[Coral-List] what does this new analysis tell us???
Douglas Fenner
douglasfennertassi at gmail.com
Fri Feb 4 08:24:48 UTC 2022
Alina,
Good point! Which is supported by the Eddy paper which surveyed
people who averaged saying just under 60% coral cover originally. The fact
that there were very few quantitative records taken early on, and of course
zero before that, could be considered compatible with that view. I think
it is a bit suspicious that the first period in the curve is flat as a
pancake while later data shows ups and downs. I don't know why the
earliest data is so flat, though it was flat for a long time. You'd think
there would be at least some hint of decline in the record if reefs had 60%
coral cover originally.
But much of what we have all been saying about the steep decline of
corals is recent, and there the record has lots of data, and shows
variations that make sense, decline in 1998 from El Nino mass bleaching,
decline from recent mass coral bleaching events. That part of the record
is likely pretty good and indicates that our observations of recent decline
are not widespread enough to show that the world's reefs have declined
recently by large amounts. Some yes, but not large amounts. Which is the
good news, I .
That said, your point is good, there is evidence from people's
memory that reefs probably had much more coral cover in the more remote
past. Some of those surveyed in the Eddy paper remember what it was like
in the Indo-Pacific. The Caribbean is important, but it is a tiny part of
the world's coral reef area, you could easily lose it in the Indo-Pacific.
So the Caribbean having huge loses and the world as a whole not having such
loses is not incompatible.
There are very nearly pristine reefs left in the world, though
there are very few. Examples are the NW Hawaiian Islands, the smaller,
uninhabited Line Islands, most of the Marianas (which are uninhabited) and
the Phoenix Is. (lightly inhabited last I knew). Also the northern Great
Barrier Reef (where there are no people), Scott Reefs in NW Australia, and
maybe Ningaloo reef on the west coast of Australia, which has very few
people now and I presume even fewer in the past. Plus Chagos and Aldabra
in the Indian O. All remote and uninhabited by humans. Most of those have
been surveyed. I recommend the article by Peter Vroom, particularly his
paper about whether "coral dominance" may be a misnomer for coral reefs.
Reference below. Take a look at the top graph in figure 2. The US remote
Pacific areas, which include 2 islands in the Phoenix Is, 3 in the remote
Line Is, plus Johnston and Wake, average about 25% coral cover. Most of
those are quite tropical. The NW Hawaiian Is average about 10% cover, they
are high latitude reefs. The remote Marianas islands average about 10%
coral cover, and are geologically young volcanoes. This study is based on
NOAA (US National Oceanic and Atmospheric Administration) data, which like
the AIMS (Australian Institute of Marine Science) monitors using both
transect techniques and the towed-diver (manta board) technique. This data
was collected using towed-diver, as were the AIMS monitoring data in the
graphs I referred to before. Towed-diver data typically reports lower
coral cover than transect data. Why? Because in towed-diver it is much
harder to avoid low coral cover areas such as sandy areas, algae on rock
areas, etc. Transects are almost always taken on "good coral" areas and
avoid those areas, hence higher recorded coral cover. We tend to define
coral reefs by the presence of coral. Diving and especially on towed
diver, it may be hard to evaluate whether there is hard calcareous buildup,
that is, a geological reef. There are rationales for both methods, towed
has less bias towards high coral cover, transects do a better job being
only on what everybody will agree are coral reef ecosystems. So they
differ in bias for absolute coral cover. But both may do just fine in
terms of recording trends over time since that is relative to what was
recorded at the same site in the same way at other times. Recording trends
is the primary goal of monitoring programs. A study that used the exact
same reef area which was surveyed by different techniques produced
reasonably similar coral cover estimates from different methods, including
transect tapes, towed diver, and visual estimates, done by people with
experience with these methods (Jokiel, et al, 2015), reference below. So
we are back to the spatial problem. Typically, even if they are done along
the same coast, towed diver and transect tapes take data from at least
somewhat different areas. The transects cover a much smaller area than the
towed diver, and they are much more likely to be on only the higher coral
cover areas than the towed diver, which covers a larger area and is more
representative of a larger area. Anyhow, that is part of the explanation
of the low coral cover reported in this study. It is unlikely to be due to
humans, there are no people on these islands, and the data was taken after
the most recent bleaching events, though after the 1998 bleaching.
