The Earth Story

Ah, the fresh exhilarating smell of ocean..... dimethyl sulfide. Imagine you are standing on a beach, the soft sand between your toes; looking out across the miles of perfect blue ocean, with a gentle sea breeze blowing through your hair. You take a deep breath in, absorbing all that blissful pure sea air. It is uplifting, it is invigorating, it is exhilarating, it is dimethyl sulphide (DMS).

Asian Carp: to eat, or not to eat?

As a means of water quality improvement, silver carp and bighead were introduced into American fisheries in 1973 in an effort to control zooplankton and phytoplankton populations. However, they were much more successful than expected and spread rapidly through the waterways. Because of their plankton-based diet, the carp compete for resources with the native plankton-eaters, such as mollusks and native juvenile fish. Silver carp are notorious for jumping out of the water due to their sensitivity to sound. Aside from potential danger to boaters and fisherman, they make for an easy fishing trip. To quote Landers, "This was the easiest fish I ever caught in my life, but it wasn’t exceptional. A dozen more voluntarily followed it into the boat without any encouragement..." (http://slate.me/1GwyS2z).

The silver carp has an undeserved reputation for being unpalatable. Its cousin, the common carp, is known throughout North America as fairly inedible due to its bony flesh and bottom-feeding diet. However, unlike the common carp, the silver carp feeds on plankton. This results in flesh that is low in fat and low in mercury. The firm, white flesh is described by many to be comparable in taste to Atlantic cod or tilapia. To encourage consumption of the silver carp, industries have renamed it "silverfin" or "Kentucky tuna." The average fish is 13-30lbs, but can exceed 50lbs. It is easy to catch, abundant, large-bodied, and good to eat, making it an excellent game fish.

The harvest of silver carp would allow for an increase in the economy, a decrease in silver carp population, and hopefully an increase in native fish populations. Next time you go fishing, or even just grocery shopping, give the silverfin a try, you'll be surprised.

Jumping silver carp: https://www.youtube.com/watch?v=qfG4vsJ5_xI Asian carp identification: http://bit.ly/182DOxd Distribution map: http://bit.ly/18tPbOM More information & FAQ: http://www.freep.com/article/20110720/NEWS06/110720021

~Rosie Image credit: AP Photo/Illinois River Biological Station References: http://eattheinvaders.org/asian-carp/ http://slate.me/1GwyS2z http://bit.ly/1Bi4Yf1 http://bit.ly/1Nz5fzl http://bit.ly/1FyhoPJ http://bit.ly/1Mm3RyK

A Sea of Stars: One of the most beautiful examples of evolutionary adaptation can be seen in these pictures taken in the Maldives. The biological light, or bioluminescence, in the waves is the product of marine microbes called phytoplankton. Phytoplankton have adapted to the darkness of the ocean by utilising chemicals known as luciferins to ‘glow’. The light is produced by a series of oxidation reactions set off by a catalyst called luciferase. Bioluminescence is very useful in the open ocean, be it for finding food and mates, thwarting predators, or simply lighting the way. This phenomenon can be seen all over the World and is a true testament to the wonder and beauty of our lovely home. -Jean A nice paper on phytoplankton can be found in the link below. http://fau.digital.flvc.org/islandora/object/fau%3A6664 Alternatively; here is a nice comprehensive article entitled "Animals that Glow : The Science of Bioluminescence": http://docmo.hubpages.com/hub/Animals-that-Glow-The-Science-of-Bioluminescence Images courtesy of Will Ho

Unlocking Shallow Sea Secrets

Surrounding nearly every continent and island across the globe is a thin but vivid band of life that thrives in shallow seas. Because they are composed of submerged continental shelves, these seas reach only 200 meters deep and make up only 5% of total ocean ecosystems. Despite their small size, they contain 15-20% of ocean life. In fact, 90% of the world's fisheries depend on these waters, as do some of the biggest animals on earth - whales.

Plankton, which is what baleen whales eat, are composed of two types of organisms: phytoplankton are marine plants, and zooplankton are marine animals. These tiny little organisms, each only millimeters long, give the oceans a muddy look and are known to scientists as “marine snow”. About 1/2 of the oxygen we breathe comes from the phytoplankton living in these shallow seas. Carbon dioxide dissolves into the oceans when atmospheric levels are greater than oceanic levels. Phytoplankton “eat” the dissolved carbon dioxide when they photosynthesize. As a byproduct, they release oxygen into the ocean (and into the atmosphere), and keep the carbon for food. In all, the seas remove about 1/3 of the total carbon we dump into the atmosphere every year.

