Dive Into Your Imagination

When we woke up on August 8th, we had traveled more than one thousand miles.  The tension was rising on the New Horizon because the mantas continued to have small bits of plastic in them, but the scientists really wanted to reach the highest area of accumulated plastic within the North Pacific Gyre.  So it became a waiting game.  As the waiting game ensued, the mantas, dip netting, and visual observations continued, and the acoustic array continued to be deployed.  By the 7th day, I not only fully understood what constituted the North Pacific Gyre, but I also learned a lot more about plastic.  I knew that many plastics are made from oil and that they contained chemicals that were bad for us.  Thanks to Chelsea I started to understand the extent of all the harmful effects these can have on life: both the actual constitution of water, the organisms and how it can work its way up the food chain to us.

What is Plastic?
Many plastics are petroleum based products made of polymers. The raw materials for plastic are made from coal, oil, and natural gases; in other words, plastic is made from limited resources.  Plastic cannot biodegrade.  It can only photodegrade, meaning light breaks it down into smaller and smaller pieces termed confetti by Dr. Charles Moore.  It never goes away completely.  This is because plastic was a miracle invention only adopted widely once it was absolutely indestructible. Plastic was originally invented in 1862 and eventually replaced products made from natural materials.  With the average human being creating one ton of trash per year, millions of pounds of trash are entering our Ocean, and much of this is plastic.

Why is plastic in the ocean harmful?
There are 5 main issues surrounding plastic entering the ocean, explained in detail below this list:

1. Because plastic confetti pieces are so small, they resemble the organisms at the base of the food chain: zooplankton and phytoplankton.  These small pieces get eaten by small fish, and larger pieces of marine debris are eaten by seabirds.  There are two major reasons why this is a problem.  First, plastic is difficult to digest, and may build up in their system.  The animal then never becomes hungry and will starve. 

2. Second, plastic is created with certain chemicals in its structure.  Because chemicals such as BPAs are pollutants, scientists are studying their effects on the marine environment.  The pollutants leach out into the water and tissues of organisms. This may have adverse effects on the water chemistry, all marine life, and everything that consumes marine life- including us.

Bioaccumulation is an effect in a food web when chemicals in the water or in the food animals eat are transferred to and accumulate in an animal’s tissue.  This pollution becomes more and more concentrated in tissues of animals higher up on the food web, and this increased concentration up the food web is called biomagnification.  For example, imagine that one fish eats a small piece of plastic resembling zooplankton. A larger fish eats that fish, but because it is larger it needs to eat multiple fish; it then gets a heavier load of chemicals.  As you move into larger predators, they get higher levels of the chemical because 1. They eat more and 2. Their prey has a higher accumulation because they too are further up the food web.  This can have dire effects on marine mammals and humans because we are on the top of the food web.  This is the same with mercury building up in fish tissue and it is why it is important for humans to monitor the amount of canned tuna eaten to avoid mercury poisoning.

3. Other types of pollution can interact with plastic.  These are known as Persistent Organic Pollutants. 

Persistent Organic Pollutants are foreign substances already existing in water.  Flame-retardants are just one example and are found all over our houses.  They are in our furniture, our carpet, and even the walls to protect us from fire.  Pollutants like this enter the water through multiple means such as urban runoff, dumping, and boat pollution.  These POPs float around in the water and may become attracted to plastic.  This adds to the pollutants such as BPAs that are already in plastic and they may also bioaccumulate.

4. Another problem relates to the organisms that colonize onto plastic.  All materials, organic or manufactured, that enter the ocean become a potential habitat for organisms.

Dispersal is key for organisms to distribute themselves and their young.  The natural mechanisms for dispersal are 1. walking or swimming and 2. being carried by ocean currents.  The most common examples of dispersal are animals that reproduce by broadcast spawning, which means they shoot their sperm and eggs up into the water column.  In this way, their gametes meet, and the resulting larvae are easily transported by currents to a new location.  This allows young to move into an optimal habitat with more food and potential mates and less competition.  Think about a coconut that travels across the ocean, lands on an island, and grows into a palm tree.

Floating pieces of plastic, no matter the size, become a dispersal mechanism not only for larvae but also for larger animals that are normally sessile (stuck in one place) or would have to walk or swim to a new location.  As you can probably imagine, a small animal walking or swimming is not going to get as far as a light piece of plastic carried by ocean currents.  Animals that hitch a ride on plastic are known as fouling communities. A fouling community is a community of sessile organisms that live on boats, docks, and in this case, plastic.  Many fouling communities found on plastic also include mobile organisms such as crabs or even fish eggs. In the top picture, you can see what a natural fouling community would be- eggs on a feather; in the bottom picture there is a crab and fish eggs on a piece of plastic.  This transport of organisms across the ocean and high supply of dispersal material could possibly lead to a problem with invasive species. Invasive species are species that are not native to a location.   They become introduced usually by unnatural, anthropogenic means and can cause an entire shift in food webs and ecosystem dynamics.

Not only do large organisms settle onto plastic pieces, but also biofilms of bacteria may form.  In areas with a lot of plastic, usually all carrying biofilms, the natural nutrient balance of the ocean may be disturbed.  Although the effects of this are unknown, it may change the way nutrients naturally cycle through the system and may also cause a shift in food webs.  It is important to know the effect bacteria have because bacteria play a vital role in the world’s (and specifically the ocean’s) life cycle as decomposers and recyclers.  They are also the primary source of nitrogen for photosynthesis because they fix nitrogen.  Biofilms may contribute to invasive species because it is thought that biofilms could be cues for other animals to colonize onto plastic.

5. Finally, animals may become entangled in debris, or could choke on it.  This is why it is important to cut up the plastic rings that package soda cans and crush yogurt containers before recycling.

For more information go to check out these sites:
http://www.seaplexscience.com
http://www.projectkaisei.org
http://kaisei.blipback.com

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