Scott Reef complex in NW Australia had about 42% coral cover when
first monitored in 1995, which increased to about 50% before the mass
bleaching in 1998, and then fell to a bit under 10% and by 2011 had
recovered to about 42%. This comes from the AIMS monitoring program,
https://www.aims.gov.au/sites/default/files/Discovering%20Scott%20Reef%20-%20Reef%20Monitoring.pdf
Chagos had average coral cover that varied between about 54% and 80%
at different depths when first recorded in about 1978, with an overall
average of about 65% and fell to an average of about 15% after the 1998 El
Nino mass bleaching. That comes from Figure 11.6 in Sheppard and Sheppard
(2019), reference below.
The Northern Great Barrier Reef had about 26% coral cover, with up
and down variation but no overall trend, from when it was first recorded
about 1986 to 2010. As shown in their graph in the AIMS monitoring report
I referred to in my previous email.
Ningaloo Reef on the west coast of Australia averaged about 35%
coral cover in the first several years that it was monitored (Gilmour et
al, 2019). Ningaloo is the world's largest fringing reef, so it isn't some
little tiny reef.
Anyhow, most of the studies of pristine reefs do not replicate the high
coral cover reported in the Eddy paper from people's memories, with the
main exception being Chagos which does. Memories can play tricks on us,
and one way they can do that is by not being representative. It is
possible to remember high coral cover areas and forget low coral cover
areas. Even if there are high coral cover areas, there are likely to also
be low coral cover areas as well. Unfortunately, every method has its own
weaknesses.
All this is not relevant to my observation that there was a lot of
attention paid to the loss of coral reef cover on the Great Barrier Reef in
recent years, but I know of NO attention paid to the recovery of coral
cover on the Great Barrier Reef. The popular press tends to focus on bad
news, that's what gets people interested. Stories like "there were no
problems yesterday" simply don't get printed, nobody's interested. It is
not just the press, it is driven by reader and viewer interest. But we're
trying to be scientists and objective and not biased, aren't we??? If we
were, we'd be paying as much attention to the recovery as to the loss. But
it doesn't fit with the prevailing view that the reefs are dying, and it's
not bad news. So no interest. I think we can do better, we scientists say
we work on finding out the truth about nature, not neglecting things that
don't fit with our views. It is said that Darwin was always looking for
information that didn't fit with his theory of evolution. We don't seem to
be doing that, I think we can do better.
Cheers, Doug
Vroom, P. S. 2011. "Coral dominance": a dangerous misnomer? Journal of
Marine Biology Article ID 164127
Jokiel, P. L., et al. 2015. Comparison of methods to estimate coral cover
in the Hawaiian Islands. PeerJ 3:e954
Sheppard, C and Sheppard, A. 2019. British Indian Ocean Territory (Chagos
Archipelago) Pp. 237-252 in Sheppard, C., World Seas, an Environmental
Evaluation, Vol. 2. Elsevier.
Gilmour et al. 2019. The state of Western Australia's coral reefs. Coral
Reefs 38: 651-667.
On Thu, Feb 3, 2022 at 4:35 AM Alina Szmant <alina at cisme-instruments.com>
wrote:
> Hi Doug:
>
> I commend your hopeful enthusiasm, but as you imply in later parts of
> uour long post, I feel that your optimism is a victim to the shifting
> baseline. Those of us old enough to remember coral reefs in the 69s and
> 70s when there was little coral cover measurements taking place can attest
> to many (not all) reefs have upwards of 60% coral cover. Thus persistent
> 28-30 % cover is still a loss of 50% compared to near 'pristine' levels
> back when. Likely the more sensitive species are gone replaced by more
> tolerant ones. By still much less coral building 3-d structure than decades
> ago. Sadly my observations for the Caribbean area from Curacao to Florida
> Keys leaves no room for optimism. Many reefs are doqn to below 15% cover.
> It would be great if the much larger Indo-Pacific region is doing better.
>
> Alina
>
>
>
>
> Dr. Alina M. Szmant, CEO
> CISME Instruments LLC
>
>
>
> -------- Original message --------
> From: Douglas Fenner via Coral-List <coral-list at coral.aoml.noaa.gov>
> Date: 2/3/22 7:44 AM (GMT-05:00)
> To: Lauretta Burke <lb.was.here at gmail.com>
> Cc: coral list <coral-list at coral.aoml.noaa.gov>
> Subject: [Coral-List] what does this new analysis tell us???
