“Happy birthday to youuuu”. After hearing this famous birthday song, one might wonder whose birth we should actually be celebrating. No, neither your favorite singer’s nor some obscure African President’s. Funnily enough, September 2019 marks the 350^th anniversary of the discovery of the P element, better known as phosphorus. However, if you are not a chemistry die-hard fan, you might not be acquainted with all the marvelous qualities of the 15^th element of Mendeleev’s table.

Its name is derived from the ancient Greek and it was the original denomination of planet Venus, literally meaning “light-bringer”. Some fun facts about this element are connected with the human body – it is indeed the second most abundant mineral found in human beings, with most of it concentrated in our bones and in our brains to strengthen memory.

What people often do not know about phosphorus however, is that this element is currently endangering the equilibria of our seas, possibly causing the deterioration of many ecosystems around the world. Being the most important component of agricultural fertilizers, a large concentration in the estuaries and coastal waters enriches the ecosystem with nutrients that cause large blooms in algae growth. Phosphorus, along with Nitrogen are the primary elements behind this process, called eutrophication. The presence of a disproportioned amount of nutrients causes algal blooms and reduction of oxygen in waters (hypoxic) that can kill fish and seagrass and damage critical fish habitats.

But how do phosphorus and nitrogen actually accumulate in the marine ecosystem? Most of it comes from agricultural sources including fertilizer overflow and septic system waste to atmospheric fallout coming from consumption of fossil energy sources —which enter waterways and trigger the overgrowth of algae, which, in turn, decreases the quality of the marine habitat and damages estuarine and coastal bionetworks. While most of the worst causes of pollution have been tackled in the previous years and significant improvements have been achieved, including the betterment of wastewater treatment facilities and the cut on production runoff, in some areas of the world eutrophication is still a concerning issue.

The Baltic Sea is a blatant example of a water basin that is being heavily affected by this process. As a matter of fact, its waters hold 5 times as much nitrogen and 8 times as much phosphorus as they used to do, 100 years ago. Outputs from land-based activities (including sewage, industrial and municipal waste and agricultural waste) comprise about 80% of the sources of nutrients present in the water. The remaining 20% derives largely from nitrous gasses, produced with the burning of fossil fuels, traffic, industry and heating systems employment. Given the predicted spike in agricultural development in the region, the eutrophication process will surely worsen if cuts in nitrogen- and phosphorus-rich substances leaking into the Baltic Sea are not performed.

The Baltic bionetwork is dependent on both long‐term and periodic climate changes.  Climate oscillations usually happen periodically, due to spikes in water salinity and oxygen concentration in deep Baltic water bodies. However, this process is connected to eutrophication as well. The causes are threefold:  i) the increasing saturation of carbon dioxide in the atmosphere, ii) the rising temperature of the atmosphere, and iii) higher dynamic forces of the atmosphere. Heightened concentrations of carbon dioxide in the atmosphere lead to acidification and a subsequent decrease in the pH of surface waters in the basin. Increased atmospheric concentrations of carbon dioxide and acidification of surface layers may add up on this process, leading to an increase in scales and much lower pH values than the current ones. Finally, the heating up of waters in the Baltic Sea will stimulate the growth of phytoplankton colonies, which may be connected to a further boost in the eutrophication process

While it is not too late to revert the process, many more “closed” basins, including lakes, may incur in the same fate of the Baltic Sea if not tended to. It is our responsibility, as a generation that is increasingly attentive towards the ecosystem, to design alternative solutions to cut the amount of phosphorus and nitrogen in the water and prevent eutrophication from destroying whole bionetworks.