[Coral-List] Algae and nutrients and herbivory in oligotrophic waters
reefpeace at yahoo.com
Fri Jun 20 17:37:34 EDT 2008
Very interesting observations! And worth to well note for perhaps future anthropomorphic coral restoration methodology rather than just wait and see what the ecosystem does to repair itself despite human affection - however meant to be beneficially applied.
Can you (and Coral-L members) please take a look at this web page and look-see the Gallery:
This is a serious eutrophication situation that basically affects the entire coral reef platform from Talofofo Bay inlet to Ylig Bay inlet, whereas, it has been blamed primarily from the Baza Gardens wastewater treatment plant discharge into the Togcha River. (Forgive me for noting areas that you may not know their locations..but to make a point here)
Interjection here: By the way, can anyone ID the blue-green alga in the photos please?
The volume reported to be discharged from the Baza WWTP after secondary treatment is an average of .6 mil g/day. I have walked the river that receives the discharge and I am not convinced that it's Only the Baza WWTP the source of nutrients feeding the reef platform. In fact, I feel the B-WWTP is a minor contributor if secondary treatment is correctly applied (removal of 50% Nitrate load; 30% Phosphate load).
The entire Talofofo region and Ipan area exists on top of a large limestone section of MARIANA LIMESTONE (Pliocene to Pleistocene), whereas, existing on this section there are 3 golf courses and a 4th in the planning stages, Windward Hile/Baza Gardens residential housing; Talofofo residential housing, and Ipan residential housing. A quick assessment for the volume of freshwater utilized by this region is enormous when considering the golf courses a part of it.
Hydrologic Resources of Guam
Prepared in cooperation with the
WATER AND ENVIRONMENTAL RESEARCH INSTITUTE (WERI)
UNIVERSITY OF GUAM
U.S. Department of the Interior
Gingerich Hydrologic Resources of Guam WRIR 03-4126
By Stephen B. Gingerich
U.S. Geological Survey Water-Resources Investigations Report 03-4126
Only a minor area uses the Baza WWTP and .6 mil g/d is minor when assessing the areas using old septic tanks (those without bottoms) and newer septic tanks with bottoms & leach field discharge.
A recent reef platform survey (with underwater photos) shows that the entire reef platform has substantial and thick growth of the blue-green alga in various locations where there are sandy bottoms and no exposed coral / limestone base rock....as well as gross overgrowth of the typical macro-alga (notably Caulerpa, Padina). On two locations on this same reef platform, my partner and I could actually smell 'sewer water' in areas of the cooler freshwater discharging up from the reef platform.
My point in all this?
Septic tank discharge water in limestone regions do not filter or treat the high nutrient water. In fact, the same water will quickly flow through the limestone until it may reach a less permeable layer (volcanic rock) and continue to flow downhill via gravity and discharge at a much lower altitude ( beach side or even out on the reef platform itself.
Any comments would be greatly appreciated. References to any studies and Papers available would also be appreciated.
The first step is to ID the sources. The second step is to suggest remedial solutions - no matter how much the cost may be.
I would initially suggest that all new septic tanks be banned in the region and a new waste water treatment plant be installed to accommodate all residential housing to connect too at minimum cost or no cost to existing residence housing. The golf courses? Well......again.....can anyone suggest eco-friendly guidelines for golf course irrigation and the efficient & proper use of fertilizers?
The trade off with doing nothing? The death and "Alga-fication" of the shallow coastal limestone platform...no longer calling it a 'coral' platform. And No fish to catch as fish do not eat the blue-green algae.
Dean Jacobson <atolldino at yahoo.com> wrote: Dear lister:
Tom's response reminded me of a dive this week. On Wednesday I was revisiting a site that was devastated by COTS several years ago, Irooj Island next to the northern pass on Majuro atoll, a location far from human source of pollution. I had expected the thick cyanobacteria and Dictyota bloom that followed predation on coral to have diminished after three years, but to my surprise the algal biomass is as thick as ever. No coral have recruited, other than the most shallow substrates that are free of algae. Yet an identical COTS-devasted patch reef just a few hundred meters to the west is free of algae, and dead coral surfaces are thick with young Acropora recruits. I am guessing an eddy forms around Irooj (where there is a "dead end" corner next to the pass) and has trapped the nutrients. There appears to be many herbivorous fish, but in seven years I have never observed any grazing on Dicytota. So, I concur with Tom Goreau's observations on bottom-up
Also, have witnessed local scarids avoid live coral, as well, as well as bit-marking a minority of Porites colonies.
