Recently we at Deep-Sea News have tried to combat misinformation about the presence of high levels of Fukushima radiation and its impact on marine organisms on the west coast of the United States.  After doing thorough research, reading the scientific literature, and consulting with experts and colleagues, we have found no evidence of either.  In the comments of those posts and on Twitter, readers have asked us about the “evidence” of dead marine life covering 98% of ocean floor in the Pacific as directly attributed to Fukushima radiation.  After some searching I found the main “news” article that is referenced.

The Pacific Ocean appears to be dying, according to a new study recently published in the journal Proceedings of the National Academy of Sciences. Scientists from the Monterey Bay Aquarium Research Institute (MBARI) in California recently discovered that the number of dead sea creatures blanketing the floor of the Pacific is higher than it has ever been in the 24 years that monitoring has taken place, a phenomenon that the data suggests is a direct consequence of nuclear fallout from Fukushima.

Before I discuss this “evidence” further, I want to provide a little background.  I am a deep-sea biologist and over the last several years my research has focused on the biodiversity of deep-sea communities off the California coast.  Like many others, I am also working toward understanding how deep-sea life will respond to increased anthropogenic impacts particularly climate change.  This resulted in a high profile publication in the Proceedings of the National Academy of Science.  I mention this background because 1. It explains why I view myself as an expert to comment on this and 2. it explains why I was confounded for a moment when I thought I had missed a paper in a journal I have published in, on a geographic region I study, and on a topic close to my own research.  And to boot from researchers at institution (MBARI) I was formerly employed with.

The reason I am unfamiliar with a study providing evidence of  “Dead sea creatures cover 98 percent of ocean floor off California coast; up from 1 percent before Fukushima” is because no such study exists.  Here are the details of the actual study.

Ken Smith’s group at MBARI has monitored a deep-sea abyssal site called Station M off the California coast continuously since 1989 (24 years).  Their work has lead to many major findings.  A majority of deep-sea animals are completely reliant on the sinking of food from the surface, i.e. marine snow. One of the most important findings from Smith and colleagues’ work is that rhythm of deep-sea life is intrinsically linked to the production of phytoplankton at the oceans surface. Thus El Nino/La Nina cycles and other such meteorological/oceanic events leave a deep-sea signature.  Ken’s research has been paradigm shifting for deep-sea research.  We have moved from a belief of a stable and climate-buffered view of the deep sea to one of a dynamic system intimately related to seasonal, annual, and decadal changes in surface production and ocean currents.

This group’s newest paper

Smith, K. L., H. A. Ruhl, M. Kahru, C. L. Huffard, and A. D. Sherman. (2013). Deep ocean communities impacted by changing climate over 24 y in the abyssal northeast Pacific Ocean. Proceedings of the National Academy of Sciences, www.pnas.org/cgi/doi/10.1073/pnas.1315447110.

reports findings that large and episodic pulses of marine snow occur.  These large blizzards are met by hungry deep-sea animals that quickly gobble the meal.  The amount of food these blizzards deliver are huge equaling years, if not decades, of normal marine snow.  But the amounts and frequency of both normal marine snow and the blizzards are changing.

From 2003 to 2012 the amount of phytoplankton production, fodder for marine snow, was higher than years prior.  After 2006, the frequency of spikes in marine snow, i.e. blizzards, also increased.   In the summer of 2011, the first of three dramatic blizzards occurred.  During this event a large number of diatoms bloomed at the surface and sank rapidly to the seafloor.  The second event in the spring/early summer of 2012, was triggered by a major bloom of gelatinous salps. As mentioned in the press release of the paper, “These salps became so abundant that they blocked the seawater intake of the Diablo Canyon nuclear power plant, located on the California coast east of Station M.”  When these salps died, as they do after a bloom, they carpeted the seafloor.  In September 2012 another plankton bloom occurred and this combined with fecal pellets from salps (who hungrily munched on the algae) again carpeted the floor with marine snow.  In addition the greatest amounts of marine snow and consumption by deep-sea life (as measured by respiration rates) occurred in the last two years of the time series.

What caused these recent changes in marine snow?

