Electrical Stimulation Greatly Increases Settlement, Growth, Survival, and Stress Resistance of Marine Organisms

Thomas J. Goreau
Global Coral Reef Alliance, Cambridge, USA Email: goreau@bestweb.net
Received 23 May 2014; revised 26 June 2014; accepted 5 July 2014
Copyright © 2014 by author and Scientific Research Publishing Inc.
This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/

Abstract
Increasing stress from global warming, sea level rise, acidification, sedimentation, pollution, and unsustainable practices have degraded the most critical coastal ecosystems including coral reefs, oyster reefs, and salt marshes. Conventional restoration methods work only under perfect conditions but fail nearly completely when the water becomes too hot or water quality deteriorates. New methods are needed to greatly increase settlement, growth, survival, and resistance to environmental stress of keystone marine organisms in order to maintain critical coastal ecosystem functions including shore protection, fisheries, and biodiversity. Electrolysis methods have been applied to marine ecosystem restoration since 1976, with spectacular results (Figures 1(a)-(c)). This paper provides the first overall review of the data. Low-voltage direct current trickle charges are found to increase the settlement of corals 25.86 times higher than uncharged control sites, to increase the mean growth rates of reef-building corals, soft corals, oysters, and salt marsh grass— an average of 3.17 times faster than controls (ranging from 2 to 10 times depending on species and conditions), and to increase the survival of electrically charged marine organisms—an average of 3.47 times greater than controls, with the biggest increases under the most severe environmental stresses. These results are caused by the fundamental biophysical stimulation of natural biochemical energy production pathways, used by all organisms, provided by electrical stimulation under the right conditions. This paper reviews for the first time all published results from properly designed, installed, and maintained projects, and contrasts them with those that do not meet these criteria.

How to cite this paper: Goreau, T.J. (2014) Electrical Stimulation Greatly Increases Settlement, Growth, Survival, and Stress Resistance of Marine Organisms. Natural Resources, 5, 527-537. http://dx.doi.org/10.4236/nr.2014.510048

1. Introduction
Low-voltage direct current trickle charges using Biorock electrolytic technology [1] [2] grow limestone structures
of any size or shape in the sea and produce the only self-repairing marine construction material that gets
stronger with age [3], and grows breakwaters capable of rapidly growing back severely eroded beaches [4]. But
in addition to physical benefits the process also has profound stimulatory effects on all forms of marine life.
Biorock structures have been repeatedly shown to greatly increase the settlement, healing, growth, survival, and
resistance to stresses such as extreme high temperatures, sedimentation, and eutrophication in stony corals [5]-[9], soft corals [10], oysters [11]-[13], sea grasses [14], and intertidal salt marsh grasses [15]. Many other organisms, including clams, tunicates, sponges, and fishes have also been observed to greatly increase their populations in electrical fields, but few measurements have been made on them to date. This review summarizes the available data on the effects of low-voltage direct current electrical stimulation on growth rates, survival, stress resistance, and physiology, which suggest the mechanism is a completely general one that benefits all organisms [16]. Results from projects that were properly designed, installed, and maintained are included in the main part of this paper. Because understanding the causes of negative results play an important role in the scientific method, projects that do not meet those criteria of proper design, installation, and maintenance are discussed separately.

 

2. The Impact of Electrical Stimulation on Marine Organisms

 

2.1. Published Results from Properly Designed, Installed, and Maintained Projects
The very first Biorock project, built at Grand Isle, Louisiana in 1976, was completely covered by multiple layers of spontaneously settling oysters that grew to adult size in about 3 months [17]. Recent Biorock projects in New York City show dense spontaneous settlement of oysters on rocks near Biorock structures. Nevertheless, no controlled studies of oyster settlement have yet been conducted. By the late 1980s it was found that electrically stimulated corals grew 3 – 5 times record rates for their species, even under conditions of severe stress. Since then hundreds of projects have been built all across the Caribbean, Pacific, Indian Ocean, and Southeast Asia, with most projects being in Indonesia, the global center of marine biodiversity. While slowly growing Biorock structures have been densely covered with hundreds of spontaneously recruiting corals [5] [16], only two studies have documented coral settlement on them [5] [6]. When these are compared to spontaneous recruitment of corals in natural habitats in the same units (recruits per square meter per month) the rates of settlement on electrically charged Biorock are found to be 1 to 4 orders of magnitude greater (Figure 2(a)), with a mean of 25.86 times higher than those reported from field settling experiments.

