Far below the surface of the Pacific Ocean, three quarters of a mile deep, lies the peak of an underwater mountain.  Rising 1.4 miles off the abyssal plains, Davidson Seamount, nearly 26 miles long and 8 miles wide, is one of the largest known seamounts in U.S. waters. Davidson contains an abundance of life including massive groves of large bubblegum corals and reefs of glass sponges.  Life is so abundant at the seamount, we proposed nearly a decade ago that Davidson Seamount with its dense aggregations of invertebrates may serve as source of many species to nearby canyons and rocky outcrops off the California coast.  Davidson may be a perfect habitat for many species allowing their populations to explode.  This Davidson Seamount cradle then may serve as source of migrating individuals into other less perfect habitats nearby.  This idea of Davidson as a biodiversity source was instrumental in getting Davidson added to the Monterey Bay National Marine Sanctuary (MBNMS) in 2009.

A recent expedition by NOAA, MBNMS, and Nautilus, returned to Davidson Seamount.  And is typical of Davidson delivered with a spectacular display of life.   Over 1,000 individuals of the small sized octopus Muusoctopus robustus were caught on video hugging the rocks in a brooding position.  It is unclear why these octopuses are using the seamount as a nursery.  Higher currents around seamounts may bring more oxygenated waters.  The dense aggregations of other animals may provide abundant prey.  The crevasse, cracks, and rocky rubble of this old volcano may provide shelter from predators.

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Monofilament fishing line is not what you expect to see on the deep ocean floor.  What would your response be if I told that enough occurs at depths over 1000 feet you can tally it?  And what if I told you it occurs frequently even in marine sanctuaries?  What if I told you it is not just fishing line but fishing poles, empty bait cans, longlines, nets, traps, fishing gear, fishing weights along with nonfishing items of beverage cans, bottles, construction debris, boxes, 55-gallon drums, artillery, anchors, chains, cables, lines, hub caps, tires, outboard motors, and let’s not forget the tank. That’s right a freaking tank.

On multiple surveys with a submersible, Watters and colleagues found all these items on the deep seafloor habitats off the California coast…often in marine sanctuaries.  In some localities, a piece of trash occurred every eight feet, just a little more than the height of most doors.

You should stop reading here if you don’t want to cry

The discovered trash was dominated by plastics and typically monofilament line from recreational fishing.  These densities of the trash diminished as frequency from ports like Monterey, Santa Cruz, and Moss Landing, increased.  As distance from shore increased, trash “diversity” increased with fishing debris becoming less common.  As most California fisheries target rockfish, rocky surfaces contained disproportionally more trash.  Also disheartening,

Although we did not observe a change in the overall distribution, types, or sources of debris found off central California between the 1990s and 2007, the amount of debris in- creased over time as traditional sites continued to be fished.

Is there good news?  A glimmer of hope in the findings?

Along the Big Sur coastline south of Monterey and absent of towns and ports, trash was virtually absent.

Sorry that was all I could find in the paper.

Watters, D., Yoklavich, M., Love, M., & Schroeder, D. (2010). Assessing marine debris in deep seafloor habitats off California Marine Pollution Bulletin, 60 (1), 131-138 DOI: 10.1016/j.marpolbul.2009.08.019

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