Scientists working for the project Shelf Sea Biogeochemistry are trying to understand what role phytoplankton will have in a warming climate. By studying water and organisms at various depths, temperatures, currents, and varying salinities, they are hoping to understand how carbon might become sequestered through phytoplankton's natural life cycle; as waste from the organisms fall to the ocean floor, it takes some of the carbon with it, removing from the carbon cycle. This information will provide even more effective models of global warming.

In addition, many scientists are trying to understanding how these shallow seas ecosystems will be affected by ocean acidification, a result of global warming. As more CO2 is dumped into the atmosphere, more is dissolved into the oceans. This lowers the pH of the water; some climate models suggest the pH could fall to 7.8. To put this in context, oceans normally have a pH of approximately 8.2. But like the Richter scale, the pH scale is logarithmic. So far, ocean pH levels have fallen by .1 which is a 30% increase in acidification. If the pH hits 7.8, the oceans will be 150% more acidic than they were in 1800.

What does this mean for life in the shallow seas? In isolated spots where pH levels have dropped naturally due to volcanic activity, not much life is present, but scientists are still trying to figure out why. One reason might be that many marine organisms do not have the mechanisms necessary to self regulate their pH like humans do. The acidification interferes with the way they build shells or control biochemical processes.

Projects like the Shelf Sea Biogeochemistry project might give us a better understanding of phytoplankton in a warming world, including how they might effect potential ocean acidification levels, giving us a glimpse of what our future oceans might look like.

For more on how shells are eaten by acidification visit: https://www.facebook.com/TheEarthStory/posts/693223044072076

Further reading: http://www.nerc.ac.uk/research/funded/programmes/shelfsea/

and

http://ngm.nationalgeographic.com/2011/04/ocean-acidification/kolbert-text

Picture: Landsat 8 captured this view of a phytoplankton bloom near Alaska’s Pribilof Islands on September 22, 2014, courtesy of NASA's Earth Observatory, https://www.flickr.com/photos/nasaearthobservatory/

-Colter

Iron fertilisation to mitigate climate change?

These light blue smoke-like plumes are phytoplankton in bloom off the coast of Argentina in the South Atlantic Ocean. Phytoplankton plays an important role in iron fertilisation, one of several proposed methods of mitigating climate change known as geoengineering. Geoengineering is the deliberate and extensive intervention in the Earth’s geochemical or biogeochemical cycles with the intent to mitigate climate change. In recent years, understanding of climate change has become widespread in mainstream media. As a result, many mitigation and adaption methods have also been widely publicised along with some interesting, and sometimes frightening, geoengineering proposals. One idea of reducing carbon dioxide in the atmosphere was suggested by oceanographer John Martin. Martin’s iron hypothesis suggested that fertilising the sea with iron could slow global warming by increasing phytoplankton photosynthesis.

It sounds quite simple; at the ocean’s surface atmospheric CO2 is dissolved in sea water. Phytoplankton then absorbs carbon dioxide by photosynthesis turning it into insoluble organic carbon. When phytoplankton dies, dead organic matter sinks to the ocean floor where it gets buried into the geological record and is trapped for aeons. Iron is a trace element all plants need for photosynthesis, hence, by adding iron, phytoplankton blooms can be increased leading in turn to more CO2 being removed.

But is it really that simple? Are iron infusions and boosted phytoplankton activity like this harmful to other organisms? How much added iron is enough and how much is too much? Several studies have examined the effect of spreading finely powdered iron into the surface waters, but very little is known about the side effects. Critics point out that adding iron to the sea could as well favour species that negatively impact other organisms. Other concerns are runaway chemical changes in the surrounding ocean and unforeseeable impacts on marine ecosystems.

Besides, the efficiency of this method is uncertain. It only works if the carbon is actually buried and is not released back into the atmosphere as it could be the case when Phytoplankton is eaten by animals, because their metabolism sends CO2 back into the atmosphere by respiration. So CO2 trapping cannot be guaranteed, as the carbon cycle is not the same for every area and therefore an unpredictable component. Moreover, in many areas growth of phytoplankton is not limited by a lack of iron, thus only certain areas would bloom if iron was added.