Growth rates of reef building hard corals [5]-[9], gorgonian soft coral [10], oysters [11]-[13], and salt marsh grass (Spartina alterniflora) [15] have been quantitatively compared on Biorock with identical clones off Biorock
in the same habitat. The results show that the electrically stimulated organisms grow typically 2 to 10 times faster (Figure 2(b)), with a mean of 3.17 times greater than controls. In addition hard and soft corals that have
been collected naturally broken and badly damaged are observed to heal completely, release little or no mucus, and regain bright color and polyp extension within a day, while controls remain pale and continue to look injured
and release mucus for two weeks [16]. Corals in electrical fields are observed to bud and branch more densely [8] [18]. This is reminiscent of the well known role of DC electrical fields in healing ruptured cellular membranes and cuts in the skin of organisms: if the polarity is correct the cut rapidly heals and closes, while if it is reversed the cut opens up [19]. Survival of hard corals [6]-[9], soft corals [10], oysters [11]-[13], and salt marsh grass [15] in electrical fields compared to un-electrified controls also show many times higher survival (Figure 2(c)), with a mean of 3.47 times higher than controls. This is especially the case in extreme stress conditions from excessively high temperatures, sedimentation, or eutrophication, when almost all the controls die, but most of the electrically charged organisms survive. For example in the severe 1998 Maldives bleaching event Biorock reefs had 16 to 50 times higher coral survival than surrounding reefs, and every single control coral transplanted onto cement structures died [20]. In the 2010 Thailand bleaching events corals bleached less (in some cases not at all), recovered faster, and had much higher survival than the same species of corals on surrounding reefs [21]. Similar results have been seen with oysters [13], salt marsh grass [15], and seagrass [14]. Control oysters in New York City nearly all died over a severe winter, and the shells of the survivors shrank in size because they were etched and dissolved from acidity caused by increased CO2 solubility in cold water. In contrast Biorock oysters continued to

biorock, goreau, pemuteran, bali, indonesia

Biorock, Pemuteran, Bali, Indonesia, mineral accretion, Goreau, Taman Sari
Figure 1. (a) Five-year-old Biorock electrical reef grown on formerly barren sand in Pemuteran, Bali, Indonesia, showing prolific coral growth and fish populations (photograph by EunJae Im); (b) Site at Pemuteran, Bali in 2001 at start of project (photograph by Rani Morrow-Wuigk); (c) Same location 10 years later in 2001 (photograph by Rani Morrow-Wuigk).

Electrical stimulation, Biorock, Goreau, figure 2
Figure 2. (a) Coral recruitment rates on Biorock limestone substrates [5] [6] versus natural limestone rock and artificial substrates (full list of citations given in [16]). Biorock coral settlement rates range from around 1 to 4 orders of magnitude higher when compared in the same units, spontaneously settling juvenile corals per square meter per month. The mean settlement rate on Biorock was 25.86 times higher than controls; (b) Linear growth rates of electrically stimulated corals [5]-[9], gorgonians [10], oysters [11]-[13], and salt marsh grass [15] versus controls. Each dot represents the average value of times series on populations of treated and control organisms. Mean growth rates of electrically stimulated organisms over the same time interval were 3.165 times higher than identical controls without electrical fields, ranging between 2 – 10 times higher. All points above the 1:1 line indicate electrical stimulation, to an extent indicated by the slope to the origin; (c) Survival of electrically stimulated corals [6]-[9] [20], oysters [11]-[13], gorgonians [10], and salt marsh grass [15] versus controls. Mean survival of electrically stimulated organisms was 3.47 times higher than controls, especially under severe stress conditions resulting in nearly total mortality of controls.
grow throughout the normally dormant period, and their shells were shiny with no signs of dissolution from acidity [13]. This is in part because the Biorock electrolytic process generates net alkalinity, and so counteracts acidification [3]. A comparison of 6 genera of corals grown on Biorock with genetically identical clones in the same habitat [22] showed that electrically stimulated corals had higher densities of the symbiotic alga Symbiodinium sp. (Figure 3(a)), even higher Symbiodinium cell division rates as measured by mitotic indices (Figure 3(b)), but had generally lower chlorophyll per Symbiodinium cell (Figure 3(c)). This is analogous to the lowered chlorophyll content of corals exposed to high light, which is interpreted as a mechanism to prevent excessive photosynthetic production and symbiotic alga growth [23]-[25]. The greatly increased growth rate of corals with electrical stimulation appears to occur despite less dependence on the symbiotic algae, and therefore is a direct effect of the electrical field itself.

