Expansion of Brachiopods and Pycnogonids in The Arctic Basin: Ways and Barriers

Abstract

The analysis of two different strategies in the Late Cenozoic distribution of bottom Invertebrates at the Arctic Basin was made for attached sedimentators (Brachiopoda) and for mobile predators - sea spiders (Pycnogonida). For the both groups some hydrological factors were found as the most important: disposition of the global gyres in surface and intermediate waters, directions of currents and vertical structure of water masses. It is shown that for 7 species of brachiopods which populate the Arctic shelves and slopes graduate penetration to the East along Eurasian Continent is limited by their tolerance to the temperature of the Atlantic intermediate waters. The species with the broad Arctic- Boreal geographical ranges are characterized by more slow growth-rate and longer lifetime in the Arctic to compare them in the Boreal parts of their ranges. It is supposed that brachiopods live in the Arctic Seas at the boards of their ability. For pycnogonids (43 species and subspecies from 21 genera of 7 families) two ways of origin are cleared (from Atlantic and from Pacific), and also the existing of endemic species and subspecies are found now. It is noted that some juvenile features are present in adult and breeding forms whose population was found during the 54th Expedition of R/V «Academic Mstislav Keldysh» in year 2007 at the Kara Sea in cold shallow waters with lower salinity.

Keywords

• Brachiopoda
• Pycnogonida
• Brachiopoda
• Pycnogonida
• invasion to the Arctic seas