From the paper,

The abyssal area surrounding Station M is influenced by the California Current, which is experiencing increased wind stress, resulting in increased upwelling of nutrient-rich subsurface waters, contributing to increased primary production. With increasing primary production there has been a corresponding increase in POC flux and detrital aggregate accumulation on the sea floor over the past several years.

And from the press release,

The researchers note that deep-sea feasts may be increasing in frequency off the Central California coast, as well as at some other deep-sea study sites around the world. Over the last decade, the waters off Central California have seen stronger winds, which bring more nutrients, such as nitrate, to the ocean surface. These nutrients act like fertilizer, triggering blooms of algae, which, in turn, sometimes feed blooms of salps. The fallout from all of this increased productivity eventually ends up on the seafloor.

Nowhere does the paper or the press release mention radiation or Fukushima. Nilch, negatory, nadda, never.

But this is not good enough for staff writer Ethan Hunt and others outlets that continue to recycle this story.

Though the researchers involved with the work have been reluctant to pin Fukushima as a potential cause — National Geographic, which covered the study recently, did not even mention Fukushima — the timing of the discovery suggests that Fukushima is, perhaps, the cause.

MBARI today also issued a press release addressing the “several misleading stories [that] have been in circulation on the internet.”  The press release points out the obvious.

1. MBARI research actually showed evidence that there were MORE algae and salps living in California surface waters during 2011 and 2012 than during the previous 20 years.
2. Salps are small gelatinous animals that eat single-celled algae. They are known to experience large blooms in their populations. Large populations of salps have been periodically documented in California waters since at least the 1950s.
3. Blooms of gelatinous animals (including salps) and single-celled algae are a common occurrence off the California Coast. They come and go, running their course when they use up their food and nutrients.
4. Animals and algae that live in the surface waters eventually die. If they are not eaten in surface waters then they sink to the deep sea. This is the main food source for deep-sea animal and microbe communities.
5. Soon after the salp bloom and die-off at the surface in 2012, the deep seafloor at the researchers’ study site was littered with dead salps. This was observed at one location, and salps were the only dead animals observed in large numbers.
6. There is no indication that any of the events in this study were associated with the Fukushima nuclear accident.

I will also note the Fukushima disaster occurred in March 2011, five years after the researches begin to see changes in surface production.   To reiterate the statements points, there is evidence of more life recently in California waters. The supposed “die off” is a common feature of any bloom of short-lived invertebrates. The “die off” was experienced at one location and with one species.  The entire Pacific seafloor is not littered with dying organisms.  I would also point out that these massive food falls of marine invertebrates are a common occurrence. For example, in 2002 a massive deposition of jellyfish was seen in the deep Arabian Sea.

As I write this post on this cold Saturday morning, my attitude matches.  I have wanted to write about this paper for a while here at DSN.  And I’m sorry I did not.  I shoudn’t be defending great science against propaganda and poor journalism.  I should be writing about how this paper answers a major question about the deep sea.  Previous studies have noted that the energy requirements of deep-sea animals could not be met by normal and minimal marine snow.  Research over the last decade or so set out to determine how this deficit is made up.  Smith and colleagues’ work solves this riddle.  Deep-sea animals simply wait for a sporadic feast.  Smith’s work suggests this is likely linked to climatic events.

If anything the paper is a cautionary tale of climate change not radiation.

The post Is the sea floor littered with dead animals due to radiation? No. first appeared on Deep Sea News.

While the Census of Marine Life may be the most recent call to survey the ocean, deep-sea exploration has a rich, paradigm-shifting history. It has all the makings of a Hollywood blockbuster: colorful characters, high seas action, the drama of antagonistic actions between “men of honor”, you name it! Probably has a bit of romance in there too, but that tends to get left out of the scientific literature. Examining the history of deep-sea exploration is an excellent case study in how technological advances continue to yield new insights and increase our ability to ask better questions. This section of Deep Sea 101 will be composed of 4 parts.

Nearly 2400 years ago Socrates (via Plato) posited of the deep sea:

“… everything is corroded by the brine, and there is no vegetation worth mentioning, and scarcely any degree of perfect formation, but only caverns and sand and measureless mud, and tracts of slime wherever there is earth as well, and nothing is in the worthy to be judged beautiful by our standards.”

Such a damning indictment from such a classical thinker indeed! Curiously, the Greeks and other civilizations during this time were in no position to make such bold statements having an inability to visit and sample past a mere tens of a meters.

