Climate Change and Pollution Threaten Marine Mammals

By Vivian Guido

Vivian Guido is an intern who worked last semester with the International Marine Mammal Project and Shark Stewards of Earth Island Institute. Vivian is a Master’s student at Toronto’s York University in the faculty of Environmental Studies.

Marine mammals around the world, and in the United States especially, have been directly impacted by climate change, and the current cases of marine species decline are surpassing scientific predictions. As marine mammals help preserve aquatic habitats and play a key role in maintaining the balance of the ocean, their conservation is paramount. The increase of atmospheric carbon, sea level rise, ocean warming, and acidification are all major factors that are affecting the vital marine species that directly support planetary and human health.

The impacts on cetaceans specifically are significant due to ocean warming because of melting of polar ice, alongside the changes in prey range for larger marine predators. Large marine mammals such as whales, dolphins, seals and sea lions are also severely affected by increasing pollution and have often been sighted, entangled in plastic fishing nets or accidentally ingesting plastic debris. Cetaceans are also particularly at risk because of increased strikes from fishing vessels and cargo ships operating in marine areas where these species are known to be. Some species have declined to the point of extinction or near extinction, such as the critically endangered North Atlantic right whale (Eubalaena glacialis), the blue whale (Balaenoptera musculus) and the small vaquita porpoise (Phocoena sinus).

Climate change has also decreased ecosystem productivity in coral reefs, seagrass meadows and mangrove forests, which are nurseries for many small juvenile fish that become prey to larger fish and marine mammals. The changes in nutrient uptake and the dispersion of zooplankton and nekton have had an increased effect on filter feeding cetaceans such as whales and can directly impact their food supply. This process of ecosystem productivity is extremely important because many of these tiny organisms generate most of the world’s oxygen and food that provide other organisms with energy.

Plastics have been a clear factor in the decline of several marine species from the tiniest corals to the biggest whale. The magnitude of America’s plastic problem has shown no signs of slowing even after the constant visual and medical evidence that human-made, synthetic materials pose a risk to humans and other animals alike. With about 14.3 million tons (13 million metric tonnes) of plastic entering the oceans annually, nature cannot keep up with the level of environmental degradation associated with these practices.

Marine mammals have been seen, and documented time and time again by scientists, divers, and members of the general public, entangled in plastic debris. Whales and dolphins are especially prone to becoming caught in discarded fishing nets and buoys, synthetic rope, plastic tarps and large plastic bags. Seals, sea lions and sea otters are often trapped in plastic containers, rings or wrappers as well as fishing gear and plastics. Even seabirds are affected by plastic marine debris, often being seen entangled in zip ties, plastic drink rings and fishing line. Birds often pick up bottle caps and other bits of plastic from the ocean and feed the often-lethal plastic to their babies. Marine mammals and other ocean dwelling species regularly come in contact with plastic waste and have shown significant population impacts due to this issue.

Marine mammals are also harmed by microplastics and the toxic chemicals they carry and that leach into the ocean. Countless studies conducted on the effects of large plastics breaking down into microscopic pieces of debris have shown dangerous and detrimental physical effects on marine species. Health issues associated with microplastic ingestion include hormonal and reproductive problems, nervous system and kidney damage, digestive and heart problems as well as cancers and parasitic diseases. Additionally, chemical toxins derived from plastics or attached to plastics can cause changes in growth patterns, feeding, mating and other regular psychological habits or behaviors. Consequently, plastic pollution in all forms can significantly increase the risk of harm and death to marine mammals.

The threats of climate change are only predicted to increase in the coming years, and the pressure on ocean ecosystems is rising. Whales, dolphins, and other vital marine mammals are facing rapid and significant population declines, and in America specifically, these impacts could be better mitigated and reversed to promote a safer, healthier future for our oceans.

**********************************

IMMP has been active in protecting the most critically endangered cetaceans and fighting to end offshore oil drilling. IMMP has also focused their efforts in successfully phasing out the last drift gillnet fishery in the US which severely impacts marine mammals through bycatch. We are currently collaborating with our parent group, Earth Island Institute, in suing ten major companies, aiming to hold them accountable for their share of ocean plastic pollution and false claims of recyclability. We oppose offshore oil drilling to protect our oceans and our climate. Please donate to help IMMP’s ongoing efforts to reduce and eliminate ocean plastics to benefit the health and lives of marine life and the health of the planet.