Algae in Lake Kinneret in the north of Israel .
Algae in Lake Kinneret. It can have many positive uses. Photo by Gil Eliyahu
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Kinneret
Satellite image of algae concentration in the Kinneret, with red indicating high density.

Scientists have been studying the possibility of monitoring the algae in the Kinneret from space, in a bid to map the water quality in the lake more effectively. The findings of the study, financed by the Water Authority, were published recently in the periodical "Eretz HaKinneret."

The scientists used SISCAL - Satellite Information System for Coastal Areas and Lakes - which analyzed photographs from two satellites that pass over the Kinneret daily and one that passes over it every three days. Until recently the algae movement in the Kinneret was monitored by five measuring stations in the lake.

The scientists believe comparing the data measured on land with those from space will enable more effective monitoring the algae concentrations and the pollution they cause. The satellite photos will also enable building a multi-year data bank of the Kinneret's water quality.

During 2010, 304 satellite photographs were fed into SISCAL, then compared and calibrated with data from the five measuring stations operated by the Kinneret Limnological Laboratory, at the Israel Oceanographic and Limnological Research.

The study was conducted by Dr. Gideon Tibor and Dr. Yosef Yacobi of the limnological institute and Lana Ashkar of the Geological Institute.

"The satellites are a complementary device. Until today we knew what was going on at a specific point at a week's frequency. Now we know what is happening over the whole lake in real time," says Tibor.

However, pictures from the satellite provide data only a few meters deep, while the local measurements sample the entire water shaft, he says.

"The satellite photos show only the appearance of algae - now we must study a higher resolution of them to identify the type of algae as well, he says.

The study is especially important in view of the changes in the Kinneret over the past 20 years. For example, the peridinium algae, which used to flower in the lake annually, started blooming intermittently since 1996, while a different kind of alga appeared. Another case in point is the sudden appearance of an alga in 2008, which first seemed like sewage pollution, with a greenish stain with foam waves above it. When studied in the Kinneret Limnological Laboratory, headed by Dr. Tamar Zahari, this transpired to be a flowering alga that created foam, coloring the water olive-green. It was a new species of alga in the Kinneret that has not been defined yet.

The scientists believe the major causes of instability in the Kinneret are man-made, such as fishing and pollution, in addition to the fluctuating water levels.

Read this article in Hebrew