Man Made Effects on Biodiversity

Lake Tahoe Biodiversity

Lake Tahoe is hailed as one of the most beautiful lakes in the United States. Over the last century or two, the fish biodiversity of the area has been a sight to behold. However, biodiversity tends to change over time. This particular report focuses on fish and there is much to be said even about fish in particular. This report will consult multiple sources and will create a rough timeline of what has been happening with the fish biodiversity of Lake Tahoe over the last one hundred and sixteen years. While some fish biodiversity changes are caused by entirely natural factors, human presence and activity has surely played a role as well.

One rather odd and vexing thing that has happened with the Lake Tahoe fish population over the years has been the introduction of non-native species to the ecosystem that is the lake. Indeed, there have been some developments over the last five years or so that involve a breed of bass that is not native to the area. A problem with this development is that the bass species in question is extremely invasive and aggressive. The bass in question is the smallmouth bass and they are extremely adaptable because they can survive in a litany of different climates and situations. They are much abler to adapt and survive to different environments than other species of bass. The solution used thus far to address the issue has been to remove the invading bass from the area. As of 2011, a total of five thousand bass have been expunged. The effort has been the part of a larger effort by the California Department of Fish and Game. They created the Lake Tahoe Aquatic Invasive Species Program (Associated Press, 2011).

A major method that has been used to counteract the invasive and harmful species, not to mention pollution and other manmade problems, is to reintroduce species that are native to the area and in a way that allows the fish to be self-sustaining in terms of its population. Precisely that was done when 90 Lahontan cutthroat trout weighing up to two dozen pounds were allowed to spawn and thrive in the greater Lake Tahoe area. This is a startling reversal of something that ostensibly stopped when the fish stopped spawning in the river in 1938 and they died out in 1940. Human activity has been a concern then and now given that the cutthroat fish are highly sought and prized by anglers who fish in the areas that have the fish. Very large cutthroat trout were caught in the area as far back as the 1920's with a 41-pound cutthroat being caught in 1925. Current prospects for the trout are quite good because there are over 182 spawning areas being present now. The southern shore of Lake Tahoe in particular seems to be the best area for the trout (Griffith, 2014).

However, most of the changes that have occurred in the fish biodiversity of the Lake Tahoe area. Indeed, an article that ran nearly 30 years ago in an environmental journal referred to Lake Tahoe as a "fragile ecosystem." As noted before, the threats are not all man-made, or entirely man-made. For example, it was posited in 1989 that the algae in the lake would seem to be able to "obliterate" the clarity and clearness of the water of the lake. This condition, in combination with about two future generations of run-off, was seen as a way to lead to an uncontrolled flow of nutrients. It has to be known first that Europeans have only known about the Lake Tahoe area since 1844 when General John Charles Fremont came across it. Obviously, there were Native American and other indigenous people before that. However, the emergence and arrival of the Europeans obviously change everything. There were two clear environmental shifts that have occurred in Lake Tahoe over the years. The first actually predates the 1900's, but just barely. From 1870 to 1900, the trees around the Lake Tahoe area were heavily harvested and removed. The second disturbance came from the emergence and creation of towns, cities, rows, buildings and casinos in the Lake Tahoe area. Of course, a massive amount of people flocking to the area accompanied all of this building. The rapid spread of algae mentioned before was a result of these disturbances. The biodiversity of the Lake Tahoe area was greatly impacted for the worst as this went on. There were efforts in the 1910's to make Lake Tahoe a national park but they failed. Concurrent to this, there was a huge loss of wetlands in the areas surrounding Lake Tahoe (Goldman, 1989).

As for fish in particular, the effects above are not having good results. In general trends, native fish populations are on the decline and the prior-mentioned invasive species are on the rise. Nutrient shifts, algae overgrowth and alterations to habitat have all exacerbated these trends even with the efforts to remove the invasive fish and introduce (or reintroduce) species that are must self-sustaining and healthy for the area. To put numbers to the declines above, a total of twenty-six sample locations were assessed. Of those, nearly six in ten (58%) showed declines with the native species, assuming any of the native species existed at the location at all. By the end of the 1990's, it was found that non-native largemouth bass and blue-gill, both of which were not introduced into the area legally and with good reason, were common in the Lake Tahoe area. On the other hand, the native red-side shiner and speckled dace populations were minimized or even gone near the south end of the lake. As mentioned before, the southern end of the lake is the prime area for the native species of the lake. The major cause of these problems has been identified as near-shore areas that have been the subject of human disruptions and other bad behavior or inactions on the part of the public and the applicable regulatory agencies ("Study: Native Fish," 2011).

One factor that has affected the fish biodiversity of Lake Tahoe over the years has included something that is not man-made, but rather sun-made. Indeed, ultraviolet radiation has created conditions favorable to the invasive fish mentioned throughout this report. In this case, the ultra-violet radiation has actually mitigated the invasion of the aforementioned bluegill. Indeed, it was found that areas lower in ultra-violet radiation were much better for bluegill than areas where ultra-violet radiation was present and thick. Even so, the ultra-violet radiation over the years that saw invasive species rise and native species falter was only slowed down by the radiation. It certainly was not stopped (Tucker et al., 2010).