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We love seeing dolphins surf, swim with kids and appear by the thousands in magical stampedes, but seeing dolphins with skin lesions is a sight none of us wants to see. Unfortunately, researchers studying dolphins in Santa Monica Bay have noticed a steady increase in the number of bottlenose dolphins with skin lesions and even tumors, which are thought to be caused by pollution in the bay.
A study from 2009 revealed that nearly 80 percent of common bottlenose dolphins observed in Santa Monica Bay have at least one lesion, and scientists are now witnessing even more skin disorders on the species, along with other species such as the long-beaked common dolphin, according to KPCC.
Marine biologist Maddalena Bearzi, co-founder of the Ocean Conservation Society has been tracking the marine mammals from Malibu to Rancho Palos Verdes for the past 17 years, and has compiled one of the longest running data sets on dolphins in the world. She believes, along with other researchers in the area, that runoff pollution from the streets and other sources, is weakening the animals' immune systems.
The high levels of pesticides, PCBs and toxic metals such as lead that pour into the bay leave the dolphins vulnerable to viruses that cause the skin disorders. According to Bearzi, "We know that [pollutants] transfers from mother to calves in the milk, so we know that some of the calves have high concentrations of these pollutants."
And while the ongoing drought has actually helped to reduce the amount of water pollution, according to Heal The Bay, it only takes one inch of rainfall to send 10 billion gallons of contaminants into the water.
R.H. Defran, a marine mammal researcher at San Diego State University, who uses the dolphin data collected by Bearzi, points out that the health concerns are not just a local issue. He tells KPCC, "It’s not that it just affects Santa Monica Bay dolphins; it affects dolphins up and down the coast as they pass through this area of pollution."
