| Parafluvial ponds were initially selected according to an inundation, permanent or ephemeral, and a substratum, cobble or depositional, treatment. The first study season indicated the sample sites contained high degrees of diversity, over 100 genera of macroinvertebrates, 14 macrophyte species, and 5 vertebrate species. The second season was sites were subjected to the same inundation and substratum treatments. Ponds contained similar levels of diversity and assemblage composition both years.; The first two years of study non-native brook trout were almost exclusively found in the permanent cobble pond subtype. Native trout, such as cutthroat and bull trout, were almost entirely absent from these critical spawning and rearing areas. Thus, the third study year ponds were experimentally manipulated in order to determine behavioral interactions between native cutthroat and nonnative brook trout in these pond types. Cutthroat trout were added to six study sites in the same size and abundance as brook trout were found. The other six sites were brook trout only as experimental controls. Brook trout occupied the more optimal habitat as a result of their significantly higher levels of aggression than cutthroat trout. This aggressive behavior marginalized the cutthroat trout to the shallower, warmer, and more exposed areas of the pond. This study, for the first time, documented the extremely high biodiversity both within and between ponds as well as their importance in mediating the composition of fish assemblages. |