It was not until Aristotle we could really call anyone a marine biologist. He dedicated much of his life to describing the life on the Aegean coasts, describing 180 marine species nearly 1700 years before Linneaus. Aristotle was the first person to study form, function, ecology and behavior and developed a classification system based on multiple traits. He is perhaps most famous for describing the mouth parts of sea urchins, which is named in his honor (called Aristotle’s Lantern, at right).

But his enthusiasm for the ocean did not catch on in the ancient period and an attitude of complacency persisted all the way towards the Victorian Era when deep-sea exploration really took off, chiefly out of economic and imperial interests. Echoing the contented ignorance of the time, or perhaps a fear of the unknown, noted historian Pliny the Elder wrote in 40 AD:

“By Hercules, in the sea and in the ocean, vast as it is, there exists nothing that is unknown to us, and a truly marvelous fact, it is with those things that that has concealed in the deep that we are best acquainted!”

It took until the 17th century, during the tail end of the Renaissance, for these unfounded assertions to be even questioned, and by none other than Robert Hooke who stated:

“Animals and Vegetables cannot be rationally supposed to live and grow under so great a Pressure, so great a Cold, and at so great a Distance from the Air, as many Parts at the Bottom of very deep Seas are liable and subject to…

We have had instances enough of the Fallaciousness of such immature and hasty Conclusions…” (emphasis mine)

What Hooke has done was twofold. He first provided a set of testable hypotheses for absence of life in the deep sea disguised as common sense. Then, he made a statement hinting that perhaps we ought to actually test this because if past experience shows, common sense might not always be correct.

For the next 100-200 years the deep sea was considered lifeless based on 4 criteria: temperature, light, pressure and stagnancy of the environment (i.e. it was all uniform). The first three of these criteria were well-reasoned, though no one knew what the true depths of the deep sea were. But it was well-known that light was refracted by water and the visible spectrum gets filtered out, the deeper you go the more pressure an organism must bear – this is easily calculated estimating forces, and without the energy from the sun’s rays warming the deep waters it could be reasoned that it must be cold down there. In fact, some early scientists thought the bottom of the sea must be ice.

The last criteria of stagnancy is an interesting one that I am not entirely sure how it came about since they had no direct knowledge of deep-sea life until the mid-1800s. It may have been derived from calculation of the current speeds. Surface currents are wind-driven and any given body of water tends to be stratified, or composed of different layers. The top layer of the water moves at a given speed but experiences drag from rubbing against the layer of water below it. This causes the lower layer to move with the upper layer but at a slower speed because there is energy loss from friction against the seafloor (see figure at right). Because of this, water currents near the seafloor are typically much slower than surface currents. Therefore one can posit that at some depth water speed eventually just stops. This has important implications because animals down there would need fresh, constant input of dissolved nutrients (nitrogen, oxygen, etc.). Stop the flow, there’s no grow!

During the golden age of deep-sea exploration in the 1800s the Azoic Hypothesis of the deep-sea was largely championed by Edward Forbes and was based on his observations in the Aegean Sea, between Greece and modern-day Turkey (map below). I’ll refer to the Azoic Hypothesis as tied specifically to Forbes, but recognize that it had much earlier roots. Forbes was merely the first to study it scientifically. As I’ll go on to explain though, the Azoic Hypothesis was largely the result of common sense thinking, an unfortunate study area, inadequate sampling gear and ignoring previous results.

Though not known at the time, the Aegean Sea was a poor choice for a study site. First of all, it is not very deep and we now know it is not a very productive area away from coastal areas. The map above (at right) shows the concentration of chlorophyll – the pigment used by phytoplankton to capture solar energy to use in photosynthesis – in the Aegean Sea based on satellite measurements. Green to red signify higher concentrations of phytoplankton, and hence higher amounts of surface primary production. Blue is low productivity and you’ll notice that in the center of the Aegean Sea where the deep water is it’s mostly blue, or unproductive. Oligotrophic waters (meaning with few nutrients) are defined as containing less that 80 grams of carbon per square meter. The central Aegean Sea has about 30 grams of carbon per square meter. With very few plankton at the surface, there is very little food that falls down to support the denizens of the deep.

