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Connected 2017 Level 3 - Mahi Tahi, Testing the Waters

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by Bronwen Wall

How clean is the water in your river? Scientists are testing the health of the Maitai River. Find out what data they collect and what can be done to make our rivers cleaner and healthier for everyone.

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by Bronwen Wall How clean is the water in your river? Scientists are testing the health of the Maitai River. Find out what data they collect and what can be done to make our rivers cleaner and healthier for everyone. Back to series Return to top ^

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Two dogs have died after eating toxic algae from a Wairarapa river.

The deaths occurred after the dogs had been at the Waipoua River and reinforced the importance of monitoring dogs and children at riversides, Greater Wellington Senior Environmental Scientist Dr Mark Heath said.

The algae was irresistible to dogs and owners need to be extra vigilant.

"We are very sorry to hear of this awful tragedy and we feel for the owners. Once dogs sense the musty odour of toxic algae they go straight for it."

READ MORE:
* Where we used to swim: Toxic algae takes its toll on popular Wairarapa swimming spots
* Dog owners told to stay away from Wairarapa river covered in toxic algae
* High levels of toxic algae found in Waikanae river on Kāpiti Coast

Toxic algae grows on submerged river stones and has a shiny brown/dark green-to-violet coating. It can also become unstable and detach, floating to the surface forming small brown/black mats at the water's edge.

Hot dry summers present perfect conditions for the algae to grow. It is also potentially toxic for people.

Heath said the regional council had been warning of the presence of the algae in the Waipoua River for the past month, using riverside signage, media, social media and websites to alert the public.

It was impossible to have signage at all points along rivers so dog owners need to learn how to recognise the algae and check the status of the river before heading out with their dogs.

A regional council spokesman said the dogs died in separate incidents and the council was alerted by a veterinarian.

Specific site warnings are current for:

·Otaki River, warning extends from State Highway 1 bridge to river mouth

·Waikanae River, warning extends from Main Rd (old SH1) to river mouth

·Hutt River, warnings for Melling and Silverstream sites

·Waingawa River, warning for south road site

·Ruamahanga River, warning for Morrisons bush site

·Waipoua River, warning extends from Paierau Road to confluence with the Ruamahanga

River conditions will be reassessed on Monday.

People should see a doctor or contact Healthline 0800 611116 if they have been in contact with toxic algae and develop the following symptoms: nausea, vomiting, numbness, tingling, muscle twitches, shaking, weakness.

Seek urgent medical attention for anyone with breathing difficulties, convulsions or loss of consciousness.

People can stay safe by finding out about toxic algae at http://www.gw.govt.nz/safeswim/. Before swimming, find out where it is safe to swim at https://www.lawa.org.nz/explore-data/swimming/ which shows water quality at rivers and harbours throughout the country.

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Two dogs die after eating toxic algae at Wairarapa river

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Two dogs have died after eating toxic algae from a Wairarapa river. The deaths occurred after the dogs had been at the Waipoua River and reinforced the importance of monitoring dogs and children at riversides, Greater Wellington Senior Environmental Scientist Dr Mark Heath said.

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Well, we can't stop the legacy nutrients from entering the lake, but we can prevent more being produced.
You can help by:

washing you car on the grass - that means that nutrients from detergents feed the grass rather than going straight down the drain to our streams and the lake

what goes down the grate ends up in the lake, so make sure it's only water - anything else going down our stormwater drains will end up in our rivers lakes and oceans and can cause eutrophication or other problems

planting trees - just like algae, trees need nitrogen and phosphorus, so they can suck some of it up before it reaches our waterways

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Will we get the worst-case scenario? All the fish dying?

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Will we get the worst-case scenario? All the fish dying?

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Probably not, here are some reasons:

the lake is large and deep, so there's lots of space where our animals can survive until the water in one spot goes back to normal

the lake doesn't usually stay calm for too long - eventually winds mix the algae up and reduce the impact of the bloom

we constantly have highly oxygenated water entering the lake from our rivers

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What Is Eutrophication | Agriculture | Biology | FuseSchool

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VideoLink lets you share videos on YouTube easily, without distracting third-party content or advertisements.

