Plastic in the ocean – a depressing thought

A myctophids (photo by G. Hanke RBCM)

“No scientist would ever use the state of Texas as a unit of measurement”

       – Captain Charles Moore

My husband and I went to a talk by Captain Charles Moore recently. He wrote ‘Plastic Ocean’, a book I’ll read and write a review of (we have been planning to get the book for some time). He brought up some interesting and depressing points about how much plastic is in our oceans and what it’s doing to the life there.

Only about 10% of the garbage that gets into the oceans washes ashore; the rest is concentrated into the mid-ocean gyres. An unfortunate side effect of our convenience-based consumer lifestyle is that much of the garbage produced is plastics, which float and don’t breakdown. It takes approximately 6 years for the garbage to travel around a gyre and the average life of the garbage in a gyre is 10 revolutions – that is 60 years.

At first the plastics resemble what they started as – a milk crate, a laundry basket, etc. Since plastic presents a hard substrate, algae eating fishes claim larger chunks as shelter and keep the surface fairly algae free. This clean plastic eventually gets colonized by barnacles and corals creating a new multi-level trashy ecosystem – with algae as the base, then on to herbivores, planktivores, secondary invertebrate consumers, and so on ending at the top predators (large fishes, birds, dolphins and relatives).

As hard-shelled invertebrates grow, their mass overcomes the buoyancy of the plastic. The reef sinks, and over time, the attached organisms decay or dissolve in the cold ocean depths. Buoyant once again, the plastic floats to the surface and the cycle of colonization can begin anew.

In the long run, this plastic garbage will rub up against other debris or be broken by wave action. The plastic pieces get smaller and smaller. A ruby-red bottle cap might be scooped up by an albatross to be fed to its chick or the plastic rings holding a six-pack together might end up around a sea turtle, restricting normal shell growth. Captain Moore mentioned myctophids, an abundant group of lantern fishes which are a vital part of the open ocean food web. Dissections of their stomachs show some of these fish are eating as much plastic as food. Even the tiniest pieces can be ingested by filter feeders.

Plastics are known to absorb pollutants. Species low on the food web eat plastic scraps, creating another way for pollutants to end up in our food. I wonder, what that tuna I ate for lunch ate for its lunch?

So what can we do? I try to use as little as plastic as possible. I have my own metal water bottle and ceramic coffee cup. I keep food in glass containers, and use re-fillable bottles for shampoo and cleaning products. Any other ideas?

as a tangent: thanks to my husband for helping me with this one.

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