>
> I want to start out by thanking Lauretta and everyone involved in this
> for all the time and effort that went into this. This is fantastic. I see
> that the graphs on average world coral cover and algae cover are based on
> the latest report from GCRMN (Global Coral Reef Monitoring Network) which
> it has a link to. They did the work in the Herculean task of putting
> together the vast number of sources of data into regional reports and into
> the world report. We owe them a debt of gratitude. To my knowledge, this
> is the very first time that anyone has produced from hard data, a graph of
> the trends of coral cover for the whole world as well as regions in the
> world. This is indeed FANTASTIC in my view.
> To find the graph in the report, first click on the link Lauretta gave
> for "Global Coral Reef Profile." Go down just a little bit to the "Table
> of Contents" on the right, and click on "coral reef condition." Some pink
> bars will jump up. Move down just a little and find "Live hard coral
> cover" on the left, and "live algae cover" on the right. Scroll down just
> a bit to the graphs for these two things. Pink on the left for the coral,
> and green on the right for algae.
> Here is where I have to compliment Lauretta and the team there.
> Notice the axis on the left, down at the bottom is 0% cover. This is the
> way it should be graphed, because it allows the reader to see the relative
> magnitude of the changes. The original graph in the GCRMN Status report I
> found truncated that axis, the axis only goes down to 25%. That magnifies
> the variation in the graph. If you want to see the GCRMN report, just
> click the black disc with the exclamation point to the right of the title,
> and that opens an explanation, scroll down to the end and there is the link
> to the GCRMN report, and click on it and it will open up in a separate
> window. You have many sub-reports to choose from and browse through.
> Easiest to see the graph is to click on the executive report. The graph is
> on page 17.
> Now a question, what is the biggest, most general thing the graph
> shows?? I think that's best seen in the graph that is in the Resource
> Watch report Lauretta pointed to. What I see is stability!!! What???
> Aren't most of the world's coral reefs badly degraded or even dead???
> Shouldn't it show drastic decline??? Not according to this graph based on
> something like 12,000 data sets from all over the world. HUH??? Oh, there
> is some decline, indeed. But look at the size of the decline. Down from
> about 33.5% to 30% in the first decline, and 28% in the second. Does that
> fit with the impression we get from various published papers and the
> media?? How many media reports have said that half the coral on the Great
> Barrier Reef are dead??? I don't remember the exact terminology they
> used. If they said "have died," well that's true. Look at the AIMS
> monitoring data, the most recent version of it. I'll give the link below.
> Yes, half of the corals died, but amazingly, and contrary to all
> expectations I would suggest, coral cover completely recovered!!! (isn't
> that the definition of "resilient"?) I've pointed this out before, not a
> single person posted a response on coral-list and not a single person sent
> me an email about it. Not one. Huh???
> OK, now with a straight face, tell me that the world's coral reefs
> are dead or dying. Tell me that half the corals on the Great Barrier Reef
> are dead. They aren't any more!
> Please, tell me is this good news or bad??? Surely it is good news
> for coral reefs. So why aren't people celebrating??? Why aren't there
> "the corals aren't all dead" parties going on all over the world? Where is
> the confetti, the balloons, the silly hats and the noise makers?? Don't we
> want the reefs to survive? Surely it isn't because no one cares,
> scientists have been crying in their masks looking at dead reefs.
> Don't get me wrong, there is no evidence that all that mountain of
> reports and evidence of individual reefs being mostly dead and the
> Caribbean having had a huge decline in corals are wrong. None whatsoever.
> I trust every one of them. The El Nino in the Indian Ocean killed about
> half the coral there over the whole ocean. Some reefs like Chagos had
> about 90% of their corals killed. There are published pictures showing
> it. It is beyond discussion, it was real. But notice, some of those reefs
> recovered. When I got to go to Chagos in 2014 I think it was, there was
> lots of coral. If I didn't know the history, I would not have suspected
> that 90% of the corals had been killed. And of course the more recent
> bleaching years have done it again in Chagos. My fingers are crossed that
> the corals recover again. Maybe they will, maybe they won't. Scary!
> Anyone can ask, "how many times can they recover?" As these events happen
> more often as the world warms, when will they happen so often the corals
> can't recover? That time is coming whether we like it or not, and will be
> here sooner than any of us want. We're sitting on the railroad tracks as
> the train approaches going full blast.
> OK, there are lots more things to discuss and figure out. For one,
> is 35% cover "high" cover??? Not in my book. The Eddy et al paper
> reported that scientists who saw reefs before the decline began estimated
> from memory coral cover of 58 or 59%. That is a LOT higher than 35%. I
> notice that there is no hint of decline early on in this graph. So that's
> a puzzle. Some people have even thought that originally coral reefs had
> near 100% coral cover. 35% is a LONG ways from that.