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Eutrophication and dead zones | Ecology | Khan Academy

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VideoLink lets you share videos on YouTube easily, without distracting third-party content or advertisements.

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VideoLink lets you share videos on YouTube easily, without distracting third-party content or advertisements.

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Algae need sunlight to photosynthesize, so it makes sense that the longer summer days encourage algal growth. They also grow better in warmer, settled waters. So droughts, calm weather, and long-term climate change can create perfect conditions for algae to thrive.

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What kinds of things can affect these limiting factors?

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What kinds of things can affect these limiting factors?

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Distribution and biology of invasive algae in Aotearoa

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Distribution and biology of invasive algae in Aotearoa

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Rock snot (Didymo), water net and Lake snow.

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Blue-green algae are usually found in very low concentrations in Lake Taupō - low enough that they do not cause health issues. When a bloom occurs, the high concentration of these microscopic organisms can cause severe health problems in humans, pets, and livestock. Read more below.

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Not all algae is bad for us, but some can be toxic if swallowed, or cause reactions if you come in contact with them.

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Warm, settled conditions with little wind favour algal growth. The warmth stimulates growth, and the lack of wind allows the algae to build up (rather than being mixed under again).
Combine these conditions with the ongoing effects of legacy nitrogen, and you have the perfect opportunity for an algal bloom.

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Phosphorus is less available, and may now be the key limitor of algal growth in the lake.

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Past land-use in our region was more intensive (e.g. adding more fertilizers). These extra nutrients have leached into the wainuku/groundwater. Groundwater moves very slowly, so these nitrogen-rich waters are still being supplied to the lake over time, we call this 'legacy nitrogen'. It is expected that peak nitrogen will occur around 2080.

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DR ROSS MONAGHAN

Nutrient leaching is an environmental issue for two reasons. The first is too much nitrate getting into our groundwater aquifers that are used for drinking water supplies. High concentrations of nitrate in drinking water that's used for making infant formula poses a risk to young infants because they can't process that nitrate that we as adults can. So we want to make sure that the drinking water we provide has a concentration that the World Health Organisation recommends is less than about 10 milligrams of N per litre.

The second aspect that is coming to attention more frequently in New Zealand and abroad is the problem of eutrophication. Eutrophication is a term that describes the nuisance growth of weed and algae in surface waters, in streams and estuaries. That process is really driven by two nutrients - nitrogen and phosphorous. So nitrate that leaves this farm ends up in a lake or an estuary. If it arrives with phosphorous, together, that's quite a fertile combination that will promote that nuisance weed and algal growth. And the growth can have lots of undesirable effects in terms of how we might be able to use that water for recreational purposes, and habitat value, choking out all the other wildlife that can occur.

Winter is a high-risk period for nitrogen leaching because of at least two reasons. The main one is that it's the time of year when we have a lot of surplus rainfall arriving and thus a lot of drainage and transport of any nitrogen that's sitting in the soil, potentially available for leaching, and secondly, it's a time of year when plant uptake is quite low, so particularly if you've got a relatively bare paddock, for example, a forage crop paddock that's been recently grazed, there's a lot of nitrogen that's being returned to that paddock in the form of urine but very little plant uptake until temperatures warm up in the following spring. So those two factors cause winter to be a high-risk leaching loss period of the year.

Acknowledgements:
Dr Ross Monaghan, AgResearch, Invermay
Juliet Milne, Otago Regional Council
Tamara Douglas

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DR ROSS MONAGHAN Nutrient leaching is an environmental issue for two reasons. The first is too much nitrate getting into our groundwater aquifers that are used for drinking water supplies. High concentrations of nitrate in drinking water that's used for making infant formula poses a risk to young infants because they can't process that nitrate that we as adults can.

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Algae need sunlight to photosynthesize, so can be light limited. For example algae in a small stream may be limited because trees absorb the light before it reaches the algae.

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All life requires phosphorus - for DNA, cell membranes, and energy transfer molecules (ATP).

