How might a landlocked lake become a complete ecosystem?

I'm guessing that your question about endorheic basins is about the buildup of salt and other minerals. Certainly there are many aquatic animals who live in fresh water and many that live in salt water, but not many who are okay with a change from the former to the latter over time.

The solution to that (no pun intended) is a lake that doesn't get the mineral build up of most endorheic basins. For example:

Crater Lake in Oregon, USA, also mentioned by Michael Richardson. Despite the fresh water coming in, "the lake has relatively high levels of dissolved salts, total alkalinity, and conductivity. The average pH has generally ranged between 7 and 8." Even so, it supports aquatic life, including fish.

The largest lake in the world, the Caspian Sea, between Europe and Asia, is also an endorheic basin. "It has a salinity of approximately 1.2% (12 g/l), about a third of the salinity of most seawater."

Modern times, including pollution, have harmed its ecosystem, but it flourished for quite some time. Its fauna include: turtles, mussels, gulls, terns, and seals. Even other aquatic mammals.

Technically it doesn't meet your requirements for never having been attached to other bodies of water. But it has been landlocked for 5.5 million years, which should count for something. The fact that it supported a wide variety of plants and animals a century ago is more about its current ecology than about its past.

Your question may also reference the "seeding" of the lake with various fauna and flora. Zeiss Ikon talked about how to get fish eggs (without human intervention) over land. But I'll also maintain that your requirement of "a complete ecosystem" doesn't mean it has to have fish. Some aquatic fauna for sure, but there are many many choices.

Plants can adapt, and their seeds or even pieces of root can be carried by animals that travel by land or water. In addition to fish eggs, traveling animals can carry snails, small reptiles or amphibians, or their eggs. Insects can fly or crawl or hitch a ride.

Given enough time, an ecosystem can and will develop around any water source. And it will adapt with slowly changing conditions.

posted almost 5 years ago

Cyn‭

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