Figure 3. (a) Density of Symbiodinium sp. in corals grown on Biorock versus the genetically identical mother colony from which they were transplanted in the same environment nearby [22]. Electrically stimulated corals had on an average 1.25 times higher symbiotic alga densities than controls; (b) Cell division rate of Symbiodinium sp. as measured by mitotic indices (percentage of dividing alga cells) in Biorock corals versus controls [22]. Electrically stimulated corals have an average of 1.74 times higher cell division rates, and presumably growth; (c) Chlorophyll content per Symbiodinium cell in Biorock corals versus controls. Birock corals have an average of 0.69 times less chlorophyll per symbiotic alga cell as controls [22]. This suggests that their productivity is being suppressed, as happens in high light [23]-[25]. Since coral calcification is normally proportional to photosynthesis of Symbiodinium sp. [26], this implies that the higher growth rate of Biorock corals is not due to higher photosynthesis, but due to greater energy availability provided by the electrical field.
All of these phenomena indicate that electrical fields in the right range greatly stimulate the health of marine organisms. These effects are not residual, they occur only when the electrical field is on (Figure 4(a)). These results are no surprise, since all forms of life from bacteria on up maintain a roughly tenth of a volt potential difference between the outside of the cell and the inside, and use electron and proton flow along this voltage gradient to make ATP and NADP, the fundamental energy and reducing currencies of all life. ATP production and protein synthesis are both directly stimulated by DC electrical currents over a very broad range spanning orders of magnitude [27], increasing with current to a maximum and then decreasing at excessive levels (Figure 4(b)). 2.2. Results from Improperly Designed Experiments This section discusses published results from projects that do not meet the criteria of proper training, materials, design, installation, and maintenance according to the inventors of the electrical stimulation method. All have failed to get the results achieved by those with proper training and materials, for several different reasons. As

Figure 4. (a) Control corals grown in extremely poor water quality habitat steadily lost weight while electrified corals grew very fast over 16 weeks. When the power was cut they started to decline like the controls, but immediately resumed growth when power was restored. This shows that coral growth stimulation is a property of the actively applied field, and does not have residual effects. Data from [28] plotted in [16]; (b) ATP concentration in micromoles per gram of tissue is shown as a function of electrical current. A five times increase in ATP is seen at the peak. Data from [27], plotted in [16].
there are several different causes for their failure to achieve prime results, these inappropriate projects are reviewed below by major categories of the flaws in their design or execution.

2.2.1. Mistake -1: Current Reversed

In these projects the power leads are connected backwards. Instead of the cathode being protected from corrosion, it rusts very rapidly instead, and the anode, instead of being clean, is instead heavily overgrown by rapid growth of soft minerals. Sometimes it takes months before they realize their mistake, and often the error was only recognized much too late when the author visited and pointed it out. These mistakes can easily be prevented by promptly sending photos for advice. In some cases reports based on this mistake have been published claiming that the method is a total failure. A report by the Texas A&M University Galveston Coastal Geology Laboratory was paid for the State of Texas General Lands Office (GLO), in order to see if electrical methods could protect steel with mineral coatings, as had been shown by Hilbertz in the 1970s. Texas A&M found instead that the charged structures rusted even faster than the controls! They never realized their mistake, nor apparently did Texas GLO.

2.2.2. Mistake 0: No Current

This can result from power supply failure or from cable breakage.

In some of these cases the project was properly designed and installed, but those running the project failed to realize that it was not under power and send photos to the author for confirmation and advice on how to fix it. Some of these continued making measurements for up to year not realizing that the project was not under power, and the mistake was only realized afterwards when they finally sent the first photographs to the author, who immediately recognized they were not receiving electrical current. That is why even trained groups are advised to send frequent photos for advice.

Other cases were by untrained imitators using incorrect design and materials. These failures were largely caused by power supplies burning out, electrical cables breaking, or bad contacts. Most such failures were caused by extreme storm events, such as hurricanes, typhoons, and cyclones, and were not properly diagnosed or repaired. In other cases they resulted from deliberate destruction by people running boats over the cables, breaking cables by dragging anchors over cables, by people dumping anchors on top of projects accidentally or deliberately, or saboteurs who cut cables for bizarre reasons of their own, usually involving a personal grudge against a local partner rather than the project itself. Unfortunately several projects that received no current resulted in published theses and papers.

One example is a thesis project by Zaidy Khan at the University of the South Pacific, which found no difference in growth rates of corals on structures which were thought to be under power but which in fact were not, and control structures known to receive no power.

The same error occurred in a thesis project by Andrew Taylor of James Cook University, supervised by Bette Willis, who sought to compare coral growth on structures with and without power. Taylor did not build any electrified structures, he simply used one of our field sites without permission, which his thesis advisor did not seem to realize was fundamentally unethical. The structure he thought was under power was in fact not, due to a burned out power supply that had not been repaired or replaced. In addition Taylor’s control corals died from disease, but a poster was presented anyway at the International Coral Reef Symposium claiming that Biorock corals did not grow faster than controls.

Another experiment done by Bogor University at Pramuka Island in the Seribu Islands north of Jakarta was victim of deliberate turning off of the power. The local power supply was in a commercial restaurant that was paid for supplying power, but which in fact turned the power off except during short visits by students making measurements. The interpretation of several Master’s theses was compromised by failure to realize what had happened until later.

