Here's a video sampling of some of the work going on in our lab. More to come!...
A video montage of some work by Shaun Killen, Lauren Nadler, and colleagues at the Lizard Island Research Station on the Great Barrier Reef. Includes the full circle - fish capture, lab experiments, and then release of fish back to their coral home!
From top to bottom, these three videos show: a young clownfish, a Trinidadian guppy, and an Atlantic mackerel in a swimming tunnel, which is basically a treadmill for fish. The speed of the water flow can be controlled and the fish will swim to match the speed of the water. This is similar to tests of human athletes where, for example, individuals wear a mask to record oxygen use or CO2 release while on an exercise bike. Using this sort of swimming tunnel we can estimate the energetic costs of many different behaviours in fish and how this may be affected by things like diet or temperature. Note the green plant beside the swim tunnel: we have found guppies feel more comfortable and swim better when the tunnel is surrounded by plants. The guppy video was part of this study. This swim tunnel with the clownfish and guppy is about 150 ml and is suitable for small fish. We also have larger swim tunnels (30 L, 90 L) which can be used to swim larger fish or groups of fish. The mackerel is swimming in a 90L swim tunnel as part of some work done with John Steffensen, Stefano Marras, and Paolo Domenici.
This video shows a trawling simulation with minnows and miniature trawl net within a swim flume, collected as part of this paper. You can see that each fish is tagged with a different colour for identification. The time that they spent in the net was quantified and related to their physiological characteristics, including aerobic and anaerobic swimming ability, minimal and maximal metabolic rates, and anaerobic capacity. It was found that fish show a very high degree of vulnerability to capture - some were captured very easily while others were never captured. Further, it was those with a higher anaerobic capacity for fast burst-type swimming that spent less time in the net.
This video shows two post-larval Ambon damselfish fighting over a piece of coral in the lab at the Lizard Island Research Station. This setup is similar to that used to collect data for this paper. At this life-stage, this species is extremely aggressive as they fight for territories which will provide the most protection from predators.
This video shows a small shoal of juvenile golden grey mullet swimming against a current in a swim flume. You can see that the fish are individually marked with a unique pattern. This helps us identify each fish for recording their behaviours. Some of the fish were also tested for a range of physiological traits and swimming ability in isolation. This setup allowed us to collected the data for this paper and this paper.
Many of the experiments we do in the lab include the automated tracking of animal movements with specialised software. With these programs we can measure all kinds of things including the average speed of the fish, time spent not moving, and average distance from the wall or other objects in an arena. Both of these examples to the right were performed using the freely available software Ctrax.
When a fish is attacked by a predator - such as a bird or another, larger fish – a few milliseconds will determine whether or not the fish is captured or will survive to see another day. One way that fish can escape attacks is by using a reflexive escape response whereby the fish bends its body and then quickly flicks its tail to launch itself away from the threat. This response can occur within 15 milliseconds after the fish senses an attack and can propel the fish at around 15 body lengths per second over short distances (e.g. around 2 meter per second for a 13 cm fish)! Researchers can perform a frame-by-frame analysis of this escape behaviour by filming the escapes with high-speed video. This video shows a juvenile mullet Liza aurata escaping a dropped stimulus and was framed at 240 frames per second. The stimulus dropping from above simulates an attack from an aerial predator such as a bird. This video was part of work done for the following publication:
Killen SS, Reid D, Marras S, and Domenici P (2015) The interplay between aerobic metabolism and antipredator performance: vigilance is related to recovery rate after exercise. Frontiers in Physiology. 6:111. doi: 10.3389/fphys.2015.00111