Most phosphorus is in forms that are unavailable to plants and algae.

Algae rely on the small amount of phosphorus that is in available form.

Learn more about the phosphorus cycle.

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All life on earth requires nitrogen - it forms the basis of the building blocks for life, including DNA and other proteins.

While nitrogen is abundant in air, the gas is difficult to use, meaning that algae, and other organisms, rely on a limited pool of 'fixed' nitrogen.

Learn more about the nitrogen cycle, te hurihanga hauota.

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What normally keeps algae in check? (Limiting factors)

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What normally keeps algae in check? (Limiting factors)

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The most common factors that limit algal growth are sunlight, nitrogen, and phosphorous.
That means that if we add lots of one of those three things the algae can start growing like crazy!

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Lake Taupō is ultra-oligotrophic - it is naturally extremely low in nutrients, and usually has low algal production. Oligotrophic lakes often have high water quality and support complex food webs.

From  olígos, meaning “few”, & trophikós, “pertaining to food or nourishment”.

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Algae generate their food through photosynthesis: taking carbon dioxide and water, and producing sugars and oxygen - all using energy from the sun. Algae also need nutrients such as nitrogen and phosphorous in order to grow.

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Good, simple overview from DOC.

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What are algae?

Algae are simple, aquatic, plant-like organisms that do not have true roots, stems and leaves. Many are single-celled so can only be seen using a microscope, while others grow in filaments or mats that are quite conspicuous. Algae have chlorophyll and can make their own food through the process of photosynthesis.

Although algal growths can often be seen in the water, a microscope is required to appreciate their beauty and complexity.

Spirogyra under a microscope

Why are algae important?

Algae produce oxygen as a waste product of photosynthesis. Cyanobacteria are amongst the most ancient forms of life and they have been contributing oxygen to the world's atmosphere for the last three billion years.

Cyanobacteria are able to fix nitrogen from the atmosphere. All organisms require large amounts of nitrogen for their metabolism and cyanobacteria play an important role in making atmospheric nitrogen available in nutrient cycles.

Algae help to 'purify' water by absorbing nutrients and heavy metals from streams and rivers.

Algae are the basis of most aquatic food webs. They are food for many small aquatic invertebrates, and in turn, these small creatures are food for larger animals such as fish. Algae also provide important habitats for invertebrates and fish. Without organisms that can capture energy from the sun by photosynthesis, none of the higher organisms would exist.

Algae can be valuable indicators of environmental quality. Many are sensitive to changes in pH, in nutrient levels or in temperature. Monitoring species abundance and composition can be useful to identify changes in water quality caused by changes in surrounding land use.

Where are algae found?

Freshwater algae are found growing underwater on rocks and mud in streams and rivers. They are usually more abundant in slower streams than in fast flowing rivers. Didymo, the exotic pest alga commonly known as 'rock snot', is one of the few species that grow well in swift rivers. However, even didymo cannot withstand turbulent flood waters.

Gomphoneis
What types of freshwater algae are there?

The main groups of algae found in streams are the green algae (Chlorophyta), red algae (Rhodophyta), blue-green algae (Cyanobacteria) and diatoms (Bacillariophyta).

Green algae: Green algae often look like strands of green hair flowing in the current. Spirogyra is a common green alga. Under a microscope its chloroplasts are clearly seen as spirals.

Red algae: Red algae, such as Audouinella, uses a different part of the light spectrum it is able to grow in places where the other algae can't, so tends to be found in shaded places such as under rocks or banks.

Blue-green algae: The chlorophyll in the alga Cyanobacteria is not in chloroplasts but diffused throughout the cell. Pigments, other than chlorophyll, contribute to their colouration so cyanobacteria are not usually bright green. Nostoc is another cyanobacteria that is often conspicuous in streams. It looks like bubbles of firm jelly attached to the rocks. The 'bubbles' are masses of small chains of cells. .

Didymo

Diatoms: Mats of brown growth, fluffy masses or slimy layers on rocks are some of the ways diatoms appear to the naked eye. Gomphoneis forms thick, glistening, light-brownish mats on river substances and is often mistaken for didymo. However, didymo has much larger cells and grows in tougher, more fibrous mats.