In several cases groups in places like Thailand, the Philippines, Germany, Japan, the United States, and other places, who falsely claim to be trained in Biorock methods have been making unauthorized projects that have been complete failures. Their pitiful results are an obvious failure to all visitors, and an embarrassment because the imitators then say the method doesn’t work, not that they aren’t trained to do it properly.

2.2.3. Mistake 1: Current Too Low

This mistake results from powering too large an area with too small a power source, or failure to recognize that cables are broken or inadequate. One example comes from Terlouw [29], who reports measurements made on a project in Ko Tao, Thailand that was partially installed, but whose installation was never completed to standards. As a result of inadequate and broken cables the project received only a little power in the first year. In the second year new cables were installed and a failed power supply replaced so the project received power, but in the third year the cables broke and or the power supply failed, so only a small trickle or no power reached the project. These conditions were identified by the author from photographs sent from the project, but were not recognized by Terlouw, who reported that corals on Biorock grew faster than control corals by a factor of 1.54 in Year One, by a factor of 5.04 in Year Two, and by a factor of 1.33 in Year Three. Terlouw, not recognizing the cause of the variations, suggested that benefits are mixed, but our interpretation is that the higher results in Year 2 are due to that being the only year with adequate power, while Year 1 and Year 3 were underpowered, resulting in lower rates.

A similar mistake was made with oysters by Piazza et al. [30]. In this particular case the oysters thought to be getting electrical current were in fact getting almost none at all, because flawed experimental design concentrated the current onto fresh pieces of bare steel. Piazza et al. found that the oysters that they incorrectly thought to be under power grew only 1.15 times faster than controls.

2.2.4. Mistake 2: Current Too High

Over-charging has been known to cause negative effects from the very start, but most groups that set up experiments without proper training or materials use high power to get quick results. As shown in Figure 4(b) of this paper, excessive current causes negligible benefits, and if too high, causes negative effects, killing corals. Unfortunately most of those who get negative results due to overcharging do not realize their error, and many of them have published their results anyway. This mistake is the cause of the very poor results reported by Schuhmacher, Schillak, Van Treeck, Sabater, Yap, Eggeling, and their colleagues [31]-[39]. Since these authors did not realize their mistakes and published negative or minor results, it has been widely claimed that the method does not work, but in fact their poor results were entirely due to lack of proper training, experimental design, materials, etc. Such mistakes are even worse when done in a closed system tank. As a result of their overcharging the corals had only very small increases in growth rates, or they bleached and failed to grow entirely, or died.

2.2.5. Mistake 3: Ethical

Borrell et al. [40] [41] reported that one coral species grows a bit faster with electricity but that another species had its growth reduced and inhibited by the electrical field [40] [41]. In fact, the alleged reduction of one species’ growth was for a completely different reason: terminal phase male parrotfish established their breeding territories on the Biorock project, and marked them by biting off all the growing tips of that one species only, while ignoring them in the control site. The author of this paper personally set that project up, and documented the cause, but this was completely and knowingly ignored by the authors of the report, causing deceptive and false conclusions.

3. Conclusions

These results all point in the same direction: low-voltage trickle charges can greatly enhance the health of marine organisms. Voltage gradients in the right range appear to create the ideal biophysical conditions for the creation of biochemical energy, stimulating healing, growth, survival, and resistance to stress. The external field maintains the cell membrane gradient and greatly reduces the need for cells to spend a large part of their energy pumping electrons, protons, and ions to maintain the gradient, freeing this energy for metabolism, growth, and resisting environmental stress.

Unfortunately many people copying the Biorock method think they can do so without training. The results of improperly designed, installed, and maintained projects set up by people without training using improper materials always fail to replicate the results of projects by trained people using approved methods and materials, for several obvious reasons. These people inevitably blame the technology itself and not their lack of training. Almost every data point in these graphs represents populations of different species grown in the field under different electrical conditions, most of which are likely to be suboptimal. For example oyster growth rates next to a former toxic waste dump in New York City increased with current, up to 10 fold (NB, length increase only, the volume increase is a thousand fold), even though they were getting power less than a quarter of the time, and probably would have grown even faster with more power [13]. Much more work is needed to find out the optimal conditions, which are likely to be subtly different for each species. It has not escaped our attention that because membrane electro-chemical gradient-driven energy production is universal among all cellular life, going back to the last common ancestor, the method will apply to all organisms, although the effects and best conditions will depend on the electrical conductivity of their medium.