> Coral monitoring data is NOT perfect. BUT, in the absence of any
> other hard data on coral cover in the past, isn't this the "best available
> scientific evidence?" The "best available scientific evidence" is often
> quoted as the best standard for management. Why?? Wouldn't "perfect"
> evidence be better?? Sure, everybody knows that. But we NEVER have that.
> If we wait for perfect evidence to manage anything, we will never manage
> anything, and we'll lose the resource. That's why it was adopted for
> fisheries management (though all too often probably not followed). Science
> is progress, rarely if ever perfection or final proof. Always subject to
> improvement in the future.
> So I will state that I think this graph is now the "best available
> scientific evidence" on the trends and status of coral reefs around the
> world. Anybody can take a shot at showing me wrong. Might be good if
> people did.
> For one thing, the methods used to get to such graphs are not very
> transparent to us average nobodys (I'm talking about myself!) who are not
> experts in statistics and methods for doing this sort of thing. I'll point
> out one major problem I've never seen addressed. And that is that coral
> reefs are famously "patchy." Stated differently, they have high spatial
> variation over a wide range of scales. If you want to detect change, you
> need to hold other variables constant, particularly ones that are powerful
> and could produce large artifacts. Spatial differences are one such
> variable for monitoring. If someone takes data on coral cover at one
> location one year and a different location at a later time, and claims that
> the corals have gone down or up, does the data support that conclusion???
> Well, strictly speaking, NO. Except during powerful disturbances, coral
> change over time tends to be gradual, growth is gradual and slow. Spatial
> difference can be huge. One spot has near 100% coral, another is nearly
> all sand, and on and on. Now for these big studies, they have to combine
> data from many different locations, and it is a good assumption that the
> different locations have different coral cover at the same time. By
> "locations" I mean everything from transect sites to islands or reefs to
> archipelagoes. It is common, even typical, for monitoring programs to
> start, run for a while, then stop, maybe restart. Combine lots of records
> from different places, when there are differences between locations, and
> there are gaps of missing data from particular sites in some years, and for
> reefs or islands or even archipelagos, all at different times. How do
> people doing these things balance those things out to minimize the
> artifacts due to spatial location and get only signal from changes in
> time??? Ideally, every location would have data for the entire time
> period. We KNOW that is NOT true, there is very little early data and
> mountains of late data. What if the locations for early and late are
> different?? They HAVE to be different. OK, I'm NOT saying that the
> analyses have no way to pull the temporal signal out and throw away the
> spatial signal. I just don't know how they do it, or even whether they do
> it at all. Often methods sections are very densely written and someone who
> isn't an expert on the exact thing the paper is about could never replicate
> the paper. All too often.
> So OK, I confess to raising a lot more issues than I can address, but
> maybe someone can do that for us.
> The bigger picture, however, is that there is a clear conflict
> between what this data shows, and what we have been saying. There is no
> conflict between what has been reported before, destruction of coral has
> surely occurred everywhere it has been reported. BUT, BUT, no one has seen
> all the world's reefs. Our monitoring sites are not chosen in a random
> fashion across archipelagoes, islands, or reefs, even if they are within
> reefs. It is too late to change that for data from the past. But at least
> shouldn't we acknowledge it? Our monitored reefs may be unrepresentative
> of the world's reefs. Maybe. The first report of a huge decline that I
> know of was Terry Hughes' report of the decline in Jamaica after Hurricane
> Allen and the die off of Diadema. As subsequent analyses were done, the
> decline in other Caribbean reefs was not so bad. Then analysis of the
> Pacific reported less decline than the Caribbean (so Jamaica decline was
> real, but not completely representative). The Indian O certainly got hit
> hard by the 1998 El Nino mass bleaching, but some recovered. Now this
> analysis reports an amazingly small amount of coral decline when you look
> at the world as a whole. That implies that there are a lot of reefs that
> have not declined.
> Shouldn't we be celebrating? I have to admit, that I'm very
> suspicious that people are disappointed that it doesn't show the death of
> the world's coral reefs. But notice, this has nothing to do with the
> predictions of the upcoming decimation of coral reefs, nor the many reports
> of many individual reefs having experienced mass mortalities. All those
> are real. There are just a lot of reefs that haven't yet had bad declines.