Can algae be bad?

Excessive nutrients in runoff from land used for intensive agriculture will alter the natural composition of algae in streams and rivers. If the natural balance is disturbed algal blooms may occur, causing undesirable discolouration, scum and odours and even toxic effects.

Didymo (Didymosphenia geminata) is an example of an introduced organism that has grown into unsightly mats over stream and river bottoms. In many places it has out-competed the native algae and destroyed invertebrate and fish habitat. Be fastidious in taking measures to stop the spread of didymo. Follow the simple rules - Check, Clean, Dry - when moving from one waterway to another.

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Algae are simple, aquatic, plant-like organisms that do not have true roots, stems and leaves. Many are single-celled so can only be seen using a microscope, while others grow in filaments or mats that are quite conspicuous. Algae have chlorophyll and can make their own food through the process of photosynthesis.

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New Zealand has had a reputation for being 'clean and green' - a country of environmental beauty. Compared to many countries in the world, this is true. However, it's becoming apparent that New Zealand has an environmental pollution problem. An OECD (Organisation for Economic Co-operation and Development) report (2007) describes deterioration in water and air quality in New Zealand - due, in part, to agriculture.

Water quality

Water quality describes the condition of water and includes its chemical, physical and biological characteristics. Standards developed for water quality relate to the suitability of water for a particular purpose, for example, the water quality needed for healthy ecosystems (lakes, estuaries and rivers), human recreation (such as swimming) and drinking. Standards are being developed in New Zealand to rate the quality of water in our waterways.

Water pollution

Concerns have been raised about the effect of intensification of farming on water quality. Farmers add fertilisers to improve pasture growth to ensure animals have enough to eat. Fertilisers contain chemical compounds that add to the nitrogenphosphorus and potassium content of the soil. Effluent from farm animals also adds nutrients to the soil. Excess fertiliser not taken up by plants can be leached from the soil or carried away in run-off. The nutrients may end up in waterways and groundwater.

Eutrophication

Nutrients are carried into lakes, rivers and estuaries. This enrichment - particularly of nitrogen and phosphorus - causes excessive growth of aquatic plants. These plants take up room, making less room for fish. As the nutrients are used up, the plants die off. As they decay, they take up oxygen from the water, leaving less oxygen for other organisms and causing them to die off. This is known as eutrophication. Excessive plant growth also limits sunlight from penetrating the water, causing the death of benthic organisms dependent on sunlight (such as seagrass in estuaries). Animals that depend on these plants for food and shelter need to leave the area or die.

Toxic water

Excessive nitrogen in its nitrate form can become harmful when it gets into groundwater. When consumed, the water has been known to be toxic to babies and pregnant animals.

Erosion and water

Erosion from land clearance and other farming practices can add fine sediment to water, spoiling the aesthetic appeal of streams and lakes and making it unfit for swimming or drinking.

Contaminated soil

Soil is considered contaminated when the levels of hazardous substances are higher than that of 'normal' levels and there is likely to be a risk to the health of people, animals and the environment. Scientists set normal (or background) levels for specific areas of land at a standard deemed to be safe. Agricultural soils can be contaminated, for example, by the overuse or wrong use of fertilisers and pesticides.

Greenhouse gases

Gases that trap heat in the atmosphere are known as greenhouse gases (the atmosphere warms up like it does in a greenhouse). The gases allow sunlight to enter the atmosphere freely. When sunlight strikes the Earth's surface, some of it is reflected back towards space as infrared radiation (heat). Greenhouse gases absorb this infrared radiation and trap the heat in the atmosphere. This stops us from being too cold and gives us a pleasant atmosphere in which to live.

Global warming

The concern among some scientists today is that more of these greenhouse gases are being produced than previously. In time, this causes an overall warming of the atmosphere known as global warming. The main contributors of greenhouse gases are water vapourcarbon dioxide, methane, nitrous oxideozone and fluorinated gases from industrial processes.

