Introduction 



Prairie stream systems throughout North America 

 have suffered neglect due to a lack of 

 comprehensive study and understanding (Matthews 

 and Robison 1988. Dodds et al. 2004). Only 

 recently have there been efforts to sample and 

 describe the interactions among the state's prairie 

 stream aquatic biota, and to relate prairie system 

 aquatic communities to their landscapes. This 

 study covers one such undocumented area. South 

 Dakota's Slim Buttes region. From the smallest 

 prairie spring (Figure 1 ) to the Little Missouri River 

 as it leaves South Dakota a large prairie river 

 (Figure 2), the Slim Buttes region contains a wide 

 variety of aquatic ecosystems. 



Figure 1. Picnic Spring in the Cave Hills, a small 

 Northwestern Great Plains perennial spring. 



As a whole, the Slim Buttes area is an important 

 part of a large swath of untilled prairie area in the 

 Level III Northwestern Great Plains ecoregion 

 (Omerink 1995) (Figure 3), also known as the 

 Northern Great Plains Steppe (TNC 1999). Four 

 Level IV ecoregions are found within the Slim 

 Buttes area (Figure 4). Because intact watershed 

 landscapes at the regional scale have been shown 

 to support aquatic communities with high biological 

 integrity (Allan et al. 1997), we surmised that the 

 Slim Buttes region might support some of the most 

 intact native prairie fish and macroinvertebrate 

 communities in the state. One fairly recent study in 

 the Moreau River Basin downstream from our 

 study area reported 1 9 species of fish ( 1 6 native) 

 (Loomisl997). 



To determine if this were true, we used an aquatic 

 ecosystem classification approach developed by the 

 Montana Natural Heritage Program (MTNHP) to 

 increase the understanding of Montana's aquatic 

 prairie ecosystems (Stagliano 2005). Ecosystem 

 classification provides a way to understand the 

 complexity of ecosystems and creates distinctions 

 among ecosystem types based on factors that 

 determine the distribution of ecological processes 

 and biota (Hawkins and Norris 2000). We 

 previously classified biological communities (fish 

 and macroinvertebrates) within the Missouri River 

 Zoogeographic Region with respect to the common 

 repeatable habitat units within the watersheds that 

 they occur. The Slim Buttes area is within the 

 same Level III ecoregion. so we hoped that utilizing 

 these classifications would validate their regional 

 applicability while allowing us to predict community 

 types in the scope of watersheds and aquatic 

 ecological units. 



I ly^iD'c J. I he l.iiilc Missouri River at the North 

 Dakota border, a large prairie river 



