What are HABs

Harmful algal blooms, or HABs, occur when colonies of algae — simple plants that live in the freshwater — grow out of control and produce toxic or harmful effects on people, fish, shellfish, mammals and birds. The human illnesses caused by HABs, though rare, can be debilitating or even fatal.


Q1 - Why are algal blooms occurring more frequently in lakes?

A1 - Higher frequencies of HABs are often associated with one or more of the following: 1) higher water temperatures due to climate change, 2) higher levels of nutrients in the water due to human activities, and 3) changes in nutrient cycling within lakes – incl. altered food webs due to invasive species. Researchers around the world are trying to understand the interaction among these major drivers and others.

Q2- Do algal blooms occur naturally?

A2 - Yes, cyanobacteria in the “primordial soup” in the very early stage of the earth after the Big Bang is the origin of oxygen in the atmosphere. All algae and plants today are descendants of cyanobacteria.

Q3 - Are blooms triggered when the confluence of warm water temperature (24-25C), abundant nutrients and calm waters provide an optimum environment for reproduction of all phytoplankton?

A3 - Most freshwater algae (not cyanobacteria) in northern temperate zones do not do well at 24-25 deg C (but not entirely killed or anything like that – they can persist in the lower, cooler water column especially when water transparency is high, as there is still enough light for them). So the higher temperatures gives a competitive edge to cyanobacteria.

Q4 - Are cyanobacteria naturally present within a waterbodies phytoplankton community and would normally benefit (reproduce) proportionately within the phytoplankton community during an algal bloom?

A4 - The first part (“cyanobacteria are naturally present within a waterbodies phytoplankton community”) is correct. A “bloom” of algae is not necessarily bad – e.g., we sometimes refer to an early spring boom of nutritious diatoms in the water as a bloom (which feeds zooplankton and small fish to have a healthy start for the year). Harmful algal/cyanobacterial blooms occur when one type of alga or cyanobacterium dominates a bloom to the extent that it is considered harmful. A general increase in phytoplankton density in warmer months (i.e., greener water or higher chlorophyll a concentrations) is not considered a bloom per se.

Q5 - Are cyanotoxins produced by cyanobacteria naturally present in both the water column (extracellular) and within the bacteria (intracellular)?

A5 - Cyanotoxins are NOT always present in water column, and NOT all cyanobacteria contain toxins. Many lake samples with a lot of cyanobacterial cells do not have any detectable amounts of cyanotoxins. Cyanotoxin production requires extra nitrogen in addition to that required for regular growth and reproduction. Many cyanobacteria do not even have the gene to make cyanotoxins. Even those that have toxin-producing genes do not always express the genes (i.e., the gene is not turned on). This is why NYSDEC’s policy is to make people avoid contact with cyanobacterial blooms regardless of toxin production status. The same bloom may not be producing toxins today, but if they have the gene for toxin production, and if it is turned on for some reason overnight, the same bloom may become toxic tomorrow.

Q6 - Do all algal blooms contain some cyanotoxins as well as other pathogens?

A6 - No (for the reasons above). [Cyanotoxins are technically toxins (chemicals made by cyanobacterial cells) and not pathogens (disease-causing organisms such as bacteria, fungi, viruses, and parasites) – the latter enter and reproduce within the animal body and then cause illnesses.

Q7 -What does the designation of a hazardous algal bloom (HAB) mean?

A7 - New York State (NYS) and many other states as well as the general limnological research community define it as an overabundance of a particular type of alga or cyanobacterium that causes problems, which are not limited to toxin production and can include odors and dissolved oxygen depletion from the decomposing algal/cyanobacterial biomass that can lead to the death of fish and other aquatic animals.

Q8 - Is the municipal water safe to drink?

A8 - Standard municipal drinking water treatment systems are designed to remove the microcystins at concentrations observed at Otsego Lake. Cyanobacterial HABs interfering with drinking water treatment is a problem when the water is pea-soup green with cyanobacteria. This does not apply to the current blooms at Otsego Lake. The problem here is that the blooms in Otsego Lake have been accompanied, at times, by unexpectedly high microcystins (types of cyanotoxin that the test performed at BFS can detect) concentrations despite the relatively diffuse appearance of the blooms. The highest microcystin concentrations reported by BFS as surface accumulations (scums) so far were around 50-60 micrograms per liter. The infamous HAB event in Toledo, OH, that led to the shut-off of the municipal water system, was estimated to have contained up to 4500 micrograms per liter in the raw water that actually entered the intake pipe. An extremely high concentration of cyanobacterial cells in raw water, even without cyanotoxin production, can be problematic if it overcomes the particle removal capacity of a water treatment plant. For example, some non-toxic compounds from cyanobacterial cells can impart moldy flavor in the finished water or react with chlorine and produce carcinogens.



SUNY Oneonta Biological Field Station HABs Updates

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