Food web structure across basins in Lake Erie, a large freshwater ecosystem

Understanding spatial variation of aquatic food web structure and how ecosystem boundaries should be delineated is important. Here, we investigated the spatial variation in food web structure within Lake Erie across its three basins using δ 13 C and δ 15 N. Fish and lower trophic level composition were similar but differences in food web structure were observed among basins. The food web in the central basin had the smallest δ 13 C and δ 15 N range and total area based on stable isotope values by the aquatic community, likely due to chronic epibenthic hypoxia in the summer that affects fish habitat and resources. The largest δ 15 N range was in the east, driven by the high trophic position of lake trout present in this deepest basin. The western basin had the largest mean distance to the centroid of all three basins, indicating a large trophic diversity, probably due to high nutrient loadings and productivity. This research revealed spatial variability of food web structure in large lake ecosystems and the importance of considering smaller sub-units, such as basin, in large lakes.