H2O Learning Center

Can we “push” oceans as far as lakes?

This week scientists from around the world are coming together in Portland, Ore. for Ocean Sciences 2010.  Although not official, one of the themes of the conference emerging thus far is the changing state of the world’s oceans.  Through ocean acidification, larger oxygen depleted areas, lower coral coverage, and the invasion of the well recognized lionfish from the Pacific, scientists are identifying symptoms of change similar to those seen in lakes of the Northeast.

The term ocean acidification may bring to mind the acid rain of the Adirondacks.  Since becoming a familiar term in the 1970s, we have associated acid rain with “dead” lakes, dying trees, and corroded buildings.  Unlike fresh water, the ocean is not actually becoming acidic, but it is becoming less basic, hence, acidifying.  The ocean’s salinity originates from sediments and atmospheric exchanges, and the complex chemistry allows life as we know it to exist.  Organisms such as corals, shellfish, and crustaceans that depend upon certain chemicals to build their homes or regulate their metabolism are thereby affected when that chemistry changes.   Another familiar story in the Northeast is the “death” of Lake Erie.  Most upper latitude lakes have seasonal changes in which they “turnover” with both the formation and melting of the ice.  During the summer, the bottom of a lake may go completely without oxygen if the upper waters are algal rich.  This anoxia may be extended by increased nutrient availability and other forms of pollution.  Lake Erie was so polluted, that it was unable to freeze for a number of years, hence interrupting the natural process of “rebirth”.  Off the coast of British Columbia, Ca, scientists have identified areas of the ocean that are staying anoxic longer and growing larger than ever previously seen.

The invasion of the zebra mussels is well known to any recreational user of the fresh waters of the Northeast.  While they have demonstrated an amazing ability to help in the “cleanup” of polluted bodies of water, due to their ability to survive in harsher environments, they have still had a massive impact on the surface communities of the rivers and lakes.  Lionfish are a graceful, fairly popular aquarium fish, famous for their brown and white striped fins that are reminiscent of a turkey displaying its tail feathers.   According to Dr. Marc Slattery, these fish are now more frequently sighted in the Caribbean than in their native Pacific.  While there is not conclusive evidence, it is believed that their presence has led to extreme shifts in benthic reef communities from largely coral and sponge dominated areas to algal dominated areas below the usual 100ft range of most divers.  Originally spotted offshore of Florida about ten years ago, their expanse throughout the basin has been rapid.

While each of these changes is alarming on its own, together they create a picture of a behemoth environment being stressed in ways similar to smaller, fresher bodies.  Although the collapse of fisheries through the generations has shown us the impacts man can have on the ocean, these non-direct methods of changing the ecosystem may have greater consequences.  Ask anyone that has seen a body of water change for the worse what they can imagine happening is this occurs ocean-wide.