In a possible solution to a marine chemistry mystery that has puzzled scientists for several decades, researchers have now calculated the contribution of teleost fish (bony fish) to marine carbonate (CO3) concentrations. They estimate that such fish secrete up to 15% of the ocean’s carbonate production, through their intestines, or guts (these are conservative estimates; the more liberal estimates show up to 45%).
This is important because sea water is saturated with calcium ions (Ca+2), which must be combined with carbonates to form the shells (as in bi-valves like clams and scallops) and habitat structures (as in gastropods, like conchs, and coral communities) made of Calcium carbonate (CaCO3). CaCO3 is a “neutral” (non ionic/reactive) and stable compound (within normal ocean ph ranges), and, with its plentiful constituent ions (Ca2+ and CO3-), it is an ideal material for marine creatures to utilize in constructing their shells and skeletons.
So-called “dead zones”–patches of ocean lacking aerobic (oxygen breathing) life–will most likely increase due to a rise in carbon dioxide (CO2) concentrations.
Because of CO2 build up in the atmosphere, its level of concentration in the oceans also increases. There, some of the CO2 converts to a simple acid called carbonic acid. (H2CO3).
What is becoming a much-studied phenomenon in recent years, these dead zones of depleted oxygen (02) - typically found at depths between 300 and 600 meters–are the result of several factors working separately and in combination: lower sea surface 02 levels, less heat exchanging (”ventilation”) with mid-level ocean depths due to over-all warming, and “euthrophication events” (an over-growth of a species due to excess nutrients).
The remarkable recovery of the Atlantic haddock (Melanogrammus aeglefinus), a commercial fish species once in serious decline from over fishing, is described with reference to an article in The Scientist (July 1, 2009) and a discussion of the theorized causes for this fish species’ rebound. Quote from the post:
The decline of commercially valuable ground fish stocks is symptomatic of the global, over-fishing crisis. Perhaps no other region on the globe is more indicative of this crisis than New England [...]
Twenty years ago last month, the supertanker Exxon Valdez struck a reef in Prince William Sound and ran aground, releasing 40 million liters {approximately 10 million gallons) into the surrounding sea and onto the beaches. It remains the worst oil spill in US maritime history. In the days that followed, impact inventories revealed the lethal outcome: a quarter of a million sea birds had been killed, along with 22 Orca whales, nearly 3000 sea otters, 300 harbor seals, and unknown millions of fish eggs.
In 1991, the Alaskan and US Governments reached an agreement with Exxon Mobil in a 900 million dollar settlement, almost 200 million of which was set aside for scientific study of the disaster and its impact on the PWS ecosystem. Exxon Mobile also funded its own studies (generating 400 papers and reports) which were frequently in disagreement with the government scientists’ reports and findings.
Twenty years after, the Exxon Valdez spill has become the most studied maritime, industrial disaster ever. A news report in Science Magazine (March 26, 2009) by Lila Guterman (with Jacopo Pasotti reporting) presented some of the scientific findings from the post-spill research.
