[Coral-List] Coral reef restoration
Martin Moe
martin_moe at yahoo.com
Mon Feb 13 10:08:19 EST 2017
Back in 2001, Ken Nedimyer and I, coming from differentbackgrounds, were convinced that the loss of Diadema antillarum was a keyfactor in the decline of the coral reefs of the Florida Keys. We were (are)both members of the Sanctuary Advisory Council and we developed a year longstudy supported by the Sanctuary and NURC (NOAA’s National Undersea ResearchCenter) to replace Diadema on two experimental patch reefs with two control reefsof similar size. NURC did a rapid benthic analysis before the Diadema(juveniles collected on a nearby rubble zone on Conch and Pickles reefs) wereplaced on the reefs and then again after the Diadema had been on the two experimentalreefs one year later. The entire study can be found on the website of the FloridaKeys National Marine Sanctuary. The environmental analysis was extensive and detailed. This is a summary of just some of the basic results of this project. Summary of survival and density of Diadema on theexperimental reefs. Experimental Reef # 127% survival after 17 months Average density over the 17-month study, 1.6/sq. mFinal Density on 02/05/03 , 1.2/sq. m Experimental Reef # 2 20% survival after 17 months Average density over the 17-month study, 1.0/sq. mFinal density on 02/05/03 , 0..6/sq.m Control Reef # 3No placement of urchins on this reef Control Reef #4No placement of urchins on this reef(Note: A small population of Diadema urchins, about 6 to 10adults , was present on this reef before and during the study.) Results of the ecological assessments NURC carefully assessed the ecology of all four reefs beforeand after translocation of the Diadema urchins. The ecological effects of thetranslocated Diadema urchins on the two experimental reefs in the short spaceof one year were remarkable. Some of the most significant data developed fromthis project are summarized here and the entire study is posted on the FloridaKeys National Marine Sanctuary web site. This data reports the major changes inbenthic ecology between 08/31/01 and 09/18/02 as documented by the NURCassessments. Percent total stony coral cover Perhaps the most important statistic is the percent stonycoral cover. This measures the actual extent of coral tissue recovery and alsoincludes the amount of new coral tissue cover that may have developed from newsettlement of juvenile corals. Percent coral cover on experimental and control reefs beforeand after urchin placement. Experimental reef # 1 Experimental reef # 2 ControlReef # 3 Control Reef # 4Before After Before After Before After Before After14.00% 21.50% 5.50% 9.00% 6.25% 5.00% 12.00% 8.50% 54% increase 64% increase 20% decrease 29% decrease Loss of coral cover may be due to loss of coral tissue todisease or bleaching, or loss of coral tissue at the point of interaction withmacro algae. This data show that over all coral cover increased significantlyon the experimental reefs and decreased significantly on the control reefs.Whatever the dynamics of corals, algae, and urchins, this demonstrates that thepresence of the urchins results in recovery of coral cover. And this is thebottom line for recovery of the coral reefs of the Keys. Juvenile coral density Total mean density (number per sq. m) of juvenile stonycorals Experimental reef # 1 Experimental reef # 2 ControlReef # 3 Control Reef # 4Before After Before After Before After Before After 6.57 13.14 5.77 17.47 5.93 11.06 7.21 8.81100% increase 203% increase 87% increase 22% increase Although juvenile corals increased on both experimental andcontrol reefs, the experimental reefs, with the translocated urchinpopulations, had a much greater increase. This indicates that the presence ofthe urchins changed the ecology of the experimental reefs to favor thesettlement and/or survival of juvenile hard corals. Percent crustose coralline algae The presence of crustose coralline algae is very good forthe reefs. Unlike foliose algae, crustose coralline algae coats the rocksurfaces and presents a smooth, hard substrate free of foliose algae, sedimentand algae turf. This is a substrate that attracts settlement and survival ofjuvenile stony corals. It has been shown that lettuce coral, A. agaricites, isstimulated to settle by the chemical secretions of coralline algae. Experimental reef # 1 Experimental reef # 2 ControlReef # 3 Control Reef # 4Before After Before After Before After Before After6.25% 18.50% 8.75% 19.50% 6.25% 9.75% 9.25% 6.75%196% increase 123% increase 56%increase 27% decrease Obviously thepresence of the urchins stimulated growth of coralline algae on theexperimental reefs as these algae increased three fold. Coralline algaeincreased a bit on control reef # 3, perhaps conditions favored it’s growtheven without urchins present, or the transects in the assessment procedure cutacross a point of stronger coralline algae growth in the second assessment.Control reef # 2 decreased, perhaps due to a loss of the urchins that were onthat reef initially. It is obvious, however, that the presence of the urchinsapparently contributed greatly to the expansion of this important substrateconditioning algae on the experimental reefs. Brown foliose algae Percent cover of brown foliose algae. This is the type ofalgae that competes directly with corals for space and light. It grows muchfaster than coral and diminishes coral cover where it occurs on the reefs.These brown algae are typically in the genera Tubinaria, Lobophora, Dictyotaand Padina. (The green calcareous algae in the genus Halimeda also impact thereefs.) Experimental reef # 1 Experimental reef # 2 ControlReef # 3 Control