Sea Vegetable Cultivation in Indonesia

I recently found this video about sea vegetable cultivation in Indonesia. Although not a traditional cultivation mode (like land farming), sea vegetables are a new source of income for Indonesians. This is especially important because increased drought and over farming of the land has made traditional farming increasingly harder. Sea vegetables give these people chance to raise their standard of living.

Although this is great for the Indonesian economy, I'm concerned about water pollution, overcultivating, overharvesting, and their methods of growing. The seaweed cultivated in Indonesia is exported for use in cosmetics, pharmaceuticals, ice cream and other food fillers, and countless other things. Because sea vegetables easily absorb pollution from the water, I'm concerned about the water pollution in these areas since Indonesia has a lot of environmental issues related to overpopulation and poverty.

I was also concerned to see that they are using plastic bottles to suspend the sea vegetables in the water for better growth and (maybe) easier harvesting. I wonder if sea vegetables can also absorb plastic particles?