“When I did my veterinary degree in Kenya we never used to learn about aquatic stuff. It was rarely taught. But,” says Collins Kamunde, “when I did my postgraduate work, I found myself interested in
aquatics and ended up studying aquatic physiology and toxicology. Deep inside, this is what I wanted to do.”

A year’s NSERC-funded industrial postdoctoral fellowship in British Columbia further refined the expertise he brought to AVC in January 2004, where he is an Assistant Professor in the Department of Biomedical Sciences. His NSERC- and CFI-funded research—“looking at the relative importance of water versus food as uptake vectors for metals in indigenous aquatic organisms” —is a crucial signpost in monitoring our surroundings and helping to frame regulations to protect them.

“My work is important, as it takes a short time span for metals to get into fish and then it can also be a short time to get lab results applied in the real world. It has direct implications in developing the criteria for metals in the environment—such as how much metal that industry is permitted to release into a water system. My PhD work on this has been used to develop some of those environmental guidelines.

“In some ways, I think the aquatic environment is better than it was 15 or 20 years ago. Some areas with heavy industry were practically devastated, but thanks to new research, and increased industry compliance, water quality has improved. But these days, when environmental quality is a major concern for everybody, when pollution and the environment are as important to Canadians as health, it’s important to understand: if it’s dirty, if it’s polluted, you can’t claim you are leading a good life. We are as healthy as the environment,” he contends.

One of his major projects is looking at how metals actually get into fish. “A fish is unique compared to humans or terrestrial animals. Living in water, it can take up these metals with food, but it also has gills. The gills exchange oxygen, but also absorb these pollutants. Then the metals can accumulate and damage the fish—and, if people eat it, the metals can potentially harm people.

“Take copper, for example. It is an essential metal, in the right
quantities, but toxic when accumulated in high amounts. We have found that if you expose fish to food that is contaminated with copper, the fish are able to down-regulate how fast they take up copper through the gill surface. There is a clear relationship. So it’s a tightrope: take too much and it’s toxic, take too little and you have a nutritional deficiency. I look at how the fish tries to maintain that balance.

“I also study zinc, another essential trace metal, which is more tightly regulated by fish than copper, and cadmium, one of the most toxic non-essential metals. The central theme of my research here is to unveil the nature of cross-talk between dietary and waterborne uptake pathways, and to understand the mechanisms of action and physiological handling strategies of these metals.”

Overall, when metals accumulate in biota, they can generate reactive oxygen species or impair the antioxidant defense system causing oxidative damage to cells and impairing the function of many enzymes, including  the ones that promote detoxification.

Data generated from Kamunde’s laboratory has challenged some earlier theories of metal toxicity. “It was believed, for example, that when the fish’s ability to excrete and detoxify metals is exceeded, metals spill over into metal-sensitive compartments, but we found that cadmium, copper, and zinc actually bind everywhere at the cellular level. There is no selective binding; all subcellular compartments appear to bind metals irrespective of dose and duration of exposure.

“We have also been trying to develop models that allow us to predict the binding of metals to the gill surface. Here, metal binding constants to the gill are determined and, in combination with the water chemistry, are used to predict if a given concentration of a metal would or wouldn’t be toxic.” Many factors influence the binding of metals to fish gill. “We need to know, for example, how hard the water is. Hard water has more calcium and magnesium, both of which can be protective by competing with metals for binding sites on the gill surface. We also need to know how much dissolved organic matter is in the water because it is also protective; it binds metals and keeps them from going into the fish.” By inputting water chemistry data and metal binding constants to the gill into what’s called a biotic ligand model (BLM), researchers can predict the toxicity of metals in the water. “The beauty of the BLM as a tool for environmental regulation is that it allows decisions to be made without the need for toxicity tests which are expensive and require animal use. The long-term goal of my work is to develop a model that can accurately predict metal uptake and toxicity from both water and food for use in metals risk assessment and regulation.”

He is also looking at the possibility of encapsulating recommended levels of essential metals in fish feed “including some active ingredients that once they are released in the intestines would bind phosphorus—which causes algal blooms in water—and limit its bioavailability in the aquatic environment. If we can bind it so that it doesn’t move into the environment, making feed that is highly environmentally friendly, it will limit some of the problems of eutrophication, where over-enrichment of water bodies with nutrients causes excessive growth of organisms such as algae, with depletion of oxygen levels.”

Kamunde spends a lot of time in his office, often arriving at AVC before dawn. “I like it. In Kenya I always used to be the top student in my class, so I continue to push myself. I maintained that performance here in Canada and won a Governor General’s Academic Gold Medal at McMaster University for my PhD research. I never give up. I like to succeed. I never give up pushing.”

One of his biggest satisfactions? “My master’s student just
defended her thesis. To me that was a major milestone. My appointment to the editorial board of the Bulletin of Environmental Contamination and Toxicology is also a source of pride and satisfaction
in my research and contribution to environmental toxicology.”