The potential problem with microplastics in marine ecosystems is the same as other toxic pollutants... biomaginfication. Not that the plastics themselves will kill you, but the toxins they absorb will. So if fish... especially local fish... is a big part of your diet, it's likely the microplastics issue is closer to home than the mid ocean trash heap, which is considered a "biological desert." Don't get me wrong... it's a serious problem, and needs to be stopped. But the microplastics issue is something we can't ignore either.
til a better solution arrives.....robots? IN with the bad water; OUT with the good water. or; attack from the air. a commercial (BOAT) drone/garbage grabbers.... not unlike an aircraft carrier...(!?)