How Plastic Ingestion Impacts Dolphins and Porpoises
Plastic ingestion is one of the biggest threats facing these beloved creatures.
Dolphins and porpoises are some of the most adored animals in the ocean. Perhaps it’s because they’re so playful and friendly. Or perhaps it’s because their high intelligence and sociable nature are similar to ours. Either way, despite our love and admiration for them, dolphins and porpoises are facing some serious threats. And they all come from humans.
Plastic ingestion can be deadly, but not always in the most obvious ways
At least 48 species of cetaceans, including dolphins, have ingested plastic pollution. Obviously, eating plastic isn’t a healthy option for any animal. It can cause fatal tears and blockages, lead to illness and disease, or impart a false feeling of fullness that leads to starvation. But for predator species like dolphins and porpoises, there’s another risk that really affects the entire food chain.
POP goes the dolphin… and the porpoise… and the food chain
Plastics in the ocean can absorb toxins called POPs from the surrounding environment. POPs is shorthand for persistent organic pollutants, which are toxic organic compounds that resist breakdown and adversely affect human health and the environment. Some POPs can take up to a century to degrade. A piece of microplastic can have concentrations up to 1 million times greater than its surrounding environment.
POPs have what scientists call a high lipid solubility, which means they’re attracted to fats and oils. This means the toxins can pass through cell membranes and enter the fatty tissue of living beings. Over time, the toxins build up in the body and can have adverse effects on health.
Where do POPs come from?
Many of these toxins, or POPs, enter the ocean as runoff from land-based sources. POPs include a number of different substances including chemicals used in agriculture, disease control (such pesticides for disease-carrying pests like mosquitos), manufacturing, and industrial processes. PCBs (polychlorinated biphenyls), DDTs (trichloroethane), and dioxins are some of the most common.
How POPs enter the food chain
Plastics in the ocean don’t go away. They just shred and break into smaller and smaller pieces called microplastics, which can be smaller than a grain of rice or sand. Animals at the bottom of the food chain, like plankton, ingest these microplastics.
Prey species ingest the plastic-filled plankton. They may also ingest larger pieces of plastics on their own. The toxins from the plastic bioaccumulate, or build up, inside the animal over time.
The toxins inside these prey species become more concentrated inside the predator species that feed on them in a process called biomagnification, which means predators species like dolphins and porpoises are more affected by the toxins than animals lower down the food chain.
How POPs affect dolphins and porpoises (and people)
Marine mammals, especially cetaceans like porpoises and dolphins, aren’t able to detoxify these organic pollutants very well. They can impact their immune system and leave them more vulnerable to disease.
POPs can also disrupt several bodily systems including the endocrine, reproductive, and immune systems. Brain development and the nervous system are some of the most vulnerable. In humans, POPs can cause cancer, diabetes, thyroid problems, and behavioral problems.
What we’re doing to help
We have captains and crews removing plastic and other debris from the ocean 7 days a week. Every 4ocean bracelet purchased removes one pound of trash from the ocean and coastlines, keeping it out of habitats where dolphins and porpoises live.