How can human activity negatively impact marine ecosystems?

Human activity negatively impacts marine ecosystems primarily through pollution and habitat destruction. Pollution can come in various forms, including chemical runoff from agriculture, plastic waste, and oil spills. These pollutants can lead to harmful algal blooms, toxic substances entering the food chain, and overall degradation of water quality, which threatens marine life. Habitat destruction occurs due to coastal development, bottom trawling in fishing practices, and the destruction of mangroves and coral reefs. These actions disrupt the complex relationships within marine ecosystems, leading to declines in species populations and biodiversity.

Aiding in the recovery of coral reefs or increasing marine biodiversity would indicate positive impacts from human activity, which do not align with the question regarding negative impacts. Preventing ocean stratification does not accurately reflect how human activities affect oceans; in fact, stratification is a natural process that can be influenced by climate change, which is often exacerbated by human actions. Thus, the correct answer highlights the predominant ways in which humanity threatens marine ecosystems through detrimental practices.