Lake Eyre
Lake Eyre, also known as Kati Thanda–Lake Eyre, is Australia's largest salt lake, located in the northern part of South Australia. This unique desert lake is typically dry, filling with water only every two to three years, making it a challenging environment for plant and animal life. When filled, it features a saline crust and supports a complex ecosystem, although most of the time, it consists of a series of water holes. The lake experiences extreme climate conditions, with high evaporation rates and low annual rainfall, averaging just 5 inches.
The biota of Lake Eyre includes a few hardy aquatic plants, around 20 fish species adapted to high salinity and temperature, and various migratory birds that utilize the area during flood years. These fish, such as gobies and bony bream, have evolved to thrive in small, often extreme habitats, while nomadic birds rely on the lake's resources for breeding. Environmental concerns, such as rising temperatures and changing rainfall patterns, pose potential risks to the delicate balance of life in and around Lake Eyre, influencing species distribution and habitat stability. The lake serves as a fascinating example of life adapting to harsh conditions within an inland aquatic biome.
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Lake Eyre
- Category: Inland Aquatic Biomes.
- Geographic Location: Australia.
- Summary: A desert lake that is most often dry, Lake Eyre is home to hardened species with special adaptations.
Officially known as Kati Thanda–Lake Eyre, Lake Eyre is located in the deserts of Australia and holds the title of being Australia's largest salt lake. Lake Eyre provides an extremely unique habitat for its inhabitants, as the lake does not always contain water. On average, the lake fills up with water every two to three years, and on a very irregular basis, making it difficult for most plants and animals to survive. Historically, the lake rarely fills up, and since the 1860s the lake was only at capacity three times. Mostly, the lake is a string of water holes, leaving very little water to dependably support its inhabitants. Only the hardiest species of plants and animals are able to survive in this environment. The small populations of flora and fauna that do call Lake Eyre home have learned to adapt and thrive in this unusual environment, and they've created a complex ecosystem in the process.
Geography and Climate
Lake Eyre is located in the northern part of South Australia. The lake is generally flat, with the lowest portion about 50 feet (15 meters) below sea level. The lake is surrounded by sandy and stony desert, and the climate is arid to semi-arid—when it rains. During the year, the temperature fluctuates from 70 degrees F (21 degrees C) in July, the coolest time of year, to 99 degrees F (37 degrees C) in January, the area's summer.
Lake Eyre receives about 5 inches (127 millimeters) of rainfall per year, which is about three times less than the world average rainfall. The lake's evaporation rate is about three times higher than the world average, with the evaporation rate exceeding 140 inches (3,556 millimeters) per year. When filled, Lake Eyre is Australia's largest saline lake, containing a 15-inch- (38-centimeter-) thick salt crust on the lake's floor.
Lake Eyre is divided into two parts, north and south, connected by the Goyder Channel. The northern part of the lake is 90 miles (145 kilometers) long and 47 miles (76 kilometers) wide, while the Lake Eyre South is 40 miles (64 kilometers) long and 14 miles (23 kilometers) wide. The combined volume of both parts is 19 cubic miles (79 cubic kilometers).
The lake's basin overlies the Great Artesian Basin, one of the largest underground aquifer basins in the world; the Great Artisan Basin's mound springs are a crucial water source for the biome. During excessive rainfall, the Lake Eyre tributaries—Cooper Creek, Diamantina River, and Georgina River—will feed the lake, but only in very small amounts. Most of the moisture is lost to evaporation prior to reaching Lake Eyre.
Biota
Since European colonists first documented the lake in 1840, it has rarely filled. The first recorded filling was in 1949—and before that, it was thought to be permanently dry. As it fills irregularly, the lake cannot be relied upon to sustain most plants and animals. As a result, the lake is home to few aquatic plants, mainly including a few species of diatoms, green algae, and blue-green algae.
Surprisingly, there are about 20 species of fish that live in the lake. During dry periods, these fish survive in water holes, some of which are extremely small—but the largest are up to 12 miles (19 kilometers) long. These water holes have an average temperature of 95 degrees F (35 degrees C) or higher for days at a time, and are high in salt, making it possible for only the hardiest species to survive.
These fish, which include six species of goby as well as the bony bream, spangled perch, rainbowfish, and silver tandan, have adapted. Many have evolved into smaller versions of their species, enabling them to thrive in small spaces for long periods of time. They can thrive in the harsh conditions and are able to live by consuming the lake's few algae species for food. Their reproductive cycles are adjusted to match the lake's flood years.
There are some invasive species in the lake area, including crayfish, lobsters, shrimp, and crabs. All of these species have had to adapt, as well; the crabs that now live in the lake can survive long periods with little or no water, and dwell in the desert sand. During flood years, the environment can drastically change, and several species of nomadic birds will make the lake home during flood years; these species include the black swan, Australian pelican, cormorants, silver gull, and pink-eared duck. These birds rely on the fish as well as the invasive species for food sources, and use the lake as breeding grounds.
Environmental changes such as rising temperatures from global warming could alter the composition of Lake Eyre—with desert plants filling in the dry riverbeds instead of water. Extended dry spells could endanger the species that have adapted to the river's current cycle, as hardened as they may be. If, however, rainfall increases enough to counter evaporation, then aquatic activity would spring to life in the altered life cycles of the river region's inhabitants. Associated shifts in habitats beyond the lake could alter species distribution in ways that would impact all of the Lake Eyre life forms.
Bibliography
Cockayne, Bernie. "Climate Change Effects on Waterhole Persistence in Rivers of the Lake Eryre Basin, Australia." Journal of Arid Environments, vol. 187, Apr. 2021, www.sciencedirect.com/science/article/abs/pii/S014019632030327X. Accessed 30 Sep. 2024.
Cohen, Tim J., et al. "Late Quaternary Climate Change in Australia's Arid Interior: Evidence from Kati Thanda–Lake Eyre." Quaternary Science Reviews, vol. 292, 2022, p. 107635.
Kerezsy, Adam. Desert Fishing Lessons. UWA Publishing, 2011.
Kotwicki, Vincent. Floods of Lake Eyre. Engineering and Water Supply Department, 1986.
McMahon, Thomas A, et al. Hydrology of Lake Eyre Basin. Sinclair Knight Merz, 2005.
Measham, Thomas G. and Lynn Brake, editors. People, Communities, and Economics of the Lake Eyre Basin. Desert Knowledge Cooperative Research Centre, 2009.
Timms, Brian V. “The Biology of the Saline Lakes of Central and Eastern Inland of Australia: A Review With Special Reference to Their Biogeographical Affinities.” Hydrobiologia, vol. 576, no. 1, 2007.