Agricultural emissions

Since 1990, New Zealand's agricultural greenhouse gas emissions have grown by about 1% each year. In 2010, just under half of the total greenhouse gases were produced by agricultural activities (47.1%). Intensified farming has led to added emissions of nitrous oxide and methane in particular. Although there is more carbon dioxide in the atmosphere than other greenhouse gases (apart from water vapour), methane is 23 times more powerful than carbon dioxide at trapping heat, and nitrous oxide is 310 times more powerful!

Nitrous oxide is formed during the nitrogen cycle. Excessive nitrogen compounds in the soil - added through fertilisers or effluent - produce more nitrous oxide. Methane is a byproduct of animal rumination (released in sheep and cow burps) and organic decay.

Balancing food production with sustainability

There is no doubt that agricultural intensification can come at a cost to the environment. However, we need to balance this cost with the importance of food production. As the Earth's population grows, so does the need for farmers and others to produce more food.

Using scientific research - such as nitrification inhibitors and denitrification beds - can help maintain water quality. Farm management practices such as fencing off streams are also effective. Other solutions may lie in regulations (such as the Resource Management Act 1991 to control nitrogen fertiliser use), market-based initiatives (such as pollution permits) and incentives to farmers to reduce their nitrous oxide emissions and nutrient losses.

Nature of science

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New Zealand has had a reputation for being 'clean and green' - a country of environmental beauty. Compared to many countries in the world, this is true. However, it's becoming apparent that New Zealand has an environmental pollution problem.

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Keep our waterways safe from invasive algae and other pests.

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Kids Greening Taupo | Learning Through Nature

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Also known as 'rock snot', didymo is an invasive freshwater algae that is spreading throughout rivers in the South Island. It is microscopic and can be spread from one drop of water! We really do not want this algae spreading further and invading other rivers and waterways in New Zealand. You can help! Check, clean, and dry your gear when moving between waterways, and treat every waterway like it is infected with didymo. You must clean your boots, boat, inflatable toys, fishing/diving equipment and anything else that has contacted the water. Watch the video below, and then find out more at BiosecurityNZ.

When you have learnt about didymo, make a poster or video and spread the word! Teach others what they can do to protect our waterways. After doing this, you can click HERE to see how you can receive a Toyota Kiwi Guardian Medal.

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Protect our Waterways from Didymo - Kids Greening Taupo | Learning Through Nature

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Also known as 'rock snot', didymo is an invasive freshwater algae that is spreading throughout rivers in the South Island. It is microscopic and can be spread from one drop of water! We really do not want this algae spreading further and invading other rivers and waterways in New Zealand.

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Algae are good, but you can have too much of a good thing!

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Algae are good, but you can have too much of a good thing!

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In simple terms, and algal bloom is an overgrowth of algae.

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Learn more about lichens and hunt out some local samples!

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Kids Greening Taupo | Learning Through Nature

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Do you know how to tell the difference between lichen and moss? HEREis a great website that explains "a moss is a simple plant, and a lichen is a fungi-algae sandwich.... Lichen lack leaves of any kind... which is an easy way to tell them apart."

After watching the video, go on a lichen hunt! How many of these kinds of lichen can you find?

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Lichen Scavenger Hunt - Kids Greening Taupo | Learning Through Nature

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You might find something on the bark of trees or on rocks that is called lichen. Is it a fungi? Yes... and no! Watch this video to find out more about fascinating lichen, and how it is actually two organisms, fungi and algae, working together.

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Some algae are fussy, and some will live in polluted water, so knowing which one is which can help us know how healthy a waterway might be.

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A bioindicator is a living organism that gives us an idea of the health of an ecosystem. Some organisms are very sensitive to pollution in their environment, so if pollutants are present, the organism may change its morphologyphysiology or behaviour, or it could even die.

One example of a bioindicator is lichens. These plants, which live on surfaces such as trees or rocks or soil, are very sensitive to toxins in the air. This is because they obtain their nutrients mostly from the air. We can tell our forests have clean air by the amount and types of lichens on the trees. Different species of lichen have different levels of susceptibility to air pollution, so we can also get an idea of the level of pollution by observing which species are present.

