Coastal zone of the world’s great lakes as a target field for interdisciplinary research and ecosystem monitoring: Lake Baikal (East Siberia)

Limnological data on the coastal zone of the world’s greatest lakes are scanty in contrast to the deep-water research that is actually the main reason for a delayed response of the researchers’ and public community to evident anthropogenic changes the lake ecosystems are experiencing worldwide. The present study reports on the interdisciplinary investigations in the coastal zone of Lake Baikal during 2000–2018 and gives a brief description of the splash zone as a principal part of the lake ecosystem poorly known in other lakes of the Planet so far. Recent surveys of Lake Baikal showed a key role of the coastal zone research for the fundamental limnology and efficient monitoring of the lacustrine ecosystems. The splash zone of Baikal is briefly described due to its peculiarity. Principal reasons of significance of lake coastal zone research such as: maximal biodiversity of lacustrine ecosystems, high macrobenthos productivity in Baikal, intensive biogeochemical processes in rift and karst lakes and their reasoning are described. This is the zone that first of all colonized by invasive species and where the obvious cyclicity in plankton-benthos relationships is clearly expressed. Early warning signs for the ecological disturbance, such as blooms and wash-ups of native and/or alien algae, degradation of pelagic and benthic communities, bioaccumulation of pollutants (including organochlorine compounds) by hydrobionts, etc. are manifested in the coastal zone. A short report of the current ecological crisis in the coastal zone by 2018 is presented. The uniqueness of Lake Baikal makes the ongoing eutrophication different from all other Palearctic lakes. Therefore, the hydrochemical indicators of the water column of great lakes do not match the commonly accepted principal eutrophication criteria pool. Biological indication approach appears most appropriate for the analysis of the initial eutrophication stages. The author points out real and potential sources of excessive biogenic element supply into the lake ecosystem such as, sewage contamination of the estuarine parts of Baikal tributaries by the coastal settlements and vessels, pollution of the ground and interstitial waters of the beaches, input of biogenic elements as a result of mass mortality of sponges and other hydrobionts, secondary contamination by decaying algal wash-ups, intensive nutrient influx after numerous forest fires on the lake coasts and aerosol contamination. All these factors provide new opportunities to evaluate the initial eutrophication stages either on Baikal or in any other of the giant lakes. Special emphasis is given to an inadequate governmental lake monitoring systems focusing on the pelagial zone without taking into consideration the coastal (splash zone included) biological communities. Our landscape-ecological method served a basis for elaborating approaches for complex monitoring of Baikal coastal zone recommended as a part of the Federal Baikal Ecosystem Monitoring.