Hung up on plastic

Ambon Bay in the Maluku province of Indonesia is one of the most exciting dive spots on the planet. There is no predicting what you will find there, but you have to be game for the hunt.

I have also felt like I was diving head first into a garbage dump. I have been told it depends on the time of the year. In the rainy season, garbage pours down from the dumps in the mountains into the bay. It doesn’t make it any more pleasant to know this-it’s still unnerving to spot a dirty diaper on a dive.

While I am considering what diving in contaminated water will do to my own skin, I also have to wonder how it can be good for anything underwater. Symbiotic relationships with bacteria are fundamental to life underwater (life in general), but the wrong kind of bacteria also happen to be bad for coral reefs.

Coral bleaching has been in our conscience for years, but other diseases also attack coral reefs and destroy tissue. Coral bleaching is the loss of the symbiotic zooxanthellae which are essential for their life. The zooxanthellae are algae which produce important nutrients for the coral using photosynthesis. Sunlight is a key component in the life of stony corals.

Other maladies of the coral reef are often of bacterial origin and can cause the loss of centimeters of tissue per day. A recent study charting the location of plastic in the ocean found an association between reef diseases of bacterial origin and plastic debris.

To come to this conclusion, scientists surveyed 159 reefs in the Asia-Pacific region where 55.5% of reefs and 73% of people living within 50 km of coast are located. The area they investigated covered four different countries, Myanmar, Thailand, Indonesia, and Australia. They first simply counted the plastic debris within each area. The maximum amount of plastic in contact with coral was sadly in the country of Indonesia (25 items per 100 m2) and the minimum was in Australia (0.4 items per 100 m2).

When corals were not in contact with plastic, diseases appeared consistently across all regions studied at a rate of 4.4%. The astonishing finding is that in the presence of plastic, disease in reefs increased by 20 fold (from ~ 4% to ~ 89%).

Reefs succumb to essentially 6 common diseases. All 6 are present in plastic free reefs. Four of these diseases have a tendency to occur in reefs in contact with plastic debris and include the following: skeletal eroding disease (1% to 49%), white syndromes (2% to 19%), and black band disease (1% to 15%).

Plastic was found in contact with structurally diverse reef forming corals. Complex corals, like branching corals (staghorn coral), were more often in direct contact with plastic, in fact up to 8 times more frequently than more rounded or massive corals, like brain coral. Although plastic was less often found in contact with massive corals, they tended to be more vulnerable to diseases. This disparity sets up the potential for disproportionate losses of coral species and consequences for biodiversity, which will ultimately impact humans.

There is no clear explanation for how plastic debris renders reefs more susceptible to disease. Or if it really is the plastic-it’s still just an association. The authors offer several possible theories. Plastic debris may cause physical injury and facilitate invasion by pathogens or exhaust immune system function during wound healing processes. It may introduce pathogens that alter beneficial symbionts or it may cause regions of the reef to experience shading. Low light can lead to reduced oxygen in the microenvironment favoring deleterious pathogens.

What can we do? Reduce plastic use? It’s easy for me to care because I dive and take photographs. But for most of us, what’s in the ocean, even living next to it, isn’t something we often have a view of.

Do we really need to perform scientific studies to prove that our garbage is bad for the environment? Probably not, but we now have scientific proof.

Outrage comes easy when you see a dirty diaper disintegrating on the ocean floor, but most of us will never witness these disturbing scenes. It’s a lesson for any type of pollution. We pat ourselves on the back for policies that are good for our local environment. But to avoid it, we are probably equally guilty of committing grave offenses against the environment in someone else’s backyard. Yeah, think of where the components of lithium batteries come from.

We can find ourselves angry at our leaders for ignoring policy regarding our environment. But really, it’s the activity of each individual that counts.

©Janice Marie Nigro/www.janikiInk.com