Stomatopods at Radiolab

Somewhat recently, the ever-excellent podcast Radiolab aired an episode all about colors and how we as humans perceive them.

During the episode, Jad and Robert talk to a visual ecologist about the fearsome stomatopod, which has 16 visual pigments (humans typically have 3).

Podcast here.


A glimpse at Davidson Seamount

Seamounts (underwater mountains) make up a a huge cumulative habitat type in the ocean, and distinct biological communities can exist on the same underwater feature.  As a part of an investigation by MBARI, Davidson Seamount and others offshore of California were surveyed with an ROV, and yielded some pretty spectacular underwater footage.

You can read more about this work at Davidson in this PLoS ONE article, authored by Dr. Craig McClain (of DSN notoriety) and colleagues.  If you listen closely to the narration in the video, you’ll hear Lonny Lundsten, a coauthor on the study, mention the idea that seamounts, while providing unique habitat in the open ocean, are not necessary the hosts of endemic species (species that are restricted to a single geographic locale).  More about that here.

[video:  MBARI on YouTube]

3 million years of a marine latitudinal diversity gradient

Perhaps the largest, most visible, macroecological trend on this planet is that there are generally more species in the tropics (low latitudes) than the poles (high latitudes). This pattern has been observed in both terrestrial and marine systems, across hugely varied groups of plants and animals. Despite the fact that this has been known for awhile now, no unified model exists that explains how this latitudinal species gradient came about or what mechanism(s) act to maintain it (intriguing hypotheses abound, however, including faster speciation in the tropics). What the structure of this gradient was like in the past is uncertain as well; for example, how stable this pattern is through time?

A recent paper in Ecology Letters by Dr. Yashuhara and colleagues uses paleotemperature information and diversity data of tiny planktonic critters called formaminfera (forams, if you’d like fit in) to investigate this latitudinal species gradient at various snapshots through time, over the past three million years.

Planktonic (residing in the water column while alive, rather than at the bottom of the sea in the benthos) forams as a groups are hugely abundant; deep-sea sediment in some parts of the world can comprise of almost 70% of forams, particularly their tests, or tiny calcium carbonate shells. Scientists have been studying forams in depth for some time now, in no small part due to their importance in studying past climate and oceanic conditions, and as a result their taxonomy is well-known. So if you’d like to take a detailed look at the latitudinal diversity gradient in the ocean over time, this is a good model system for that.

Using past datasets consisting of foram diversity and reconstructed sea-surface temperatures, the researchers investigated four specific temporal snapshots: modern, 18,000 years ago (Last Glacial Maximum), 120,000 years ago (Last Interglacial), and 3.3-3.0 millions years ago (in the Pliocene). They found that unimodal (think a relationship with a single hump-shaped peak) relationship between species diversity and latitude for all time points, with diversity generally peaking in the subtropics and falling off rapidly towards the poles. Additionally, used the reconstructed sea-surface temperature dataset, they found that species diversity tracks closely to temperature. For example, diversity was highest in the mid-Pliocene samples when it was the warmest of the time points considered here, and lowest during the last glacial maximum, the coldest. The authors even point out that the latitudinal diversity gradient was steeper during the last glacial maximum (i.e. the diversity in this set of samples decreased faster–at a steeper slope–towards the poles than the other time points), but this is likely due to the fact that the temperature is known to change more drastically with latitude during this time period.

This is important because it indicates that temperature has a big role to play in determining what species (and how many) live where. It also shows, as other studies have, that temperature is an important predictor of diversity in the ocean. This work’s central finding shows that this relationship has been robust at these various time points throughout the last three million years, even when examined at very high taxonomic resolution. Paleoecological work is really interesting and hugely useful in this vein; it can show us how things like climate can affect biodiversity over large timescales, and allow a different perspective of how large ecological patterns work.

Yasuhara, M., G. Hunt, H. J. Dowsett, M. M. Robinson, and D. K. Stoll (2012). Latitudinal species diversity gradient of marine zooplankton for the last three million years. Ecology Letters DOI: 10.1111/j.1461-0248.2012.01828.x

Quick comment re: Shark Week

Hark! A Shark! Great White offshore of Mexico. Credit: Wikipedia user Sharkdiver88. Public domain.

