Harmful algal blooms; the monster in the shallows

By Alex Steeples

Many of us will have been there, sat on a sunny beach unable to go into the sea, due to the presence of a polite sign warning you of toxic algae. To many this seems illogical; what harm can some floating green specks or tangle of sea weedy mush do? Especially when there are great white sharks and box jellyfish lurking in the deep.

Harmful algal bloom (HAB) is a non-specific term used to refer to any sudden increase in the amount of algae that is deemed to be detrimental to the environment. This harm can be either through the production of harmful toxins, primarily neurotoxins such as brevetoxin and domoic acid; or through the large increase in algal biomass reducing water oxygen content and affecting the food web.

HABs occur due to a sudden increase in the nutrient content of the water, which allows for rapid growth. These increases, particularly in nitrogen and phosphorous, are often associated with specific seasonal changes, meaning many areas suffer from repeated periodic algal blooms.

Neurotoxin producing algal species such as Karenia brevis, primarily show their effects through the killing of large quantities of fish, which later wash up on shore. Higher mammals may also be killed, or suffer severe illness, if they ingest toxins via a vector such as fish or sea grass. The consumption of contaminated fish was associated with death of over 100 bottlenose dolphins off the coast of Florida in 2004. In the case of humans, whilst fatalities are rare, shellfish poisoning often occurs. This results from the ingestion of shellfish, primarily mussels and clams, which accumulate the toxin.

Although HABs have a wide ranging ecological impact, they also have important socio-economic effects. HABs can cause the closure of fisheries, and sea side resorts for the duration of the bloom, leading to loss of income and, in some cases, livelihood.

So next time you see that sign warning you of algae, pay attention. After all, not all dangers lurk in the deep.

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There’s plenty more CO2 in the sea

By Charlie Whittaker

Life in water isn’t all plain sailing, particularly if you’re photosynthetic. As well as the problem that you’re wet all the time, it actually poses pretty big problems for a cell’s CO2 uptake (something essential for photosynthesis). Most CO2 in water is dissolved, and in the form HCO3-. As well as this, stuff in general diffuses far more slowly in water than air, all in all causing a massive problem for the organisms that need it.

Ninghui Shi

Credit Ninghui Shi

In response to these challenges, aquatic organisms have evolved a wide array of means of stuffing themselves with as much CO2 as possible. These are known as Carbon Concentrating Mechanisms (CCMs for short) and are found in a huge number of different algal species, as well as the critters that gave rise to the chloroplasts, the cyanobacteria. In algae, the CCM relies upon the usage of a subcellular structure called the pyrenoid. All of the Rubisco (the enzyme that uses the CO2) aggregates in a specific part of the chloroplast, and CO2 delivered, in doing so generating awesomely high local concentrations. Cynaobacteria on the other hand use Carboxysomes, which are protein covered boxes chock full of Rubisco.

Either way, they’re pretty neat, and enable these guys to generate over 50% of the world’s primary productivity, despite the unfavourable conditions!

Stop trimming the fat! Fat algae fuel the future

By Sophie Harrington

A recent breakthrough at the Scripps Institution of Oceanography has provided a way to increase the production of valuable fat molecules in algal biofuel production. These lipid oils are necessary for fuel production. However, they are only produced by algae in nutrient starved conditions. Previously, this had limited algal growth and, as such, prevented significant lipid accumulation.

Credit Steve Jurveston

Credit Steve Jurveston

Dr. Emily Trentacost and her team were able to genetically target lipases, the molecules responsible for fat breakdown, and limit their activity. As a result, algae grown in high nutrient conditions began producing significant quantities of lipids. Algal growth no longer has to be compromised to obtain the fats needed for biofuels.

Not only does this development lower the cost of biofuel production, but techniques used in the process have now been adapted to increase the speed of biofuel production. While it’s still a long way before algal biofuels are competitive in price to gasoline, this breakthrough is only one in a line of recent discoveries that are improving their yield and cost effectiveness. It seems like the sky might be the limit for algal biofuels!

Plants and Folklore: Coco de Mer

By Nathan Smith

A lush palm forest sits untouched by mankind. Huge leaves spread out to gather the sun’s rays and through the forest … swims a shark? This is the case of the Coco de Mer and the legend that surrounded it.

The Coco De Mer is a unique plant. The sole member of its genus, it is found naturally only in the Seychelles. Its seeds are the heaviest in the plant kingdom, weighing up to 17.6 kg. If and when a Coco de Mer fruit falls into the sea, it sinks to the bottom. After a while, the husk drops off and the internal parts of the nut decay. The resultant gases that form inside the nut cause the bare nut to float to the surface.

Those who witnessed the nut rise up out of the ocean reasoned (semi-logically) that it must grow on underwater trees located at the bottom of the ocean. Furthermore, many believed (a lot less logically) that these underwater trees to be the home of a fearsome bird-like creature that could hunt elephants and tigers.

In 1768, the origin of the nuts  was finally traced to the Seychelles by the expedition of Chevalier Marion Dufresne. His second in command, Jean Duchemin, returned a year later and exported such a quantity of nuts as to flood the market and quash much of their extraordinary reputation.

How to Build the White Cliffs of Dover

By Tom Evans

The White Cliffs of Dover are one of Britain’s greatest natural wonders. Indeed, the oldest known name for our sceptered isle is Albion—based on the Indo-European root for “white”, an allusion to this majestic landscape. The cliffs, which reach up 110 metres high, are composed of a fine, soft chalk that mostly consists of layers of intricate structures known as coccoliths, thin plates of calcium carbonate.

public domain, no creditThe plates are produced by microscopic photosynthetic algae in the sea known as coccolithophores and these single-celled creatures assemble their plates to form a protective shell, known as a coccosphere. The most abundant of these algae is Emiliania huxleyi, or EHUX. This algae is famous for its ability to bloom: dense populations of the phytoplankton can cover up to 100,000 square kilometers and are easily visible by satellites in orbit as the chalk plates turn the colour of the water a milky white.

Eventually the bloom fades away as the algae gradually die. And remarkably, their cause of death is quite often a virus. We usually think of viruses living in the air or inside our bodies, but in fact the ocean is teeming with viruses – up to as many as 100 billion viruses can be found in just one litre of seawater! EHUX virus 86 infects the algal bloom, and just as quickly as they bloomed, the algae die off. When the algae die, their coccosphere sinks to the seabed. Their boom and bust lifestyle means it gradually accumulates. And if you wait a few million years you end up with the vast and glittering White Cliffs of Dover.

Acid in the face of marine life

By James Forsythe

So the planet is warming up like the 19th century chemist Svante Arrhenius theorised it would, due to an increase in carbon dioxide (CO2) and the resulting greenhouse effect. But the oceans have absorbed approximately half of all human-caused CO2 emissions from the time of Arrhenius onwards, significantly slowing down climate change. This may sound wonderful but what are the effects of that on the ocean environment?

acid

Credit: Mikhail Rogov

Dissolving CO2 in the ocean leads to the formation of carbonic acid. This is predicted to lower the pH of the ocean by about 0.4 units by the end of the century, to levels unexperienced by sea creatures for over 20 million years, and the rate of acidification is already 100 times faster than the last time the oceans acidified 20,000 years ago.

The CO2 will also react with water and carbonate ions to form bicarbonate ions, decreasing carbonate ion availability. This combined with acidification will be bad for organisms with calcareous shells and skeletons including corals, molluscs and plankton, as they will not be able to form such shells or skeletons as easily. Some of these species are economically important, and the knock on effects of any reduction in the numbers of the affected species will doubtlessly change the face of marine life.