Maintaining ecosystem services in the face of accelerating global climate change will require methods that increase growth, survival, and resistance to escalating stress. These results indicate that the Biorock process is unique in accelerating settlement, growth, healing, branching, survival, and resistance to environmental stress. This allows marine organisms to be kept alive under conditions that would otherwise kill them, and enables entire complex ecosystems to be restored in a short period of time in places where there is no natural recovery (Figure 1). The Biorock electrolysis method, by stimulating the natural energy production mechanism, is the only ecological restoration method known that can maintain and restore marine ecosystems under conditions of accelerating global warming, sea level rise, ocean acidification, sedimentation, and excessive nutrient inputs, especially under severe stress where all other methods fail. It is urgent that the method should be optimized and applied on a large scale as soon as possible, especially in coral reefs, the ecosystem most threatened by global warming [42] [43], and in extending oyster reefs and salt marshes seaward to reduce coastal damage caused by global sea level rise.

References

[1] Hilbertz, W. (1979) Electrodeposition of Minerals in Sea Water: Experiments and Applications. IEEE Journal on Oceanic Engineering, 4, 1-19. http://dx.doi.org/10.1109/JOE.1979.1145428 [2] Hilbertz, W. and Goreau, T.J. (1996) Method of Enhancing the Growth of Aquatic Organisms and Structures Created Thereby. Patent 5543034. United States Patent Office. [3] Goreau, T.J. (2012) Marine Electrolysis for Building Materials and Environmental Restoration. In: Kleperis, J. and Linkov, V., Eds., Electrolysis, InTech Publishing, Rijeka, 273-290. http://www.intechopen.com/books/show/title/electrolysis [4] Goreau, T.J., Hilbertz, W., Hakeem, A.A.A., Sarkisian, T., Gutzeit, F. and Spenhoff, A. (2012) Restoring Reefs to Grow Back Beaches and Protect Coasts from Erosion and Sea Level Rise. In: Goreau, T.J. and Trench, R.K., Eds., Innovative Methods of Marine Ecosystem Restoration, CRC Press, Boca Raton, 11-34. http://dx.doi.org/10.1201/b14314-4 [5] Goreau, T.J. and Hilbertz, W. (2012) Reef Restoration Using Seawater Electrolysis in Jamaica. In: Goreau, T.J. and Trench, R.K., Eds., Innovative Methods of Marine Ecosystem Restoration, CRC Press, Boca Raton, 35-45. http://dx.doi.org/10.1201/b14314-5 [6] Jompa, J., Suharto, Anpusyahnur, E.M., Dwija, P.N. Subagio, J., Alimin, I., Anwar, R., Syamsuddin, S., Radiman, T. H.U., Triyono, H., Sue, R.A. and Soeyasa, N. (2012) Electrically Stimulated Corals in Indonesia Reef Restoration Projects Show Greatly Accelerated Growth Rates. In: Goreau, T.J. and Trench, R.K., Eds., Innovative Methods of Marine Ecosystem Restoration, CRC Press, Boca Raton, 47-58. http://dx.doi.org/10.1201/b14314-6 [7] Bakti, L.A.A., Virgota, A., Damayanti, L.P.A., Radiman, T.H.U., Retnowulan, A., Hernawati, Sabil, A. and Robbe, D. (2012) Biorock Reef Restoration in Gili Trawangan, North Lombok, Indonesia. In: Goreau, T.J. and Trench, R.K., Eds., Innovative Methods of Marine Ecosystem Restoration, CRC Press, Boca Raton, 59-80. http://dx.doi.org/10.1201/b14314-7 [8] Zamani, N.P., Abdallah, K.I. and Subhan, B. (2012) Electrical Current Stimulates Coral Branching and Growth in Jakarta Bay. In: Goreau, T.J. and Trench, R.K., Eds., Innovative Methods of Marine Ecosystem Restoration, CRC Press, Boca Raton, 81-89. http://dx.doi.org/10.1201/b14314-8 [9] Nitzsche, J. (2012) Electricity Protects Coral from Overgrowth by an Encrusting Sponge in Indonesia. In: Goreau, T.J. and Trench, R.K., Eds., Innovative Methods of Marine Ecosystem Restoration, CRC Press, Boca Raton, 91-103. http://dx.doi.org/10.1201/b14314-9 [10] Fitri D. and Rachman, M.A. (2012) Gorgonian Soft Corals Have Higher Growth and Survival in Electrical Fields. In: Goreau, T.J. and Trench, R.K., Eds., Innovative Methods