Ukrainians mining the areas around the ports has really hurt the flow of food to the world:
Desperate Ukraine Navy Lay Mines in Black Sea ‘Which May Drift to Bosphorus, Mediterranean’ 3/19/22
Mines from Ukraine drift into the Black Sea, Russia and shipping sources say, 3/21/22
https://indianexpress.com/article/world/mines-from-ukraine-drift-into-the-black-sea-7830216/
Times of India: “Moscow says Mariupol port reopened after demining” 5/25/22
All of the mines need to be cleared out.