Iron fertilisation is still discussed today; the most recent investigations carried out in July 2012 in the North Pacific by the Haida Salmon Restoration Corporation (HSRC) resulted in increased algae growth over 10,000 square miles. The project was controversially discussed as responsible entrepreneur Russ George was accused of having carried out these experiments without permission.

Another important aspect comes alongside geoengineering activities like this in general; ethics. Do we have the right to interfere with sensitive natural processes like this? If yes, where is the limit and who decides how it is done? If no, how do we intend to reduce emissions in a way it really makes a difference?

-Cé

Image Credit: http://earthobservatory.nasa.gov/Newsroom/NewImages/images.php3?img_id=17189

http://bit.ly/1s4rtSK

http://www.nature.com/news/ocean-fertilization-project-off-canada-sparks-furore-1.11631

http://www.nature.com/nature/journal/v371/n6493/abs/371123a0.html

Martin, J. H. and Fitzwater, S. E. (1988) Iron-deficiency limits phytoplankton growth in the Northeast Pacific Subarctic. Nature 331, 341-343.

The Bering Sea

Sandwiched between the long chain of the Aleutian Islands forming the Alaskan Peninsula, Russia and mainland Alaska, this frigid and wild patch of sea is an area with a diverse and productive biosphere, partly fed by the nutrients ground out of the rocks during the ice age and ferried into the sea by rivers and calving glaciers. The sea contains a deep water zone, with relics of a long disappeared oceanic plate called the Kula and an area of continental shelf in its northern reaches, and areas of shallowly submerged continental shelf. Its boreal reaches culminate in the Bering Strait that separates the two continents, linking the Pacific and Arctic Oceans. During the ice age it was a land bridge, much like the English channel, across which people and animals moved.

It was named after the Danish explorer and navigator who first explored it on behalf of the Russian Tsars, back in the days when the land from Alaska down to the Russian river in Northern California were part of their empire (a sale I bet they later regretted, as the French must have done the Louisiana sale).

The sea is filled by powerful currents, which mix nutrients and churn them around, as revealed by this bloom of phytoplankton snapped by NASA's Aqua satellite, though they've been present for months. These little green photosynthesisers are the base of the food chain, and congregate where shallow and deep waters meet. Sadly the sea's productivity is decreasing for a host of reasons, including overexploitation and global warming, and the rich fisheries it now supports may follow the cod of the Grand Banks into gradual disappearance.

Loz

Image credit: NASA

Delightful diatom

This is the species Arachnoidiscus atlanticus. These 3 photos are all of the exact same specimen; the focus on the microscope has been moved up and down, giving views of different “slices” of the silica skeleton.

Diatoms leave important records in sedimentary rocks. Their shells don’t dissolve easily, so when a diatom dies, its shell will sink to the bottom of the ocean or lake, supplying silica to that sediment.

If an area’s sediment is dominated by diatom shells, it can produce single layers dominated by silica. These shells can then be recrystallized into marine chert layers, commonly found in sediments worldwide. Alternatively, in areas where diatoms are mixed with other sediments, the diatom shells can supply silica that cements the sediments together.

If their shells stay in tact in sediments, they can also be used as indicators of environment and of time. Specific diatom morphologies exist only in certain environments or in rocks of certain ages, so they can be used by geoscientists as tools to enable larger geologic interpretations.

-JBB

Image credit: California Academy of Sciences https://www.flickr.com/photos/casgeology/6768114343

More: http://westerndiatoms.colorado.edu/about/what_are_diatoms

Cool Coccolithophores! Coccolithophores are one celled organisms, a type of phytoplankton that live in the ocean. They have been around for millions of years! These organisms cover themselves with tiny circular plates made of calcite and reproduce asexually. They are the leading calcite producers in our ocean, dumping more than 1.5 million tons per year. -KK1 https://flic.kr/p/bww7Mg https://earthobservatory.nasa.gov/features/Coccolithophores/coccolith_1.php https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/coccolithophore

Delightful Diatoms Diatoms are a type of photosynthesising (although some are heterotrophic) algae which are found in almost every aquatic environment; from fresh and marine waters to soils. Diatoms are microscopic, most falling in the range of 20 to 200 microns (0.02-0.2 mm) in diameter or length. But don’t underestimate them. Diatoms play a fundamental role in aquatic ecosystems. In the ocean itself, the oxygen given off by diatoms (and plants) supports the majority of other marine life. Without this oxygen, the water would be uninhabitable and stagnant. Diatoms are also the basis of many food chains within aquatic environments and indirectly provide a food source for us terrestrial beings. These tiny algae also provide approximately 25% of the oxygen we breathe- the greatest gift of all! They are also quite a diverse group, as you can see in this image. Their siliceous wall can be highly patterned with a variety of pores, ribs, minute spines, marginal ridges and elevations; all of which can be used to delineate genera and species. There are more than 200 genera of living diatoms, and it is estimated that there are approximately 100,000 extant species ranging in shape from circular, triangular, square, or elliptical. -Jean Photo courtesy of wikimedia commons.

