[Coral-List] Coral on the Great Barrier Reef was 'cooked' during 2016 marine heatwave. REALLY? REALLY? REALLY?

Wed May 9 05:50:58 EDT 2018

From Craig Steinberg, Senior Oceanographer, AIMS. 

The slides referred to can be accessed at:
https://www.dropbox.com/s/wa2gfvw7we23i9o/AIMS%20response%20to%20Burrows%20-%20Wooldridge_20180430.pdf?dl=0
---------------------------------------------------------------

Hi Scott - to correct and clarify a few things raised in your post we provide a few background slides (see link above) with explanations below

1) Scott refers to high level of thermal stress in the 2008-2009 summer compared to 2015-2016.  If you follow the link he provides to support this, it shows for 2015-2016 the NOAA predicted level of stress for March-June 2016 (i.e. after the main stress event – mid Autumn to early Winter).  Similarly, his inferred level of thermal stress for 2008-2009 is again based on NOAA’s projected levels of stress. Although temperatures were very warm in December 2008 they cooled off January-February 2009. In both cases he is NOT using the actual, measured levels of thermal stress/SSTs but NOAA projected levels (and for 2015-2016 he uses these for the March-June, i.e. not at the time of years when corals most at risk).

On the pdf attachment "AIMS response to Wooldridge" Slide 1: we have compiled the NOAA DHW plots comparing the footprint of accumulated heat stress for 2016 & 2017 vs 2008 and 2009. We have used the March 21 time point which accumulates the heat for 12 weeks from Jan 1-Mar 21 to capture the Summer. There is clearly a much stronger heat stress during the recent events throughout the North in 2016 and the Central & North in 2017, which matches our in water and aerial assessment of bleaching in both years. In 2008 and 2009 there is not a single reef region on the shelf which exceeds 3-4 DHW’s compared to MAX DHW’s in the 8-11 range for reef regions that bleached in 16 and 17. 

So in summary the DHW product has been a reasonable indicator of bleaching and Scott has mischaracterised 2008 and 2009 as having greater stress from incorrect forecasts of an autumn/winter period and not used actual observations through summer. 

2) Slides 2-5 summarise what did occur during 2008-2009:  Early summer warming and a hotter forecast for the rest of the summer, however the GBR then had significant monsoon rainfall during January and then TC Hamish moved SE parallel to the GBR cooling surface waters and reducing thermal stress (albeit producing significant wave damage to a vast region of the coral reefs)

So there is a fundamental misunderstanding by Scott of what happened that summer.

2) Wooldridge also refers to 2008-2009 as a strong La Nina event based on the atmospheric Southern Oscillation Index of ENSO.  Based on the SOI over the May-April year, SOI = 8.6 compared to 18.9 in the very strong La Nina of 2010-2011.  The SOI can be a quite noisy series and we find the Nino 3.4 SST index a better measure of ENSO activity. See Slide 6.  For 2008-2009 this was -0.36C compared to -1.11C in 2010-2011.  For 2015-2016 the SOI was -14.9 and the Nino3.4 was +2.12C.  So, you could possibly describe 2008-2009 as a weak La Nina.

Also note that although El Nino events typically tend to be associated with unusually warm late summer SST on the GBR, there is no consistent typical SST pattern associated with La Nina events.

3) Background on Wooldridge’s hypothesis that increased nutrients from upwelling exacerbates bleaching 

Context for the paper by Baker et al., 2018 “Climate change promotes parasitism in a coral symbiosis” that test's Scott's hypothesis.

Baker et al. (2018) found that that under increased (but sub-bleaching) temperature the symbionts assimilate more nitrate and pass on the energetic costs of doing so by translocating less carbon to their host, the studied coral species Orbicella faveolata. The results supports Scott’s hypothesis.

Kenkel and Bay (2016 and ms in prep) measure carbon translocation under both ambient and heat stress conditions, and demonstrate that carbon limitation following heat stress may exacerbate bleaching in 4 out of 6 investigated coral species. 
These results support both Wooldridge (in press) and Baker et al. (2018), but also illustrate that not all species conform.

