[Coral-List] Reef biodiversity under global change, new paper

Austin Bowden-Kerby abowdenkerby at gmail.com
Fri Oct 29 04:07:39 UTC 2021

Thanks Christopher for sharing this very useful publication.

With reluctance, I am writing yet again to the Coral List to raise my
concern to authors and reviewers and publishers: to be more careful about
ensuring accurate public perceptions - to speak with a united voice to
reaffirm the seriousness of climate change impacts on coral reefs, and that
the collapse of this most diverse system is just beginning- and that
massive changes in society must happen if we are to save them.

Unfortunately there has been a string of positive sounding titles published
in the past year or so on how coral reefs are adapting in the onslaught of
climate change, and this paper follows that trend.  My fear is that all of
this focus on hints of light among the spreading darkness, no matter how
well intentioned, might backfire by downplaying the urgency of action to
save coral reefs and to lower carbon emissions.

Of course most people have no idea what cryptobiota are, and how much can
persist even if all or most of the corals die! But that is not clearly
spelled out.  So in spite of the papers well developed and precautionary
discussion, the press and non-scientists will not likely read much beyond
the title or abstract, and might conclude that coral reef scientists are
changing their minds about the severity of climate change impacts to coral
reefs, and that it will not be not so bad for coral reefs after all?

My belief is that any title or abstract that presents a positive face on
the dire situation that coral reefs now face, will have the opposite impact
to what we need.  How else will the press perceive these words: "Contrary
to expectations, species richness in the combined future ocean treatment
with both warming and acidification was not significantly different from
the present-day control treatment.  Rather than the predicted collapse of
biodiversity under the dual stressors..."

Besides the positive spin, I have a few other comments and thoughts:

1. I find that this work is most relevant to life in tide pool and reef
flat environments, but that is not discussed in the paper.  Already living
experiments are taking place on many reefs in the extreme shallows, and not
at temperature peaks of only 30C, but at peaks of >35C every summer!  Some
of these areas are also fringed by mangroves and so have a low pH as well.
Based on the realities in the field, I would crank the temperature up
another 2C and see what you get, because this is too mild as far as the
present situation- also, does a 2C increase in the cool open ocean
translate into a much higher increase in the nearshore?  .

2. I believe that the study has an experimental flaw that makes it unlikely
to represent future conditions that we will face on coral reefs.  The flaw
is the fact that unfiltered seawater flowed in from a diverse and not yet
badly altered coral reef ecosystem, where larvae and various propagules
were abundantly available, but this will certainly not be the case once
coral reefs die.   Again, if the conclusions had focused on understanding
the stressors in the hot and acidified shallows adjacent to relatively
intact coral reef systems, conditions that already exist, I would agree
completely.  The study is relevant to life in the shallows, but I disagree
that we can deduce from it any sweeping conclusions about the future of
coral reef biodiversity.

3. For most of the IndoPacfic, Acropora dominance is typical, while coral
reefs in Hawaii are dominated by Porites and Montiipora, which elsewhere
can indicate degraded reef systems, so Hawaii may not be the best place to
look for trends with respect to coral reefs in general.  The reefs of most
of the IndoPacific are ecologically more similar to the Caribbean than they
are to Hawaii.  Not just the lack of Acropora corals and their obligate
species, but the winter water temperatures in Hawaii, are cool to the point
where they look more subtropical than tropical, and so that might explain
why a 2C warming might be beneficial to some organisms?

4. Corals and fish are discounted in the study, supporting the idea that as
long as biodiversity remains high, regardless of a shift in species
composition, that somehow high biodiversity is the goal, regardless of
ecological functioning, geological functioning, and the like.  The
cryptobionts are put on equal standing with the dominant organisms which
create, structure, and maintain the reef, and at face value, and without
that balance, the conclusions are disconnected from the grave reality of
the present crisis.
It is like saying "let's study rainforest diversity by removing the trees
and birds and raising the temperature a little bit, and lowering pH, but
let's keep the inputs coming from the rainforest seeding the experiment
with organisms day by day week by week"  But doesn't discounting the source
of all the biodiversity coming from intact living coral reefs make the
entire experiment meaningless, as far as peering into the future of climate
change and when corals on reefs are mostly dead?

