What is a “Bloom” on Our Finger Lakes?

MelRussoBy Carmelo “Mel” Russo

Recently, much news has surfaced (no pun intended) about blooms on Seneca Lake. There are usually blooms on both Seneca and Cayuga Lake each summer. A “bloom” is a visible manifestation of algae. Usually the algae are microscopic and commonly present in water but become obvious to the naked eye when they multiply exponentially. This mega-population explosion of phytoplankton is due to the presence of excessive dissolved nutrients in the water such as phosphates and nitrates, essential ingredients for plant growth. This aquatic event occurs in the upper layers of water where the temperature warms greatly due to atmospheric conditions and the stillness of the water. The increased heat in these waters causes the life activities there to accelerate. A rule of limnology is that for every 10 degrees Celsius increase in temperature, the metabolic activity of life in the water doubles.

Blooms are normal phenomena of lakes.

This metabolic multiplication factor combined with increased solubility of nutrients with increase in temperature, is the initiating cause of blooms. Often these events are usually accompanied by zooplankton blooms and biotic growth of all types. The common form of algae associated with these events is a type called anabaena. Another is nostoc. Both are single celled blue-green algae (now called cyanobacteria) but can form necklace like chains, which are noticeably visible with the naked eye. Although commonly occurring in aquatic environments, when present in the great numbers characteristic of a bloom, these algae add toxicity to water. Swimming in, washing with, or drinking the water under bloom conditions may result in nausea, vomiting, dermatitis, blindness or other serious complications.

Blooms are normal phenomena of lakes. If they are frequent and of very long duration, it is a negative health indicator of a lake. Some blooms are usual and normal for a body of water. However, very many blooms, for very long, is a sign of increasing eutrophication (aging) of a lake.

So, no, the lake is not turning over. No, the lake is not cleaning itself, per say, but in a way it is. And no, it is not lots of pollen on the surface. It is a normal event, one of which we should be aware and monitor. With the mixing and cooling of the surface waters, the bloom will diminish leaving normal populations of microscopic algae in the water until we have a another heat wave with long days, at which time the bloom is bound to return.