these lake management problems is to eliminate or lessen thermal stratification through aeration. Aeration has met with some success, although it has rarely proved to be a panacea. Anthropogenic influences Every lake has a set mixing regime that is influenced by lake morphometry and environmental conditions. However, changes to human influences in the form of land use change, increases in temperatures, and changes to weather patterns have been shown to alter the timing and intensity of stratification in lakes around the globe. These changes can further alter the fish, zooplankton, and phytoplankton community composition, in addition to creating gradients that alter the availability of dissolved oxygen and nutrients. There are a number of ways in which changes in human land use influence lake stratification and consequently water conditions. Urban expansion has led to the construction of roads and houses close to previously isolated lakes, sometimes causing increased runoff and pollution. The addition of particulate matter to lake bodies can lower water clarity, resulting in stronger thermal stratification and overall lower average water column temperatures, which can eventually affect the onset of ice cover. Water quality can also be influenced by the runoff of salt from roads and sidewalks, which often creates a benthic saline layer that interferes with vertical mixing of surface waters. Further, the saline layer can prevent dissolved oxygen from reaching the bottom sediments, decreasing phosphorus recycling and affecting microbial communities. On a global scale, rising temperatures and changing weather patterns can also affect stratification in lakes. Rising air temperatures have the same effect on lake bodies as a physical shift in geographic location, with tropical zones being particularly sensitive. The intensity and scope of impact depends on location and lake morphometry, but in some cases can be so extreme as to require a reclassification from monomictic to dimictic (e.g. Great Bear Lake). Globally, lake stratification appears to be more stable with deeper and steeper thermoclines, and average lake temperature as a main determinant in the stratification response to changing temperatures. Further, surface warming rates are much greater than bottom warming rates, again indicating stronger thermal stratification across lakes. Changes to stratification patterns can also alter the community composition of lake ecosystems. In shallow lakes, temperature increases can alter the diatom community; while in deep lakes, the change is reflected in the deep chlorophyll layer taxa. Changes in mixing patterns and increased nutrient availability can also affect zooplankton