Yes there is a lot of good discussion as to what this all means, and a lot
is cautionary, but it never discusses the relative importance of the
cryptobionts in comparison to the loss of coral cover, and so it does not
remove the simple public take home message that the reefs are still doing
fine and that these results are very hopeful for the future of coral reefs

My sincere apologies Molly and Christopher and team!  As this is way too
critical....  I have let this sit and was thinking of sending this message
to the trash, as I really don't want to hurt people's feelings and to be so
horribly negative.  Sending this off might not be a good move
professionally either, as I need all the friends I can get, but seriously
we really need to correct this very bad trend- I did not want to pick on
this particular paper other than to use it as the latest example in a
series of publications that have the unintended potential to undermine the
resolve of governments and all those who might do something to turn this
situation around.
My observation is that the more authors that a publication has listed, the
least cautious and self-critical the authors seem to become.  But where
were the reviewers, who should have enough background to catch this sort of
stuff I have raised here?  If the peer review process were working in this
case, would it have prevented such bold and possibly erroneous speculations
from being published as facts as well as a key missing assumption, while
missing the true significance of the work?  And now we have what might
become international news, misinterpreted by many, that scientists were
wrong, and that the coral reefs will survive in spite of global warming.

I see the field of coral reef science at a critical juncture, like
foresters who see the glow of the wildfire on the horizon, yet there is no
unified firefighting or disaster management strategy, few staff, and no
funds.  What could we save if we acted now?  The recent GCRMN report showed
a 14% decline in coral cover, which is bad enough, but it was only
reporting on coral cover, and thus has completely missed the phase shift
that is happening on some reefs, from Acropora to Porites, with numerous
local species extinctions in Kiribati and Chagos etc., which are on the
leading edge of the collapse. The GCRMN will only show impact when the
corals die, it does not measure coral diversity or species extinctions. It
is as if the diverse broadleaf rainforest (Acropora reefs) has been flipped
into a lower diversity pine forest (Porites reefs), but the foresters see
all trees as equal, so the monitoring only picks up the change when the
forest shifts to a grassland (algae dominated).

Besides speculations being presented as facts, if your mother, or cousin,
or taxi driver were to read this report on the Hawaii article below, what
would the take home message be?  Judge for yourself.


"New research led by scientists at the University of Hawai‘i (UH) at Mānoa
reveals that the species which dominate experimental coral reef communities
shift due to climate change, but the total biodiversity does not decline
under future ocean conditions of warming and acidification predicted by the
end of the century. The study was published on September 20, 2021, in
the *Proceedings
of the National Academy of Science*. “Rather than the predicted collapse of
biodiversity under ocean warming and acidification, we found significant
changes in the relative abundance, but not the occurrence of species,
resulting in a shuffling of coral reef community structure,” said Molly
Timmers, lead author who conducted this study during her doctoral research
at the Hawai‘i Institute of Marine Biology (HIMB) at the UH Mānoa School of
Ocean and Earth Science and Technology (SOEST).
Feeling very sad, and not wanting to push "send", but it appears that I am
the only one willing to do this.

