The aral sea

Invertebrates

Zebra mussel (Dreissena polymorpha), a former dominant member of the sea's benthic fauna, and has since returned to the North Aral Sea.

Parthenogenic brine shrimp (Artemia parthenogenetica), the dominant crustacean of the South Aral Sea and its fragments.

Prior to its shrinkage, the Aral Sea had about 250 species of native aquatic invertebrates, the majority (about 80%) being freshwater species; the rest were marine invertebrates with ties to the Ponto-Caspian and Mediterranean-Atlantic fauna. The dominant species (excluding protozoa) were rotifers, cladocerans, and copepods. Advanced crustaceans (Malacostraca) were represented by a single amphipod species, Dikerogammarus aralensis, an endemic of the Syr Darya basin. There were several native bivalves in the Aral Sea, including members of the genera Dreissena (including an endemic subspecies of zebra mussel, Dreissena polymorpha aralensis), Hypanis, and the lagoon cockle (Cerastoderma glaucum) (formerly considered distinct species Cerastoderma rhomboides and C. isthmica). Native gastropods included Theodoxus pallasi and a member of Caspiohydrobia.

Many of these invertebrates had their numbers drastically reduced due to the introduced fish species. Later, during an unsuccessful attempt to introduce mullet (Mugil sp.) to the Aral from the Caspian Sea, the rockpool shrimp (Palaemon elegans) was inadvertently introduced to the sea. The shrimp is thought to be responsible for the extirpation of the near-endemic amphipod Dikerogammarus aralensis, which now survives only in the Syr Darya basin. The copepod Calanipeda aquaedulcis was introduced to the Aral to replace the zooplankton species reduced by the herring population, and the North American mud crab Rhithropanopeus harrisii was inadvertently introduced during this attempt as well.

Later, as the lake's salinity increased, many of the freshwater-adapted species disappeared, only leaving behind the marine and saline species. However, the zooplankton population in the North Aral Sea has recovered as salinity has decreased from the 1990s onwards, with extirpated crustacean and rotifer species returning naturally via the Syr Darya River, at the expense of the saltwater species. The cladoceran Moina mongolica, extirpated by the introduced fish species, has also returned. The zebra mussel (Dreissena polymorpha aralensis) has been reintroduced. In contrast, in the South Aral Sea only a few nematodes, rotifers, and parthenogenic brine shrimp (Artemia parthenogenetica) exist. The future prospects for aquatic invertebrates in all remaining Aral Sea fragments depend on their future changes in salinity.

History

First Russian boats on the Aral Sea, watercolor by Taras Shevchenko, 1848

1853 map of the Aral Sea

Climate shifts have driven multiple phases of sea level rise and fall. Inflow rates from the Amu Darya and Syr Darya are affected by glacial melt rates at the rivers' headwaters as well as precipitation within the river basins and cold, dry climates restrict both processes. Artificial irrigation systems have impacted the Aral, beginning in ancient times and continuing to the present.

The Aral Sea was part of the western frontier of the Chinese Empire during the Tang dynasty.

The Russian expedition of Alexey Butakov performed the first observations of the Aral Sea in 1848. And the first steamer arrived in the Aral Sea three years later. The Aral Sea fishing industry began with the renowned Russian dealers Lapshin, Ritkin, Krasilnikov, Makeev, which later formed major fishing unions.

Naval

Ships of Imperial Russian Navy's Aral Flotilla in the 1850s

Russian naval presence on the Aral Sea began in 1847 with the founding of Raimsk, soon renamed Fort Aralsk, near the mouth of the Syr Darya. As the Aral Sea basin is not connected to other bodies of water, the Imperial Russian Navy deployed its vessels by disassembling them in Orenburg on the Ural River and transporting them overland to be reassembled at Aralsk. The first two ships, assembled in 1847, were the two-masted schooners Nikolai and Mikhail. The former was a warship; the latter a merchant vessel to establish fisheries. They surveyed the northern part of the sea in 1848, the same year that a larger warship, the Constantine, was assembled. Commanded by Lt. Alexey Butakov (Алексей Бутаков), the Constantine completed the survey of the entire Aral Sea over the next two years. Exiled Ukrainian poet and painter Taras Shevchenko participated in the expedition and produced a number of sketches.

Map including the Aral Sea and surrounding region (DMA, 1979)

In 1851 two newly built steamers arrived from Sweden. The geological surveys had found no coal deposits in the area so the Military Governor-General of Orenburg Vasily Perovsky ordered an "as large as possible supply" of saxaul (Haloxylon ammodendron, a desert shrub akin to the creosote bush) to be collected in Aralsk for the new steamers. Unfortunately, saxaul wood proved not to be a suitable fuel and in the later years the Aral Flotilla was provisioned, at substantial cost, by coal from the Donbas.