[ad_1]
Rose also identified a second problem: deep water is becoming increasingly clear due to a number of factors, including erosion, algae growth, and the release of fertilizer from adjacent agricultural fields and residential developments. Darker waters are less likely for plants to survive, so there is less photosynthesis and less oxygen underneath. And that, of course, is bad news for lake creatures. “Like humans, all complex life forms on the planet depend on oxygen,” says Rose. “In the water, it’s dissolved.”
Each species has only one critical oxygen threshold to survive. Deoxygenation especially affects cold-water fish, which need 7 milligrams of oxygen like trout per liter of water, and salmon, which need 6 milligrams per liter. (Warm-water species, such as bass and carp, both need 5 milligrams per liter).
“When you reach low levels of oxygen concentration requirements, it has been shown that there are impacts on the performance of individual organisms in water,” says Peter Raymond, a professor of ecosystem ecology at Yale University, who reviewed the paper. “They’re not doing so well. They are stressed out, as you can imagine. “
The combination of low oxygen and warm water is particularly worrying. For example, if temperatures and oxygen levels are not in the optimal range, it can distort the breeding time of fish, affecting the amount they breed. Warming water can overload or deactivate the immune system, which can damage the level of pathogens in a climate-changing environment.
Because fish are ectothermic, that is, they regulate body temperature according to the outside temperature, their metabolism speeds up in warm water, which increases the amount of oxygen they need to survive, says James Whitney, a biology professor at Pittsburg State University in Kansas. which had nothing to do with research. “If it gets bad enough, they can drown and cause the fish to die,” Whitney says.
For example, in the 2018 Kansas drought, Whitney recalled that the water in the streams was hotter, and less so because of the lack of rain. The fish were taking oxygen from surface water, but there was not enough to walk around, and some of them died.
Deoxygenation can become a vicious cycle. When lakes become anoxic, they form sediments at the bottom, which then release phosphorus, which can cause algae to grow on the surface. Lakes can developed harmful algal it blooms, those who eat what is left of oxygen. Some produce toxins that kill fish, mammals, and birds; in extreme cases, they can cause human disease as well as death.
“It is not hypothetical that organisms will be affected. It’s going to happen, ”Raymond says.
Although there is no way to add oxygen directly to the lakes, he noted that there are other ways to improve the health of ecosystems. The biggest change needs to happen globally: reducing greenhouse gas emissions will prevent lake waters from heating up and losing solubility. But caring for it is also important. “There is a direct impact on the climate here, but a lot can be done to maintain high oxygen concentrations at the local level,” agrees Rose.
Rose and several other research authors contribute GLEON (Global Lake Ecological Observatory Network), a team of basic scientists from around the world who are focused on conserving freshwater resources. They share data to capture ecosystem changes early, as lakes are the first to show measurable changes. Some of their recommendations are to use data from one lake to inform others and to assess the risk based on measurements of local water temperature and dissolved oxygen levels. Planting trees as buffer sites around lakes can prevent erosion, which can increase water clarity and reduce nutrient emissions. This can be coordinated by state agencies or individual lake management associations that manage water resources. The Environmental Protection Agency recommends that residents living near bodies of water use fertilizers in accordance with label instructions to prevent them from entering excess nitrogen and phosphorus lakes, inadvertently fertilizing algae blooms.
“Proactive management is necessary — or will be necessary — to sustain the status quo in the future as well,” says Rose. “With the future” doesn’t mean decades. It means the next two years. “It’s an ongoing topic,” he says.
More great KABEKO stories
[ad_2]
Source link
