Mechanisms that explain food chain length are still being considered. Rivers in the Ozark Highlands ecoregion of Southern Missouri have highly endemic fish species as a result of landscape features. Rivers within the Central Irregular Plains ecoregion in Eastern Kansas and Northern Missouri have fish adapted to prairie river conditions. Food chain length between the two ecoregions should be different as a result of the dissimilarity of the fish communities. Fish and invertebrates were collected from four rivers in the Central Irregular Plains and four rivers in the Ozark Highlands ecoregion. Fish and invertebrate samples were analyzed for trophic position using Post (2002) linear mixing model. Diversity and trophic guild structure were calculated from the fish caught by electroshocking in each river. Primary factors controlling food chain length: ecosystem size, productivity and levels of disturbance were measured. Land use was determined using remote sensing.

Results/Conclusions

Diversity and fish trophic guilds were correlated to land use, but not necessarily to water quality, though Ozark streams had lower turbidity and temperature. In particular, it appears that the amount of forest or agriculture was very important for determining fish and invertebrate stream diversity and trophic guild structure. Food chain length in the Central Irregular Plains was greater than in the Ozark Highlands ecoregion. Food chain length was not significantly related to the current theories nor community structure. However, members of the fish family Cyprinidae were very common and may explain differences of food chain length between the two ecoregions. Food chain length is driven by many processes and the effects of landscape should be considered.