Thursday, June 13, 2013

Monterey Bay Full of Trash

Monterey Bay- a beautiful ecosystem full of marine mammals, rocky reef and intertidal species, and garbage...lots of garbage.  Not exactly the pristine view of one of California's most valuable estuarine ecosystems. However, a recent study by the Monterey Bay Aquarium Research Institute (MBARI) showed exactly that.
Dolphins frolic outside Monterey Bay Aquarium [Photo: MBA]
Monterey Bay is a unique bay in Central California, acting as the outlet for the agriculturally-important Salinas River and also housing the towns of Monterey and Santa Cruz- both hotspots for marine research.

A tire, resting at 868 meters, is surrounded by various marine life [Photo: MBARI]
The Bay is bisected by a series of canyons that reach extraordinary depths - up to 2,000 meters deep in spots- that have important ecological implications and are just beginning to be studied.  These canyons aggregate marine life such as fish and even marine predators, like dolphins.  However, the sheer depth of these canyons also means that there is very little water flow or circulation occurring, meaning that what lands there, stays there.  In natural circumstances, this would act as a sink for organic runoff from rivers, along with inorganic matter, such as calcium carbonate from shells and sediment.  In today's world, it means that items we dump into it- tires, shoes, trash- sinks and stays there.
Map of Monterey Bay and its extraordinary canyons [USGS]
So what does this mean?  Well, maybe some of the trash isn't necessarily bad, but it's more of the principle of the thing.  A plastic bottle, dumped from shore, which may have taken 500 years to deteriorate,  may take much longer- or simply never do so.  Lack of oxygen, and very very cold water mean that normal rates of decomposition by microbes slow to a near halt.  What is more likely is that these items will simply become part of the ecosystem until they slowly, slowly become covered with sediment.

A rockfish hides out in a shoe at 1,500 feet 

This finding is evidence that our very momentary actions can have a very long-term effect.  If trash is dumped and accumulates much more quickly then it decomposes, we have essentially turned Monterey Bay into a landfill of sorts. And that has implications for marine species that rarely encounter hard surfaces.  It may shift the ecosystem as sessile invertebrates, such as anemones, have more surface area to attach to.  The implications of this may not be known until the change is irreversible.

MBARI says that there may be even more drastic trash deposition in the deep canyon, which is difficult to get to (1000 meters is 3,280 feet, or 2/3 of a mile).  We may not know for a long time what has already been done. 

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