Cancer, brain damage in marine animals due to pollutants

Parasites from cat faeces are causing deadly brain damage in sea otters and sea lions are suffering from cancer as a result of toxic chemicals - a result of the garbage humans dump into water.

These animals live near coastlines, spending a majority of their lives in the same waters people swim and surf in. Their daily cuisines consist of the same foods we serve up in fine seafood restaurants.

The difference is that the animals deal with the ocean conditions, good or bad, full time, while people can pick and choose when to go into the water and what to eat, says US National Oceanic and Atmospheric Administration (NOAA) spokesperson Paul Sandifer.

Another marine animal, the manatee, is dying in large numbers in Florida due to toxic algae blooms or red tide algae, science portal LiveScience reported.

Marine animals, particularly mammals, play an important role as sentinel species. When one of these species gets sick or dies from something in the water, it is often a warning to humans of disease to come.

"Some of what we throw or flow into the water will return to bite us in the gluteus maximus (posterior). You can bet on it," said Sandifer at a meeting of the American Association for the Advancement of Science.

A deadly parasite, which reproduces in cats, is the third most common cause of death due to food-borne disease in the US. It is also killing California sea otters at a rapid rate.

Toxoplasma gondii, which causes the disease toxoplasmosis in humans, has been found in 52 percent of dead otters and 37 percent of the living.

In otters, the parasite causes tremors, in-coordination, and seizures. It is the primary cause of death in some coastal otter populations.

The major culprit is freshwater runoff, which washes faeces from backyards and streets into streams, rivers, and ultimately the ocean.

The red tide algae blooms that turn waters off Florida's coast rust-coloured are becoming more frequent. Karenia brevis algae, responsible for red tide, produce toxins called brevetoxins, which can kill fish, sea turtles, birds, and marine mammals such as manatees.

In 2005, 151 manatees died from exposure to brevetoxin. Post-mortem examinations revealed that the stuff was affecting their lungs.

For California sea lions, a combination of persistent organic pollutants (POPs) and herpes virus similar to the one that infects humans has led to an increase in cancer.

Over the past 15 years, 17 percent of dead and stranded sea lions have been diagnosed with urogenital cancer, striking females in the cervix and males in the penis and prostate.

The cancer spreads to other organ systems in sea lions the same as in humans. Eventually it erodes the spinal cord, paralysing them and causing them to wash up on the shore or strand in the open water, said Frances Gulland of the Marine Mammal Center.