i dont know if poop is the problem..i thought it was the warming sea temperatures.
at the moorings they told us to keep the heads closed while in an anchorage and let it out at sea..i think most companies must do that..no anchorages seemed to be polluted at all...however the moorings also insist that you leave the heads open while at their base..we used the shore facilities but it was obvious from the occasional stench that not everyone did