Reef # 4Before After Before After Before After Before After11.00% 1.75% 9.00% 8.50% 6.00% 10.75% 3.00% 1.00%84% decrease 6% decrease 79% increase 67% decrease The reduction of brown foliose algae on the experimentalreefs, especially reef # 1, and the increase on control reef # 2 show without adoubt that the presence of the urchins greatly diminishes this competitivealgae on the reefs. Its presence in low quantities on control reef # 4 onlysupports this conclusion because of the presence of low numbers of adult urchinson this reef before and during the study.Percent total algae cover The data for total algae cover showed little change on anyreef during the course of the study. However, the figures for total algaeinclude the data on crustose coralline algae, which changed considerably duringthe study. Removal of the crustose coralline algae data from the data onpercent total algae cover on all four reefs shows the actual change thatoccurred in algae growth on all the reefs. Experimental reef # 1 Experimental reef # 2 ControlReef # 3 Control Reef # 4Before After Before After Before After Before After50.50% 33.25% 43.00% 34.25% 45.75% 43.75% 36.00% 35.25%34% decrease 20% decrease 4.4% decrease 2% decrease So without the coralline algae included in the data fortotal algal cover, the control reefs remained essentially the same in percentalgae cover while algae cover on experimental reef # 1 declined by about 34%and declined by on experimental reef # 2 by about 20%. Urchins live on algae,and other organic and inorganic matter removed from hard and soft substrates.When they were in abundance on small patch reefs, the reef had a white haloaround it where urchins left the reef at night to feed on the grass beds aroundthe reef. The high growing macro algae, such as Sargassum and Halimeda, thatthe urchins may not eat are eventually removed by the feeding activity of theurchins (bioerosion) on the substrates on which the algae grows. This activitygradually removes the existing macro algae growth and prevents new growth onthe rocky substrates surrounding live coral growth. The importance of restoration of Diadema to the Floridareefs cannot be overstated. The great importance of Diadema in the ecology ofcoral reefs was eloquently expressed by Ogden and Carpenter (1987), based onover 20 years of experiments and observations. “Through direct effects on algal communities or indirecteffects on other benthic reef organisms, grazing by Diadema is a major factorcontrolling the community structure of coral reefs. ….. Perhaps no other single species in thecoral reef environment has such profound effects on the other organismscomposing the reef community.” Of course. there are many more local and universal factorsthat negatively affect tropical western Atlantic coral reefs. This is just onestudy but it is demonstrative of the ecological importance of Diadema on ourcoral reefs. Aiding the return of Diadema to these coral reefs is not a “magicbullet” that will turn the clock back to the 1950s. However, helping the returnof Diadema in ecologically functionally numbers to our reefs is something thatstands a good chance of accomplishment, and given the value of these reefs to theeconomy and environment of south Florida, it seems that at least some serious effortsat Diadema restoration should be explored. A Diadema workshop was recently heldat the the Florida Aquarium and there is considerable interest is expandingcurrent efforts at Diadema culture and restoration. Small Diadema cultureprojects have been successful, but with problems, since about 2000 to thepresent. Enough work has been done to demonstrate that successful culture is quitepossible and present efforts should be greatly expanded.
On Monday, February 13, 2017 6:39 AM, Avigdor Abelson <avigdor at tauex.tau.ac.il> wrote:
Hi John,
A bit slow response, but I would like to step in and refer to your main issue ("It seems to me that there should be somewhere a critical review... But it does not appear that anyone has done the critical review that I expected to find...") - We have a couple of papers that (partially) address this issue in relation to marine ecosystem restoration as well as coral-reef restoration (see below references and links; all are open access).
One of these papers ("Expanding marine protected areas to include degraded coral reefs", in Conserv. Biol.), although not mentioning restoration in the title, dedicates a large section to coral-reef restoration (CRR) as an integral part of coral-reef conservation, and suggests the use of restoration as a tool to upgrade deteriorated reefs as candidate sites for MPAs, notably MPA-networks.
A third, general, manuscript, in which we deal with the main challenges of marine ecosystem restoration and suggest future directions, has been recently submitted, and once it is accepted I would be happy to send you a copy, if you are interested.
We are also currently working on a ms that focuses specifically on CRR, and in which we deal with issues of scale, the limited available tools (including the problems related to coral-reef gardening as the virtually sole CRR tool) and the common lack of basic essential steps (e.g. pre-launch assessment and post-implementation monitoring and success evaluation) - We expect this ms to be ready shortly for submission.
Referring to Sarah's response - I do agree with her claim that: "Most coral reef restoration projects fail when they don't follow basic science-based principles of ecological restoration". This is definitely a common problem. However, I also think that this is but one among diverse other problems inherent in the implementation of CRR.
