Biotic drivers of ecosystem nutrient cycling

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Human activities such as harvesting, urbanization, and agriculture have led to the decline or extinction of many top predators and herbivores. For example, there has been a significant decline in Atlantic cod and salmon stocks off the coast of Newfoundland and Labrador. Humans have also introduced a number of predators and herbivores for recreation or resource management. For example, moose were introduced to Newfoundland in the early 1900s and today moose hunting is a major industry in the province. Predators and herbivores can influence ecosystem nutrient cycling; a critical life supporting ecological service which is fundamental for food production and water purification. However, the implications of the extinction or introduction of predators and herbivores on ecosystem nutrient cycling are not well understood. The long-term goal of my research program is to investigate the role of predators and herbivores in ecosystem nutrient cycling. Over the next five years I have three objectives to disentangle the different mechanisms linking predators and herbivores to ecosystem nutrient cycling; I) assess the current state of knowledge through an empirical data synthesis, II) derive ecosystem models to predict the effect of predator and herbivore extinctions and introductions on ecosystem nutrient budgets, and III) test theoretical predictions for the relationship between predators and herbivores and nutrient cycling in aquatic and terrestrial ecosystems in the boreal region of Newfoundland. This research is important as it will enable ecologists and resource managers to better understand and predict the effects of predator and herbivore extinctions and introductions on nutrient cycling within and across ecosystems. It is of particular relevance to Newfoundland and Labrador as the province continues to study the effects of declines in native Atlantic cod and salmon stocks and the expansion of spruce budworm and non-native moose. My research program will train 2 PhD, 4 MSc, and 9 undergraduate students over the next 5 years in a unique research environment that integrates mathematical modelling and empirical data collection.