Dr. Iain McGaw
Ocean Sciences Centre
Memorial University of Newfoundland
St. John's, Newfoundland, Canada,
My research program investigates the ecophysiology and behaviour of marine invertebrates. Most of the work has focused on crustaceans and echinoderms, in particular how animals use respiratory and cardiovascular mechanisms when adapting to environmental change. Recently we have been investigating digestive processes in crustaceans and how animals modulate mechanical digestion, enzyme activity and protein synthesis. Many of these findings are applicable to fisheries or aquaculture. I am also interested in crustacean behaviour; how various behaviours often have a physiological basis and help adapt the animal to changes in environmental conditions. We use both lab and field based approaches to answer these questions. Most of the species we work on are found locally around Newfoundland. I also have long standing ties with the Bamfield Marine Sciences Centre on Vancouver Island and return regularly to work on the wide array of species found on the west coast.
Examples of research conducted in the laboratory include:
1. Balancing the demands of physiological systems
This is main area of research in my lab. We use both lab and field based experiments to determine how animals balance the demands of several physiological systems that may oppose each other in action. For example when an animal feeds and subsequently digests a meal there is an increase in metabolism (oxygen uptake) termed the specific dynamic action of food. This increase in metabolism reflects the energetic process involved with mechanical digestion and the subsequent absorption and assimilation of the meal. We are interested how this postprandial increase in metabolism affects how an animal deals with environmental change. We have investigated changes in cardiovascular and respiratory physiology, gut motility and enzyme activation and intracellular protein synthesis in response to hypoxia, emersion, temperature change, salinity.
2. Interactions between behaviour and physiology
Behavioural responses are usually an organisms first response to an environmental challenge. Historically both behaviour And physiology have been studied in isolation. We are interested in how these two are connected, can a behavioural response Be used to control physiological parameters? What are the trade-off behaviours associated with acquiring food or shelter Or avoiding predators in a physiologically stressful environment? The lab is set-up with state-of-the-art computer-controlled hardware and software to answer these questions. I also have a boat, trailer and truck which is used to monitor behavioural responses of animals in the field.
3. Use of lobsters in multitrophic aquaculture
We have been investigating interactions between lobsters and aquaculture facilities. It is possible that lobsters could be efficient scavengers under mussel farms, removing dead and decaying product that would otherwise stagnate on the seabed. We have monitored, feeding, moulting and growth and health status of cage-held lobsters in both the lab and the field.
4. Physiological responses of sea stars to environmental change
Most of my research to date has focused on crustaceans, but I am also carrying out research on sea stars. These organisms occupy nearly every marine environment, yet there is very little research on even the basic physiology and behaviour of this interesting group of organisms. I am currently investigating the physiological responses of an intertidal sea star to emersion at different temperatures.
5. Functional anatomy of the decapod crustacean circulatory system
One of the continuing research themes within the lab is crustacean cardiovascular physiology. This has been complemented with studies, using corrosion casting methods, to investigate the complex circulatory system of decapod crustaceans. Our recent evidence suggests that, at least in physiological terms, the decapod crustacean system can now be classed as one that is partially closed, rather than open.