There are many issues negatively impacting marine habitats. [1-6]
Humans are the main contributors of marine debris present in marine environments around the world. According to statistics, there are 5.25 trillion pieces of marine debris present in ocean waters. This includes plastic microbeads, plastic bags, cosmetic containers, and old toothbrushes. Organisms such as fish and birds often ingest these plastics, which have detrimental effects on their health. 
A Laysan albatross (sea bird) that died because of plastic buildup in it’s stomach. 
Video summary: Small plastic particles are so prevalent in the oceans that they are competing as a food source. These small plastic particles act as sponges to absorb high levels of toxins. When eaten, these toxins are absorbed by the tissues inside the animal and work their way up the food chain, becoming more and more concentrated.