of Marine Ecosystem Restoration, CRC Press, Boca Raton, 105-111. http://dx.doi.org/10.1201/b14314-10 [11] Karissa, P.T., Sukardi, Priyono, S.B., Mamangkey, G.F. and Taylor, J.J.U. (2012) Utilization of Low-Voltage Electricity to Stimulate Cultivation of Pearl Oysters Pinctada maxima (Jameson). In: Goreau, T.J. and Trench, R.K., Eds., Innovative Methods of Marine Ecosystem Restoration, CRC Press, Boca Raton, 131-139. http://dx.doi.org/10.1201/b14314-12 [12] Berger, N., Haseltine, M., Boehm, J.T. and Goreau, T.J. (2012) Increased Oyster Growth and Survival Using Biorock Technology. In: Goreau, T.J. and Trench, R.K., Eds., Innovative Methods of Marine Ecosystem Restoration, CRC Press, Boca Raton, 141-150. http://dx.doi.org/10.1201/b14314-13 [13] Shorr, J., Cervino, J., Lin, C., Weeks, R. and Goreau, T.J. (2012) Electrical Stimulation Increases Oyster Growth and Survival in Restoration Projects. In: Goreau, T.J. and Trench, R.K., Eds., Innovative Methods of Marine Ecosystem Restoration, CRC Press, Boca Raton, 151-159. http://dx.doi.org/10.1201/b14314-14 [14] Vaccarella, R. and Goreau, T.J. (2012) Restoration of Seagrass Mats (Posidonia oceanica) with Electrical Stimulation. In: Goreau, T.J. and Trench, R.K., Eds., Innovative Methods of Marine Ecosystem Restoration, CRC Press, Boca Raton, Florida, 161-167. http://dx.doi.org/10.1201/b14314-15 [15] Cervino, J., Gjoza, D., Lin, C., Weeks, R. and Goreau, T.J. (2012) Electrical Fields Increase Salt Marsh Survival and Growth and Speed Restoration in Adverse Conditions. In: Goreau, T.J. and Trench, R.K., Eds., Innovative Methods of Marine Ecosystem Restoration, CRC Press, Boca Raton, Florida, 169-178. http://dx.doi.org/10.1201/b14314-16 [16] Goreau, T.J. (2012) Marine Ecosystem Electrotherapy: Practice and Theory. In: Goreau, T.J. and Trench, R.K., Eds., Innovative Methods of Marine Ecosystem Restoration, CRC Press, Boca Raton, 263-290. http://dx.doi.org/10.1201/b14314-20 [17] Goreau, T.J. (2012) Innovative Methods of Marine Ecosystem Restoration: An Introduction. In: Goreau, T.J. and Trench, R.K., Eds., Innovative Methods of Marine Ecosystem Restoration, CRC Press, Boca Raton, 5-10. http://dx.doi.org/10.1201/b14314-3 [18] Stromberg, S.M., Lundalv, T. and Goreau, T.J. (2010) Suitability of Mineral Accretion as a Rehabilitation Method for Cold-Water Coral Reefs. Journal of Experimental Marine Biology and Ecology, 395, 153-161. http://dx.doi.org/10.1016/j.jembe.2010.08.028 [19] Zhao, M., Song, B., Pu, J., Wada, T., Reid, B., Tai, G., Wang, F., Guo, A., Walczysko, P., Gu, Y., Sasaki, T., Suzuki, A., Forrester, J.V., Bourne, H.R., Devreotes, P.N., McCaig, C.D. and Penninger, J.M. (2006) Electrical Signals Control Wound Healing through Phosphatidylinositol-3-OH Kinase-􀈖 and PTEN. Nature, 442, 457-460. http://dx.doi.org/10.1038/nature04925 [20] Goreau, T.J. and Hilbertz, W. (2005) Marine Ecosystem Restoration: Costs and Benefits for Coral Reefs. World Resource Review, 17, 375-409. [21] Goreau, T.J. and Sarkisian, T. (2010) Electric Coral Reef Restoration in Thailand. Asia Pacific Coral Reef Symposium, 2, 100. [22] Goreau, T.J., Cervino, J. and Pollina, R. (2004) Increased Zooxanthellae Numbers and Mitotic Indices in Electrically Stimulated Corals. Symbiosis, 37, 107-120. [23] Wethey, D.S. and Porter, J.W. (1976) Sun and Shade Differences in Productivity of Reef Corals. Nature, 262, 281-282. http://dx.doi.org/10.1038/262281a0 [24] Porter, J.W., Muscatine, L., Dubinsky, Z. and Falkowski, P.G. (1984) Primary Production and Adaptation in Light- and Shade-Adapted Corals of the Symbiotic Coral Stylophora pistillata. Proceedings of the Royal Society of London B, 222, 161-180. http://dx.doi.org/10.1098/rspb.1984.0057 [25] Hennige, S.J., Suggett, D.J., Warner, M.E., McDougall, K.E. and Smith, D.J. (2009) Photobiology of Symbiodinium Revisited: Bio-Physical and Bio-Optical Signatures. Coral Reefs, 28, 179-195. http://dx.doi.org/10.1007/s00338-008-0444-x [26] Goreau, T.F. and