Nature of science

Bioindicators can be plants, animals or microorganisms:

If toxins are present, certain plants may not be able to grow in the area affected.

Monitoring population numbers of animals may indicate damage to the ecosystem in which they live.

Algae blooms are often used to indicate large increases of nitrates and phosphates in lakes and rivers.

If pollution causes the reduction of an important food source, the animals dependent on it for food may also decrease. Animals may also change their behaviour or physiology if a toxin is present. For example:

the levels of certain liver enzymes in fish increase if they are exposed to pollutants in the water

changes in the functioning of the nervous systems of worms are used to measure levels of soil pollution

the increase in the number of mutated frogs found in the USA is used as an indicator of toxins in their environment.

Microorganisms can also be used as indicators of toxins in an ecosystem. Some microorganisms will produce stress proteins if exposed to certain pollutants. By measuring the levels of stress proteins, we can get an idea of the level of pollution present in the environment.

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A bioindicator is a living organism that gives us an idea of the health of an ecosystem. Some organisms are very sensitive to pollution in their environment, so if pollutants are present, the organism may change its morphologyphysiology or behaviour, or it could even die.

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Blue-green algae (which are actually bacteria known as cyanobacteria) fix nitrogen gas from the air, and turn it into a form that other organisms  can use. This is an important part of the Nitrogen Cycle.

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Nitrogen fixation is the process by which nitrogen is taken from its stable gas form (N ₂) in air and changes into other nitrogen compounds (such as ammonia, nitrate and nitrogen dioxide) useful for other chemical processes. It is an important part of the nitrogen cycle.

Nitrogen is fixed in biological and non-biological ways:

Biological

Microorganisms that fix nitrogen (diazotrophs)

Cyanobacteria are in most environments on Earth. They play key roles in the carbon and nitrogen cycle of the biosphere. Cyanobacteria use many sources of combined nitrogen, like nitrate, nitrite, ammonium, urea, or some amino acids.

Several cyanobacterial strains are also capable of diazotrophic growth. Diazotrophs fix nitrogen from the air, an ability that may have been present in their last common ancestor in the Archaean. Cyanobacteria in coral reefs can fix twice the amount of nitrogen than on land-around 1.8 kg of nitrogen is fixed per hectare per day. The colonial marine cyanobacterium Trichodesmium may fix nitrogen on such a scale that it accounts for almost half of the nitrogen-fixation in marine systems on a global scale.

Root nodule symbioses

Legume family

Plants that contribute to nitrogen fixation include the legume family - Fabaceae - with taxa such as kudzu, clovers, soybeans, alfalfa, lupines, peanuts, and rooibos. They have symbiotic bacteria called in nodules in their root systems, producing nitrogen compounds that help the plant to grow and compete with other plants. When the plant dies, the fixed nitrogen is released, making it available to other plants and this helps to fertilize the soil. Most legumes have this association, but a few genera (e.g., Styphnolobium) do not. In traditional farming practice, fields are rotated through various types of crops, which usually includes one consisting mainly or entirely of clover or buckwheat (non-legume family Polygonaceae), which are often referred to as " green manure".

Non-leguminous

Although most plants able to form nitrogen-fixing root nodules are in the legume family Fabaceae, there are a few exceptions:

Parasponia, a tropical genus in the Cannabaceae also able to interact with rhizobia and form nitrogen-fixing nodules

Actinorhizal plants such as alder and bayberry, can also form nitrogen-fixing nodules, thanks to a symbiotic association with Frankia bacteria. These plants belong to 25 genera in eight plant families. In these families, not all can fix nitrogen. For example, of 122 genera in the Rosaceae, only 4 genera are capable of fixing nitrogen.

All these families belong to the orders Cucurbitales, Fagales, and Rosales, which together with the Fabales form a clade. In this clade, Fabales were the first lineage to branch off; thus, the ability to fix nitrogen was lost in most descendants of the original nitrogen-fixing plant.

Biological nitrogen fixation was discovered by Hermann Hellnegel (1831-1895) and Martinus Beijerinck (1851-1931).

