Off the Angolan African coast, these researchers document one whale shark and three ray carcasses at 1200 meters on the seafloor.  This is the first time any of these have been documented as deep-sea food falls and only recently have living whale sharks even been documented off Angola.

Despite one of the carcasses being covered in 54 eelpouts, a considerable amount of flesh still existed on the carcasses.

[in prior studies] When presented with elasmobranch and tuna bait on a baited camera trap, scavengers clearly preferred tuna and only consumed the elasmobranch once the tuna was gone…Repeated experiments in this region using [bony] fish as bait showed a 10-fold increase in scavenging rates compared to that when elasmobranch was used.

So why in a food desert like the deep sea would fresh meat not be consumed quickly?  Apparently, elasmobranch, i.e. shark and ray, flesh is bit unpalatable and tough to chew.  The tough, sand-paper-skin may prove a formidable barrier to scavenger jaws.  The high ammonia content of elasmobranch flesh may also be, to say the least, unappetizing.  The carcasses may also smell like death and deter other scavenging elasmobranchs.

Other uncharacterized chemicals that are found in rotting elasmobranch flesh (necromones) have been proven to strongly deter shark scavenging and invoke an alarm response, even among different species of elasmobranch. If this phenomenon extends to deep-sea scavenging elasmobranchs, it can be assumed that the Portugese dogfish, Centroscymnus coelolepis, would have been deterred from scavenging the elasmobranch carcasses. This will have severely hindered utilization of the carcasses by other species, since C. coelolepis is the dominant scavenger off the Angola margin.

Yet despite the smell of death and urine, a dead elasmobranch still provides an essential snack in the deep sea.  The researchers estimate that these elasmobranchs represent 4% of the total amount food that sinks to the seafloor off Angola in the form of marine snow.

Higgs, N., Gates, A., & Jones, D. (2014). Fish Food in the Deep Sea: Revisiting the Role of Large Food-Falls PLoS ONE, 9 (5) DOI: 10.1371/journal.pone.0096016

The post Dead Elasmobranchs on the Seafloor are Not as Appetizing as One Might Assume first appeared on Deep Sea News.

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.

But the food not so delightful,


But since we’ve got no place to go,


Let It Marine Snow! Let It Marine Snow! Let It Marine Snow!

In the late 1960’s, two marine biologists, Howard Sanders and Robert Hessler, made a shocking find–the biodiversity of the deep-sea floor is astoundingly high. In an area the size of a coffee table over 300 species can coexist, a number that rivals tropical rainforests and coral reefs. Yet these findings also raised a paradox. High diversity is typically associated with physically complex habitats, like forests and reefs, plentiful with food that allow for a variety of niches. In the food poor, homogenous mud flats of the deep sea, how can so many species coexist? The answer is snow.

The lack of light in the deep oceans precludes photosynthesis. Thus, primary production of carbon, the base of a food web, is virtually absent. Deep-sea organisms are reliant upon a trickle of falling material from the productive shallow oceans overhead. This material is largely a low quality and low quantity mixture of decaying bodies and feces degraded further by bacteria on its decent into the deep. Roughly 2-5% of the total carbon on the ocean’s surface falls to the deep seafloor, the equivalent of roughly 2-3 tablespoons from a 5-pound bag of sugar. This sinking material, marine snow, falls as a dusting on the ocean bottom. But like a light snow in your yard does not form an even layer and Buffalo receives more snow than Miami, marine snow too is denser in some spots whether an area the size of coffee table or an entire ocean.

In this marine snow medley lays the answer for our deep-sea paradox.

In the 1970’s, Howard Sanders, Fred Grassle, and Paul Snelgrove proposed instead of the deep-sea floor being a homogenous wasteland, it was comprised of a variety of patches each with a unique set of organisms, i.e. the patch-mosaic hypothesis. The deep-sea floor is essentially a patchwork quilt of different small habitats. I began this year by publishing a study addressing how heterogeneity in marine snow of distances of just a few yards can lead to completely different communities of organisms. At the end of this year, just today in fact, I with coauthors show this same pattern over several thousands of kilometers.

In 2006, Jim Barry and I during my tenure at the Monterey Bay Aquarium Research Institute sampled a 3203-meter deep site off the Monterey Bay. We collected with the robotic arm of a remotely operated vehicle 44 sediment cores over approximately 400 yards. Each core we sieved and removed the small invertebrates living in the sediment, from worms to crustaceans to molluscs plus much more. Equally important, we measured the carbon content, of the sediment as an indicator of marine snowfall. Largely, we found that invertebrate communities in cores taken adjacent to each other were just as likely to be similar as dissimilar to one another. Indeed, cores adjacent to one another were just 3% more likely to share common species than cores taken 350 meters apart! Why would communities right next to one another be so different? Differences in marine snow accumulation. Invertebrate communities receiving comparable marine snowfall were more similar.

