Risk assessment of threats to large lakes around the world — a pilot survey

Risks to the productivity, diversity, and use of aquatic resources in large lakes around the world can be evaluated by identifying threats and by estimating the potential impacts of the threats on biodiversity and fish populations. Risk assessment is a procedure that allows lake managers to rank threats and develop management p laos based on the level o f risk to the lake ecosystems. The primary threats to valued ecosystem components are ranked and prioritized based on the magnitude and likelihood of impact and the estimated time frame ofimpact. The goal o f this study was to compare threats and evaluate risks to large lakes around the world. Our interest was to compare our experiences with the Laurentian Great Lakes to other large lakes. Specifically, our objectives were to address 4 questions: (l) Are threats dependent on lake size or region? (2) Do threats to lower trophic levels pose a greater risk to lakes than threats to upper trophic levels? (3) Are threats increasing over time? and (4) Can this type of comparative risk assessment be useful to managers? This pilot survey showed that risk assessment based on expert knowledge was instructive for addressing all 4 questions. Comparative risk assessment is a useful resource tool for the management of large lakes.