The extensive algal bloom that hit the coast outside Gaza and Israel, among others, has previously been reported on by the Israeli Haaretz. The algal bloom must have stretched up to 50 miles along the coastline, and was at least two miles wide.
"I have worked in the Mediterranean for many years and have never seen anything like this," Geology and Environment Professor Or Bialik at the Israel Oceanographic and Limnological Research (IOLR) told Haaretz.
The bloom was described as a crisis and threatened Israel's drinking water supply. 80 percent of the country's drinking water in cities and households comes from six desalination plants, five of which were clogged by the massive bloom and had to close temporarily.
In mid-October, the capacity of the desalination plants was still lower than normal, due to continued algae bloom problems, according to the Times of Israel. The Israeli government must now spend the equivalent of SEK 150 million on crisis-proofing parts of the facilities for the future.
When the desalination plants closed, their water supply to Gaza, which receives a third of its water from Israel, was halted. The consequence was a shortage of drinking water for one million Palestinians in Gaza at the beginning of September, reports Haaretz.
The algal bloom is said to have started in the mouth of the Nile in the southeast corner of the Mediterranean Sea, and moved up towards Israel and Gaza with underwater currents.
High water temperatures and the war's destruction of Gaza's infrastructure contributed to the algal bloom outbreak, experts told Haaretz. Israeli environmental scientist Avner Gross of Ben Gurion University says that leakage from Gaza's destroyed sewage system may have contributed, and that the war may have caused the problems in more ways than one.
"The waste water contributed to the bloom, but it was not the only factor. I propose an additional source of nutrients for the algae: war dust. When a sandstorm blows in from the desert, we see that algal blooms occur due to nutrients that the storm carries with it to the water," he, who has researched dust and environmental impact, told Haaretz.
At the same time, he points out that the reasons for the extent of the algal bloom have not been determined and need to be investigated further.
Agnes Karlsson is associate professor in marine ecotoxicology at Stockholm University. She confirms that a collapsed sewage system can be a favorable environment for algal bloom bacteria.
- Unclean sewage discharge contains phosphorus and nitrogen, which are the most important building blocks for algal blooms, she says.
This bloom is said not to be caused by toxic bacteria, what are the consequences of non-toxic algal blooms?
- In addition to mechanical consequences, such as the clogging of desalination plants, the cloudy water can disadvantage fish that need to see. The fish in the Mediterranean are generally used to clear water. If there is a lot of algae bloom, it also leads to a lack of oxygen in the sea, which is generally negative, she says.
As Israel depends on desalination for its water supply, the algal bloom that clogged the facilities has highlighted the need to secure future drinking water despite increasingly warmer, and algal bloom-friendly, ocean temperatures.
- Climate change worsens the situation. Warmer seas are more favorable for algal blooms, which can then grow faster. In addition, the lack of oxygen problem worsens, because warm water does not hold oxygen as well as cold water, says Agnes Karlsson.
