Direct and Indirect Effects
Climate change has a direct, as well as an indirect effect on clownfish.
Direct: Earlier Life History
Ocean acidification had no apparent effect on embryonic duration, egg survival, and size at hatching of clownfish (Munday et al. 2009). The growth rate of larvae, however, was found to increase with acidified habitat (Munday et al. 2009). With a weak positive relationship between length and swimming speed of clownfish, it could be considered that large size may be advantageous for the larvae (Munday et al. 2009). Though this may be true, it may be advantageous for only a short-term. Donaldon (2009) speculated that the rapid growth could mean that the juveniles disperse only a short distance from their parent’s anemone before their instinct to find their own anemone kicks in. This could lead to clustered clownfish distribution, leading to more competition for food and space, a greater chance of inbreeding, as well as a higher chance of predation (Donaldson 2009).
Direct: Olfactory Response
Most coastal marine species, including clownfish, depend on their sense of smell to find a suitable habitat at the end of their larval stage (Munday et al. 2009). It was found that olfactory preferences for suitable habitat was innate in clownfish when juveniles reared in laboratory settings showed the same olfactory preferences as ones reared in the ocean (Dixson et al. 2008). To test whether ocean acidification has an effect on this crucial response, Munday et al. (2009) tested the olfactory response of larval clownfish in ocean acidification simulating conditions. At a higher acid level, the larvae showed strong attraction to smells that they normally avoided in current seawater (Munday et al. 2009). At an even higher acid level, there were no responses to any olfactory stimuli (Munday et al. 2009). If ocean acidification continues as it is, many marine species will suffer from impaired sensory functions, reducing the marine species population sustainability, and consequently marine diversity (Munday et al. 2009).
Direct: Auditory Behaviour
Like many other fishes, clownfish also rely on hearing for survival. Their hearing is important for orientation, habitat selection, predator avoidance, and communication (Simpson et al. 2011). Simpson et al. (2011) studied the influence of carbon dioxide (CO2)-enriched water conditions on juvenile clownfish hearing by testing their responses to daytime reef noise. The results showed that juveniles reared in current-day CO2 conditions responded as expected by significantly avoiding the reef noise, whereas those reared in CO2-enriched conditions showed no such response (Simpson et al. 2011).
Although the study by Simpson et al. (2011) showed that clownfish hearing was affected by acidification of the ocean, the physical structure may not be affected. Munday et al. (2011) tested the susceptibility of clownfish otoliths (earbones) to reduced availability of carbonate ions due to acidification, and found the earbone area and maximum lengths to be actually larger under highly acidic conditions than at current acidic conditions (Munday et al. 2011).
This shows that ocean acidification may not have negative physical effects on the auditory structures of clownfish, but still have detrimental effects on its hearing.
Indirect: Loss of Habitat
Clownfish has an obligate symbiotic relationship with sea anemones, and depends on them for protection and food. Since sea anemones are most frequently found on coral reefs, and the climate change is causing coral bleaching, clownfish are unavoidably affected as well (Donaldson 2009).
This webpage was completed by Amy Kim as an assignment for BIOL 3236: Biological Adaptation to Climate Change at the University of Queensland, Australia.
Direct: Earlier Life History
Ocean acidification had no apparent effect on embryonic duration, egg survival, and size at hatching of clownfish (Munday et al. 2009). The growth rate of larvae, however, was found to increase with acidified habitat (Munday et al. 2009). With a weak positive relationship between length and swimming speed of clownfish, it could be considered that large size may be advantageous for the larvae (Munday et al. 2009). Though this may be true, it may be advantageous for only a short-term. Donaldon (2009) speculated that the rapid growth could mean that the juveniles disperse only a short distance from their parent’s anemone before their instinct to find their own anemone kicks in. This could lead to clustered clownfish distribution, leading to more competition for food and space, a greater chance of inbreeding, as well as a higher chance of predation (Donaldson 2009).
Direct: Olfactory Response
Most coastal marine species, including clownfish, depend on their sense of smell to find a suitable habitat at the end of their larval stage (Munday et al. 2009). It was found that olfactory preferences for suitable habitat was innate in clownfish when juveniles reared in laboratory settings showed the same olfactory preferences as ones reared in the ocean (Dixson et al. 2008). To test whether ocean acidification has an effect on this crucial response, Munday et al. (2009) tested the olfactory response of larval clownfish in ocean acidification simulating conditions. At a higher acid level, the larvae showed strong attraction to smells that they normally avoided in current seawater (Munday et al. 2009). At an even higher acid level, there were no responses to any olfactory stimuli (Munday et al. 2009). If ocean acidification continues as it is, many marine species will suffer from impaired sensory functions, reducing the marine species population sustainability, and consequently marine diversity (Munday et al. 2009).
Direct: Auditory Behaviour
Like many other fishes, clownfish also rely on hearing for survival. Their hearing is important for orientation, habitat selection, predator avoidance, and communication (Simpson et al. 2011). Simpson et al. (2011) studied the influence of carbon dioxide (CO2)-enriched water conditions on juvenile clownfish hearing by testing their responses to daytime reef noise. The results showed that juveniles reared in current-day CO2 conditions responded as expected by significantly avoiding the reef noise, whereas those reared in CO2-enriched conditions showed no such response (Simpson et al. 2011).
Although the study by Simpson et al. (2011) showed that clownfish hearing was affected by acidification of the ocean, the physical structure may not be affected. Munday et al. (2011) tested the susceptibility of clownfish otoliths (earbones) to reduced availability of carbonate ions due to acidification, and found the earbone area and maximum lengths to be actually larger under highly acidic conditions than at current acidic conditions (Munday et al. 2011).
This shows that ocean acidification may not have negative physical effects on the auditory structures of clownfish, but still have detrimental effects on its hearing.
Indirect: Loss of Habitat
Clownfish has an obligate symbiotic relationship with sea anemones, and depends on them for protection and food. Since sea anemones are most frequently found on coral reefs, and the climate change is causing coral bleaching, clownfish are unavoidably affected as well (Donaldson 2009).
This webpage was completed by Amy Kim as an assignment for BIOL 3236: Biological Adaptation to Climate Change at the University of Queensland, Australia.