[Coral-List] fish and algae

Dennis Hubbard dennis.hubbard at oberlin.edu
Tue Feb 18 13:06:03 EST 2014

Hi Alina:

It's nice to know that I can always count on a reasoned and unbiased
observation from you. I hope people keep responding, but my sense is that
the discussion will eventually have to go in the direction of, "So, what do
we do? Kill damselfish, increase their predators, do something an the algal
side, or suck it up and watch the results of our past actions. To me, this
is where science meets management. Will listing corals negatively impacted
do anything to fix this? If we are going to insert ourselves into the
natural system.... again..... what specifically do we do, other than
"something"? Unless something has changed in the science, adding nutrients
into the mix muddies the water even more. What fun!!


On Tue, Feb 18, 2014 at 10:28 AM, Szmant, Alina <szmanta at uncw.edu> wrote:

> Margaret Miller and I looked at damselfish effects on large coral heads
> back in later 1990s.  Very large Montastraea faveolata heads (now
> Orbicella) had pretty significant damselfish laws up on the tops and sides
> of colonies that were many hundreds of years old.  Those colonies would
> obviously not have grown to those sizes with large lawns on their upper
> surfaces, thus this was a new issue for those colonies.  Our hypothesis was
> that lack of predation was allowing the damsels (mostly 3 spot) to be brave
> and have their lawns up in the reef penthouses instead of hiding in clumps
> of A. cervicornis where they were formerly abundant, but we really had no
> way to actually test that.  I saw similar problems in La Parguera with tops
> of coral heads including large Dendrogyras all colonized by damsels and
> also Echinometra (boring urchins that basically ground down these coral
> heads to sand and silt).
> The question is whether these fish and urchins were more abundant that in
> the good ol' days because of continued over fishing over the decades,
> whether the damsels moved from branching coral hide outs to  reef
> pent-house real estate because of the loss of the branching coral coupled
> with lower demise rate due to predation if their lawns are more exposed, or
> some additional/other issue affecting damsel fish abundance.  In my mind,
> looking back over 40 years of PR diving, and 30 years in the FL Keys,
>  these lawns are more abundant and more exposed than when my attention was
> first drawn to them by Les Kaufman's work.
> "Great minds discuss ideas; average minds discuss events; small minds
> discuss people." Eleanor Roosevelt
> "The time is always right to do what is right"  Martin Luther King
> *************************************************************************
> Dr. Alina M. Szmant
> Professor of Marine Biology
> Center for Marine Science and Dept of Biology and Marine Biology
> University of North Carolina Wilmington
> 5600 Marvin Moss Ln
> Wilmington NC 28409 USA
> tel:  910-962-2362  fax: 910-962-2410  cell: 910-200-3913
> http://people.uncw.edu/szmanta
> *******************************************************
> -----Original Message-----
> From: coral-list-bounces at coral.aoml.noaa.gov [mailto:
> coral-list-bounces at coral.aoml.noaa.gov] On Behalf Of Bill Allison
> Sent: Tuesday, February 18, 2014 8:07 AM
> To: Dennis Hubbard
> Cc: coral-list at coral.aoml.noaa.gov
> Subject: Re: [Coral-List] fish and algae
> Hi Dennis,
> No doubt damsels kill coral. As you suggest, it is most likely that
> underlying causes such as bleaching, pollution, and overfishing tilt the
> playing field too allow more coral destruction, or less construction, or
> both, but it's much more satisfying spiritually and economically to have a
> critter to blame and kill, non?
> On several reefs that I have surveyed over time corals survived only in
> Stegastes nigricans territories after repeat COT outbreaks (I also noticed
> coral survival in damsel territories after the 1998 bleaching). During the
> second COT outbreak all the preferred COT prey were gone and the COT were
> eating whatever was left. Some coral colonies within but near the periphery
> of S. nigricans territories were damaged along their outer edges but apart
> from that, corals in S. nigricans territories survived these invasions
> unscathed. I am not the first to have noticed this (e.g., Glynn and Colgan,
> 1988)
> Glynn, P. W. and M. W. Colgan (1988). "Defense of corals and enhancement of
> coral diversity by territorial damselfish." Proc. 6th ICRS, Townsville 2:
> 157-164.
> On Sun, Feb 16, 2014 at 5:56 PM, Dennis Hubbard
> <dennis.hubbard at oberlin.edu>wrote:
> > When I was a young reef geologist, I was told by most biologists visiting
> > West Indies Lab that Damselfish "farm" the algal turfs and actually crop
> > them for maximum yield. As such, they help maintain this autotrophic
> system
> > which transforms organic carbon and nutrient into a form (algal tissue)
> > that can work its way up the food chain. Walter Adey used turfs to
> maintain
> > balance in his "microcosms" at the Smithsonian, has been a valued
> > consultant to aquaria (including the large GBR tank) and has received
> > patents for "algal scrubbers". So my sense was that the service provided
> by
> > both the turfs and the fish that regulated them is still recognized.
> >
> > I was just looking for photos to shamelessly use for class and came
> across
> > an NPR piece (*Tiny Damselfish May Destroy a Ree*f) dated August 11 in
> > which Richard Harris (who regularly appears on *Morning Edition* and *All
> > Things Considered*) described a "war going on between corals and 'a
> > creeping menace'.... algae". This crux of the story is that parrotfish
> are
> > the "allies of coral" and 'damselfish promote algal growth by killing
> coral
> > to create new space for algal colonization'. Enter the fishermen who have
> > taken out the predators who used to "keep the damselfish in check". The
> > result is that damselfish are disproportionately opening up more space by
> > killing corals while scaring off the "coral-friendly" parrots by shear
> > tenacity.
> >
> > Might anyone put this into perspective for me so I don't tell a story
> that
> > is no longer true? Each of these points has a ring of truth...
> overfishing
> > is real and algae can inhibit coral recruitment. However, the
> > transformation of damsels from fish "tending their gardens" to "the
> primary
> > ally of the creeping manace" seems a bit dramatic. It also seems to
> > conflate algal turfs (which I understand the damsels are cultivating) and
> > macroalgae (which can be equally damaging to both corals and turfs by
> > shading and a host of other pathways).
> >
> > As I hope to get to this in about a week in class, I'd appreciate it if
> > folks who are closer to this can give me a sense of whether eradicating
> > algal turfs and the scurrilous damselfish that encourage them is the new
> > reef paradigm. If there is a place I can send a smart undergraduate (not
> > necessarily a NS student) to read about this new balance, that would be
> > even better. What I have read has argued that there are ties between
> > macro-algal proliferation and both overfishing and increased nutrient
> > input. While there have been numerous thoughtful discussions about the
> > details of these interactions, I have understood that both of these
> > possible linkages are are still considered to act at some level. I can
> also
> > imagine a delicate balance between the benefits of encouraging turfs and
> > clearing space by chomping on live coral.... and that fishing has
> impacted
> > this. My question is whether situation portrayed in this NPR interview is
> > correct and that the damselfish/turf ralationship shas gon awry to the
> > point that we need to stop worrying about lionfish and focus on what I
> > agree is, "pound-for-pound", the meanest fish on the reef.
> >
> > Dennis
> >
> > --
> > 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"*
> >  Benjamin Stein: "*Ludes, A Ballad of the Drug and the Dream*"
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> >
> --
> "... the earth is, always has been, and always will be more beautiful than
> it is useful." - Ophuls, 1977
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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"*
 Benjamin Stein: "*Ludes, A Ballad of the Drug and the Dream*"

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