Today in the Proceedings of the Royal Society with collaborators Allen Hurlbert and James Stegen from the University of North Carolina, I unravel the paradox of the deep a little further. Given the difficulty of conducting deep-sea work, patterns of diversity of entire oceans are rare. In 2008, John Allen, working previously with Howard Sanders, published an amazing dataset of deep-sea bivalves taken form 270 sites across the Atlantic Ocean. We combined this dataset with data on bivalve sizes and genetic relatedness with multiple datasets on the environment, including annual marine snow accumulation. We found that the availability of both chemical, i.e. marine snow, and thermal, i.e. temperature, energy explained differences in compositions of bivalves communities across the Atlantic Ocean. Interestingly, and in contrast to current thinking (including my own!) that invertebrates with planktotrophic larvae should be able to disperse everywhere, we also detected the importance of dispersal ability in explaining community differences. In other words, some of what determines where a bivalve is located in the Atlantic is determined by its dispersal ability and the amount of energy it requires.

But we went one step further and developed a simulation. We constructed virtual bivalves allowing them to evolve traits, fill environmental niches, and disperse across a virtual Atlantic Ocean. This is a computationally complex and demanding operation and required a cluster of computers at UNC to run. In each simulation, we could control the dispersal ability and food requirements for the bivalves. For each simulation, we would then compare the patterns that emerged with those in our real Atlantic bivalves communities. This would allow us to determine the exact level of dispersal ability and food requirements of bivalves to produce changes in community compositions across the Atlantic. From our simulations, we found that 95% of bivalves could disperse 749 km from their natal site. We also found that 5% of bivalve juveniles would not be able to persist in habitats that deviated from their optimum habitat more than 2.1 grams of carbon per meter squared per year. That translates to about 1 teaspoon over a dining room table over the course of an entire year! Bivalves are extremely sensitive to the amount food available.

Overall, these studies illustrate that the deep-sea floor is like your Grandma’s quilt presenting a variety of patches of material. These patches, driven by differences in marine snow, whether occurring over inches or miles, provide unique habitats that allow a variety of different animals to coexist. And much like humans prefer different amounts of snow (give me warm weather or give me death!), deep-sea species are uniquely adapted to differences in marine snow.

Craig R. McClain, James C. Stegen, and Allen H. Hurlbert Dispersal, environmental niches and oceanic-scale turnover in deep-sea bivalves Proceedings of the Royal Society B: Biological Sciences published online before print December 21, 2011, doi:10.1098/rspb.2011.2166

UPDATE 1:
Also take a look at the great write ups by Wired and IO9. Love the titles! The Bounty of Species in a Single Scoop of Seafloor Mud and The Ocean Floor is Like a Rainforest Where Feces and Dead Animals Rain From the Sky

UPDATE 2: I was asked for a legend to the animals above.  Hopefully this helps. As for the species, I could give you the actual species names but perhaps that would not be helpful to readers.  Instead I will give you the general groupings that may be more informative.

So in this orientation above from left to right

Row 1 bivalve, polychaete, ophiuroid, polychaete, bivalve, cumacean, amphipod

Row 2 cumacean, anemone, aplacophoran, bivalve, cumacean, bivalve, aplacophoran

Row 3 polychaete, bivalve, cumacean, bivalve, big polychaete, amphipod, 2 oligochaetes

Row 4 scaphopod, bivalve, aplacophoran, long polychaete, cumacean, amphipod, bivalve

Row 5 bivalve, polychaete, aplacophoran, amphipod, bivalve, amphipod, polychaete

Row 6 ostracod, polychaete with tube, bivalve, anemone, polychaete, amphipod, polychaete, bivalve

Row 7 polychaete, gastropod, amphipod, caprellid shrimp, scaphopod, bivalve, polychaete, cumacean

Echinoderms

ophiuroid http://en.wikipedia.org/wiki/Brittle_star

 Molluscs

bivalve http://en.wikipedia.org/wiki/Bivalve

aplacophora http://en.wikipedia.org/wiki/Aplacophora

scaphopod http://en.wikipedia.org/wiki/Scaphopod

gastropod http://en.wikipedia.org/wiki/Gastropod

 Annelids

polychaete http://en.wikipedia.org/wiki/Polychaete

oligochaete http://en.wikipedia.org/wiki/Oligochaete

Crustaceans

cumacean http://en.wikipedia.org/wiki/Cumacean

amphipod http://en.wikipedia.org/wiki/Amphipod

ostracod http://en.wikipedia.org/wiki/Ostracod

caprellid http://en.wikipedia.org/wiki/Skeleton_shrimp

Cnidarian

anemone http://en.wikipedia.org/wiki/Sea_anemone

The post Let It Snow, Let It Snow, Let It Snow first appeared on Deep Sea News.

