Research

Our research focuses on how links between physiology and behaviour influence life-history strategies and trade-offs involved with foraging and predator-avoidance behaviours. We are also interested in the effects of environmental stress on animal behaviour, and the scaling of metabolic rate with body size in organisms and its relationship to ecology. Most of our work in these fields focuses on freshwater and marine fishes, and we have several general research themes under way, listed below. You can also read about other projects being conducted with colleagues on the "collaborators" page.

Below are some of our main research themes, but to give a a quick idea of what we study, to the right is a word cloud from the titles of our publications! 

 


The role of individual physiological traits in collective animal behaviours

A school of Atlantic mackerel at the North Sea Oceanarium in Hirtshals, Denmark.

Links between physiological traits and behaviours have been demonstrated in a number of contexts. Interestingly, however, most of this work has been performed using individual animals, while in reality most animals live in groups. Focusing on fish schooling behaviour, this project investigates the role that the physiological traits of individuals play in shaping the behaviour of entire groups, and how environmental factors such as temperature and oxygen availability may affect this relationship.

This project is funded by a NERC advanced fellowship. A portion of this project is being conducted at the Northsea Oceanarium in Hirtshals, Denmark in collaboration with John Steffensen (University of Copenhagen). This facility contains an enormous schools of mackerel allowing us to study the behaviour of individual animals within the group.


The role of physiology in fisheries-induced evolution

Our first-generation attempt at simulating trawling at a small scale using a swim flume and common minnows.

Our first-generation attempt at simulating trawling at a small scale using a swim flume and common minnows.

There is increasing evidence that intense commercial fishing pressure can not only reduce fish stocks but can also cause evolutionary changes to fish populations. However, the mechanisms which underlie these changes remain largely unknown. This research project investigates the role of animal physiology in fisheries induced evolution. Within a given species, variation in physiological traits among individuals – and especially those related to energy balance (e.g. metabolic rate) and swimming performance (e.g. aerobic scope) – could make some fish more vulnerable to capture or more likely to suffer mortality after discard. Selection on these traits could produce major shifts in the fundamental structure and function of fish in response to fishing pressure. You can read more about this project, find info on the research team, and follow updates at PHYSFISHproject.net.


The causes and consequences of compensatory growth 

A three-spine stickleback.

A three-spine stickleback.

Upon re-feeding after a period of  food-deprivation, individuals of many species will grow much quicker than normal and actually “catch-up” in size compared to regularly feeding animals. In other words, they somehow grow faster than they normally do. This occurs in many species and not just fish. The mechanism for how they achieve this more-rapid-than-usual growth isn’t entirely understood, but it’s amazing to think that under normal conditions, animals are not growing at their maximum possible rate – even though they are clearly capable of doing so. This is especially astounding given the extreme benefits of being larger in terms of avoiding predation and ensuring reproductive success. So, given that fish can increase their growth rates after food deprivation, why do they not grow this fast all the time?

The theme of my previous NERC fellowship was compensatory growth in the three-spine stickleback Gasterosteus aculeatus and common minnows Phoxinus phoxinus. This project examined the consequences of compensatory growth on a wide range of behavioural traits including boldness, activity, and sociality. The project also included the first examination of the metabolic response to alarm substance in fishes, with growth compensated fish showing a decoupling of the physiological and behavioural responses to this cue as compared to controls. My work has shown that growth compensated fish also displayed a preference for cooler temperatures. This response may allow individuals to maximise growth efficiency by reducing baseline energy requirements.


Links among energetic demand, aerobic capacity, and behaviour in individual animals

A European minnow.

A European minnow.

Within a given species, it is becoming recognised that all animals are not the same. Some are more athletic, some require more food, some are more aggressive, some are more shy, and so on. A common goal through much of my research is to understand how this variation is important for the ecology of animals and how it may affect how different animals respond to challenges in their environment (e.g. food shortages, temperature changes). 

My work in this area has led to numerous collaborations with Neil Metcalfe (University of Glasgow, UK), David McKenzie (Université Montpellier II, France), Paolo Domenici (CNR, Italy), Stefano Marras (CNR, Italy), Guy Claireaux (University of Brest, France), and John Steffensen (University of Copenhagen, Denmark).


Thermal tolerance of invasive freshwater fishes

The sublethal effects of thermal stress on metabolic demand and aerobic capacity may affect the behaviour and geographical distribution of species. An increase in water temperature, for example, could allow species with wider thermal windows to gain a competitive advantage. In the context of global climate change, such species could expand their range into northern latitudes. Specifically, this project examines how the thermal tolerances of invasive species compare with native species and how this affects behaviour and ecological interactions. This project forms the basis of the PhD work being conducted by Julie Nati.