In the throes of this year’s rendition of Discovery’s cacophony of teeth and excited narration, I think it’s prudent that we keep in mind that sharks are way, waaaay down the list of things that could potentially kill you. In 2011, for example, there were 75 total, both fatal and non-fatal, shark attacks. Loss of life is tragic, and there is always some risk associated with being in the ocean. That being said, you have a enormously higher chance of falling victim to car accidents, the flu, drowning, lightning, cancer, heart disease (these and more at this list, a small sampling, but I think you get the idea) than to the great toothy beasties of the deep.

For a longer, and generally more complete take on that, see this post I wrote on the onset of last year’s Shark Week (located an embarrassingly few number of posts down from this one).  If you’re interested, here’s the page for the International Shark Attack File, and here’s the summary for the 2011 shark attacks.

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.

Ove Hoegh-Guldberg speaks on climate change in the ocean

From the 2011 National Council for Science and the Environment conference in Washington, D.C.  You can find out more about Dr Hoegh-Guldberg at his laboratory site.

Video:  John Bruno on Vimeo (cc).  Via SeaMonster.

Debris patch from Japan’s tsunami en route to US

As if the tragic loss of life and ongoing nuclear woes weren’t enough, researchers Nikolai Maximenko and Jan Hafner at the International Pacific Research Center, University of Hawaii, predict that the massive deluge of debris that last month’s tsunami washed into the  sea is headed across the Pacific.  Using data from drifting oceanic buoys, the model predicts the debris will first spread out within the North Pacific Subtropical Gyre and start washing up in the Papahanaumokuakea Marine National Monument (NW Hawaiian islands) in a year.  In three years, the rest of the Hawaiian islands, the US West Coast, British Columbia, Alaska, and Baja California will see effects on their shorelines.  After the journey, the researchers predict that the debris will enter the North Pacific Garbage Patch and eventually get broken done into smaller particles.  In five years, Hawaii is expected to see another, more severe plume of oceanic trash.  Hopefully, these projections will help to inform clean-up responses.  The oceanic trash that does not either wash up on shorelines or sink, can end up in marine organisms.

The animation from the International Pacific Research Center shows likely debris path and timeline (press release, PDF).  Top image: Debris offshore of Honshu, Japan.  Image:  US Navy.  Hat tip:  Emmet Duffy at SeaMonster.

Stomatopod SMASH!: biomechanics of an invertebrate’s weaponry

This is the mighty stomatopod, the last thing some unlucky sea creatures ever see.  The energy for the stomatopod’s strike comes from a spring-type mechanism, which helps to explain the incredible speed of the attack.  In the below video from the Dunn Lab’s CreatureCast, Nati Chen takes us through the motions of this swift invertebrate.

Be sure to also check out this TED talk from Sheila Patek, who studies animal speed, including stomatopods’.  Before being usurped by another arthopod, Dr Patek showed that a species of stomatopod held the title of fastest feeding strike of any animal.

Image:  Wikimedia Commons, originally from Flickr user Silke Baron (cc)
Video:  CreatureCast (Casey Dunn) on Vimeo (cc)

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.

Marine debris

The 5th International Marine Debris Conference has been ongoing this week in Honolulu, Hawaii.  The above video from NOAA gives some insight as to what is meant by ‘marine debris’ and why it’s an issue.  While the video focuses on the larger pieces of debris, it’s important to remember that microplastic pollution, especially as they accumulate in oceanic gyres over time, is an another issue of enormous consequence to ocean creatures great and small.

You can follow the conference on the Twitter machine here and by keeping up with the hashtag #5imdc for the extra Twitter literate.  For more information, check out the Seaplex Science blog (more about the Seaplex expedition here) which debunks some misleading headlines about the North Pacific garbage patch.  Miriam Goldstein, a PhD student at the Scripps Institution of Oceanography, studies the impacts of plastics on marine invertebrates and frequently talks plastic over at Deep-Sea News, along with various sea shanties of course.

Find out about NOAA’s Marine Debris Program here.