veronika dashkova
Gigantic dwarfs of Lake Balkhash: Journey into a microscopic world of phytoplankton.
“Nature has created a wealth of wondrous forms whose beauty and diversity way exceed anything that has been created by man”.
Ernst Haeckel
What do you see standing on the lake, river or sea shore and looking attentively at the water surface in front of you? You will surely see the colour of the water, the moving or steel surface, reflection of the sky, trees, buildings and other objects. If the water is transparent enough, you might see some floating bugs, small fish in the water column and bottom with sand, stones, mud or even corals. However, there is much more that our human eye cannot catch, a tremendous underwater world full of tiny microscopic organisms called plankton. These planktonic organisms drift in the water column, following a current anywhere it brings them. Plankton populate almost all water bodies on the Earth, from small ponds and lakes to the oceans. Although they are invisible to a naked eye, they play a gigantic role in the functioning of a whole aquatic ecosystem. As all terrestrial plants, phytoplankton use sun energy to synthesize organic elements from inorganic through the process of photosynthesis, and produce about 50% of all oxygen on the Earth. It is believed that the activity of ancient phytoplankton Cyanobacteria resulted in the rise of oxygen in the atmosphere and oceans around 2,4 billions years ago, which facilitated the diversification of Life on our planet.
Diatomea. Ernst Haeckel. Kunstformen der Natur (1904). http://www.silentplankton.com/Gallery/View/Haeckel
But that is not all. Every cell of phytoplankton is uniquely shaped and coloured, forming an incredible diversity of beautiful forms. Mother Nature created astonishing artwork, that blows up the imagination and fascinates with the perfect geometry of a cell structure architecture. Likewise, a 19th century German biologist, Ernst Haeckel, was so fascinated by the beauty of these forms and inspired to publish graphical illustrations of plankton in a monograph Kunstformen der Natur (Art Forms in Nature) in 1904.
Images of phytoplankton from Lake Balkhash (10x magnification)
Not an exception, Lake Balkhash is inhabited by hundreds forms (species) of phytoplankton.
Covering the territory of 15,730 sq. kilometers, Lake Balkhash is one of the largest endorheic lakes in the world, enclosed inside the continent without a connection to the ocean. This feature makes the lake susceptible to climate change mediated or man-made impact. The strongest example of the fragility of endorheic lakes and the dependence on human activity is the current fate of the Aral Sea, a similar lake located in the arid region. You can think of it as a cyclic process: any substantial and long-standing change brought by the environment, whether it is natural or man-made, mediate changes in the aquatic trophic webs, which in turn will affect the quality of life of local human communities and the economy of a whole region. For example, phytoplankton are the base of an aquatic trophic web, responsible for primary production and serving as food for larger plankton and fish, fueling the energy up to the higher trophic levels. The availability, composition and quantity of phytoplankton will therefore affect the diversity and quantity of fish stock in the lake, which is important for us.
Images of phytoplankton from Lake Balkhash (10x magnification)
The unique symbiosis of freshwater and brackish water and availability of micro-niches in the lake creates a ground for co-existence of various phytoplankton communities. There are about 400 different species of phytoplankton found in Lake Balkhash spanning taxonomic groups from Bacillariophyta, Cryptophyta, Haptophyta, Dinoflagellata, Chlorophyta, Charophyta, Euglenida, Cyanobacteria and others. Each species has found a place in the lake with favourable conditions of water with appropriate range of salinity, pH, oxygen level, organic and inorganic substances. For example, phytoplankton community of freshwater sites in the western part of the lake is completely different from the community inhabiting brackish water in the eastern part. You may think of phytoplankton as a natural indicator of what is going on outside. Despite their small microscopic size they sense and reflect any changes ongoing in the surrounding environment by changing their cell shapes, colour, size and abundance. By identifying the composition of the phytoplankton community, we can judge about the state of the ecosystems and presence of disturbants. Some phytoplankton are even able to withstand thermal and heavy metal pollution associated with the activity of the metallurgic plant nearby the city of Balkhash.Hidden in the water column, these organisms have always been witnessing different changes the lake was experiencing and have always been interacting with them.
Expedition to Lake Balkhash. June 2016.
Veronika Dashkova is a professional ecologist, PhD candidate in ecology, Nazarbayev University, Nur-Sultan, Kazakhstan.
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