The Quark is a transnational area between Finland and Sweden, the majority of which lies in the former, that is dotted with 5600 islands. The Quark displays some unique biological conditions because of the rapid land uplift, a geological phenomenon caused by the last ice age. The annual uplift is one of the fastest in the world and greatly shapes the geology and biology of the area. The Quark is included in the World Heritage List of UNESCO because of its unique geological features.
The Quark forms a shelf creating a transition zone between two sub‑basins, the Bothnian Bay and the Bothnian Sea, and limiting water exchange. These conditions create differences in salinity in these sub‑basins, which affect species composition in the Quark. Some marine species reach their northern distribution limit precisely at the Quark. The sea bottom is characterized by bedrock and rocks ranging in size from pebbles to big boulders, but patches of sand do occur. The Quark and the area south of it include a number of small marine protected areas, both in Finnish and Swedish waters.
As far north as it is, the ice season in Quark lasts from around 120 days from January to April in the outer coastal parts of the Quark, to around 150 days in the inshore areas. The Gulf of Bothnia is less exposed to nutrient leaching than the rest of the Baltic Sea, as fewer people are living in the catchment area.
Oceana conducted fieldwork in the southern part of the Quark in 2011 and 2013, with the use of an underwater robot (ROV), scuba divers and bottom samples. Both marine (e.g. bladder wrack) and freshwater (e.g. the seamoss Fontinalis antipyretica) species were documented.
Sweden and Finland show an interest in protecting the Quark, but there exist no official announcement yet.
