). These behavioral alterations may disrupt social hierarchies, mating systems, and group dynamics, with potential consequences for population structure and ecosystem functioning.

Moreover, the impact of ocean acidification on predator-prey relationships has been a topic of growing concern. Impaired sensory perception and altered behavior in both predators and prey can modify the outcome of predator-prey interactions, potentially reshaping food webs and community structure (Ferrari et al., 2011). For example, reduced predator avoidance behavior in prey species may increase their vulnerability to predation, while impaired sensory abilities in predators may affect their foraging efficiency and selectivity.

Ecological Implications and Future Directions
The effects of ocean acidification on the sensory perception and behavior of marine organisms have far-reaching ecological implications. Altered habitat selection, disrupted social interactions, and modified predator-prey dynamics can impact population dynamics, community structure, and ecosystem functioning (Nagelkerken & Munday, 2016). As ocean acidification progresses, it is crucial to understand how these changes will propagate through marine food webs and influence the resilience and adaptability of marine ecosystems.

To address these challenges, future research should focus on several key areas. First, expanding the taxonomic and geographic scope of studies is essential to gain a more comprehensive understanding of the sensory and behavioral responses to ocean acidification across diverse marine taxa and ecosystems. Second, investigating the potential for adaptation and acclimation to acidified conditions is crucial to predict the long-term consequences for marine organisms and communities. Third, integrating sensory and behavioral responses into ecological models and risk assessments will provide valuable insights into the broader impacts of ocean acidification on marine ecosystems.

Furthermore, interdisciplinary collaborations between ecologists, physiologists, and behavioral scientists will be necessary to unravel the complex interplay between sensory perception, behavior, and ecosystem dynamics in the context of ocean acidification. By combining field observations, laboratory experiments, and modeling approaches, researchers can develop a more holistic understanding of the effects of ocean acidification on marine life and inform effective conservation and management strategies.

Conclusion
Ocean acidification poses a significant threat to marine organisms, not only through its direct physiological effects but also by altering their sensory perception and behavior. The disruption of critical sensory modalities, such as olfaction, hearing, and vision, can lead to maladaptive behavioral responses, affecting habitat selection, social interactions, and predator-prey relationships. These changes have the potential to propagate through marine food webs, influencing population dynamics, community structure, and ecosystem functioning.

To mitigate the impacts of ocean acidification on marine life, it is imperative to expand our knowledge of the sensory and behavioral responses of marine organisms to changing ocean chemistry. Future research should prioritize taxonomic and geographic diversity, investigate the potential for adaptation and acclimation, and integrate sensory and behavioral responses into ecological models and risk assessments. By adopting an interdisciplinary approach and collaborating across scientific disciplines, we can develop a more comprehensive understanding of the effects of ocean acidification on marine ecosystems and inform effective conservation and management strategies to protect these vital resources in a changing world.

References:
Devine, B. M., Munday, P. L., & Jones, G. P. (2012). Rising CO2 concentrations affect settlement behaviour of larval damselfishes. Coral Reefs, 31(1), 229-238. https://doi.org/10.1007/s00338-011-0837-0

Dixson, D. L., Munday, P. L., & Jones, G. P. (2010). Ocean acidification disrupts the innate ability of fish to detect predator olfactory cues. Ecology Letters, 13(1), 68-75. https://doi.org/10.1111/j.1461-0248.2009.01400.x

Ferrari, M. C., Dixson, D. L., Munday, P. L., McCormick, M. I., Meekan, M. G., Sih, A., & Chivers, D. P. (2011). Intrageneric variation in antipredator responses of coral reef fishes affected by ocean acidification: implications for climate change projections on marine communities. Global Change Biology, 17(9), 2980-2986. https://doi.org/10.1111/j.1365-2486.2011.02439.x

Kroeker, K. J., Kordas, R. L., Crim, R., Hendriks, I. E., Ramajo, L., Singh, G. S., Duarte, C. M., & Gattuso, J. P. (2013). Impacts of ocean acidification on marine organisms: quantifying sensitivities and interaction with warming. Global Change Biology, 19(6), 1884-1896. https://doi.org/10.1111/gcb.12179

Munday, P. L., Dixson, D. L., Donelson, J. M., Jones, G. P., Pratchett, M. S., Devitsina, G. V., & Døving, K. B. (2009). Ocean acidification impairs olfactory discrimination and homing ability of a marine fish. Proceedings of the National Academy of Sciences, 106(6), 1848-1852. https://doi.org/10.1073/pnas.0809996106