Gulf of Koper towns of Koper, Izola and Piran (the northern shore), along with the villages of Ankaran, Bertoki, Jagodje, Dobrava, Strunjan and Fiesa, are located by the gulf. Gulf of Koper The Gulf of Koper or Koper Bay (, , ) is located in the northern part of the Adriatic Sea, and is a part of the Gulf of Trieste. The gulf, named after the city of Koper, is part of the Slovene Riviera and is entirely located in Slovenian territory. Crossed by the river Rižana, it is 18 km² large and spans from Debeli Rtič, next to the borders with the
Gulf of Mexico Island. The Gulf contains a hypoxic dead zone that runs by east-west along the Texas-Louisiana coastline. In July 2008, researchers reported that between 1985 and 2008, the area roughly doubled in size and now stretches from near Galveston, Texas, to near Venice, Louisiana. It is now about , nearly the record. Poor agricultural practices in the northern portion of the Gulf of Mexico have led to a tremendous increase of nitrogen and phosphorus in neighboring marine ecosystems, which has resulted in algae blooms and a lack of available oxygen. Occurrences of masculinization and estrogen suppression were observed as a result.