[Coral-List] Mixed Messages
Risk, Michael
riskmj at mcmaster.ca
Sat Aug 3 21:38:51 UTC 2019
Hello Alina, and thank you for the response.
I did not mis-attribute anything you wrote. I said, "We have been led
to believe..." In your 2002 Estuaries paper, you state "The evidence
that nutrient enrichment has widely impacted coral reefs is poor", and
"While nutrient enrichment may be the major factor in the decline of a
few reefs, it appears to mostly play a secondary role..."
In short, you led us to believe this-as I said.
Science advances by consensus. There have not been many others papers
denying the importance of nutrients on reefs. In my limited experience,
I have seen your Estuaries paper cited by (a) your students, and (b)
developers.
I certainly accept that grazing is a major factor-I said some while
back there has been little new in the field since Stephenson and
Searles. There also is no question that global warming, if unchecked,
will put the boots to the few reef remnants that still exist. Our 1997
paper still scares me (Smith et al., Nature 386: 818), because we
suggest that "...the initiation of the Younger Dryas may have taken
place over as few as 5 years". The Younger Dryas, some believe, was a
major reorganisation of Atlantic circulation, triggered by a meltwater
event-of which we currently have sufficient. The final blows from
climate change may therefore come more quickly than we already fear.
What bothers me is the decades-long reluctance by many reef biologists
to accept the importance of nutrients. Where would reefs be to-day if
the worlds' reef biologists had stood up on their hind legs 40 years
ago and shouted with one voice "Clean up the freakin water!" but they
were collectively unable to assemble their feces, and chased various
shiny objects.
There never should have been the slightest doubt about the importance
of nutrients. In the late 1960's and early 70's, Colin Stearn and Terry
Scoffin and their students produced an enormous study of the carbonate
budget of a then-healthy reef, Barbados. They showed us, almost a
half-century ago, that accumulation rates of even a healthy reef were
within the error bars of destruction (bioerosion) rates. We all know
the response of bioerosion, especially by algae and sponges, to
increased nutrients. So by 1977, we knew that bioerosion was an
extremely important aspect of reef health, quantitatively more
important even than coral growth rate.
Anyone who doubts the tendency of reef biologists to chase shiny
objects, I invite them to tabulate papers in, say, Coral Reefs. By
rights, half those papers should cover aspects of bioerosion. Hoo Boy.
It is time to accept that, with a few notable champions, this subject
has been sadly ignored. (Hi, Christine.)
I appreciate that you "may change your mind" after you read Brian's
paper-which was, after all, the origin of this thread. I am well aware
you do not believe eutrophication has been the cause of the decline in
Florida's reefs. If you have not been convinced by "Sewage-derived
nitrogen sources have persisted at the Backcountry, Lower Keys and
Middle Keys reef sites since the 1970s and there has been a marked
increase in d15N since ca. 1993, suggesting even greater insult to the
reef ecosystem from land-based sources of pollution" (Ward-Paige et al,
2005a) or "Sanctuary wide, coral cover declined while Clionid sponge
abundance increased from 1996 to 2001" and "Coral loss in the Florida
Reef Tract is a result of land-based stress, rather than "global
change" (Ward-Paige et al 2005b) then I don't know what it would take.
Mike
(ps-some may feel I have been hard on reef biologists. Suck it up. M
Risk, PhD Biology.)
Ward-Paige, C.A., Risk, M.J., Sherwood, O.A., 2005a. Reconstruction of
nitrogen
sources on coral reefs: d15N and d13C in gorgonians from the Florida
Reef Tract.
Marine Ecology Progress Series 296, 155-163.
Ward-Paige, C.A., Risk, M.J., Sherwood, O.A., Jaap, W.C., 2005b.
Clionid sponge
surveys on the Florida Reef Tract suggest land-based nutrient inputs.
Marine
Pollution Bulletin 51, 570-579.
On Aug 1, 2019, at 12:39 PM, Alina Szmant
<[1]alina at cisme-instruments.com> wrote:
Hello Mike:
1) I did NOT write that coral reefs are the " the ONLY ones not
affected by nutrients (Szmant, 2002)." Read the paper carefully with an
open mind and you will see that. My objective was to critically review
a contentious issue where some folks put the answer ahead of the
question and data. My points were that: a) nutrients can be a cause of
algal overgrowth but so can a bunch of other factors such as loss of
herbivory (tons of experimental work showing less grazing more
impactful than moderate nutrient enrichment). B) Lots of great reefs
that have good historical accretion and high coral cover (at least back
in prior decades) in spite of natural nutrient enrichment such as
seasonal upwelling. C) There are many places remote from humans, with
clear as gin water column and BDL nutrient concentrations where corals
are in worse shape that reefs near humans because global warming killed
them. D) Physiologically, corals are animals and they need nutrients
from both heterotrophy and uptake of inorganic and organic nutrients to
survive and grow. And they grow better and faster and have heathier
tissues when they get the right kind of ambient nutrient (particulate
and dissolved) regime for their physiology. Lots of experimental work
out of Australia (Ken Anthony's work and others), aquarium community,
showing importance of feeding to coral health and grow, that varies by
species.
