The Ringed Seal
Subnivian lair, by Aqqalu Rosing-Asvid (Greenland Institute of Natural Resources 2012)
Ringed seals (Ursus maritimus), known for the ring shapes on their coats, are a keystone species of marine mammals for which icy habitats are crucial for breeding, hunting and resting (Moore and Huntington 2008 and Ferguson 2005). Four subspecies of the ringed seal have recently been listed under the Endangered Species act and the remaining subspecies, the arctic ringed seal, was already under the protection of the marine mammal protection act of 1972 (NOAA Fisheries 2012). Unlike most other marine animals in the area which must migrate south in order to survive (Rosing-Asvid 2006), ringed seals are able to remain in these freezing habitats over the cold winter as they are able to maintain breathing holes in the thick ice. Ringed seals are the smallest species of artic seals, which allows them to build subnivian lairs over their breathing holes (Stirling and Smith 2004). These subnivian lairs are crucial in providing protection from predation to newborn seals, which are too young to dive, and adult seals, which have come up to rest (Stirling and Smith 2004). This protection is especially important during birthing of pups, which occurs during March to April, and subsequent moulting and weaning (Ferguson 2005). Newborn pups suckle for 6 weeks until being weaned prior to the spring ice break up between May and June (Ferguson 2005). The timing of the spring ice break up is critical to ensure the pups have enough time to be weaned, as suckling pups require sea ice for resting between diving due to the high energy requirements of diving (Ferguson 2005).
Protection is also crucial when pups possess their lanugo (Stirling and Smith 2004). The lanugo is a thick layer of fur that the pups are born with (Stirling and Smith 2004), which allows them to survive on exposed ice (Ferguson 2005). When wet, the pups require protection from the subnivian lair in order to avoid hyperthermia (Stirling and Smith 2004). Furthermore, if the temperature falls below 0 degrees, access to the lair is important in order for the pups to thermoregulate (Stirling and Smith 2004). Adult ringed seals usually possess a number of subnivian haul-out lairs in order to facilitate movement between breathing holes whilst providing protection from predators such as polar bears (Stirling and Smith 2004). Because of the ringed seals evolutionary adaption to the ice, they are the perfect indicator of climate change, and the consequent rate of ice melting (Ferguson 2005). Furthermore, their abundance is a good indicator of the health of an ecosystem due to their high trophic position (Rosing-Asvid 2006).
Protection is also crucial when pups possess their lanugo (Stirling and Smith 2004). The lanugo is a thick layer of fur that the pups are born with (Stirling and Smith 2004), which allows them to survive on exposed ice (Ferguson 2005). When wet, the pups require protection from the subnivian lair in order to avoid hyperthermia (Stirling and Smith 2004). Furthermore, if the temperature falls below 0 degrees, access to the lair is important in order for the pups to thermoregulate (Stirling and Smith 2004). Adult ringed seals usually possess a number of subnivian haul-out lairs in order to facilitate movement between breathing holes whilst providing protection from predators such as polar bears (Stirling and Smith 2004). Because of the ringed seals evolutionary adaption to the ice, they are the perfect indicator of climate change, and the consequent rate of ice melting (Ferguson 2005). Furthermore, their abundance is a good indicator of the health of an ecosystem due to their high trophic position (Rosing-Asvid 2006).