[Coral-List] fish and algae - damselfish aren't always bad

Amy Briggs amy.a.briggs at gmail.com
Wed Feb 19 13:34:30 EST 2014

Hi Dennis,

For a contrasting point of view to the NPR piece, there have also been
studies showing that damselfish facilitate the survival of coral recruits
that settle within their territories by protecting them from predation by
corallivorous species (e.g. Gochfeld 2010).  This way over a longer time
scale, damselfish may actually promote a shift back towards a
coral-dominated state by protecting coral juveniles until they reach a size
that is resilient to predation.  I've seen many examples of this in Moorea,
French Polynesia, where juvenile Acropora will grow in the center of
damselfish territories, which are often on areas of dead, or partially dead
Porites colonies.  These Porites colonies were damaged by a cyclone and a
COT outbreak, which potentially opened up the space for the damselfish
territories in the first place.  I believe researchers at UCSB like Russel
Schmitt and Sally Holbrook have also done research on this phenomenon, and
can tell you more about it.

So, most likely the impact of damselfish on the competitive interactions
between algae and corals is a complex interplay between many factors, such
as water nutrient levels, local abundances of different functional groups
like corallivores and predators of damselfish, and what  species of coral
that you are talking about.  Likely all of this  also depends on the time
scale on which you base your observations.

Gochfeld DJ (2010) Territorial damselfishes facilitate survival of corals
by providing an associational defense against predators. Mar Ecol Prog Ser

Amy Briggs
M.S. Student
California State University, Northridge
Message: 1
Date: Tue, 18 Feb 2014 13:06:03 -0500
From: Dennis Hubbard <dennis.hubbard at oberlin.edu>
Subject: Re: [Coral-List] fish and algae
To: "Szmant, Alina" <szmanta at uncw.edu>
Cc: "coral-list at coral.aoml.noaa.gov" <coral-list at coral.aoml.noaa.gov>,
        Bill Allison <allison.billiam at gmail.com>
        <CAFjCZNaw3wkxJ1XbKbvnFPw-8D2_jSQB3bME7hOG_+NkqP48xQ at mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1

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!!


> -----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*"
> > > _______________________________________________
> > _______________________________________________
> Message: 5
> Date: Wed, 19 Feb 2014 08:21:37 +0900
> From: Nicole Crane <nicrane at cabrillo.edu>
> Subject: Re: [Coral-List] fish and algae
> To: coral-list at coral.aoml.noaa.gov
> Message-ID: <5303EB01.7020204 at cabrillo.edu>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> This is a great discussion, and I felt inclined to weigh in.  We've been
> surveying reefs in Micronesia, and while we have quantitative data sets,
> we didn't look specifically at damselfish, so I'm afraid I have no
> empirical evidence for the following observation (other than having
> looked at many reefs):
> The 'healthiest' reefs we see (high coral morphology diversity, high
> cover, high biomass and diversity of fish etc.), are places where I see
> damselfish (on shallow flats) and their 'gardens'.  The more degraded
> reefs seem to have far fewer of them (I'll mention that Acropora is
> harvested from some reefs for the lime that is chewed with beetlenut).
> Not that this bolsters any specific argument, but I am reminded of how
> we need to be careful to make sensational, simplistic stories from a
> complex stage.  I am reminded of the African Elephant who has long been
> blamed for their destructive eating habits and the negative impacts on
> acacia trees (an ecosystem disservice?).  Yet, by eating the seed pods
> of certain acacias, they sterilize the seeds, protecting them from
> certain death from a parasitic grub that will otherwise kill them.  Upon
> defecation on to the fertile grassland soil, a very high percentage of
> these seeds will germinate (an ecosystem service?).
> Thus the charismatic mesofaunal damselfish (to distinguish it from the
> marine megafaunal superstars) probably has a complicated story behind
> it.  Steve said it well!
> Maybe its our responsibility in part to make sure that when these
> stories are told in a public forum, simplification and sensationalism is
> really not necessary - the whole story is really the interesting one.
> Nicole
> --
> Nicole L. Crane
> Cabrillo College
> Division of Natural and Applied Sciences
> 831-479-5094
> nicrane at cabrillo.edu
> www.cabrillo.edu/~ncrane <http://www.cabrillo.edu/%7Encrane>
> Oceanic Society
> Senior Conservation Scientist
> www.oceanicsociety.org

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