Based on a review of research that showed various mechanisms by which the availability of excess nutrients (nitrogen, phosphorus and carbon) can increase the susceptibility of corals to bleaching, the 2017 Scientific Consensus Statement (Chapter 1, Schaffelke et al. 2017) concluded: 
“It is expected that improvement of water quality would improve the tolerance of inshore corals to thermal stress, although observations during the 2016 bleaching event suggest that good water quality may not add extra benefit during very extreme thermal stress events.”

AIMS has a current NESP-funded project (led by Line Bay & Neal Cantin) to further investigate the link between water quality (incl. nitrate availability) and thermal tolerance. This project will use a combination of field observations of bleaching, environmental modelling (collaboration with CSIRO) and SeaSim experiments.

4)  Scott is arguing that summer offshore upwelling can predispose the reefs with a high sensitivity to thermal stress. 
Scott does not discuss the counter action of upwelled water having reduced temperatures, and therefore buffering the ‘surface - down’ heating. Upwelling is a process in which deep, cold and nutrient rich water rises toward the surface. These nutrients “fertilize” surface waters, meaning that these surface waters often have high biological productivity. Both reduced temperatures and nutrients delivered via upwelling can be mixed, dissipated and utilised, and to understand what dominates in terms of impacts (temp reduction as  an ameliorating  impact, or increased nutrients as deteriorating impact) we need more process based studies. If upwelling of nutrient rich waters were to exacerbate the coral bleaching response then we could possibly expect the eastern Torres Strait and certainly the outer ribbon reefs of the NGBR to show more bleaching in 2016. Slide 7 shows significant MODIS Chla in these regions and also cool waters from the upwelling on Feb 22, 2016. This cooling from upwelled water is quite persistent as it also shows up in March during the peak of the bleaching. These areas were the only areas that did not bleach in the region and so we conclude that the thermal cooling is the dominant factor ameliorating the response here.

5) Thermocline shallowing during El Nino
Steinberg (2007) is invoked in some of the arguments about the characterisation of ENSO thermocline variability however it isn’t well recounted by Wooldridge. The schematic (Fig 3.4) courtesy of NOAA/PMEL/TAO describing the basin wide thermocline response (at the equator) is an oversimplification and so it isn’t surprising that Scott expects a similar response on the GBR.

The ENSO thermocline shallowing during El Nino is correct for the West Pacific Warm Pool (WPWP)– north of PNG, including the Solomons and via the ITF teleconnection down the WA coast to SA, but not along the east coast of Australia. We have looked at ARGO data and the GBR/Coral Sea may actually do the reverse –as it seems to be de-coupled from the rest of Australia. This is also borne out on the 2016 Palm Passage IMOS mooring near the shelf edge off Townsville where intrusions were suppressed in the summer of that year.

Steinberg 2007 – deliberately leaves the thermocline variability due to ENSO in the GBR as vague. An area that needs further understanding, Sea level observations indicate that ENSO related variation is much smaller than that observed to the north.

“Actual thermocline response along the GBR by ENSO is unknown and may not necessarily occur south of the WPWP, however it can be inferred from the sea level anomaly data that there should be a response. There is an El Niño related sea level increase of 10 cm that can be seen as far south as South Australia. Here the thermocline has been observed to shallow to 60 to 120 metres, 150 metres above the mean thermocline depth. This signal however is thought to propagate from the Indo-Pacific WPWP via the Indo-Pacific throughflow and along the shelf edge wave guide from Western Australia to South Australia, not along the east coast”

Regards, Craig Steinberg and on behalf of Neal Cantin, Janice Lough, Line Bay, Britta Schaffelke and Richard Brinkman.

-----Original Message-----
From: coral-list-bounces at coral.aoml.noaa.gov [mailto:coral-list-bounces at coral.aoml.noaa.gov] On Behalf Of Mark Eakin - NOAA Federal
Sent: Wednesday, 9 May 2018 12:29 AM
To: Coral -List <coral-list at coral.aoml.noaa.gov>
Cc: Russell Reichelt <Russell.Reichelt at gbrmpa.gov.au>; Roger Beeden <roger.beeden at gbrmpa.gov.au>; David Wachenfeld <david.wachenfeld at gbrmpa.gov.au>; Scott Wooldridge <swooldri23 at gmail.com>
Subject: Re: [Coral-List] Coral on the Great Barrier Reef was 'cooked' during 2016 marine heatwave. REALLY? REALLY? REALLY?

