The ecosystem of a lake includes biotic (living) plants, animals and micro-organisms, as well as abiotic (nonliving) physical and chemical interactions.
Lake ecosystems are a prime examples of lentic ecosystems. Lentic refers to standing or relatively still water, from the Latin lentus, which means sluggish. Lentic waters range from ponds to lakes to wetlands, and much of this article applies to lentic ecosystems in general. Lentic ecosystems can be compared with lotic ecosystems, which involve flowing terrestrial waters such as rivers and streams. Together, these two fields form the more general study area of freshwater or aquatic ecology.
Lentic systems are diverse, ranging from a small, temporary rainwater pool a few inches deep to Lake Baikal, which has a maximum depth of 1740 m. The general distinction between pools/ponds and lakes is vague, but Brown states that ponds and pools have their entire bottom surfaces exposed to light, while lakes do not. In addition, some lakes become seasonally stratified (discussed in more detail below.) Ponds and pools have two regions: the pelagic open water zone, and the benthic zone, which comprises the bottom and shore regions. Since lakes have deep bottom regions not exposed to light, these systems have an additional zone, the profundal. These three areas can have very different abiotic conditions and, hence, host species that are specifically adapted to live there.
The Frolikha Adventure Coastline Track (F.A.C.T.) is a 100 km Long-distance trail at the Northern part of Lake Baikal in Siberia (Russia).
The trail was built by Russians and Germans in 2009 to encourage local tourism with concepts for the sustainable development of the region. F.A.C.T. runs along the shoreline as well as old hunting and deer pathways. Half way of the trail the river Frolikha flows into Lake Baikal, making its way from Lake Frolikha, which gave the trail its name.
The tracks starts at the Northern end of Lake Baikal and runs southwards towards the hot springs of Khakussy (see coordinate), following sandy beaches and bays, climbing steep cliff lines, and looping Lake Frolikha. Snow-covered, jagged mountain ranges up to 2000 meters in height contrast with the large yet shallow delta of the Verkhne Angara river and the vast Siberian taiga seaming the coastline of the oldest and deepest lake of the world.
The Trail should be used by experienced hikers only. Baikalplan e.V. from Dresden in Germany, having been involved in planning and establishing the trail, published a brochure with a very detailed trail description in March 2010.