Primary Mechanisms of Harm
Plastic bags harm ocean wildlife mainly through ingestion and entanglement. Marine animals often mistake floating plastic bags for food, such as jellyfish, leading to internal blockages that cause starvation, malnutrition, or suffocation. Entanglement occurs when bags wrap around limbs, necks, or bodies, restricting movement, causing injuries, and increasing drowning risks. These impacts contribute to high mortality rates among species like sea turtles, seabirds, and marine mammals.
Key Biological and Ecological Components
The harm stems from the bags' lightweight, durable nature and slow degradation in seawater, where they break into microplastics that enter the food chain. Ingestion disrupts digestive systems by filling stomachs without providing nutrition, while toxins like BPA leach into tissues, causing reproductive issues and weakened immunity. Ecologically, population declines from these threats disrupt food webs, affecting predator-prey balances and biodiversity in ocean habitats.
Practical Example: Sea Turtles and Jellyfish Mimicry
Sea turtles frequently confuse plastic bags with jellyfish, their primary prey. A turtle ingests a bag, which blocks its intestines, leading to bloating and inability to eat real food. In one documented case, a rescued green sea turtle had over 100 plastic items, including bags, in its stomach, resulting in severe dehydration and death without intervention. This illustrates how visual similarity exacerbates the risk for endangered species.
Broader Importance and Conservation Applications
The harm from plastic bags underscores the urgency of reducing single-use plastics to protect ocean biodiversity. Applications include policy measures like bag bans, which have reduced marine debris in areas like California, and public education on proper disposal. Addressing this issue helps mitigate species extinction risks and supports sustainable fishing and tourism industries reliant on healthy marine ecosystems.