Marine organisms transported by seabirds may contribute significantly to Arctic charr diet in coastal High-Arctic lakes

The rich marine resources along the western coast of Spitsbergen (Svalbard) have given rise to colonies of breeding seabirds, which likely represent an important vector of nutrient transport from marine to terrestrial environments. These seabirds may also supply additional nutrients to lakes via their droppings, while bathing and/or when being attacked by other birds during flight to their nest sites. To study the importance of such droppings in the diet of freshwater fish, we sampled Arctic charr by gillnetting during a three-week period in the oligotrophic Lake Arresjøen in northwestern Svalbard. Marine fish and invertebrates made up more than 12% of the dry weight of the stomach contents of Arctic charr larger than 24 cm captured in the littoral zone. This suggests that the seabird transport of marine organisms contributes directly to the diet of Arctic charr in coastal High-Arctic lakes, but this contribution may also give a higher load of mercury and polychlorinated compounds.