For those following this thread, I’m afraid there seems to be some misapplication of our Coral Reef Watch products in these posts. The document cited below in ResearchGate uses our Four-Month Bleaching Outlook to compare the heat stress in 2009 with that seen in 2016:

On Apr 20, 2018, at 12:12 AM, Scott Wooldridge <swooldri23 at gmail.com> wrote:

.... Would it also surprise people to know that the same far northern reefs experienced heating levels in excess of 8-10 degree heat weeks stress (highest level on NOAA 4-level scale) in the austral summer of 2008/09, yet NO bleaching was recorded despite extensive regional searches from dedicated cruises?

See here for a comparison of the heating stress in 2008/09 and 2015/16.

https://apac01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.researchgate.net%2Fpublication%2F324644910_&data=02%7C01%7Cs.bainbridge%40aims.gov.au%7C0c629eb8f19b431b89c608d5b51ff3c8%7Ce054a73b40dc4ae39fce60c537aa6fac%7C0%7C0%7C636614071202599867&sdata=0UfRLZZD3zg1kqMfq0kuAt73JqIzvZIhbq5R4tpZImI%3D&reserved=0
Comparison_of_heat_stress_in_the_northern_GBR_for_201516_and_200809

I remember in great detail the 2008/09 situation because I helped plan cruise trips to search for coral bleaching based on the NOAA heat stress maps. We fully expected to observe severe bleaching, as evidenced by the media reporting of the day. But we found nothing (zero bleaching)

Those products in Figures A and B of the document on ResearchGate are not maps of satellite-observed heat stress. They are the climate model-based Four Month Outlooks of potential heat stress. In fact, Fig. A in that document is totally mislabeled as "Heat stress in the northern GBR for
2015/16 bleaching event”. Instead, it is the global map of the 60% probability outlook of heat stress for March to June of 2016 run on March
15 2016. In short, it is a map of the likely global heat stress in the month _after_ the heat stress had peaked in 2016.

The actual image for the maximum heat stress alert levels during the 2016 marine heatwave would be found at:
https://apac01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fcoralreefwatch.noaa.gov%2Fdata%2F5km%2Fv3.1%2Fimage%2F&data=02%7C01%7Cs.bainbridge%40aims.gov.au%7C0c629eb8f19b431b89c608d5b51ff3c8%7Ce054a73b40dc4ae39fce60c537aa6fac%7C0%7C0%7C636614071202599867&sdata=y0CeJkmPUcxhR55vzukYc0gln3EuSFBw2IHuGQ%2FnbWc%3D&reserved=0
composite/annual/gif/2016/coraltemp5km_baa_max_2016_australia_gbr.gif

In it you can see the reefs of the Far Northern GBR were under Alert Level
2 conditions. In fact, using the Degree Heating Weeks figure found at:
https://apac01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fcoralreefwatch.noaa.gov%2Fdata%2F5km%2Fv3.1%2Fimage%2F&data=02%7C01%7Cs.bainbridge%40aims.gov.au%7C0c629eb8f19b431b89c608d5b51ff3c8%7Ce054a73b40dc4ae39fce60c537aa6fac%7C0%7C0%7C636614071202599867&sdata=y0CeJkmPUcxhR55vzukYc0gln3EuSFBw2IHuGQ%2FnbWc%3D&reserved=0
composite/annual/gif/2016/coraltemp5km_dhw_max_2016_australia_gbr.gif

you can see most of the reefs passed 10°C-weeks of heat stress.

In contrast, the maps for 2009 show that the maximum alert level for those reefs was between a Bleaching Warning and Alert Level 2:

https://apac01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fcoralreefwatch.noaa.gov%2Fdata%2F5km%2Fv3.1%2Fimage%2F&data=02%7C01%7Cs.bainbridge%40aims.gov.au%7C0c629eb8f19b431b89c608d5b51ff3c8%7Ce054a73b40dc4ae39fce60c537aa6fac%7C0%7C0%7C636614071202599867&sdata=y0CeJkmPUcxhR55vzukYc0gln3EuSFBw2IHuGQ%2FnbWc%3D&reserved=0
composite/annual/gif/2009/coraltemp5km_baa_max_2009_australia_gbr.gif

