Live deep-sea footage

The Visions ’11 cruise is streaming live deep-sea video footage via an ROV puttering around in the depths.  Read more about the cruise here and check out the live video feed here.  (If you’re having trouble with the feed, right click/command click on the video, hit ‘settings’ and uncheck the ‘enable hardware acceleration’ box.)  This leg of the cruise is over Axial Seamount in the Pacific.

Via Alden Denny, geology and GIS extraordinaire.  You can follow expedition updates on the twitter machine @VISIONS11ops.

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The deep sea of the Coral Triangle

Last year, Dr. Tim Shank led an expedition into the deep sea of the Coral Triangle, finding dozens of new species. The diversity of species the team is describing may be evidence for a deep-sea Wallace line. Read more at the Economist.

Frontiers: The deep sea and climate

When we think about climate change and the ocean, many minds turn immediately to images of shallow-water corals, bleached white from the lack of zooxanthellae (internal, photosynthetic symbionts), driven away by heat and other types of stress.  However, the consequences of an increased atmospheric CO2 reach much deeper into the ocean.  The global ocean has an average depth of 3800 meters and comprises 71% of the total area of Earth, making the deep-sea far and away the largest biome on this planet.  In terms of volume, the deep-sea pelagic—the water-column itself—contains over a billion cubic kilometers of seawater.  Less than 5% of the deep benthos (the seafloor) has been remotely sensed, and less than a hundredth of one percent has been observed directly, sampled, and studied.  Even so, species diversity in the deep-sea is among the highest known1.

As a society, we still collectively get excited about the discovery of new species. And we should—such discoveries are essential to science.  The public being interested in new species is also quite importance for the continued funding of exploratory research.  Since 1840, 28 new habitat or entire ecosystems have been discovered in the deep ocean.  Not simply new species, but entirely new environments. Cold seeps, hydrothermal vents, brine pools, xenophyophore fields, just to name a few—these are all habitats that have only been known since the 1970s1.

Year of discovery of new habitat/ecosystem in the deep sea since 1840 (Ramirez-Llodra at al. 2010)

However, the lack of taxonomists to classify and describe the new species in these novel habitats dampens the spirit of discovery somewhat—specimens languishing in collections, as of yet unidentified due to the lack of support for specialists, harkening back to the last, frustrating scene in Raiders of the Lost Ark.

Atmospheric carbon dioxide concentrations are predicted to exceed 500 ppmv before 21002,a value not seen in the past few million years3.  This is contributing towards both warming and ocean acidification4,5.  It is uncertain how benthic organisms and their associated ecosystems as a whole will react; particularly little is known regarding the effects of climate change in the deep-sea. Continue reading

Sea debris: shipping containers and marine life

Approximately 10,000 shipping containers tumble off into the sea every year, bobbing around for a bit before, in most cases, sinking into the deep ocean.  To discover what happens to these containers after reaching the seafloor and what potential effects these abrupt structures may have on marine communities, the Monterey Bay Research Institute is teaming up with the Monterey Bay National Marine Sanctuary to investigate the biological community found on a shipping container offshore of California.  The benthos in much of the deep-sea, including the vast abyssal plains, is primarily composed of sediment.  These containers could suddenly provide hard substrate in an environment that usually lacks it, altering the habitat’s physical characteristics and possibly changing the suite or abundance of species present.  Researchers will be using a remotely-operated vehicle to compare sites at different distances from the shipping container, which is under about 1,300 meters of seawater.

Fittingly, the funding for these research cruises came from a settlement between  the National Oceanic and Atmospheric Administration and the shipping company whose vessel lost this specific container and 14 others in 2004.  The discovery of this container (chock-full of 1,159 steel-belted tires) lends an important opportunity to study the impacts of this global issue.

Read the MBARI press release here (via Ed Yong on Twitter).

Image: runner310 on Flickr (cc)

Lunar cycles and reproduction in the deep sea

Some biological patterns in marine species, particularly concerning reproduction, are related to the moon.  Shallow-ocean corals, for example, undergo mass spawning events (the synchronous release of eggs and sperm into the water column to combine), the timing of which, are set to the lunar clock.  Reef fishes, shallow-ocean echinoderms, mollusks and more, also time spawning events in respect to the phase of the moon.

The deep-sea, the largest biome on Earth, covering more than 326 million km2, has not been explored in terms of this lunar-synchronicity.  The dearth of photosynthetically-useful sunlight below 200 meters* would appear to make such moonlight-related cycles unlikely at best.

However, in a recent paper, Annie Mercier and her colleagues have shown that this may not be the case.  They demonstrate in both lab and field settings evidence of lunar periodicity in the reproduction of 6 deep-sea species, containing members from two different phyla:  Cnidaria and Echinodermata.

The researchers examined preserved samples of Phormosoma placenta (a deep-sea echinoderm) collected at various stages of the moon.  They found that despite being collected from between 700 – 1400 meters beneath the waves, physiological signs of recent spawning in both sexes coincided with the new moon.

Back in the lab, gamete and larval releases (reproduction events) were observed in captive specimens from 5 different species according to lunar patterns.  These specimens were collected between 100-1000 meters, with most species collected below 400 meters.  A minimum of 3 lunar months’ worth of data was compiled; some species actually repeated breeding periods in this timeframe.

The question remains if these animals are displaying internal rhythms that are kept in time by some sort of lunar cue, or if they are responding to something externally that follows the lunar period.  But what cues, or drivers, of a lunar period could be detectable at such great depths, where even sunlight wanes or is essentially eliminated?

Organic matter from surface waters falls into the deep sea; there is the possibility that these fluxes of sustenance may show lunar patterns.  Previous work has shown growth bands in some species of deep-sea corals that may correspond to monthly or lunar periods.  Other hypotheses include the idea that these animals can somehow directly perceive moonlight at great depths, or that deep tidal (related to lunar phase) currents exist.

In this study, internally brooding corals released larvae during the full or during the waning phase.  The 4 free-spawning species released gametes with the new moon.  The authors note that while this is opposite to the mass spawning events in shallow-ocean corals, which release during the full-moon, this may be due to the very different environmental and biotic factors in shallow areas versus the deep sea.

 

* This is the reason that little to no primary production occurs (that is, organisms producing chemical energy) in most, but not all, ecosystems known in the deep-sea.  Some deep-sea organisms are capable of undergoing chemosynthesis and can use inorganic chemicals, rather than sunlight as in photosynthesis, as an energy source.  However, even with a widespread lack of primary productivity and severe food limitation in most areas, diversity in the deep sea is among the highest on the planet.

Image:  Flicker user ZedZap (cc 2.0)

Sources:
ResearchBlogging.orgMercier A, Sun Z, Baillon S, & Hamel JF (2011). Lunar rhythms in the deep sea: evidence from the reproductive periodicity of several marine invertebrates. Journal of biological rhythms, 26 (1), 82-6 PMID: 21252369
Ramirez-Llodra E, et al. (2010). Deep, diverse and definitely different: unique attributes of the world’s largest ecosystem Biogeosciences, 7 (9), 2851-2899 : 10.5194/bgd-7-2361-2010