Goreau, N.I. (1959) The Physiology of Skeleton Formation in Corals. II. Calcium Deposition by Hermatypic Corals under Various Conditions in the Reef. Biological Bulletin, 117, 239-250. http://dx.doi.org/10.2307/1538903 [27] Cheng, N., Van Hoof, H., Bockx, E., Hoogmartens, M.J., Mulier, J.C., De Ducker, F.J., Sansen, W.J. and De Loecker, W. (1982) The Effects of Electric Currents on ATP Generation, Protein Synthesis, and Membrane Transport in Rat Skin. Clinical Orthopaedics and Related Research, 171, 264-272. [28] Beddoe, L., Goreau, T.J., Agard, J.B.R., George, M. and Phillip, D.A.T. (2010) Electrical Enhancement of Coral Growth: A Pilot Study. In: Lawrence, A. and Nelson, H.P., Eds., Proceedings of the 1st Research Symposium on Biodiversity in Trinidad and Tobago, University of the West Indies, 116-122. [29] Terlouw, G. (2012) Coral Reef Rehabilitation on Koh Tao, Thailand: Assessing the Success of a Biorock Coral Reef. Vrije Universiteit, Amsterdam, 31. [30] Piazza, B.P., Piehler, M.K., Grossman, B.P., La Peyre, M.K. and La Peyre, J.L. (2009) Oyster Recruitment and Growth on an Electrified Structure in Grand Isle, Louisiana. Bulletin of Marine Science, 84, 59-66. [31] Schuhmacher, H. (2002) Use of Artificial Reefs with Special Reference to the Rehabilitation of Coral Reefs. Bonner Zoologische Monographien, 50, 81-108. [32] Schuhmacher, H. and Schillak, L. (1994) Integrated Electrochemical and Biogenic Deposition of Hard Material—A Nature-Like Colonisation Substrate. Bulletin of Marine Science, 55, 672-679. [33] Schuhmacher, H., Van Treeck, P., Eisinger, M. and Paster, M. (2000) Transplantation of Coral Fragments from Ship Groundings on Electro-Chemically Formed Reef Structures. Proceedings of the 9th International Coral Reef Symposium, Bali, 2, 23-27. [34] Van Treeck, P. and Schuhmacher, H. (1997) Initial Survival of Coral Nubbins Transplanted by a New Coral Transplantation Technology-Options for Reef Rehabilitation. Marine Ecology Progress Series, 150, 287-292. http://dx.doi.org/10.3354/meps150287 [35] Van Treeck, P. and Schuhmacher H. (1998) Mass Diving Tourism—A New Dimension Calls for New Management Approaches. Marine Pollution Bulletin, 37, 499-504. http://dx.doi.org/10.1016/S0025-326X(99)00077-6 [36] Van Treeck, P. and Schuhmacher, H. (1999) Artificial Reefs Created by Electrolysis and Coral Transplantation: An Approach Ensuring the Compatibility of Environmental Protection and Diving Tourism. Estuarine, Coastal and Shelf Science, 49, 75-81. [37] Sabater, M.G. and Yap, H.T. (2002) Growth and Survival of Coral Transplants with and without Electrochemical Deposition of CaCoB3B. Journal of Experimental Marine Biology and Ecology, 272, 131-146. http://dx.doi.org/10.1016/S0022-0981(02)00051-5 [38] Sabater, M.G. and Yap, H.T. (2004) Long-Term Effects of Mineral Accretion on Growth, Survival and Corallite Properties of Porites cylindrica Dana. Journal of Experimental Marine Biology and Ecology, 311, 355-374. http://dx.doi.org/10.1016/j.jembe.2004.05.013 [39] Eggeling, D. (2006) Electro-Mineral Accretion Assisted Coral Growth: An Aquarium Environment. Townsville Aquarium, Queensland, 21. [40] Borell, E.M. (2008) Coral Photophysiology in Response to Thermal Stress, Nutritional Status and Seawater Electrolysis. Centre for Tropical Biology, University of Bremen, Bremen, 134. [41] Borell, E.M., Romatzki, S.B.C. and Ferse, S.C.A. (2009) Differential Physiological Responses of Two Congeneric Scleractinian Corals to Mineral Accretion and an Electrical Field. Coral Reefs, 29, 191-200. [42] Goreau, T.J. and Hayes, R.L. (2005) Global Coral Reef Bleaching and Sea Surface Temperature Trends from Satellite- Derived Hotspot Analysis. World Resource Review, 17, 254-293. [43] Goreau, T.J., Hayes, R.L. and McAllister, D. (2005) Regional Patterns of Sea Surface Temperature Rise: Implications for Global Ocean Circulation Change and the Future of Coral Reefs and Fisheries. World Resource Review, 17, 350- 374.