and at DHW values of 3-4 °C weeks:
https://apac01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fcoralreefwatch.noaa.gov%2Fdata%2F5km%2Fv3.1%2Fimage%2F&data=02%7C01%7Cs.bainbridge%40aims.gov.au%7C0c629eb8f19b431b89c608d5b51ff3c8%7Ce054a73b40dc4ae39fce60c537aa6fac%7C0%7C0%7C636614071202599867&sdata=y0CeJkmPUcxhR55vzukYc0gln3EuSFBw2IHuGQ%2FnbWc%3D&reserved=0
composite/annual/gif/2009/coraltemp5km_baa_max_2009_australia_gbr.gif

An important distinction in the pattern of heat stress in those two years is that not only was heat stress much higher in 2016 but the high levels of heat stress clearly penetrated inside the main reef line, whereas in 2009 it stopped at the reef line.

While there is great value to using the climate model-based Four-Month Bleaching Outlook to understand what heat stress _may_ be seen in the future, it is only a probabilistic forecast product and does not record actual values. The satellite-based observation products must be used to understand that stress actually experienced by corals.

Cheers,
Mark

------------------------------------------------------------------
C. Mark Eakin, Ph.D.
Coordinator, NOAA Coral Reef Watch
National Oceanic and Atmospheric Administration Center for Satellite Applications and Research Satellite Oceanography & Climate Division
e-mail: mark.eakin at noaa.gov
url: coralreefwatch.noaa.gov
Twitter: @CoralReefWatch FB: Coral Reef Watch

NOAA Center for Weather and Climate Prediction (NCWCP)
5830 University Research Ct., E/RA32
College Park, MD 20740
Office: (301) 683-3320     Fax: (301) 683-3301
Mobile: (301) 502-8608    SOCD Office: (301) 683-3300

“My hope is that Congress will, at long last, acknowledge that climate change is real, that humans are contributing to it, and that the potential consequences of inaction are far greater than the projected costs of action."
Christine Todd Whitman, EPA Administrator under President George W. Bush, June 18 2014

On Fri, Apr 20, 2018 at 12:12 AM, Scott Wooldridge <swooldri23 at gmail.com>
wrote:

