A Comparison of Potential Mixes in Two Southeastern Lakes: Lake Jocassee, SC and Carters Lake, GA

In the Southeast United States most lakes tend to be warm monomictic lakes, mixing during one season each year. However, under circumstances of great relative depth, lakes may tend towards meromictic conditions. In this case the bottom layer of the lake, or the monimolimnion, never mixes completely. Carter’s Lake in Chatsworth, Georgia was created in 1977 after the creation of Carter’s Dam, and is an example of a meromictic lake. Lake Jocassee is a reservoir located in Salem, South Carolina on the Savannah River Basin. The reservoir was created in 1973 upon the completion of The Jocassee Pumped Storage Hydroelectric Station. Like Carter’s Lake, Lake Jocassee is very deep and large, and has the possibility of behaving as a meromictic lake. Past data suggests that Lake Jocassee behaves more frequently as a warm monomictic lake while occasionally not mixing completely. We wanted to further study Lake Jocassee’s morphometry to dig deeper into the possibility of meromixis within the lake by looking at the level of mixing in the Winter of 2014

Data from: Hindlimb muscle function in turtles: is novel skeletal design correlated with novel muscle function?

Variations in musculoskeletal lever systems have formed an important foundation for predictions about the diversity of muscle function and organismal performance. Changes in the structure of lever systems may be coupled with changes in muscle use and give rise to novel muscle functions. The two extant turtle lineages, cryptodires and pleurodires, exhibit differences in hindlimb structure. Cryptodires possess the ancestral musculoskeletal morphology, with most hip muscles originating on the pelvic girdle, which is not fused to the shell. In contrast, pleurodires exhibit a derived morphology, in which fusion of the pelvic girdle to the shell has resulted in shifts in the origin of most hip muscles onto the interior of the shell. To test how variation in muscle arrangement might influence muscle function during different locomotor behaviors, we combined measurements of muscle leverage in five major hindlimb muscles with data on muscle use and hindlimb kinematics during swimming and walking in representative semiaquatic cryptodires and pleurodires. We found substantial differences in muscle leverage between the two species. Additionally, we found that there were extensive differences in muscle use in both species, especially while walking, with some pleurodire muscles exhibiting novel functions associated with their derived musculoskeletal lever system. However, the two species shared similar overall kinematic profiles within each environment. Our results suggest that changes in limb lever systems may relate to changes in limb muscle motor patterns and kinematics, but that other factors must also contribute to differences in muscle activity and limb kinematics between these taxa