Had Forbes actually been in a productive area he still might not have found much life in the deep because he was using a dredge that was modified from ones used by oystermen. It was inadequately designed to sample the muddy deep seafloor. The mouth of the dredge was narrow and the bag was small. Note the design of the canvas bag (below, at right), there are vents only in middle of the sides. The dredge would immediately fill up with mud and thereafter become a wrecking ball let loose upon the seafloor until it was brought up. Curiously though, and deceptively, Forbes made an illustration of sea creatures all-too-happy to enter into his dredge for his book Natural History of the European Seas (his initials are under the dredge). But the difference between the dredge he used versus this idealized dredge that he illustrated is actually quite important. The illustrated dredge would have been ideal to use since it has a wide mouth and plenty of vents to discharge mud.

Throughout his sampling, he failed to document life in the deep, but did document very thoroughly patterns of animal abundance with depth. In general, the deeper his dredge dove the fewer organisms he found. He wrote in 1859, the same year as Darwin published On the Origin of Species:

“As we descend deeper and deeper in this region, its inhabitants become more and more modified, and fewer and fewer, indicating our approach towards an abyss where life is either extinguished, or exhibits but a few sparks to mark its lingering presence.”

By means of extrapolation he asserted that life ceased to exist beyond 550 meters. Which probably seemed pretty reasonable to Forbes’ contemporaries. Forbes had went out to sea, carried out an extensive sampling program and had based his conclusions on data. In hindsight we can say that Edward Forbes was ill-prepared to adequately sample the deep sea and had a poor choice of study area, but was his extrapolation just the result of bad luck, or is there more to the story?

Find out in the next installment of Deep Sea 101 as we continue to examine the early evidence for life in the depths during Forbes’ time and enter whom I refer to as the father of modern oceanography, Sir Wyville Thomson!

The post Deep Sea 101: Early Paradigms and Exploration first appeared on Deep Sea News.

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6 February 2010

Sampling the Inverted Benthos

The Palmer has spent the last four days south of James Ross Island waiting for clear skies in order to access geological sampling sites on the Peninsula via helicopter. Heavy snowfall has smoothed the pack ice into a featureless white sheet that extends south to the horizon. Indications that we are at sea—rocking of the ship, waves crashing against the hull, birds wheeling overhead—are absent. It is tempting to draw analogies between our present station and one of the vast, white deserts in the Antarctic interior.

Tempting, that is, until a leopard seal exploded out of the water with an emperor penguin struggling in its jaws. Leopard seals are top predators and require waters productive enough to sustain stocks of their preferred prey, penguins and other seals. So despite its blank surface, the ocean here must be very much alive.

Curiously, the CTD fluorometer reports only trace levels of chlorophyll in the water column. If there is effectively no phytoplankton, then what primary producers support this ecosystem? What lives here that can build biomass from inorganic molecules? The answer becomes apparent when the ship moves, leaving behind a wake of cracked and overturned ice streaked with olive green. We scooped chunks of this dirty-looking ice onboard yesterday for a closer look. The streaks consisted of either densely packed, millimeter-wide vertical channels inside the ice or slime at the ice-water interface. Melting the ice in buckets precipitated bright green, mucous-covered strings and brownish fluff. Inspection under the microscope revealed these fractions to be microalgae and diatoms, respectively, interspersed with the occasional photosynthetic dinoflagellate (a type of protist). Collectively, this community of primary producers is called “sea-ice algae” and it contributes to the base of the food web ultimately supporting our leopard seal and its penguin prey.

Sea ice forms an ocean roof that in many ways mirrors the ocean floor. Like seafloor sediments, sea-ice communities are species-rich. With a taxonomic key in hand, we might have identified tens of species of microalgae and perhaps 100 species of diatoms, although succession often leads to just a few species dominating. Just as sediment hosts infauna, sea ice hosts microscopic herds of herbivores. Crustaceans called copepods and amoeboid protists called foraminifers inhabit brine channels inside the ice where the temperature stays below 0 °C and salt concentrations approach Utah’s Great Salt Lake. Foraminifers are transient visitors that can also be found suspended in the water column. At least two species of copepods, on the other hand, pass their entire lives grazing within the ice. And just as invertebrate deposit feeders graze along the surface of the seafloor, larger zooplankton such as krill swim upside-down beneath the ice to graze on microalgae and diatoms. For these reasons, sea-ice is often called the “inverted benthos.”

