User:Appletree4life/Chemocline

Microbial Ecology related to a Chemocline

Example of thermal stratification by light presence.

Chemoclines are created by the stratification of a body of water that has different chemical compositions at different layers within that body of water. The stratification, or separation of the lake into different layers, would be supported by the microbial communities that live in the body of water. Chemocline creation is initially supported by thermal stratification (Thermocline) that is present as the light and heat from the sun will weaken as the depth increases. This light gradient will separate a lake into a photic and aphotic zone. The photic zone will support photosynthetic activities. The aphotic zone will occur deeper in the lake where organic material is decomposed by microbial activity depleting the oxygen in this layer. This will further stratify the lake by creating an oxygen gradient by depth, an oxic (oxygen present) to an anoxic (oxygen absent) zone. The thermal, light, and oxygen gradients within a body of water will constrain the microbial communities that will be able to survive and carry out their metabolic processes. The varying bacteria species will have differing metabolic processes, providing different metabolic waste or byproducts that are characteristic to a species of bacteria.

Meromictic lakes provide a good resource to study when understanding the microbial makeup of a lake that ultimately leads to the formation and regulation of a chemocline. In Mahoney Lake in British Columbia the microbial diversity of the lake is separated into the sulfide-oxidizing phototrophs that inhabit the photic layer of the chemocline and the microbes that inhabit the aphotic layer below the chemocline in the hypolimnion. In this study they showed that the sulfide required by the sulfide oxidizing phototrophs in the chemocline is supplied by the sulfide reducing organisms found in the hypolimnion and the sediment. Another example of the varying distribution of microbes in a body of water would be Lake Shunet in Siberia Russia. Here the distribution of ciliates was determined to be highest right in and above the chemocline that is defined by the purple and green sulfur bacteria that inhabit it. The sulphur oxidizing bacteria in the chemocline provides the nutrition that allows the Ciliates to survive. The Ciliates providing nutrition up the trophic levels. In the sinkhole, Hospital Hole, located under the Weeki Wachee River in Florida, a chemocline is present and the aquifer is stratified into a hypoxic layer, the chemocline, and the anoxic sulfur layer. These layers have varying microbial communities with varying bacterial metabolic activities that allows for the varying products to be used across the different layers in the aquifer. This overall supports the diversity of the microbial communities within it. Lake Cadagno is another example of a Meromictic lake that is defined the bacterial diversity that is spread across the different strata of the lake. The lake has different bacterial species composition in the mixolimnion, chemocline, and monimolimnion. The mixolimnion is the upper layer of a meromictic lake that is mixed by wind. The monimolimnion is the bottom layer of a meromictic lake that does not mix. The communities present in each of these strata are co-dependent on each other as the interactions between the communities in these layers are important to maintain their survival. In Soap Lake in Washington State it was found that the lake was stratified into an aerobic mixolimnion and an anaerobic monimolimnion that was determined to have an unusually high concentration of sulfur. The mixolimnion and the monimolimnion are separated by the chemocline present. The sulfur oxidizing bacteria in the chemocline facilitates the transfer of the sulfide into the aerobic mixolimnion supporting its community.

Chemoclines existence can vary based on seasonality and their microbial makeup. Holomictic lakes can provide an example of this as they mix during a specific time of the year due to certain environmental conditions dependent on the season. A chemocline will dissipate due to a mixing event and usually reestablish itself within the lake after the mixing. During the period after the mix where stratification of a lake is reestablished and the chemocline begins to form again, the structure and makeup of the chemocline can be changed . Different microbial species will be present during differing times of the year changing the chemical characterization of the lake.

Overall, bodies of water that are chemically stratified will allow for the creation of various habitats within the different layers indicating the biological significance of chemoclines along with the microbial communities that make them up.