Germany’s Admiral Souchon is now the commander-in-chief of the Turkish navy. The nucleus of that navy are his two ships, the Goeben and Breslau, now renamed as the Yavuz Sultan Selim and the Midilli respectively (for convenience their original names will continue to be used here). The two ships are still crewed by Germans, though they all have fancy new Turkish uniforms. The presence of the Goeben in the Black Sea changes the naval balance there; the Russians have nothing to match this modern battlecruiser.
Yet the Ottoman Empire has not yet joined the war. Until today. For now Souchon leads his two ships and some other vessels of the Turkish fleet to attack the Russian ports of Odessa, Sevastopol and Novorossiysk. The Turkish flagged vessels blast the ports, destroying Russian shipping and devastating shore targets.
Wilhelm Souchon image source (Wikipedia)
SMS Goeben image source (Wikipedia)