From Monterey Bay Aquarium Research Institute…In the ocean, there are places where it looks like it is snowing. These magical places are near undersea volcanic activity. The snow particles are clumps of bacteria that use chemicals to make food. Chemicals they use include hydrogen sulfide, which is toxic to virtually all other life. Most other ecosystems on earth depend on organisms that require sunlight to create food. Vents release hot water, minerals, and chemicals from beneath hardened lava. The fluid is almost 30 degrees F warmer than the surrounding water. The bacteria live beneath the seafloor and are also released from the vent. These tiny one-celled microbes provide food for many animals. A thick mat of white bacteria builds up; little worms and crustaceans feed on it. Nearby, “black smoker” vents may form when vents spew minerals in water up to 750 degrees F. In time, an amazingly robust community with thousands of animals flourishes here. This video was recorded 480 km (300 miles) west of the Oregon coast at 1,516 m (4,974 ft) depth with remotely operated vehicle Doc Ricketts.

The post TGIF: Marine Snow first appeared on Deep Sea News.

The 285  macrourid fishes, the rattails, whiptails, and grenadiers, are one of, if not the, most abundant fish in the deep.  You cannot throw…well anything…without hitting one.  What do all these fish eat?  In one scenario, macrourids feed on organisms living on the seafloor, that in turn originally feed on detritus, i.e. marine snow, raining from the surface.  Or these fish could cut out the middle man and feed directly on dead prey originally from surface. Or they could do both?

In simplified terms, phytodetritus is consumed by deposit feeders, which in turn are consumed by primary carnivores and so on to the top trophic positions including many fishes.  However, an alternative trophic pathway exists. Many deep-sea fishes are attracted to cameras baited with pelagic carrion and a few studies have noted carrion in their diets.  However, these observations have rarely been quantified. Scavenging on the sunken carcasses of epipelagic nekton bypasses the conventional benthic food web, although the beginning of each path shares primary production in surface waters. The relative importance of these 2 trophic pathways remains uncertain.

The question may seem trivial but the answer gets at nothing less than the pathway of carbon into the deep, and impacts how we understand carbon cycling and sequestration. A new study by Drazen et al. in Marine Ecology Progress Series examines the fatty acids of two macrourids and a whole host of their potential prey items.  All the samples were collected from the well-known Station M site (see map).

[googlemap lat=”34.9″ lng=”-123″ width=”500px” height=”500px” zoom=”7″ type=”G_HYBRID_MAP”]Station M[/googlemap]

What is generated from the data are the two plots below.  All you need to know is that the closer two points are on the graph the more similar the fatty acid content of their tissue.  The first plot is for macrourids and benthic prey and the second plot adds a few more pelagic prey.  Macrourids are black, echinoderms green, polychaetes, orange, anemones purple, crustaceans blue, and either living or dead on the seafloor, depending on the plot, pelagic species in red.

So it is obvious what is going on here , right?  Benthic crustaceans and pelagic-derived carrion taste good.  Echinoderms and polychaetes not so much.

So Number 1, as the press release for this paper states “This indicates that epipelagic populations constitute a significant part of the diet in abyssal fishes”, and thereby circumventing part of the food web.  And Number 2, no doubt making Chris Mah smile, and a bit of conundrum, is that they do not eat echinoderms.  As Chris Mah would quickly tell you, probably over cocktails at a party, echinoderms are one of the most dominant taxa in the deep.  You cannot throw a macrourid without hitting one.  Why do macrourids, obviously opportunistic scavengers/predators, not eat the most abundant food source in the deep?

Drazen, J., Phleger, C., Guest, M., & Nichols, P. (2009). Lipid composition and diet inferences of abyssal macrourids in the eastern North Pacific Marine Ecology Progress Series, 387, 1-14 DOI: 10.3354/meps08106

The post Simple Summer Recipes for Dead Seafloor Carrion first appeared on Deep Sea News.