[Coral-List] New paper on the dispersal (or lack of) of coral larvae across the East Pacific Barrier

[Dennis Hubbard]

A very interesting paper. My simplistic understanding of this previously
was that the Isthmus of Panama created a barrier between Caribbean and
Pacific regions and that larval flow was dominantly (perhaps solely) from
east-to-west in the Trade Winds. This would seem to be consistent with
these new findings. I was not aware that there was a lot of thought of
westward flow into this area, although the eastward flow of larvae from the
Tuamotus to Easter Island seems reasonably well documented.

Might there be any value in looking at the development of the species of
interest following the closure of the Isthmus of Panama to see whether
those furthest east (which, if my recollection of the literature is
correct, were the first to be impacted - Peter Glynn's papers) might have
been the original sources of larvae to the west way back when? If so, might
this infer that recent events are "unprecedented" over the past 2 million
years?
Dennis

On Wed, Oct 5, 2016 at 5:55 AM, Sally Wood <Sally.Wood at bristol.ac.uk> wrote:

> A bit late but some of you might be interested in a new paper published in
> Nature Communications in August, which revisits the theory that El Niño
> events may promote long distance dispersal across the East Pacific Barrier:
>
> El Niño and coral larval dispersal across the Eastern Pacific marine
> Barrier
> <http://www.nature.com/articles/ncomms12571>, Wood, S., Baums, I.B.,
> Paris,
> C.B., Ridgwell, A., Kessler, W.S., Hendy, E.J., Nature Communications
> 7:12571 (2016).
>
> The study, which compares a modelling approach with genetic data across the
> Pacific, is a collaboration between the University of Bristol's Coral Reef
> research group, the Paris laboratory at RSMAS and the Baums laboratory at
> Penn State, with input from oceanographer Billy Kessler at NOAA's Pacific
> Marine Environmental Laboratory and climatologist Andy Ridgwell at the
> University of California at Riverside.
>
> The press release (printed below) can be viewed here
> <http://www.bris.ac.uk/news/2016/august/reef-castaways.html>, and the full
> paper obtained here <http://www.nature.com/articles/ncomms12571>. An
> animation of example modelled dispersal paths by month of release can be
> viewed here <https://www.youtube.com/watch?v=mMzuPcBTq5c>.
>
>
> *---------- U. Bristol press release 23rd Aug 2016 -----------*
>
> *Reef castaways: Can coral make it across Darwin’s ‘impassable’ barrier?*
>
>
>
> An international team of researchers have shown that vulnerable coral
> populations in the eastern tropical Pacific have been completely isolated
> from the rest of the Pacific Ocean for at least the past two decades.
>
>
>
> Ocean currents can change speed and even direction depending on the season
> or climatic events like El Niño.
>
>
>
> The new study led by University of Bristol researchers has used a
> state-of-the-art computer model to trace the journeys of coral larvae
> transported at the whim of these currents.
>
>
>
> The international team discovered that even during the record-breaking El
> Niño of 1998, coral larvae could not survive long enough to make the 5,000
> km trip from reefs in the central Pacific to those in the east.
>
>
>
> These findings support the opinion of Charles Darwin, who considered this
> intimidating expanse of open ocean ‘impassable’ - countering recent
> arguments that the ‘East Pacific Barrier’ must be breachable since the same
> coral species are found on both sides. If so, the study argues, such
> breaches have not occurred recently.
>
>
>
> Dr Sally Wood
> <http://www.bristol.ac.uk/earthsciences/people/person/
> sally-wood/overview.html>,
> from the Coral Reef Research at Bristol
> <http://www.bristol.ac.uk/biology/research/ecological/coral/> (CRAB) group
> in the School of Earth Sciences <http://www.bristol.ac.uk/earthsciences/>
> and lead author of the paper, explains: “Coral build the framework of
> tropical coral reefs, creating habitats which support one of the most
> diverse ecosystems on Earth.
>
>
>
> “Whether coral reefs can survive the pressure of climate change as well as
> local stresses will depend to a large extent on the ability of coral to
> reproduce and disperse; to replenish damaged populations, migrate from
> deteriorating conditions and colonise new frontiers. So it’s important to
> map where coral are able to get to.”
>
>
>
> Dr Erica Hendy
> <http://www.bristol.ac.uk/earthsciences/people/person/
> erica-hendy/overview.html>,
> Lecturer in Biogeochemical Cycles in the School of Earth Sciences, added:
> “However, you simply can’t tag a coral larvae to follow where it ends up as
> you would a large marine animal like a turtle or shark. Coral larvae are
> smaller than a poppy seed, soft-bodied and released in overwhelming
> numbers.
>
>
>
> “When swept off their home reef, they have an infinitesimally small chance
> of ever reaching a suitable place to settle and become a coral colony. We
> therefore use computer simulations to answer these critical questions about
> coral biology and conservation.”
>
>
>
> The study tracked the journeys of over five billion model ‘larvae’ from 636
> remote reefs scattered across the central and eastern Pacific Ocean over a
> 14 and a half year period. Using the state-of-the-art Connectivity Modeling
> System <https://github.com/beatrixparis/connectivity-modeling-system>,
> developed by Claire Paris
> <https://www.rsmas.miami.edu/people/faculty-index/?p=claire-paris-limouzy
> >,
> associate professor of ocean sciences at the University of Miami’s
> Rosenstiel
> School of Marine and Atmospheric Science
> <https://www.rsmas.miami.edu/people/faculty-index/?p=claire-paris-limouzy>
> and run on the University of Bristol’s BlueCrystal supercomputer
> <https://www.acrc.bris.ac.uk/>, the researchers could manage the massive
> computational demands of modelling such large numbers.
>
>
>
> This allowed the team to test, for the first time, a long-standing theory
> that countered Darwin - that El Niño events promote long-distance dispersal
> of coral larvae across the Pacific Ocean.
>
>
>
> The results showed that the eastern Pacific corals (from Baja California in
> the north to the coastline of Ecuador and the Galapagos Islands in the
> south) have been completely cut off from the rest of the Pacific since at
> least the 1998 El Niño.
>
>
>
> As is happening worldwide at the moment, this extreme El Niño wiped out
> many of the corals in the eastern Pacific.
>
>
>
> Coral populations recover from such stress events through the proliferation
> of survivors and colonisation by new recruits from neighbouring
> less-impacted reefs. However, the more isolated a reef, the more
> self-reliant, and the higher the likelihood of local extinctions.
>
>
>
> The study’s findings provide evidence that local conservation is essential
> for the sparse and poorly-protected, but economically and
> environmentally-important coral reefs of the eastern Pacific Ocean.
>
>
>
> Dr Wood concluded: “Our results demonstrate that it is even more important
> to conserve the genetic diversity of the remote reefs in this
> environmentally hostile part of the Pacific.
>
>
>
> “They’re on their own out there, so whatever we can do to protect them
> locally really will have an impact.”
>
> *Dr Sally Wood  *
>
> School of Earth Sciences, University of Bristol
> Wills Memorial Building, Queens Road, BRISTOL BS8 1RJ
> +44 (0)117 954 5429 | w: salwood.weebly.com | t: @SalWood82
> <https://twitter.com/SalWood82>
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-- 
Dennis Hubbard
Chair, Dept of Geology-Oberlin College Oberlin OH 44074
(440) 775-8346

* "When you get on the wrong train.... every stop is the wrong stop"*
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