> I think this new graph is the "best available scientific evidence"
> now, until we get better. I think we need to change our tune, and
> celebrate a little (even though this does NOT mean that we humans saved the
> reefs, rather simply that we haven't killed them all YET.) We are blessed
> with more coral in the world than we thought we had. That's GOOD NEWS!
> (no denying it won't last, though!!)
>
> In summary, I'd like to paraphrase Mark Twain. When a newspaper reported
> he had died, he said "My death has been greatly exaggerated." Clever guy.
> Of course later he did pass away.
>
> So I'll paraphrase him: "The deaths of the world's coral reefs has been
> greatly exaggerated." Anybody care to argue otherwise?? (I actually would
> welcome that, I think it needs to be discussed and NOT IGNORED.)
>
> Personally, I think we need to make our statements, especially to the
> press, so that they fit with the actual "best available scientific
> evidence" the best we can. If we cry "wolf" too many times and there is no
> wolf, and then when there really is a wolf, nobody may come to help, and
> the reefs will be in even worse trouble. No??
>
> Cheers, Doug
>
> Eddy, T. D., Cheung, W. L., and Bruno, J. F. 2018. Historical baselines of
> coral cover on tropical reefs as estimated by expert opinion. PeerJ 6:
> e4308
>
>
> The AIMS most recent monitoring report:
>
> https://www.aims.gov.au/reef-monitoring/gbr-condition-summary-2020-2021
> Scroll way down for the graphs for the northern, central, and southern
> Great Barrier Reef. See the huge declines and the amazing recovery.
>
> On Fri, Jan 28, 2022 at 10:40 AM Lauretta Burke via Coral-List <
> coral-list at coral.aoml.noaa.gov> wrote:
>
> > The World Resources Institute
> > <
> >
> https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.wri.org%2F&data=04%7C01%7CLauretta.Burke%40wri.org%7C8ddf465f154a47ab0dae08d9e299a1d3%7C476bac1f36b24ad98699cda6bad1f862%7C0%7C0%7C637789971762899865%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=y6jbaqL74YGSqFtABvZ8%2BTXHvL4viuHMvOqcUzU15nA%3D&reserved=0
> > >
> > and partners have developed a *Global Coral Reef Profile*
> > <
> >
> https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fresourcewatch.org%2Fdashboards%2Fcoral-reefs&data=04%7C01%7CLauretta.Burke%40wri.org%7C8ddf465f154a47ab0dae08d9e299a1d3%7C476bac1f36b24ad98699cda6bad1f862%7C0%7C0%7C637789971762899865%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=cqV65BjexngQp%2FQfpbPfGUfTqEdzS3rSifOaSidngGo%3D&reserved=0
> > >
> > and ten regional dashboards
> > <
> >
> https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fresourcewatch.org%2Fdashboards%2Fcoral-reef-dashboards&data=04%7C01%7CLauretta.Burke%40wri.org%7C8ddf465f154a47ab0dae08d9e299a1d3%7C476bac1f36b24ad98699cda6bad1f862%7C0%7C0%7C637789971762899865%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=q8M2cAkxUkhTqPK51p4ph6NvLoM1Ur3h3Me%2BAIBlUZA%3D&reserved=0
> > >
> > which provide an overview of the world’s coral reefs including
> > consolidated, map-based information and indicators on the value of coral
> > reefs, the threats they are facing, the factors which promote coral
> > resilience, progress on protecting reefs, and what actions are needed to
> > save them.
> >
> > The dashboards integrate information from the Global Coral Reef
> Monitoring
> > Network, NOAA Coral Reef Watch, Mapping Ocean Wealth, UNEP, Global
> Mangrove
> > Watch, Protect Planet / World Database on Protected Areas, MPAtlas, 50
> > Reefs, and data on local threats to coral reefs, including water quality.
> > The maps and indicators provide links to all the original data sources
> and
> > data providers.
> >
> > See https://resourcewatch.org/dashboards/coral-reef-dashboards
> > <
> >
> https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fresourcewatch.org%2Fdashboards%2Fcoral-reef-dashboards&data=04%7C01%7CLauretta.Burke%40wri.org%7C8ddf465f154a47ab0dae08d9e299a1d3%7C476bac1f36b24ad98699cda6bad1f862%7C0%7C0%7C637789971762899865%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&sdata=q8M2cAkxUkhTqPK51p4ph6NvLoM1Ur3h3Me%2BAIBlUZA%3D&reserved=0
> > >
> > for access to all.
> >
> > Please send me any comments.
> >
> > Best,
> >
> > Lauretta Burke (lauretta at wri.org)
> > _______________________________________________
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