The scant few grams dry weight of microalgae and diatoms thawed from our cubic foot of inverted benthos may not look like much, but on a regional scale the ice is staggeringly productive. The halo of sea ice surrounding Antarctic swells from 4 to 20 million square kilometers in extent every austral winter, or roughly one-half to twice the land area of the United States. Primary producers associated with Antarctic sea ice produce about 35.7 Teragrams of organic carbon per year. If the average human weighs 75 kg, is 70% water, 20% bone, and 10% carbon, then Antarctic sea-ice algae annually produces enough carbon to make 5 billion people! The ice-shrouded Weddell Sea (recall our trouble reaching the Larsen B embayment) alone accounts an annual harvest of 2.5 billion human-carbon equivalents.

Primary production estimates such as these derive from satellite images of sea-ice chlorophyll content. Tracking the ecological fate of organic matter produced in sea ice, however, requires fieldwork. We will occasionally sample sea-ice algae during the next month to quantify the extent consumers in the benthos rely on primary producers in the overlying inverted benthos. To do this, we will measure the chemical composition sea-ice algae as well as kelp, phytoplankton, chemoautotrophic bacteria, and (ideally) all other primary producers present in the ecosystem. These measurements will form a library of chemical tracers we can then use to investigate diets of individual consumers.

One tracer we will include in our library is the ratio of the rare ¹³C stable isotope of carbon to the more common ¹²C stable isotope. This tracer distinguishes between phytoplankton and sea-ice algae because enzymes that fix atmospheric CO₂ into organic compounds preferentially react with CO₂ molecules containing ¹²C. Phytoplankton is immersed in a steady supply of ¹²CO₂ and manufactures molecules that contain mostly ¹²C. Primary producers locked in ice, on the other hand, quickly deplete the lighter isotope and are forced to incorporate kinetically unfavorable ¹³CO₂, resulting in the production of biomass that is distinctly enriched in ¹³C. Since carbon stable isotope compositions of organic matter change little with each trophic step, benthic consumers enriched in ¹³C can be inferred to rely substantially on organic matter derived from sea-ice algae if no other ¹³C-enriched primary producers are present in the ecosystem. Furthermore, if we are confident that we have measured the carbon stable isotope composition of the each potential primary producer in the ecosystem, we can use a mixing model to calculate the proportional contribution of each primary producer to a given consumer’s diet.

What is the carbon stable isotope composition of the red smear left behind by the leopard seal? Perhaps organic carbon entering the marine food web as green streaks of ice algae may eventually color the snow as penguin blood.

The post Dispatches from Antarctica – Sampling the Inverted Benthos first appeared on Deep Sea News.

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22 January 2010

Barilari Bay

Next stop in our fjord-hopping: Barilari Bay.

Andvord Bay and Barilari Bay are complete opposites. Andvord Bay was productive and teemed with life. Surface waters were thick with krill and phytoplankton. Whales surrounded the Palmer at all times, breaching and bubble-net feeding. The seafloor was strewn with kelp fragments and swarms of brittle stars. Rocks were covered with giant sponges and soft corals. Barilari Bay is comparatively quiet and barren. Surface waters are crystal clear. Seafloor life is much sparser and more fragile, consisting mostly of holothurians and small, sessile salps.

Glaciers likely play a role in this sharp contrast between the fjords. While Andvord Bay had only one large tributary glacier at the head of the fjord, Barilari Bay has six. Marine phytoplankton is averse to glacial runoff and as a result Barilari may have lower levels of primary productivity than fjords with fewer glaciers such as Andvord. Benthic communities in Barilari Bay are also likely to be strongly influenced by the glaciers, which spew carbon-lean rock flour onto the seafloor.

Andvord and Barilari are excellent sites to study the interaction between glaciers and the marine ecosystem. As our glaciologists fly to out to field sites, we will spend the next few days using CTD casts, water column samples, ROV transects, yo-yo cam images, and mega core samples to map patterns of primary productivity and benthic diversity in Barilari Bay.

The post Dispatches from Antarctica – Barilari Bay first appeared on Deep Sea News.