The loss of biodiversity in marine environments is attributed to many sources, including human activities such as hunting and commercial fishing, the addition of toxins and chemicals to surrounding waters and loss or degradation of coastal habitats. Many factors contribute to the loss of marine biodiversity, but human activities are among the worst offenders. Commercial fishing, for instance, removes key organisms from the environment, which disrupts the food chain and deprives other organisms of their traditional sources of food.
Loss of biodiversity is attributed to short- and long-term events. Oil spills, storms and fishing are all examples of immediate threats facing marine environments. Toxins and chemicals that accumulate in streams and waterways and the growth of urban areas and city centers, which replace wetlands and coastal habitats with artificial structures, are additional factors.
Many marine species spend their lives roaming great distances and reproduce using methods of broad dissemination, such as the dispersal of eggs into strong ocean currents. Dispersal routes may be interrupted by harsh environmental conditions and other factors, which ultimately jeopardize the survival of dispersal-dependent species. Nutrient and chemical pollution is also a cause of biodiversity loss. Only the hardiest species can adapt to altered conditions caused by the addition of toxins and chemicals into their ecosystems, which weeds out the weakest and most vulnerable organisms.