Hypnotic

The Operational Land Imager on the Landsat 8 satellite captured this image in July as it passed over the Baltic Sea. Plankton blooms in the ocean are often visible from space as the photosynthetic organisms produce their own pigments. Here a plankton bloom in the Baltic has been caught in a vortex, producing a magnificent spiral pattern. A few ships are actually visible in this shot just to the west of the vortex (they might look like only a few pixels), they can give some scale. While this shot is amazing, these plankton blooms actually are doing harm to the Baltic Sea itself. When the bacteria that produce these colors die, their bodies sink to the bottom of the Baltic and use up oxygen, contributing to the growth of oceanic dead zones (more here: http://bit.ly/2ndkIyq).

-JBB

Image credit: https://earthobservatory.nasa.gov/images/92462/summer-blooms-in-the-baltic-and-barents_ _

Covering the oceans in darkness….

Phytoplankton blooms produce some fascinating textures in Earth’s oceans, and consequently we’ve shared images of them taken from orbit many times (http://tinyurl.com/qhzwbr9, http://tinyurl.com/pwasxol). This bloom, however is a bit different from the others – in this photo from NASA’s Aqua satellite, it looks, well, black. This bloom is produced by an organism known as Myrionecta rubra, described as a ciliate protist. It’s not true phytoplankton since it doesn’t use the sun for energy and consequently it is showing up as a different color. Supposedly if viewed close-up, these waters appear red, but they are quite dark in this satellite photo. If you look close to the shoreline west of the dark bloom, you can in fact see a smaller, blue-green bloom with the more normal color expected from phytoplankton.

Interestingly, you can almost certainly track the source of this bloom coming out of Guanabara Bay and the city of Rio de Janeiro. The normal ocean currents in this area should flow to the south along the coastline, controlled by the gyre pattern in the south Atlantic, exactly as seen here. Some sort of nutrient is enabling the growth of this organism and that nutrient is being carried south from the inhabited areas near Rio along the coastline.

-JBB

Image credit: NASA http://earthobservatory.nasa.gov/NaturalHazards/view.php?id=82968

Algal bloom in the Gulf of Aden Caught in mid February by the MODIS instrument aboard NASA's AQUA satellite is a winter bloom of phytoplankton that delineates the shifting currents in the narrow stretch of sea between Arabia and Africa (though the image has been processed to extract the maximal subtlety of data possible by highlighting colour differences). It is likely that several types of phytoplankton are present, though current spectroscopy does not permit us to tell them part, even though this information would be useful; to fisheries. Until the PACE mission now in development gets to launch we have to rely on fieldwork to calibrate them, whether reports from the shore of research vessels out at sea. Loz Image credit: NASA https://go.nasa.gov/2GtW8kJ

Glowing sand in the Maldives

The Maldives are a nation composed of a pair of island chains in the Indian Ocean, southwest of the Indian subcontinent. On the beaches of these islands at night…a beautiful glow can be found, shown in these photos taken by a visitor to the islands. This glow is produced by a type of plankton, most likely a dinoflagellate. These single-celled organisms are bioluminescent, producing a pale blue light via a chemical reaction when they are disturbed.

Almost any subtle disturbance can make the critters begin to glow, whether it is natural wave action or something as simple as a footprint.

Although the glow can be lovely, the most common bioluminescent species also produce chemicals that can be toxic to humans, so swimming in waters producing these blue lights in many cases may not be safe (check with the local authorities to be sure if you ever wonder).

-JBB

Image credit: Mr. Ho - reproduced here with permission http://www.flickr.com/photos/78546112@N00/with/11268957205/

Read more: http://science.howstuffworks.com/zoology/all-about-animals/bioluminescence.htm http://www.sciencedaily.com/articles/b/bioluminescence.htm