Caspian Sea

The Caspian Sea, bordered by Azerbaijan, Iran, Kazakhstan, the Russian Federation, and Turkmenistan, boasts exceptional biological diversity and rich oil and gas resources. The region's climate is influenced by various factors, while its brackish waters have an average salinity of 12.7 grams per liter. The Caspian Sea faces threats from river regulation, illegal fishing, sea-level changes, pollution, and invasive species. Its legal classification as a sea or lake remains unresolved, complicating regulatory efforts. Urgent ecological surveys and transboundary biodiversity management strategies are needed to safeguard the region's biodiversity and ensure its long-term ecological health.

The Caspian Sea and its coastal zone boast exceptional biological diversity, rendering the region among the world's most valuable ecosystems. Characterized by a remarkably high rate of biological endemism, the Caspian Sea hosts a plethora of species spanning nearly all major phyla on Earth. Its diverse habitats, ranging from expansive river systems to extensive wetlands, sustain a rich variety of flora and fauna with abundant natural productivity. Despite its ecological significance, the Caspian region is also abundant in oil and gas resources. However, the escalating exploitation of these resources poses a significant threat to the region's biodiversity.

The Caspian Sea, situated between Europe and Asia, stands out as a distinctive natural reservoir. Encompassing approximately 392,600 square kilometers, it holds the title of being the world's largest landlocked water body. Its expansive water area equals that of the Baltic Sea, which spans 387,000 square kilometers, and surpasses that of the Adriatic Sea, covering 139,000 square kilometers.

• The Caspian Sea is bordered by Azerbaijan, Iran, Kazakhstan, the Russian Federation and Turkmenistan.

Cities : Major cities on or nearby the sea’s coast

• Baku ( Azerbaijan) is the largest port on the Caspian Sea and is also the largest capital city on the southern shore of the Absheron Peninsula
• Resht and Ramsar (Iran),
• Makhachkala and Astrakhan (Russian Federation)

Rivers : The Caspian Sea receives water from numerous rivers, each contributing to its unique ecosystem and hydrological balance.

• The Kura River from Azerbaijan, the Sefid-Rud River and Gorgan River from Iran, the Atrek River from Turkmenistan, and the Ural River passing through Kazakhstan and the Russian Federation are among the major rivers that flow into the sea. These rivers not only provide freshwater input but also transport sediments and nutrients, which are essential for maintaining the Caspian's ecological health.
• Additionally, the Volga, Terek, Sulak, and Samur Rivers from Russia, with the Samur River acting as the border river with Azerbaijan, further enrich the Caspian's biodiversity and support diverse aquatic and riparian habitats. The intricate network of rivers and their interactions with the Caspian Sea underscores the interconnectedness of terrestrial and aquatic ecosystems in the region.

• The regulation of the Caspian Sea hinges on its legal classification and the corresponding body of law. If considered a 'sea' in legal terms, the United Nations Convention on the Law of the Sea (UNCLOS) of 1982 would apply, whereas if classified as a 'lake,' customary international law concerning border lakes would be relevant.
• However, the Caspian Sea does not fit neatly into either category, posing significant challenges for resolution. Its legal status must be unanimously agreed upon by all littoral states, highlighting the complexities involved in determining its final classification.
• Moreover, the Caspian's legal status has implications for resource management, territorial claims, and environmental protection, further complicating efforts to resolve its classification.

The climate in the Caspian Sea region is influenced by various factors, including cold arctic air, moist sea air from the Atlantic Ocean, dry continental air from Kazakhstan, and warm air from the Mediterranean Sea and Iran. The sea's semi-enclosed nature moderates temperature extremes, resulting in relatively mild winters and warm summers. The Caspian's climate variability has implications for its hydrology, ecology, and socio-economic activities, highlighting the need for adaptive management strategies to address climate-related challenges.

• Salinity: The Caspian Sea's brackish water is characterized by a unique combination of freshwater input from rivers and saline influx from the surrounding environment. This brackish composition, with an average salinity of 12.7 grams per litre, supports a diverse array of aquatic life adapted to varying salinity levels
• Temperature: The sea's temperature regime exhibits seasonal fluctuations, with surface water temperatures ranging from 24 to 27°C in summer and from 0°C in the northern region to 11°C in the south in winter. These temperature dynamics influence biological processes, nutrient cycling, and species distributions in the Caspian ecosystem.

• The Caspian Sea region is renowned for its rich biodiversity, encompassing a wide range of species adapted to its diverse habitats and ecological niches.
• The sea serves as a vital spawning ground for sturgeon, a commercially valuable fish species prized for its caviar. Additionally, its wetland habitats support over 100 bird species for nesting and migration purposes, making it an important stopover for migratory birds along their annual journeys
• Notably, the Caspian Sea is inhabited by the native Caspian seal, which is the sea's sole marine mammal species

Main threats faced by the biodiversity of Caspian Sea are

• Regulation of Caspian rivers, leading to reduced delta vegetation area and loss of reeds, cattail, and bushes. This loss of vegetation results in the decline of aquatic and coastal fauna, impacting many anadromous and semi-migratory species' natural spawning grounds.
• Illegal fishing and overfishing practices, leading to a dramatic reduction in the sturgeon population, a vital species in the Caspian Sea ecosystem.
• Sea-level changes causing the loss of essential habitats like spawning grounds and nesting sites, further endangering various species.
• Pollution, which negatively affects biological processes, including the growth of commercially important fish, and disrupts the overall ecological balance.
• Introduction of invasive species causing chronic (long-term) or acute (short-term) impact.

An immediate ecological survey is imperative to assess coastal and marine species and habitats, along with their uses, values, and associated threats across the five Caspian states. This survey will help establish an inventory of Caspian ecological resources. Additionally, it is essential to devise strategies for managing transboundary biodiversity, especially focusing on threatened or endangered migratory species. By undertaking these measures, the Caspian states can effectively address the conservation and sustainable management of their shared biodiversity, ensuring the long-term ecological health of the Caspian Sea region