The harsh fact is that no one is in charge, so there is no war on the
collapse of coral reefs, no unified strategy, no generals, no battle plans-
not that I can see at least!  Please inform me if I am wrong..... the old
strategies of cleaning up the waters and establishing no-take areas is not
the armor that we had hoped.  The only newer strategy that I have read
abandons the front line and focuses on the coral reefs which are doing the
best.  But isn't the devastated front line where the most important lessons
might be learned that might slow the spreading fires from reaching the core
areas? Anyone who has adopted that triage strategy, will not work in or
fund Kiribati, as the reefs are already too far gone- admitting defeat, and
retreat.  But the saddest thing is that the Kiribati government, who are
the only ones who might do something now, relies on the scientific
community for their information, but all they have received is 4-5 very
hopeful sounding reports, so they remain unaware that in spite of the
positive spin, that their coral reefs are mostly dead or have shifted into
an alternate state- with massive local species extinctions- the reefs most
impacted by bleaching on the planet, as indicated by the online multi-year
NOAA data.  Horrific ciguatera and food insecurity is unfolding in this
nation, as the sea level rises.... This is the reality of the front lines.

We are developing battle plans, and are carrying out an assisted natural
recovery strategy for Kiritimati Atoll, published in the recent Vaughn
Edited book on active restoration, and we are also implementing a strategy
to facilitate and accelerate bleaching resistance and adaptation on the
coral reefs of the less impacted areas like Fiji, and I am writing that up

Kind regards,


Austin Bowden-Kerby, PhD
Corals for Conservation
P.O. Box 4649 Samabula, Fiji Islands
TEDx talk https://www.youtube.com/watch?v=7PRLJ8zDm0U

Teitei Livelihoods Centre
Km 20 Sigatoka Valley Road, Fiji Islands
(679) 938-6437

On Tue, Oct 26, 2021 at 4:55 AM Christopher Jury via Coral-List <
coral-list at coral.aoml.noaa.gov> wrote:

> Dear colleagues,
> Given recent discussions regarding reef biodiversity responses to global
> change I wanted to direct you to our new article published in PNAS. The
> title, abstract, and link to the paper follow:
> Title: Biodiversity of coral reef cryptobiota shuffles but does not decline
> under the combined stressors of ocean warming and acidification
> Abstract: Ocean-warming and acidification are predicted to reduce coral
> reef biodiversity, but the combined effects of these stressors on overall
> biodiversity are largely unmeasured. Here, we examined the individual and
> combined effects of elevated temperature (+2 °C) and reduced pH (−0.2
> units) on the biodiversity of coral reef communities that developed on
> standardized sampling units over a 2-y mesocosm experiment. Biodiversity
> and species composition were measured using amplicon sequencing libraries
> targeting the cytochrome oxidase I (COI) barcoding gene. Ocean-warming
> significantly increased species richness relative to present-day control
> conditions, whereas acidification significantly reduced richness. Contrary
> to expectations, species richness in the combined future ocean treatment
> with both warming and acidification was not significantly different from
> the present-day control treatment. Rather than the predicted collapse of
> biodiversity under the dual stressors, we find significant changes in the
> relative abundance but not in the occurrence of species, resulting in a
> shuffling of coral reef community structure among the highly species-rich
> cryptobenthic community. The ultimate outcome of altered community
> structure for coral reef ecosystems will depend on species-specific
> ecological functions and community interactions. Given that most species on
> coral reefs are members of the understudied cryptobenthos, holistic
> research on reef communities is needed to accurately predict
> diversity–function relationships and ecosystem responses to future climate
> conditions.
> https://www.pnas.org/content/118/39/e2103275118
> Best,
> Chris Jury (on behalf of co-authors)
> --
> Christopher P. Jury
> University of Hawai'i at Manoa
> Hawai'i Institute of Marine Biology
> P.O. Box 1346
> Kane'ohe, HI 96744
> Academia.edu profile <http://manoa-hawaii.academia.edu/ChristopherJury>
> Google Scholar profile
> <
> http://scholar.google.com/citations?hl=en&view_op=list_works&gmla=AJsN-F5XCN2Wpv5xaVKMvH49ZNlcyGQ9rhPTlY17Hu0OBXETn1dZp8lplT8l6DdCxoZc1BzbTHMoxJZRVRQhxFt5X8TBa4clDA&user=oLuIGVAAAAAJ
> >
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