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Projected near-future CO2 levels increase activity and alter defensive behaviours in the tropical squid Idiosepius pygmaeus.

Spady BL, Watson SA, Chase TJ, Munday PL - Biol Open (2014)

Bottom Line: Increased activity could lead to adverse effects on energy budgets as well as increasing visibility to predators.A tendency to respond to a stimulus with escape behaviours could increase survival, but may also be energetically costly and could potentially lead to more chases by predators compared with individuals that use defensive postures.These results demonstrate that projected future ocean acidification affects the behaviours of a tropical squid species.

View Article: PubMed Central - PubMed

Affiliation: College of Marine and Environmental Sciences, James Cook University, Townsville, QLD 4811, Australia ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, QLD 4811, Australia blake.spady@my.jcu.edu.au.

No MeSH data available.


Related in: MedlinePlus

Effect of elevated CO2 on resting frequency of squid.Proportion of squid that were at rest (zero line crosses), displayed low activity levels (1–25 line crosses), and high activity levels (more than 25 line crosses) in behavioural trials for individuals exposed to control (447 µatm), moderate (626 µatm), or high (956 µatm) CO2. Sample sizes are displayed above the bars.
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f02: Effect of elevated CO2 on resting frequency of squid.Proportion of squid that were at rest (zero line crosses), displayed low activity levels (1–25 line crosses), and high activity levels (more than 25 line crosses) in behavioural trials for individuals exposed to control (447 µatm), moderate (626 µatm), or high (956 µatm) CO2. Sample sizes are displayed above the bars.

Mentions: There was a significant difference in the frequency of squid at rest and active among control and elevated CO2 treatments (χ2 = 9.77, df = 4, p = 0.044) (Fig. 2). During the 5-minute observation period, 81% of squid from the control treatment remained at rest (attached to the aquarium wall), whereas only 56% of squid from the moderate CO2 treatment and 62% from the high CO2 treatment remained at rest (n = 27–29). Additionally, some squid from the control and moderate CO2 treatment, but not the high CO2 treatment, had a low level of activity (1–25 line crosses). Further analysis of movement levels showed control squid had a mean of 10 (SD = 28) line crosses compared to 61 (SD = 117) and 51 (SD = 100) line crosses in the moderate and high CO2 treatments, respectively, when all individuals (including those at rest) were included (Fig. 3). For all individuals (n = 27–29), the mean number of line crosses was significantly different between control and moderate CO2 treatments (Wilcoxon rank-sum test; Z = −2.272, p = 0.023), but not between the control and high CO2 treatments (Wilcoxon rank-sum test; Z = 1.898, p = 0.057). Among active individuals only (n = 6–12), there was a significant difference in the mean number of line crosses among the control and elevated CO2 treatments (ANOVA: F2,26 = 3.474, p = 0.046). A post hoc test showed that while there was no significant difference between control and moderate CO2 treatments (Tukey HSD; p = 0.141), there was a significant difference between the control and high CO2 treatment levels (Tukey HSD; p = 0.038). Activity levels were not affected by individual body size (negative binomial GLM; p = 0.635).


Projected near-future CO2 levels increase activity and alter defensive behaviours in the tropical squid Idiosepius pygmaeus.

Spady BL, Watson SA, Chase TJ, Munday PL - Biol Open (2014)

Effect of elevated CO2 on resting frequency of squid.Proportion of squid that were at rest (zero line crosses), displayed low activity levels (1–25 line crosses), and high activity levels (more than 25 line crosses) in behavioural trials for individuals exposed to control (447 µatm), moderate (626 µatm), or high (956 µatm) CO2. Sample sizes are displayed above the bars.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4232764&req=5

f02: Effect of elevated CO2 on resting frequency of squid.Proportion of squid that were at rest (zero line crosses), displayed low activity levels (1–25 line crosses), and high activity levels (more than 25 line crosses) in behavioural trials for individuals exposed to control (447 µatm), moderate (626 µatm), or high (956 µatm) CO2. Sample sizes are displayed above the bars.
Mentions: There was a significant difference in the frequency of squid at rest and active among control and elevated CO2 treatments (χ2 = 9.77, df = 4, p = 0.044) (Fig. 2). During the 5-minute observation period, 81% of squid from the control treatment remained at rest (attached to the aquarium wall), whereas only 56% of squid from the moderate CO2 treatment and 62% from the high CO2 treatment remained at rest (n = 27–29). Additionally, some squid from the control and moderate CO2 treatment, but not the high CO2 treatment, had a low level of activity (1–25 line crosses). Further analysis of movement levels showed control squid had a mean of 10 (SD = 28) line crosses compared to 61 (SD = 117) and 51 (SD = 100) line crosses in the moderate and high CO2 treatments, respectively, when all individuals (including those at rest) were included (Fig. 3). For all individuals (n = 27–29), the mean number of line crosses was significantly different between control and moderate CO2 treatments (Wilcoxon rank-sum test; Z = −2.272, p = 0.023), but not between the control and high CO2 treatments (Wilcoxon rank-sum test; Z = 1.898, p = 0.057). Among active individuals only (n = 6–12), there was a significant difference in the mean number of line crosses among the control and elevated CO2 treatments (ANOVA: F2,26 = 3.474, p = 0.046). A post hoc test showed that while there was no significant difference between control and moderate CO2 treatments (Tukey HSD; p = 0.141), there was a significant difference between the control and high CO2 treatment levels (Tukey HSD; p = 0.038). Activity levels were not affected by individual body size (negative binomial GLM; p = 0.635).

Bottom Line: Increased activity could lead to adverse effects on energy budgets as well as increasing visibility to predators.A tendency to respond to a stimulus with escape behaviours could increase survival, but may also be energetically costly and could potentially lead to more chases by predators compared with individuals that use defensive postures.These results demonstrate that projected future ocean acidification affects the behaviours of a tropical squid species.

View Article: PubMed Central - PubMed

Affiliation: College of Marine and Environmental Sciences, James Cook University, Townsville, QLD 4811, Australia ARC Centre of Excellence for Coral Reef Studies, James Cook University, Townsville, QLD 4811, Australia blake.spady@my.jcu.edu.au.

No MeSH data available.


Related in: MedlinePlus