2023-10-10 10:00:00
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The coasts have an incomparable smell that is commonly known as “the smell of the sea” or maresia. However, that unique aroma that the ocean gives off is much more than a simple sea breeze: it is a smell that has its roots in the chemical composition of the ocean and in all the individuals that inhabit it.
And who then is responsible for the aroma that makes you evoke sunny days by the beach? Well, neither more nor less than the sulfurlas sex pheromones of algae and bromofenol, a compound related to iodine. They don’t seem like very pleasant smells, do they? That’s because maresía is an aroma that plays with the quantities of all of them and their perfect combination in an almost idyllic way. We tell you how.
SULFUR: A MATTER OF QUANTITY
Did you know that our sense of smell is capable of responding differently, not only to different compounds, but also to different amounts of the same substance? One of the cases that best exemplifies this fact is that of skatole: in high concentrations it is responsible for the unpleasant odor of feces, while in low concentrations it is associated with the pleasant aroma of flowers and essential oils.
He sulfur joins the game of concentrations, relating to the smell of rotten eggs in high quantities, but with that of marshes and the sea when it appears low. In the latter case, sulfur appears in the form of dimethylsulfuro and is produced from phytoplankton, a type of aquatic organisms capable of feeding autotrophically through the process of photosynthesis.
Sulfur (S). Chemical properties of Sulfur from the periodic table
Thus, the phytoplankton It takes a compound called dimethylsulfoniopropionate (DMSP) present in the sea to use as a kind of sunscreen during photosynthesis. But once these organisms die, the bacteria proceed to decompose their bodies, generating dimethyl sulfide from the DMSP present in their remains. This compound is distributed throughout the maritime environment and is capable of passing into the air as a volatile substance that, when it reaches your nose in a small quantity, you identify with the smell of the sea.
Birds and other marine animals also use this compound to identify which areas are rich in phytoplankton and, therefore, in fish, and feed on them. Furthermore, the accumulation of dead phytoplankton in marsh areas, and therefore high sulfur production, would explain the strong “low tide” smell that emanate from these areas.
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Masses of water flowing in the Ukrainian Dnepr River covered by cyanobacteria as a result of the evolution of phytoplankton in warm seasons.
THE SMELL OF SEXUALITY
But dimethyl sulfide is not the only one responsible for that smell, but two more are added. One of them, perhaps the most curious, is responsible for the “algae smell” and is produced as part of the sexual reproduction of algae. These are volatile particles, called dictiopterenoswhich diffuse both through the water and through the air, mixing with the sulfur generated by phytoplankton.
It is a substance present in the sex pheromones of several species of brown algae (Phaeophyceae). The scientists discovered that dictyopterene was produced in female gametes, that is, in the reproductive cells of female algae, and that male gametes were highly attracted to it, as if it were a claim for sexual reproduction between both organizations.
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Detail of brown algae (Phaeophyceae) from the Cantabrian Sea (Galicia – Spain)
SMELL OF IODINE OR SHELLFISH?
He bromofenol is the substance responsible for salty and marine taste and smell of seafood and fish. But, do you know that in high concentrations it is responsible for aroma and taste of iodine? This is perhaps the reason why shrimp, crustaceans with high amounts of bromophenol, sometimes have an aftertaste reminiscent of iodine. It is also the explanation why fish and shellfish are the foods that top the list of “rich in iodine.”
However, it is not a compound that marine fauna possess per se, but rather they acquire it through feeding based on worms or certain algae. An indicator of this is that, normally, shellfish raised through aquaculture have a lower amount of bromophenol than those that live freely in the sea. It is also a substance that emanates from your body and remains suspended as a volatile element, adding to the sulfur and dictyopterenes to give rise to the unique marine aroma, maresía.
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