New paper: Individual variation in sensitivity to pesticide exposure in tilapia

Organophosphate pesticides are used worldwide and often end up polluting waterways. These substances are known to have sub-lethal effects on fish, generally impairing swimming ability via a range of physiological mechanisms. Most studies in this area, however, focus on mean-level responses to pesticide exposure. In this study, we aimed to determine whether individual fish within a species were more or less sensitive to exposure to organophosphate pesticides. In summary, pesticide impaired swimming performance in all fish performance by reducing swimming efficiency, but individual tilapia varied widely in their relative sensitivity. Intrinsic individual metabolic physiology determined effects of the pesticide on performance and, in particular, good swimmers remained better swimmers after exposure. This individual variation in sensitivity could play a role in selective processes and evolutionary responses in polluted habitats.  Read more in the OPEN access article, here:

http://www.sciencedirect.com/science/article/pii/S0166445X17301558

McKenzie, D. J., Blasco, F. R., Belão, T. C., Killen, S. S., Martins, N. D., Taylor, E. W., & Rantin, F. T. (2017). Physiological determinants of individual variation in sensitivity to an organophosphate pesticide in Nile tilapia Oreochromis niloticus. Aquatic Toxicology, 189, 108-114.

New Paper: Trade-offs Between Peak and Thermal Breadth of Aerobic Scope Across Fish Species

Ectothermic animals are strongly influenced by temperature. It is speculated that species face a trade-off between increased performance at a specific temperature versus being able to function over a broader range of temperatures but at a lower peak level. The balance of this trade-off – if it exists – may influence the environments that fish and other ectotherms inhabit and how they respond to climate change. A new paper by Julie Nati, Jan Lindstrom, Lewis Halsey and Shaun Killen shows that, across fish species, peak performance for aerobic scope is not linked to performance across a range of temperatures, suggesting that links between peak and thermal breadth for the capacity for aerobic metabolism may not affect responses to climate warming. Read more in on access paper here!:

http://rsbl.royalsocietypublishing.org/content/12/9/20160191

Nati, JH, Lindstrom, J, Halsey, LG, & Killen, SS. 2016. Is there a trade-off between peak performance and performance breadth across temperatures for aerobic scope in teleost fishes? Biology Letters. DOI: 10.1098/rsbl.2016.0191

New Paper: The "Calming Effect" of Shoaling in Damselfish

Many animal species live in groups to derive benefits for foraging and predator avoidance. Another potential benefit is a reduction in routine energy expenditure for each individual within the group as they share duties for anti-predator vigilance. There may also be a ‘calming effect’, whereby individuals in group experience decreased stress and energy expenditure compared to isolated individuals. In a new study on the cover of this month’s Journal of Experimental Biology, Shaun Killen, Lauren Nadler, and colleagues at James Cooke University in Australia examined these issues by measuring metabolic and growth rates in individual damselfish (Chromis viridis) with and without visual and olfactory cues from groups of other fish of the same species. They found that individuals in shoals reduced their metabolic rate by 26% from their metabolic rate when alone. As increased extreme weather events may lead to forced social isolation in gregarious fishes, this could have repercussions for individual energy budgets. Photo credit: Eva McClure. Read more in the open access article here!:

http://jeb.biologists.org/content/219/18/2802

Nadler, L.E., Killen, S.S., McClure, E.C., Munday, P.L., McCormick, M.I. 2016. Shoaling reduces metabolic rate in a gregarious coral reef fish species. Journal of Experimental Biology. 219: 2802-2805. doi: 10.1242/jeb.139493

New Paper: Effects of Size and Metabolic Rate on Risk-Taking in Young Zebrafish

Individuals within animal species often show wide variation in behavioural traits, such as willingness to explore novel habitats or take risks around predators. This behavioural variation is often correlated with other traits including body size or metabolic rate. In a new study by Shaun Killen and colleagues in Germany, it was observed that for juvenile zebrafish, the tendency of individuals to take risks was explained by variation in body length but not necessarily body mass or baseline metabolic demand.

Read more in the open access article in the Journal of Fish Biology, here!:
http://onlinelibrary.wiley.com/doi/10.1111/jfb.13100/full
 

Polverino, G., Bierbach, D., Killen, S.S., Uusi-Heikkilä, S., Arlinghaus, R. 2016. Body length rather than routine metabolic rate and body condition correlates with risk-taking behaviour in juvenile zebrafish (Danio rerio). Journal of Fish Biology. doi:10.1111/jfb.13100

New Paper: Oxidative Stress in the Extremely Long-Lived Greenland Shark

Recent evidence suggests that the Greenland shark may be the longest lived of all vertebrates, living for hundreds of years and not even reaching sexual maturity until they are at least 130 years old. How are they able to live this long? A new study by David Costantini, Shona Smith, Shaun Killen, and colleagues in Denmark examined this issue by measuring the oxidative status of Greenland shark tissues to see if minimising oxidative damage might be a mechanism by which they are able to extend their life. Although indices of protein damage in Greenland sharks are very low compared to most other animal species, it appears that this may be associated with other aspects of the ecology of Greenland sharks (e.g. adaptation to life in cold water and repeated deep dives) and not related for their long lifespan. Read more here!:

http://www.sciencedirect.com/science/article/pii/S1095643316302276 

Costantini, D., Smith, S., Killen, S. S., Nielsen, J., & Steffensen, J. F. (2016). The Greenland shark: A new challenge for the oxidative stress theory of ageing?. Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology.

The Energetic Cost of Vigilance

Myself and collaborators Donald Reid, Stefano Marras, and Paolo Domenici just published a new paper in Frontiers in Physiology, showing that individual fish that respond soonest to a simulated predator attack also take the longest to recover after exercise. This is important because prey fish will often use intense bursts of exercise to escape predators and their normal behaviour could be compromised during the recovery from this activity. This work was done using juvenile mullet:

Why do these faster responding fish take longer to recover? It seems that, after being startled, these particular fish spend more energy on being vigilant (perhaps looking out for another attack), and that this extra energy expenditure reduces resources available to fuel recovery. 

This work was done at the Institute for the Coastal Marine Environment in beautiful Oristano, Sardinia, Italy, with funds from COST Action  FA1004 Conservation Physiology of Marine Fishes.