Non-biological

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Nitrogen fixation is the process by which nitrogen is taken from its stable gas form (N 2) in air and changes into other nitrogen compounds (such as ammonia, nitrate and nitrogen dioxide) useful for other chemical processes. It is an important part of the nitrogen cycle.

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Algae produce 50-70% of the oxygen in our atmosphere. Most of this is from marine algae. Next time you breathe, thank algae!

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When was the last time you thought about your breathing? Take a breath right now and think about it. You breathe because you need oxygen, a gas which makes up 21 percent of the Earth's atmosphere. All that oxygen has to come from somewhere. You might already know that it comes from photosynthetic organisms like plants. But did you know that most of the oxygen you breathe comes from organisms in the ocean?

That's right-more than half of the oxygen you breathe comes from marine photosynthesizers, like phytoplankton and seaweed. Both use carbon dioxide, water and energy from the sun to make food for themselves, releasing oxygen in the process. In other words, they photosynthesize. And they do it in the ocean.

(NASA, Robert Simmon and Jesse Allen)

Photosynthesizers have been in the ocean for a long time. Land plants start appearing in the fossil record 470 million years ago, before dinosaurs roamed the earth. But the ocean was producing oxygen for billions of years before that. The oldest known fossil is from a marine cyanobacterium, a tiny-blue green photosynthesizer that was releasing oxygen 3.5 billion years ago. In a way, we owe the ocean for all of the oxygen that comes from land plants as well, because land plants evolved from green marine algae. If there were a race to put oxygen in the atmosphere, the ocean would have one heck of a head start.

But the ocean's long history of photosynthesis would matter very little to us if not for the photosynthesizers that live in it today. Of these, the most impressive is another cyanobacterium called Prochlorococcus. It is estimated to be more abundant than any other photosynthesizer on the planet, and to be responsible for producing 20 percent of the oxygen in the atmosphere. One in every five breaths you take, you owe to Prochlorococcus. Perhaps as amazing is the fact that scientists only discovered this super-abundant photosynthesizer in 1988-less than thirty years ago!

(Arlene Wechezak / Nikon Small World)

Another of the ocean's photosynthesizers is impressive for a different reason. Recall that sunlight is necessary for photosynthesis. That means all marine photosynthesizers have to live in what scientists call the "photic zone"-the layer at the top of the ocean that is illuminated by sunlight. The photic zone extends down to about 656 feet (200 meters) below the surface of the ocean, but it's difficult to put a depth limit on it, because photosynthesizers keep taking photosynthesis down farther than we thought possible. Eight hundred and eighty-six feet below the ocean's surface, you would barely be able to see light. But a type of red algae called Corallinales nevertheless photosynthesizes at that depth. The red color of Corallinales comes from a pigment which enables it to absorb blue and green light, which is just about the only kind of light that manages to filter down to the improbable depths at which Corallinales lives. This photosynthesizer produces oxygen despite only being able to access the tiniest fraction of sunlight.

Whether they evolved the earliest, photosynthesize the most, or dwell the deepest, marine photosynthesizers are indispensable to our survival. If they weren't around, we wouldn't be breathing. So, once in a while, take a moment to remember the ocean and its photosynthesizers. They're helping you out with every breath you take.

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With Every Breath You Take, Thank the Ocean

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When was the last time you thought about your breathing? Take a breath right now and think about it. You breathe because you need oxygen, a gas which makes up 21 percent of the Earth's atmosphere. All that oxygen has to come from somewhere. You might already know that it comes from photosynthetic organisms like plants.

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Algae are consumed by many animals, including people (seaweed on your sushi!). They are an important part of a food web because they take energy from the sun and convert it to a form that other organisms can use.

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Symbiosis means things living together on a long-term basis. Algae are known to enter many types of symbioses, including lichen, corals, sea slugs, and more.

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Lichens are fascinating, yet easily overlooked. In Dunedin Botanic Garden you can spot them growing on tree trunks, covering boulders in the Rock Garden and on the fence bordering the herb garden. Lichens are not just one organism but two or more organisms living together in a symbiotic relationship.

