No. because Seaweed does not eat smaller Seaweeds. Predator fish like Tuna can become heavier in toxins only because they are the top of a food chain gathering

No. because Seaweed does not eat smaller Seaweeds. Predator fish like Tuna can become heavier in toxins only because they are the top of a food chain gathering and concentrating said toxins. Seaweed is just a plant. It grows, then dies if not harvested. It is no higher risk than wheat.