Hi. My name is Jesse Powell and I am a Ph.D. student starting my fourth year at Scripps Institution of Oceanography. I study zooplankton and the effects that oceanic currents and fronts have on zooplankton populations. Most of my work takes place in the California Current near Point Conception just north of Santa Barbara, so traveling way out here to the Gyre is a new experience for me. Working on and in the ocean for many years now, I have grown accustomed to thinking in large scales, but this trip has broadened my perspective yet again.
Let me try to explain how absolutely enormous the ocean is. First of all, just to get to our sampling location in the gyre we will have traveled for almost five days continuously. We’ve had perfect weather, with very little swell, so when you look out from the bridge of the ship you see for six miles in all directions nothing but a featureless blue plain and wide open sky. If we had the ability to walk on water and we needed to walk back to our starting location from our current location, then we would need to walk 20 miles each day across this vast blue plain for over a month. On a percentage basis, the ocean constitutes much more than 99% of the above-ground habitable volume on earth. For example, if you consider just the water volume under the keel along our planned cruise track in a strip 500 meters to either side of the ship, then that water volume would be enough to cover the continental United States to a depth of about 1 meter. And yet this tiny strip of planned cruise track covers only about 0.003% of the Pacific Ocean. The ocean is truly, truly enormous, which is one reason studying it is such a challenge.
Another challenge is that the ocean is variable at many different space and time scales. Water properties like temperature and salinity change dramatically in the vertical direction, but sometimes very little in the horizontal direction. For example, water temperature may drop from a balmy 21°C at the surface to a bone-chilling 8°C only a few hundred meters below the surface, while in the horizontal direction the sea surface temperature has barely changed more than a degree for the last 500 miles. These properties are variable not only over different spatial scales, but also over days, weeks, months, years, decades and longer time periods as well. And the biology of the ocean is even more variable than the physics. Locations that have dense aggregations of zooplankton (krill, for example) at one time of day, may be devoid of most zooplankton at another time. As oceanographers, one of our key challenges is to describe and measure the scales of variability, both in time and space, of key physical, chemical and biological properties of the ocean.
So, the ocean is enormous, variable and challenging to study. Why study it? Well, for one thing, it is intellectually exciting, the vistas are terrific and the people are fun! Another reason is that understanding how the ocean works is fundamentally important to the welfare of humanity and our planet in general. The ocean provides us with food, oxygen and our climate. We could not live on this planet without healthy oceans. Believe it or not, it was once believed that the ocean was so vast that puny humans couldn’t possibly affect it. Global warming, ocean acidification, overfishing and pollution have proven this thinking to be untrue.
During the last day or so, as we’ve started to enter the gyre, we have begun to see more and more plastic debris floating in the water as we steam along at 10 knots (11.5 miles per hour). Yesterday, our bird and whale observers counted hundred of floating plastic pieces during the day. Only a sustained scientific survey lasting many months would be able to quantitatively estimate the true amount of plastic in the North Pacific Gyre, whereas our expedition intends to study what we believe to be one of the most impacted areas, so we cannot yet say with statistical certainty that the plastic abundances we are observing are representative of the rest of the gyre. However, when you realize that while we are underway we can only observe a tiny portion of the plastic, and only the the less numerous larger pieces (e.g. greater than 1 cm in diameter) at that, and when you also recall that our cruise track is only covering an infinitesimal fraction of the Pacific, then you begin to understand that there is all likelihood a tremendous amount of trash in the ocean. It is trash that we humans have put there and trash that we as a species must take responsibility for if we wish to protect the health of our oceans.
A piece of plastic grating, with a pelagic crab, algae, and masses of
flying fish eggs. This piece was floating at the surface and collected
with a dip net off the side of the New Horizon.