Cheers, and looking forward to meeting some of you at ICRS,
College of the Marshall Islands
--- On Wed, 6/18/08, Thomas Goreau wrote:
> From: Thomas Goreau
> Subject: [Coral-List] Algae and nutrients and herbivory in oligotrophic waters
> To: "Imam Bachtiar"
> Cc: "coral-list coral-list"
> Date: Wednesday, June 18, 2008, 10:06 AM
> Dear Imam,
> Very few of the studies on herbivory and algae are any
> good, because
> only a tiny handful have made accurate nutrient
> measurements. When
> this is done properly it is clear that nutrients drive
> productivity and herbivory is only a secondary factor,
> grazers prefer to eat some species and avoid others.
> I've looked at
> the zonation of algae species in reefs all around the world
> and these
> are sharply zoned by nutrients in ways that clearly reveal
> sources. Every place I've looked with nutrient sources
> are dominated
> by algae whether or not herbivores are present (and
> herbivore always
> dominate the fish where there are nutrient sources, whether
> these are
> from human land-based sources or from upwelling), and algae
> absent or rare where there are no nutrient sources, again
> whether or
> not there are herbivores (which there rarely are). This is
> the exact
> opposite of what top-downers predict.
> As far as coralivores go, I also think the popular
> conceptions are
> often erroneous. Most alleged coral eating is much less
> than is
> claimed. Butterflyfish mostly just suck off surface mucus
> and there
> is little or no physical damage to polyps. Parrotfish that
> allegedly biting coral are almost inevitably biting algae
> growing on
> dead coral, and avoiding the coral tissue, as you can see
> if you look
> closely where they bite. The popular claims that parrotfish
> eat coral
> is probably largely untrue, and much of their biting of
> corals is
> really territorial marking the boundaries of breeding
> rather than for food. Almost every time you look where a
> parrotfish or Napoleon wrasse has bitten into large bubble
> colonies, you will see the tubes of the burrowing clams and
> inside the coral that they were really eating rather than
> coral tissue.
> I'll talk a bit about this at the next Gili Trawangan
> workshop in
> early December. Look forward to continuing to work with you
> there and
> other sites around Lombok. My best to all my friends in
> Best wishes,
> Thomas J. Goreau, PhD
> Global Coral Reef Alliance
> 37 Pleasant Street, Cambridge MA 02139
> goreau at bestweb.net
> Date: Wed, 18 Jun 2008 11:28:37 -0700
> From: "Imam Bachtiar"
> Subject: [Coral-List] Herbivory on oligotrophic waters
> Cc: coremap2 at yahoogroups.com
> Message-ID: <000801c8d171$226bd120$67437360$@net>
> Content-Type: text/plain; charset="us-ascii"
> Dear all,
> Herbivory is thought to be a key process in coral reef
> studies have shown its importance in controlling macroalgae
> and provide
> space for larval settlement. Most papers discussing about
> exclusion experiments, however, do not clearly explain
> whether the
> of study is oligotrophic or mesotrophic. Some other papers
> also indicate
> that nutrients is not limiting factor of macroalgae growth.
> I would like
> therefore to have your opinion or comments about this.
> 1) Is there any paper studying herbivory in oligotrophic
> 2) Which one is more important in reconstruction of reef
> communities in
> oligotrophic waters: herbivory vs corallivory?
> Looking forward to have your reply.
> Best regards,
> Imam Bachtiar
> Postgraduate School
> Institut Pertanian Bogor, Indonesia
> Coral-List mailing list
> Coral-List at coral.aoml.noaa.gov
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