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The effect of drag and attachment site of external tags on swimming eels: experimental quantification and evaluation tool.

Tudorache C, Burgerhout E, Brittijn S, van den Thillart G - PLoS ONE (2014)

Bottom Line: Due to their high swimming efficiency, anguilliform swimmers are very susceptibility for added drag.The results show a significant effect of a) attachment site and b) drag on multiple energetic parameters, such as Cost Of Transport (COT), critical swimming speed (Ucrit) and optimal swimming speed (Uopt), possibly due to changes in swimming kinematics.Attachment at 0.125 bl from the tip of the snout is a better choice than at the Centre Of Mass (0.35 bl), as it is the case in current telemetry studies.

View Article: PubMed Central - PubMed

Affiliation: Institute Biology Leiden, Leiden University, Leiden, The Netherlands.

ABSTRACT
Telemetry studies on aquatic animals often use external tags to monitor migration patterns and help to inform conservation effort. However, external tags are known to impair swimming energetics dramatically in a variety of species, including the endangered European eel. Due to their high swimming efficiency, anguilliform swimmers are very susceptibility for added drag. Using an integration of swimming physiology, behaviour and kinematics, we investigated the effect of additional drag and site of externally attached tags on swimming mode and costs. The results show a significant effect of a) attachment site and b) drag on multiple energetic parameters, such as Cost Of Transport (COT), critical swimming speed (Ucrit) and optimal swimming speed (Uopt), possibly due to changes in swimming kinematics. Attachment at 0.125 bl from the tip of the snout is a better choice than at the Centre Of Mass (0.35 bl), as it is the case in current telemetry studies. Quantification of added drag effect on COT and Ucrit show a (limited) correlation, suggesting that the Ucrit test can be used for evaluating external tags for telemetry studies until a certain threshold value. Uopt is not affected by added drag, validating previous findings of telemetry studies. The integrative methodology and the evaluation tool presented here can be used for the design of new studies using external telemetry tags, and the (re-) evaluation of relevant studies on anguilliform swimmers.

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Relation of critical swimming speed (Ucrit) and minimum Cost Of Transport (COTmin) with added drag.Percentual decrease of Ucrit (reduction %Ucrit; □) and percentual increase of COTmin (increase %COTmin; ○) per individual, plotted against additional drag force (FD, N, measured at Uopt, 0.68 m s−1) of small (FD = 0.05 N), intermediate (FD = 0.10 N) and large dummies (FD = 0.20 N) at site A. The resulting polynomial graph with best fit (r2>0.99) followed the formula red%Ucrit = 102.8±49.35FD2+527.7±273.8 FD and inc%COTmin = −8.9±113.0FD2+2687±636.7FD, respectively.
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pone-0112280-g004: Relation of critical swimming speed (Ucrit) and minimum Cost Of Transport (COTmin) with added drag.Percentual decrease of Ucrit (reduction %Ucrit; □) and percentual increase of COTmin (increase %COTmin; ○) per individual, plotted against additional drag force (FD, N, measured at Uopt, 0.68 m s−1) of small (FD = 0.05 N), intermediate (FD = 0.10 N) and large dummies (FD = 0.20 N) at site A. The resulting polynomial graph with best fit (r2>0.99) followed the formula red%Ucrit = 102.8±49.35FD2+527.7±273.8 FD and inc%COTmin = −8.9±113.0FD2+2687±636.7FD, respectively.

Mentions: For the evaluation of past and future telemetry studies using external tags, corresponding changes in Ucrit and COTmin values were compared and modelled. By plotting the effect of the dummies (E) as a) the reduction of % Ucrit per individual (red%Ucrit) or as b) the increase of % COTmin per individual (increase%COTmin), over the different drag values (FD), the resulting polynomial curve (fig. 4) shows an increase following the formula E = aFD+bFD2 with a and b being constants. The values of a and b are for red%Ucrit 102.8±49.35 and 527.7±273.8, and for increase%COTmin −8.92±113 and 2687±626.7, respectively. The values for increase%COTmin and red%Ucrit at 0.05 and 0.1 N FD did not differ; however the values at 0.2 N differed significantly from each other (p<0.05, N = 8). These results provide a practical tool for the evaluation of comparative methods for the estimate of the effect of added drag on energetic parameters.


