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.
Marine biologists have discovered a dense population of mussels (the vent mussel Bathymodiolus brevior, a common, edible bi-valve “shellfish”), carpeting the sides of a submarine volcano, which has survived–despite the highly acidic environment–for the past 40 years. The results of this study were reported in a recent, on-line edition of the Journal Nature Geoscience.
The acidification of ocean habitats due to increased absorption of CO2 (which reacts with water to form carbonic acid) has become an issue of great concern over the past decade. Shellfish and other marine species (like corals and snails) that make their “homes” or shells from carbonates of calcium (CaCO3), are vulnerable to more acidic waters. A lower ph (generally below 8 on the ph scale) marine environment makes calcium ions less available to these creatures to fabricate their fortifications against nature’s predators and chemical forces. The result of this acidic exposure in shellfish is typically a much thinner shell, thus making the creature more susceptible to predation and even disease (as in the case of many corals; see: ).
