Zettler and colleagues ( 2004 ) showed that in the outer coastal waters of the Baltic Sea , the nearly black and often corroded shell form of Theodoxus fluviatilis is predominant , .
In the inner .
Zettler and colleagues ( 2004 ) showed that in the outer coastal waters of the Baltic Sea , the nearly black and often corroded shell form of Theodoxus fluviatilis is predominant , whereas in the inner .