Ilia Ostrovsky: The impact of physical factors and processes on the functioning of aquatic ecosystems: Lake Kinneret as a case study

The release date:2023-10-05view:33Set

Time of report:13:00-15:00,October 8, 2013

Place of report:B407,College of Marine Sciences

Report content:In this presentation, I will discuss the role of various physical phenomena in the formation of the biogeochemical processes in aquatic ecosystems, using the latest investigations on Lake Kinneret. We showed that the basin-scale internal seiches may induce strong diapycnal mixing in the stratified water column. The strongest mixing occurs in proximity to the lake periphery. Such a mixing induces upward nutrient transport to the upper euphotic zone and can essentially enlarge primary productivity at the lake periphery, where organisms of the higher trophic levels (zooplankton and planktivorous fish) are concentrated. The internal seiche-induced resuspension transports the bottom particulate material toward the lake interior (pelagic zone) via the benthic boundary layer and metalimnetic jets. Such a transport induces lateral heterogeneity in sedimentation processes and focuses the light organic-rich particles in the deep lake areas. The organic-rich particles accumulated in the hypolimnetic anoxic sediments play an important role in the production of biogenic methane (a highly potent greenhouse gas), which is efficiently delivered to the atmosphere via gas ebullition. I will also discuss the impact of vertical turbulent mixing and diurnal stratification in the formation of blooms of toxic cyanobacterium Microcystis sp. Further, I will illustrate the short- and long-term effects of water level fluctuations on the reproduction and formation of fish productivity and sustainability of fisheries in subtropical Lake Kinneret. I will also show the importance of the implication of non-destructive remote-sensing technologies for studying fragile aquatic organisms.

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