Many arctic lakes are oligotrophic systems
where phototrophic growth is controlled by nutrient supply.
Recent anthropogenic nutrient loading is associated with
biological and/or physico-chemical change in several lakes
across the arctic. Shifts in nutrient limitation (nitrogen (N),
phosphorus (P), or N ? P) and associated effects on the
growth and composition of algal communities are commonly
reported. The Kangerlussuaq region of south-west
Greenland forms a major lake district which is considered
to receive little direct anthropogenic disturbance. However,
long-range transport of pollutant N is now reaching
Greenland, and it was hypothesised that a precipitation
gradient from the inland ice sheet margin to the coast might
also deliver increased N deposition. In situ nutrient bioassays
were deployed in three lakes across the region: ice
sheet margin, inland (close to Kangerlussuaq) and the coast
(near Sisimiut), to determine nutrient limitation of lakes
and investigate any effects of nutrients on periphyton
growth and community composition. Nutrient limitation
differed amongst lakes: N limitation (ice sheet margin), N
and P limitation (inland) and N ? P co-limitation (coast).
Factors including variation in N supply, ice phenology,
seasonal algal succession, community structure and
physical limnology are explored as mechanisms to explain
differences amongst lakes. Nutrient limitation of arctic
lakes and associated ecological impacts are highly variable,
even across small geographic areas. In this highly sensitive
region, future environmental change scenarios carry a
strong risk of significantly altering nutrient limitation; in
turn, potentially severely impacting lake structure and
function
