Mazatlan sewage discharges to the sea put the marine ecosystem at risk


Algae biomass growth is a consequence of the excess nutrients produced by wastewater, and that could affect the development of crustaceans, mollusks, lobsters and other species, says specialist

Julia Ochoa Izaguirre, seaweed specialist

Mazatlan, Sinaloa.- The presence of algae on the beaches of Mazatlan is a natural process that will continue to be presented year after year, but differs greatly from the sargassum that affects the Caribbean; however, what should be of concern is the emergence of high algae biomass as a result of excess nutrients due to the contamination of domestic and industrial wastewater discharges in the Urias estuary and the Crestón area, warned the Doctor of Science for UNAM, Julia Ochoa Izaguirre , algae specialist.

The expert in identifying sources of contamination by nutrients, using macroalgae as bioindicators, said that if nothing is done to reduce discharges to the sea, Padina seaweed biomass will continue to grow and may endanger the ecosystem in its natural balance, affecting the development of crustaceans, mollusks, lobsters and other species.

Through the estuaries, sewage discharges go to the sea

He said that there are many studies that show the high concentration of nutrients as a result of the discharges that are made to the sea, mainly in the Urías estuary and the El Crestón area, where the main sewage treatment plant in Mazatlan operates.

Even when studying the algae found in Urias and in the Pinitos area, some high concentrations of heavy metals such as lead have been detected.

These wastewaters that are treated escapes a lot of nutrients and does not have efficient treatment to remove nitrogen and phosphorus, which are the macronutrients that algae use to make biomass

 Julia Ochoa Izaguirre

Drainage sewers discharge their waters into the Jabalines stream, which will face the estuary of Infiernillo, the navigation channel and the sea

Given the excess nutrients in the sea, he added, the algae take advantage, assimilate and begin to grow and increase biomass.

“When one species displaces another because it is able to assimilate nutrients very quickly, there are problems in the ecosystem, because there is no balance,” he said.

He clarified that the growth of Padina seaweed biomass could displace other macroalgae from the coast, which are a refuge for species of crustaceans, mollusks and lobsters in their larval age, which would lead to the emigration of some species.

Ochoa Izaguirre commented that the only solution is to lower nutrient discharges to coastal waters and remove the layers of algae that are reaching the beaches because if they return to the sea they will serve as nutrients for biomass to continue growing.

Algae biomass growth puts the marine ecosystem at risk


Julia Ochoa said that since 1981 the presence of algae of the Padina species has been registered in Mazatlan, mainly in the area of ​​Pinitos, Playa Norte and Cerritos, although in the latter place there is no longer so much biomass, which lives in where the tide rises and falls, approximately in a strip of 10 meters.

The characteristic of this seaweed is that it is fixed on rocky substrates since it is a benthic algae that has the quality of adhering; It belongs to the groups called brown or brown, to which the sargassum belongs.

“La Padina can live two weather stations or up to a year; when the algae reproduces and reaches its state of senescence, it starts to split and it is when the tide, the same current begins to take off because its fixing disc weakens, and it is very easy for the currents to tear it off and the tide what it does is take them out, ”he said.

The difference between sargassum and Padina, is that the latter lives attached to the rocky substrates, while the former survive floating and reproduce by fragmentation.

The sargassum has a great advantage because it lives on the surface of the water and has the light and nutrients directly, and the Padina lives in the background and does not get enough light, they are more limited in light and their growth is slowed down 

Julia Ochoa Izaguirre

Activity on the fishing pier contributes to water pollution


He said that the most worrying thing is that there is a lot of algae biomass on the coasts that increases year by year, due to domestic and industrial wastewater discharges.

And this not only of sewage treatment plants such as Crestón, but there are also discharges of industrial companies that dump their waste into the sea.

“All that is going to download and is exported to the sea too, so what we have is a sea and a coast with excess nutrients, and having this excess, the algae take advantage and quickly begin to assimilate it and begin to grow and increase their biomass, and they begin to displace those species that do not resist or that cannot assimilate that excess of nutrients so quickly, that is the reason why at present we see this high biomass in this area, ”he said.

For Julia Ochoa, the only solution is to lower nutrient loads to coastal waters, reducing wastewater discharges with more efficient treatment processes and removing the layers of algae that are thrown by the tides to the beach.

However, it clarifies that the growth of biomass is not a local problem in Mazatlan, but of all the coasts of Mexico, Latin America and the world.

With regard to the appearance of algae on the beaches, it is recommended to remove the layers of seaweed.

Source: el sol de mazatlan

The Mazatlan Post