How will we know that the sea we swim in is clean or dirty?

One issue that concerns us now that it's summer is how clean will be the beach where we go to swim. Especially for those who have children, this stress is greater.
Don't worry! According to the Panhellenic Center for Ecological Research there are some facts that help you check the quality of the waters where you want to swim.
Signs that the sea is not clean
When the sea turns green, then it is full of rotten algae and plankton.
When its surface is iridescent, then it is full of oil, tars, oils, sewage waste.
When the shores are full of garbage there is a possibility that the sea itself is contaminated.
When he collects a lot of jellyfish.That is, the transparent jellyfish (aurelia), which appear more often when there is organic pollution (e.g. urban waste), as it provides them with the ingredients they need to survive.
When the water has bubbles. In the event that there are bubbles or the water foams, there is a possibility that the sea is not clean. This can happen if there is a settlement near the coast that does not have a sewage network but cesspools. But there is also the possibility that the sea has bubbles, because fresh water is gushing out from somewhere. Because fresh and sea water do not mix easily, if you wear a sea mask, you will find that the water is cloudy in some places.
When it smells bad. The smell is often an indication that the sea is not clean. Sometimes, however, many non-infectious factors are responsible for the unpleasant smell, such as e.g. the smell of rotting seaweed. In the event that it smells bad and some of the other factors we mentioned also exist (bubbles or brown color, etc.), then it is better to prefer another beach to swim.
When garbage floats. Aluminum cans or plastic bags burden the marine environment, but this does not mean that the sea is also contaminated by organic factors (microbes, bacteria, etc.) or chemical pollution. In addition, garbage causes alteration of the aesthetics of the sea and differentiation of its physical characteristics. However, one cannot say that if we find a few soda cans floating on a shore, it is not clean.

Signs that the sea is clear
If it has stings or urchins: In order to survive and grow these marine species need clean water. In general, the biodiversity of the Greek seas (the many and different species) is an indication that the waters are suitable and favor the development of marine life. Most fish leave when the water is not clean. Stingrays need clean water to live (mainly pelagia, which is purple, yellow or red in color and small in size). The same applies to sea urchins.
If it has algae. Some algae are an indication that the sea is clean, but you should pay attention to the color and type of algae. The "Poseidon" meadows that exist in the Mediterranean are an indicator of purity. These algae have a dark green color and a broad leaf. But if you spot a type of seaweed called ulva, which looks like a lettuce leaf, this indicates that the sea may not be that clean.
If there are sea currents. This means that the water is constantly renewed, and thus freed from infectious or polluting agents. Also, when the wind blows from the beach to the ocean, the trash is blown inward.

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