> Dear Coral Listers,
>
>
> I draw your attention to a press release/article describing the 
> findings from the recent Hughes et al. (2018) Nature paper describing 
> the Great Barrier Reef (GBR) coral bleaching event in the austral summer of 2015/16..
>
>
> https://apac01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww.
> abc.net.au%2Fnews%2F2018-04-19%2Fmarine-heatwave-so-&data=02%7C01%7Cs.
> bainbridge%40aims.gov.au%7C0c629eb8f19b431b89c608d5b51ff3c8%7Ce054a73b
> 40dc4ae39fce60c537aa6fac%7C0%7C0%7C636614071202599867&sdata=PbhlhuZ4np
> Hkvf2wXm0VCu49MtMqrzIyDhTJEbDYFeo%3D&reserved=0
> bad-it-cooked-parts-of-great-barrier-reef/9667518
>
>
> Now I am all for making the public aware of the dire situation coral 
> reefs face during the Antropocene. And maybe such reporting of the 
> results is good enough for the general public. But it is certainly NOT 
> good enough for scientists, coral reef managers or policy makers.
>
>
> Indeed, it is my personal opinion that the entire reporting of the 
> 2015/16 coral bleaching event in the previously pristine far northern 
> GBR has been rather misleading - with a single-minded preoccupation 
> with sensationalism and media grab bites rather than the pursuit of 
> science that increases our ability to help save coral reefs into the future.
>
>
> Lets consider the facts for the 2015/16 coral bleaching event, wherein 
> the corals supposedly 'cooked' like crabs in a boiling pot of water. 
> Would it surprise people to know that the corals SEVERELY bleached at 
> surface heating levels less than 3-4 degree heating weeks. Such low 
> heating levels usually only warrant a precautionary warning from NOAA 
> (i.e. level 1 on a 4 level scale) Would it also surprise people to 
> know that the same far northern reefs experienced heating levels in 
> excess of 8-10 degree heat weeks stress (highest level on NOAA 4-level 
> scale) in the austral summer of 2008/09, yet NO bleaching was recorded 
> despite extensive regional searches from dedicated cruises?
>
>
> See here for a comparison of the heating stress in 2008/09 and 2015/16.
>
>
> https://apac01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww
> .researchgate.net%2Fpublication%2F324644910_&data=02%7C01%7Cs.bainbrid
> ge%40aims.gov.au%7C0c629eb8f19b431b89c608d5b51ff3c8%7Ce054a73b40dc4ae3
> 9fce60c537aa6fac%7C0%7C0%7C636614071202599867&sdata=0UfRLZZD3zg1kqMfq0
> kuAt73JqIzvZIhbq5R4tpZImI%3D&reserved=0
> Comparison_of_heat_stress_in_the_northern_GBR_for_201516_and_200809
>
>
>
> I remember in great detail the 2008/09 situation because I helped plan 
> cruise trips to search for coral bleaching based on the NOAA heat 
> stress maps. We fully expected to observe severe bleaching, as 
> evidenced by the media reporting of the day. But we found nothing 
> (zero bleaching)
>
>
> Claims that the corals 'cooked' in 2015/16 are quite simply absurd and 
> show a complete lack of understanding of the eitology of natural coral 
> bleaching. Rather than a preoccupation with sensationalism and media 
> grab bites, the key question driving the data analysis of the 2015/16 
> bleaching event should be, 'why such high bleaching sensitivity at low 
> thermal stress?' or reposed differently 'why such low sensitivity to 
> high thermal stress in 2008/09?' And overarching all this, 'what does 
> this mean for managing the GBR?', i.e. what can we learn from these 
> 2-events that helps provide managers with new levers to increase the 
> 'resistance' of corals to warming sea temperatures.
>
>
> In my next post, I will offer some personal insight into the above 
> questions.
>
>
> These are important times for coral reef research. We need to recommit 
> to good science. We need to ignore sensationalism at all costs. Corals 
> did not 'cook' on the far northern GBR in 2015/16. In fact they 
> severely bleached at temperatures which are not normally associated 
> with mass bleaching events. This is significant and should be clear 
> and evident to all. Indeed, this fact holds the key to the survival 
> (or not) of coral reefs into the future.
>
>
> Scott
>
>
> https://apac01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww
> .researchgate.net%2Fprofile%2FScott_Wooldridge&data=02%7C01%7Cs.bainbr
> idge%40aims.gov.au%7C0c629eb8f19b431b89c608d5b51ff3c8%7Ce054a73b40dc4a
> e39fce60c537aa6fac%7C0%7C0%7C636614071202599867&sdata=MGCI2S0U0WQsMtl7
> js%2B3Xb3JrSXsjazMc2PkQR2mcTM%3D&reserved=0
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-- 

C. Mark Eakin, Ph.D.
Coordinator, NOAA Coral Reef Watch
National Oceanic and Atmospheric Administration Center for Satellite Applications and Research Satellite Oceanography & Climate Division
e-mail: mark.eakin at noaa.gov
URL: coralreefwatch.noaa.gov
Twitter: @CoralReefWatch <https://apac01.safelinks.protection.outlook.com/?url=https%3A%2F%2Ftwitter.com%2Fcoralreefwatch&data=02%7C01%7Cs.bainbridge%40aims.gov.au%7C0c629eb8f19b431b89c608d5b51ff3c8%7Ce054a73b40dc4ae39fce60c537aa6fac%7C0%7C0%7C636614071202599867&sdata=JA1XYEDOPGjZUsWZq2TfyZ4xnCSgUGHx6aA9HUS2V9k%3D&reserved=0> FB: Coral Reef Watch <https://apac01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.facebook.com%2Fcoralreefwatch%2F&data=02%7C01%7Cs.bainbridge%40aims.gov.au%7C0c629eb8f19b431b89c608d5b51ff3c8%7Ce054a73b40dc4ae39fce60c537aa6fac%7C0%7C0%7C636614071202599867&sdata=k2hZ%2B9drfOq%2BIsbfIk0GSYKyq5I%2F2hPpmgozEi3C168%3D&reserved=0>

NOAA Center for Weather and Climate Prediction (NCWCP)
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