I am not sure that we all have the same view of what is the 'science' of CRR, or of its present state. I truly believe in the potential of CRR as an essential management tool in coral-reef conservation; but, in order to make it an applicable option we need to address certain key issues, such as expanding the toolbox beyond that of just coral- reef gardening. In other words, I don't think there is (yet) the required level of scientific knowledge to support sound CRR. )This is, probably, the reason why not so many coral-reef scientists are enthusiastic about CRR as an option to countermeasure the large-scale degradation of the world's reef).
The article by Suding et al. (2015) is indeed an important study, highlighting certain general problems of ecological restoration, some of which are prominent in CRR.
In the article the authors claim that: "There is little question that ecological restoration can provide substantial benefits that enhance quality of life". It would seem that the authors (most of whom are "non-marine") base their assertion mainly on ecological restoration achievements in terrestrial and aquatic systems (with some exceptions regarding marine systems such as mangrove forests and oyster reefs).
Beyond the potential substantial benefits, Suding et al. caution about "...declarations ["of intent to restore"] may spur actions that compromise biodiversity". I consider this to be one of the main problems of coral-reef gardening, which commonly employs only a few species, mostly fast-growing and easy to handle (for fragmentation) branching corals.
Suding et al. (2015), also draw attention to the issue of "Specialized programs such as compensatory mitigation and ecosystem service delivery can be a useful contribution to-but are not synonymous with-ecological restoration... Such distinctions are not trivial because projects undertaken in the name of restoration may in fact be something different and, in many cases, have been demonstrated to achieve neither restoration nor their intended purposes" - Another relevant issue of CRR.
And the last, related point, which worth mentioning in their paper, refers to strategies that use the term 'restoration', but are nonetheless not exactly 'comprehensive ecological restoration' in nature - "Degraded lands could be converted to carbon farms, where monocultures of fast-growing tree species are planted and managed to optimize carbon sequestration. Green infrastructure could provide vegetation that fixes carbon and increases permeable surfaces. As valuable as these strategies may be, they alone do not constitute comprehensive ecological restoration".
Despite my criticism, I do believe that the young scientific discipline of CRR will play a crucial role in our efforts to repair the damage as far as possible, and under the suboptimal circumstances of growing threats on all spatial scales.
Cheers ~AV
Links to the mentioned papers:
Abelson, A., Halpern, B.S., Reed, D.C., Orth, R.J., Kendrick, G.A., Beck, M...W., Belmaker, J., Krause, G., Edgar, G.J., Airoldi, L., Brokovich, E., France, R., Shashar, N., de Blaeij, A., Stambler, N., Salameh, P., Shechter, M.. and Nelson, P. 2015. Upgrading Marine Ecosystem Restoration Using Ecological-Social Concepts. BioScience 66(2):156-163. Dec 16:biv171
http://bioscience.oxfordjournals.org/content/early/2015/12/04/biosci.biv171...full
Abelson, A., P. Nelson, G. Edgar, N. Shashar, D. Reed, J. Belmaker, G. Krause, M. Beck, E. Brokovich, R. France, S. Gaines. 2016. Expanding marine protected areas to include degraded coral reefs. Conserv. Biol. 30(6), pp.1182-1191 http://onlinelibrary.wiley.com/doi/10.1111/cobi.12722/full
# Two additional papers that suggest/explore an alternative CRR tool (restocking):
Obolski, U., Hadany, L. and Abelson, A., 2016. Potential contribution of fish restocking to the recovery of deteriorated coral reefs: an alternative restoration method?. PeerJ, 4, p.e1732. https://peerj.com/articles/1732/
Abelson, A., Obolski, U., Regoniel, P. and Hadany, L., 2016. Restocking Herbivorous Fish Populations As a Social-Ecological Restoration Tool in Coral Reefs. Frontiers in Marine Science, 3, p.138. http://journal.frontiersin.org/article/10.3389/fmars.2016.00138/full
-----Original Message-----
From: coral-list-bounces at coral.aoml.noaa.gov [mailto:coral-list-bounces at coral.aoml.noaa.gov] On Behalf Of John Ware
Sent: Thursday, February 2, 2017 8:11 PM
To: coral-list at coral.aoml.noaa.gov
Subject: [Coral-List] Coral reef restoration
Dear List,
Back in ~mid January, I sent out a request asking the list for references to papers that provided an evaluation or critique of the process of reef restoration, coral transplants, "population enhancement"
(my personal favorite), etc.
Of the 68 papers in my file on this topic, only one is the least bit
critical:
Bayraktarov et al, Ecol Appl 26(4):1055-1074 (I believe this is open access).
Elisa et al. concentrate on financial aspects and note that few papers describe costs in sufficient detail. But they also mention that there is almost certainly a publication bias towards success.
It seems to me that there should be somewhere a critical review mentioning, for example, the relevance of scale in terms of global reef size and climate change.
But it does not appear that anyone has done the critical review that I expected to find (in a respectable journal).
Did I miss something??
John Ware
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