Remember the big Mid-West floods?  Well there was an underreported story on the affect of flood waters on agricultural lands and the runoff that was loaded with fertilizers.  The fertilizer laced river water that is injected into the ocean causes huge algae blooms such blooms trigger "dead zones" in the ocean.  Dead zones are regions of the ocean which lack oxygen.  However another effect of nitrates and algea is this:

Surface blooms of the algae known as Pseudo-nitzschia can generate dangerously high levels of domoic acid, a neurotoxin blamed for bizarre bird attacks dramatized in Alfred Hitchcock's 1963 film "The Birds."

Reuters reports that there are two long term dangers the most visible is the above quote.  However the second danger is that particulates with domoic acid sink to the bottom of the ocean.  

They found that large quantities of domoic acid were sinking to the ocean floor, invading the deep-sea food chain.

And the toxin appears to linger.

So not only will we harm life on the surface but all marine life, even life that lives in thousands of feet below the ocean's surface.