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Ever slipped on tiles or found your outdoor area slimy?

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Ponds, streams, rivers and lakes.
Photo: Kit Rutherford, NIWA

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Photo by Silas Baisch on Unsplash

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Focus on freshwater algae: what is an algal bloom?

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Focus on freshwater algae: what is an algal bloom?

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Volvox (freshwater green algae) colony, each sphere containing thousands of individual alga.

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These rotating spheres are called volvox, the genus of around 20 species of green algae that can be found in nutrient-rich freshwater environments. They were first recorded by Dutch microscopist Antonie van Leeuwenhoek in 1700.

The video above, filmed by Japan-based microbiology enthusiast Shigeru Gougi, shares one minute of their active world.

"Volvox form spherical or oval hollow colonies that contain some 500 to 60,000 cells embedded in a gelatinous wall," explains Britannica. Microbe Hunter explains how you might find them:

Microscopists who are interested in observing Volvox should try to investigate water samples from ponds and puddles. It is also possible to grow Volvox at home. Volvox likes to grow in nutrient-rich water. Dilute some plant fertilizer in water and add some pond water containing Volvox (or other green algae that you want to grow). Place the container on the window sill for several days but prevent direct sunlight as this may cause overheating, and drives out the CO2 for photosynthesis from the water. Alternatively, you can also use a plankton net to catch the colonies.

Find more microscopy photos by Gougi on Flickr, including these:

Watch more microscopy videos next:
* Hunting for microbes in Central Park's murkiest waters
* How do you find water bears (tardigrades) in the wild?
* A cell caught in the vortex created by a feeding rotifer
* Wim van Egmond's award-winning microscopic videos

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Volvox in motion | The Kid Should See This

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These rotating spheres are called volvox, the genus of around 20 species of green algae that can be found in nutrient-rich freshwater environments. They were first recorded by Dutch microscopist Antonie van Leeuwenhoek in 1700. The video above, filmed by Japan-based microbiology enthusiast Shigeru Gougi, shares one minute of their active world.

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Algae can be so tiny you'd need a microscope to see them, all the way up to things that look like seaweeds - check out the examples below. The scale along the bottom shows super tiny (1μm or 1 millionth of a millimetre) to huge (100m). Some live as single-celled organisms (living things), while others form colonies.
Figure credit Armin Hallmann.

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Phylogeny is the history of relationships between living things. The diagram below shows a simplified phylogenetic tree. On the diagram types of algae are circled in blue - note that they are not all closely related. Higher plants (with roots, shoots, leaves) are circled in green.
Figure credit Armin Hallmann.

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This example is a water alga like seaweed.

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Algae do not have true plant parts like roots, shoots, and stems. Instead they can have different forms like mats, 'leafy' like seaweeds, or even single cells existing alone.

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They are a little bit like plants; they contain chlorophyll and can make food for themselves through photosynthesis.

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CC BY 2.0

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This Padlet has been created in response to algal blooms in Lake Taupō, but provides larger context around algae in general.
Click on any image to 'embiggen' or go to the website.
Underlined words link to other websites for definitions or more information.

This Padlet brought to you by Taupō for Tomorrow

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'Algae' is plural for more than one.
'Alga' is singular - just one of them.

Sometimes microscopic algae in water (marine or fresh) are called 'phytoplankton', basically meaning floating plants. In streams algae can also be referred to as 'periphyton' when it grows on rocks or surfaces.

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Eutrophication is characterized by excessive plant and algal growth due to the increased availability of one or more limiting growth factors needed for photosynthesis (like sunlight and nutrients).

algae grow like crazy

block sunlight for other aquatic plants

algae begin to die off and are eaten by bacteria

bacteria multiply like crazy - lots of food!

bacteria use up lots of oxygen

no oxygen left for ika/fish, kōura, and other things in the water

worst-case scenario it ends up as a dead zone

Watch the videos to learn more -->

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Land clearance, and various land-uses can introduce more nutrients than are usually present in a water body.