The effect of drag and attachment site of external tags on swimming eels: experimental quantification and evaluation tool.

Tudorache C, Burgerhout E, Brittijn S, van den Thillart G - PLoS ONE (2014)

Relation of critical swimming speed (Ucrit) and minimum Cost Of Transport (COTmin) with added drag.Percentual decrease of Ucrit (reduction %Ucrit; □) and percentual increase of COTmin (increase %COTmin; ○) per individual, plotted against additional drag force (FD, N, measured at Uopt, 0.68 m s−1) of small (FD = 0.05 N), intermediate (FD = 0.10 N) and large dummies (FD = 0.20 N) at site A. The resulting polynomial graph with best fit (r2>0.99) followed the formula red%Ucrit = 102.8±49.35FD2+527.7±273.8 FD and inc%COTmin = −8.9±113.0FD2+2687±636.7FD, respectively.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4237349&req=5

pone-0112280-g004: Relation of critical swimming speed (Ucrit) and minimum Cost Of Transport (COTmin) with added drag.Percentual decrease of Ucrit (reduction %Ucrit; □) and percentual increase of COTmin (increase %COTmin; ○) per individual, plotted against additional drag force (FD, N, measured at Uopt, 0.68 m s−1) of small (FD = 0.05 N), intermediate (FD = 0.10 N) and large dummies (FD = 0.20 N) at site A. The resulting polynomial graph with best fit (r2>0.99) followed the formula red%Ucrit = 102.8±49.35FD2+527.7±273.8 FD and inc%COTmin = −8.9±113.0FD2+2687±636.7FD, respectively.
Mentions: For the evaluation of past and future telemetry studies using external tags, corresponding changes in Ucrit and COTmin values were compared and modelled. By plotting the effect of the dummies (E) as a) the reduction of % Ucrit per individual (red%Ucrit) or as b) the increase of % COTmin per individual (increase%COTmin), over the different drag values (FD), the resulting polynomial curve (fig. 4) shows an increase following the formula E = aFD+bFD2 with a and b being constants. The values of a and b are for red%Ucrit 102.8±49.35 and 527.7±273.8, and for increase%COTmin −8.92±113 and 2687±626.7, respectively. The values for increase%COTmin and red%Ucrit at 0.05 and 0.1 N FD did not differ; however the values at 0.2 N differed significantly from each other (p<0.05, N = 8). These results provide a practical tool for the evaluation of comparative methods for the estimate of the effect of added drag on energetic parameters.

Bottom Line: Due to their high swimming efficiency, anguilliform swimmers are very susceptibility for added drag.The results show a significant effect of a) attachment site and b) drag on multiple energetic parameters, such as Cost Of Transport (COT), critical swimming speed (Ucrit) and optimal swimming speed (Uopt), possibly due to changes in swimming kinematics.Attachment at 0.125 bl from the tip of the snout is a better choice than at the Centre Of Mass (0.35 bl), as it is the case in current telemetry studies.

View Article: PubMed Central - PubMed

Affiliation: Institute Biology Leiden, Leiden University, Leiden, The Netherlands.

ABSTRACT
Telemetry studies on aquatic animals often use external tags to monitor migration patterns and help to inform conservation effort. However, external tags are known to impair swimming energetics dramatically in a variety of species, including the endangered European eel. Due to their high swimming efficiency, anguilliform swimmers are very susceptibility for added drag. Using an integration of swimming physiology, behaviour and kinematics, we investigated the effect of additional drag and site of externally attached tags on swimming mode and costs. The results show a significant effect of a) attachment site and b) drag on multiple energetic parameters, such as Cost Of Transport (COT), critical swimming speed (Ucrit) and optimal swimming speed (Uopt), possibly due to changes in swimming kinematics. Attachment at 0.125 bl from the tip of the snout is a better choice than at the Centre Of Mass (0.35 bl), as it is the case in current telemetry studies. Quantification of added drag effect on COT and Ucrit show a (limited) correlation, suggesting that the Ucrit test can be used for evaluating external tags for telemetry studies until a certain threshold value. Uopt is not affected by added drag, validating previous findings of telemetry studies. The integrative methodology and the evaluation tool presented here can be used for the design of new studies using external telemetry tags, and the (re-) evaluation of relevant studies on anguilliform swimmers.

Show MeSH
Related in: MedlinePlus