In the top-level menu Environmental you will find important environmental variables of the Caspian Sea: i.e. salinity, temperature and oxygen. These environmental variables are very important for the presence of species in a certain locality.
Fishing is a very important activity in the Caspian Sea. Traditionally, the coastal countries use diverse methods to target different fish species. In general, the population of fish is stable. However, some species such as sprats decreased in the early 2000’s due to the invasion of Mnemiopsis leidyi, a jellyfish that is praying on their eggs. Since then, the populations are stable but they have not fully recovered.
The map represents the rate of total annual fish catch in the main fishing areas, which are derived by literature information and commercial fish distribution. This map does not include sturgeons, which are showed specifically in the stream flow regulation and poaching layers.
Chemical pollution is a great concern in the Caspian Sea, as many industrial sectors released chemicals in the environment, especially during the peak production at the end of the 80’s. The industrial sector collapsed at the beginning of the 90’s together with the Soviet Union. Since then, the release of pollutants decreased.
The map represents the concentration of chemical pollutants in the sediment. We included the concentration of polycyclic aromatic hydrocarbons (PAHs), DDT and Aluminium as proxies for pollutants derived by oil and gas industry, farming and mining, respectively. This approach serves as a general indication of the broad range of contaminants present in the seabed.
Sturgeons are anadromous fish, such as salmons. They need to migrate up rivers to spawn their eggs. Unfortunately, around the Caspian Sea, many dams were constructed in the past, which blocked the migration route of sturgeons. This is one of the main reason for the population downfall. The map represents the difference in past and present density of sturgeon, as an indication of the impact of stream flow regulation.
Invasive species are a well-known problem in the Caspian Sea. Most of them originated in the world oceans and reached the Caspian Sea through the Volga-Don Canal.
In the map, we modelled the habitat suitability of two longterm marine invaders, Abra segmentum and Mytilaster minimus as an indication to represent the areas of major impact. The more suitable is an area for invasive species, the more impact is considered to occur.
Oil industry disturbances
The Caspian Sea hosted the first offshore oil well in 1946, the first in the world. Since then, the oil and gas industry has been the most important activity for the Caspian coastal countries. Connected to that, there is a big impact due to well construction and transport.
In the map, we represent the location of oil and gas fields and the oil tank routes.
Coastal development is higher where there is a high concentration of human population. Along the Caspian Sea coast, this impact is rather limited given the fact that the Caspian Sea level is fluctuating extensively. In the map, we represented human density as a indication for coastal development.
Agriculture by-product discharge
Residual of fertilizers from farming may be discharged in water basins by rivers, creating an excessive production of algae, which can cause several problems to the other organisms. In the Caspian Sea, the majority of these nutrients come from the Volga river. Fortunately, the extensive vegetation covering the Volga Delta uptakes most of them, preventing the extensive growth of algae in the Caspian Sea.
In the map, we represented the discharge of the amount of Nitrogen compounds accumulated in the major river watersheds.
Chlorophyll is generally considered an indicator of eutrophication of waters. Eutrophication is basically an excessive abundance of algae that can be quantified thanks to their Chlorophyll content. When water many algae, the water quality is poor and many organisms cannot survive. So far, the Caspian Sea seems to not suffer of eutrophication consequences.
In the map you can see the average of the annual rate of change in the surface Chlorophyll concentration from 2003 to 2015.
Poaching is a great threat for the sturgeons and the Caspian seal (Pusa caspica). As it is an illegal activity, it is difficult to quantify its impact. The literature report that poaching is mostly carried out in shallow water when sturgeons are migrating. This is more efficient, because sturgeons are in high density and they swim slow.
In the map, we estimated the locations and the amount of poaching according to literature data.