Relationship: 1028



Reduced, Posterior swim bladder inflation leads to Reduced, Swimming performance

Upstream event


Reduced, Posterior swim bladder inflation

Downstream event


Reduced, Swimming performance

Key Event Relationship Overview


AOPs Referencing Relationship


Taxonomic Applicability


Term Scientific Term Evidence Link
zebrafish Danio rerio NCBI
fathead minnow Pimephales promelas NCBI

Sex Applicability


Life Stage Applicability


Key Event Relationship Description


Effects on swim bladder inflation can alter swimming performance and buoyancy of fish, which is essential for predator avoidance, energy sparing, migration, reproduction and feeding behaviour, resulting in lower young-of-year survival.

Evidence Supporting this KER


The weight of evidence supporting a direct linkage between these two KEs, i.e. reduced posterior swim bladder inflation and reduced swimming performance, is intermediate.

Biological Plausibility


The posterior chamber of the swim bladder has a function in regulating the buoyancy of fish, by altering the volume of the swim bladder (Roberston et al., 2007). Fish rely on the lipid and gas content in their body to regulate their position within the water column, with the latter being more efficient at increasing body buoyancy. Therefore, fish with functional swim bladders have no problem supporting their body (Brix 2002), while it is highly likely that impaired inflation severely impacts swimming performance, as has been suggested previously (Bagci et al., 2015; Hagenaars et al., 2014). Fish without a functional swim bladder can survive, but are severely disadvantaged, making the likelihood of surviving smaller.

Empirical Evidence


Buoyancy is one of the primary mechanisms of fish to regulate behaviour, swimming performance and energy expenditure.

Lindsey et al., 2010 reported that larvae that fail to inflate their swim bladder use additional energy to maintain buoyancy (Lindsey et al., 2010, Goodsell et al., 1996), possibly contributing to reduced swimming activity. Furthermore, they reported that the range of swimming depth varies with stages of swim bladder development.

Czesny et al., 2005 reported that yellow perch larvae without inflated swim bladders capture free-swimming prey poorly and expend more energy on feeding and maintaining their position within the water column, due to impacted swimming behaviour.

Kurata et al., 2014 observed that Bluefin tuna larvae present at the bottom of a tank, incapable of swimming upwards, had significantly lower swim bladder inflation.

Chatain (1994) associated larvae with non-inflated swim bladders with numerous complications, such as spinal deformities and lordosis and reduced growth rates, adding to the impact on swimming behaviour.

An increasing incidence of swim bladder non-inflation has also been reported in Atlantic salmon. Affected fish had severely altered balance and buoyancy, observed through a specific swimming behaviour, as the affected fish were swimming upside down in an almost vertical position (Poppe et al., 1997).

Several chemical exposures to thyroid disrupting compounds resulted in an effect on posterior chamber inflation and following a direct effect on the swimming distance of the zebrafish larvae (Stinckens et al., unpublished).

Uncertainties and Inconsistencies


Robertson et al., (2007) reported that the swim bladder only becomes functional as a buoyancy regulator when it is fully developed into a double-chambered swim bladder. This would implicate that effects on posterior chamber inflation would not directly result in effects on swimming capacity. However, it was also reported that gases in the swim bladder increase the buoyancy of zebrafish larvae just after initial inflation, but active control only after 28–30 d post hatch. Therefore, an effect on swimming capacity is still likely.

PTU exposure resulted in an effect on posterior chamber inflation, but did not result in a direct effect on the swimming distance of the zebrafish larvae (Stinckens et al., unpublished). Furthermore, the swimming activity of zebrafish larvae was reduced after 5 days MBT exposure in zebrafish, which had normal inflated posterior chambers, indicating the effects on swimming behaviour via other modes of action.

Quantitative Understanding of the Linkage


The quantitative understanding of the linkage between impaired posterior chamber inflation and effect on swimming behaviour is intermediate.

Response-response Relationship




Known modulating factors


Known Feedforward/Feedback loops influencing this KER


Domain of Applicability


Importance of swimming performance for natural behaviour is generally applicable to fish.



Roberston, G.N., McGee, C.A.S., Dumbarton, T.C., Croll, R.P., Smith, F.M., 2007.Development of the swim bladder and its innervation in the zebrafish, Danio rerio. J. Morphol. 268, 967–985, http://dx.doi.org/10.1002/jmor.

Brix O (2002) The physiology of living in water. In: Hart PJ, Reynolds J (eds) Handbook of Fish Biology and Fisheries, Vol. 1, pp. 70–96. Blackwell Publishing, Malden, USA.

Bagci, E., Heijlen, M., Vergauwen, L., Hagenaars, A., Houbrechts, A.M., Esguerra, C.V.,Blust, R., Darras, V.M., Knapen, D., 2015. Deiodinase knockdown during earlyzebrafish development affects growth, development, energy metabolism,motility and phototransduction. PLoS One 10, e0123285, http://dx.doi.org/10.1371/journal.pone.0123285.

Hagenaars, A., Stinckens, E., Vergauwen, L., Bervoets, L., Knapen, D., 2014. PFOSaffects posterior swim bladder chamber inflation and swimming performanceof zebrafish larvae. Aquat. Toxicol. 157, 225–235, http://dx.doi.org/10.1016/j.aquatox.2014.10.017.

Lindsey, B.W., Smith, F.M., Croll, R.P., 2010. From inflation to flotation: contributionof the swimbladder to whole-body density and swimming depth duringdevelopment of the zebrafish (Danio rerio). Zebrafish 7, 85–96, http://dx.doi.org/10.1089/zeb.2009.0616.

Goodsell, D.S., Morris, G.M., Olsen, A.J. 1996. Automated docking of fleixble ligands. Applications of Autodock. J. Mol. Recogonition, 9:1-5.

Czesny, S.J., Graeb, B.D.S., Dettmersn, J.M., 2005. Ecological consequences of swimbladder noninflation for larval yellow perch. Trans. Am. Fish. Soc. 134,1011–1020, http://dx.doi.org/10.1577/T04-016.1.

Kurata, M., Ishibashi, Y., Takii, K., Kumai, H., Miyashita, S., Sawada, Y., 2014.Influence of initial swimbladder inflation failure on survival of Pacific bluefintuna, Thuunus orientalis (Temminck and Schlegl) larvae. Aquacult. Res. 45,882–892.

Chatain, B., 1994. Abnormal swimbladder development and lordosis in sea bass (Dicentrarchus labrax) and sea bream (Sparus auratus). Aquaculture 119:371–379.

Poppe, T.T., Hellberg, H., Griffiths, D., Mendal, H. 1977. Swim bladder abnormality in farmed Atlantic salmon, Salmo salar. Diseases of aquatic organisms 30:73-76.

Stinckens, E., Vergauwen, L., Schroeder, A.L., Maho, W., Blackwell, B., Witter, H.,Blust, R., Ankley, G.T., Covaci, A., Villenueve, D.L., Knapen, D., 2016. Disruption of thyroid hormone balance after 2-mercaptobenzothiazole exposure causes swim bladder inflation impairment—part II: zebrafish. Aquat. Toxicol. 173:204-17.