2) Of the two cases you cite where there was rapid recovery after
reducing nutrient enrichment/eutrophication by management actions:
Kaneohe Bay was not a fast or steady recovery because there was a lot
of nutrient loading in the sediments near the low-circulation area near
the original outfall, and it took decades for the corals to come back,
and there have been other causes of coral decline in that area
unrelated to nutrient enrichment in the decades after that. With regard
to the other, I don't know much about Worthing Bay, and couldn't find
any scientific work about the effects of the sewage spills, which have
been recent and apparently government is working to remedy. There are
many more examples of where corals and reef community structure has
improved after grazers returned, or how they have gone down hill after
bleaching coupled with disease outbreaks have killed the corals and
other temperature sensitive organisms.
It is not a dichotomous choice. Both elevated temperatures and degraded
water quality can negatively impact corals and coral reefs, but one
hammer is much bigger and more widespread than the other: global
warming is just that: GLOBAL, reaching even those outpost where humans
are scarce. Reef condition is generally worse near large human
settlements, no surprise. The issue is apportioning the effects and not
expecting to sell an expensive "solution" to the public that won't work
for a particular place because water quality may not be the cause of
the problem. I do believe that the Florida Keys is one of those places
where the natural system has great flushing capacity, and
eutrophication of the reef ecosystem is not has not been happening.
This doesn't mean I support dumping sewage and other types of nutrient
sources on the reef, why would I? But It does mean that anthropogenic
eutrophication has not been/is not now, the cause of the decline of
corals in the Florida Keys. I may change my mind after I read the
newest Lapointe paper more carefully, but I doubt it.
Alina
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-----Original Message-----
From: Coral-List <[6]coral-list-bounces at coral.aoml.noaa.gov> On Behalf
Of Risk, Michael via Coral-List
Sent: Wednesday, July 31, 2019 10:16 AM
To: Douglas Fenner <[7]douglasfennertassi at gmail.com>; Steve Mussman
<[8]sealab at earthlink.net>
Cc: coral list <[9]coral-list at coral.aoml.noaa.gov>
Subject: Re: [Coral-List] Mixed Messages
Doug:
Too long.
I would remind -listers that there have been (as far as I know) only
two studies of what happens to a reef when the water is cleaned up:
Kaneohe Bay Hawaii, and Worthing Barbados. In both cases, recovery
surely an aspect of "resilience") was rapid.
The interesting (and depressing) aspect of this is, why has the coral
reef biological community been so slow to accept the impacts of
land-based stresses? The reluctance sometimes reaches heroic
proportions. In previous discussion on this thread, when Steve asked
how to reconcile the paper showing bleaching on the GBR and Brian's
30-year Looe Key work, some bright spark suggested that the GBR work
covered a huge area, whereas Brian looked only at Looe Key. As though
Looe Key were the only spot in the world's oceans where N enrichment
has occurred. (And I point out that the monitoring on the GBR is
incapable of detecting land-based stresses-see Reef Encounter, 1988.)
Due to a lot of foot-dragging, we have been deprived of a crucial
experiment: how will healthy coral ecosystems survive global warming?
In 2002, Gardner et al showed us that the Caribbean had lost >1/2 its
coral by 1980. Recent Florida efforts emphasize transplanting corals,
without tackling WQ issues. Ten years ago I said (MPB Editorial):
"I will digress here a moment to lament the current state of coral reef
science politics. Somehow, we are led to believe that, out of all the
ecosystems on the planet, reefs are the ONLY ones not affected by
nutrients (Szmant, 2002). Some of this debate is no doubt truly driven
by responsible people going where the data lead, but a cynic might note
the confluence of development money and political pressure with the
willingness of suits to say it's OK to dump/ dredge/clear/whatever,
because it's all grazing and overfishing."
________________________________________
References
1. mailto:alina at cisme-instruments.com
2. http://www.cisme-instruments.com/
3. https://www.youtube.com/watch?v=VAYeR9qX71A&t=6s
4. https://www.youtube.com/watch?v=Fa4SqS7yC08
5. https://youtu.be/QCo3oixsDVA
6. mailto:coral-list-bounces at coral.aoml.noaa.gov
7. mailto:douglasfennertassi at gmail.com
8. mailto:sealab at earthlink.net
9. mailto:coral-list at coral.aoml.noaa.gov
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