biorock_review_natural_resources_2014


Biorock Electric Reefs Grow Back Severely Eroded Beaches in Months

marine science and engineering

Biorock Electric Reefs Grow Back Severely Eroded Beaches in Months

Thomas J. F. Goreau 1,2  and  Paulus Prong 2,3

Global Coral Reef Alliance, 37 Pleasant Street, Cambridge, MA 02139, USA
Biorock Indonesia, Bali 80361, Indonesia
Pulau Gangga Dive Resort, Sulawesi 95253, Indonesia
 
Abstract
Severely eroded beaches on low lying islands in Indonesia were grown back in a few months—believed to be a record—using an innovative method of shore protection, Biorock electric reef technology. Biorock shore protection reefs are growing limestone structures that get stronger with age and repair themselves, are cheaper than concrete or rock sea walls and breakwaters, and are much more effective at shore protection and beach growth. Biorock reefs are permeable, porous, growing, self-repairing structures of any size or shape, which dissipate wave energy by internal refraction, diffraction, and frictional dissipation. They do not cause reflection of waves like hard sea walls and breakwaters, which erodes the sand in front of, and then underneath, such structures, until they collapse. Biorock reefs stimulate settlement, growth, survival, and resistance to the environmental stress of all forms of marine life, restoring coral reefs, sea grasses, biological sand production, and fisheries habitat. Biorock reefs can grow back eroded beaches and islands faster than the rate of sea level rise, and are the most cost-effective method of shore protection and adaptation to global sea level rise for low lying islands and coasts.
 
(This article belongs to the Special Issue Coastal Sea Levels, Impacts and Adaptation)
 
 

1. Introduction
 
Accelerating global sea level rise is now causing almost all beaches worldwide to erode [1]. The current rate of sea level rise, now 3 mm/year [2], will accelerate greatly in the future as the melting of ice caps increases, masked by shorter term regional fluctuations driven by local weather [3]. IPCC projections of sea level rise are often thought by the public to represent the end point of sea level rise response to fossil fuel CO2, but in fact they are merely points along the first 5, 10, 20— or at most 100—years, of the initial rise of a curve that will continue to increase for thousands of years. The time horizons for IPCCC climate change projections were chosen for political purposes, not for scientific ones, and therefore miss the vast bulk of the real world long-term sea level and temperature responses to increased greenhouse gases [4].
 
Since the ocean holds nearly 93% of the heat in the Earth ocean-atmosphere-soil-vegetation-rock-ice system [5] and it takes around 1500 years for the ocean to mix and turn over [6], Earth’s surface will not fully warm up until after the deep ocean waters, now about 4 degrees above freezing, heat up. Global temperatures and sea levels lag thousands of years behind CO2 increases because of ocean mixing, so we have not yet really begun to feel the inevitable temperature and sea level responses. Because of these politically chosen time horizons, IPCC projections do NOT include more than 90% of the long-term climate response to changing CO2 [4,7-9]. By greatly underestimating the all too real long-term responses of temperature and sea level, they have lulled political decision makers into a false sense of complacency about the magnitude and duration of human-caused climate change or the urgency of reversing them before the really serious impacts hit future generations [4].
 
Improved estimates of long-term global climate impacts are made from actual paleoclimate records of changes in global CO2, temperature, and sea levels from the Antarctic ice cores, deep sea sediments, and fossil coral reefs over the last few million years [7,9]. The last time that global temperatures were 1-2 °C above today’s level, sea levels were about 8 m higher, crocodiles and hippopotamuses lived in swamps where London, England, now stands (Rhodes Fairbridge, 1987, personal communication) [10,11], and CO2 levels were around 270 ppm, around 40% lower than today [7,9]. Comparison of long-term global climate change records suggests that the steady state climate for the present (2017) CO2 concentration of 400 ppm, once the climate system has fully responded, are about 17 °C and 23 m above today’s levels [9]. We are committed to such changes even if there is no further CO2 increase starting right now because of the excess already in the atmosphere, unless that is reduced. No amount of emissions reduction can reduce excess atmospheric CO2, only increased natural carbon sinks with storage in soil and biomass carbon can draw down the dangerous excess in time to avert extreme long term changes [4,8,12], which would last for hundreds of thousands to millions of years. Perhaps the largest cost of adaptation to climate change will be the cost of protecting low lying islands and coasts from being flooded by global sea level rise.
 
Beach erosion is largely controlled by refraction of offshore waves by bottom topography [13]. The reflection of waves by steep cliffs prevents any accumulation of sand at their bases. In contrast, shallow sandy beach fore-shores are almost always protected from waves by reefs, Waves are refracted as water passes through porous and permeable reef structures, without being reflected.
 
Conventional methods of shore protection rely on “hard” solid structures like sea walls and breakwaters that are designed to reflect waves, like rock cliffs. This concentrates all the energy of the wave at the hard, reflecting surface, and the force on the structure itself is twice the momentum of the wave due to the reversal of the wave direction vector [14,15]. The inevitable result of this energy focusing is that first all the sand is washed away in front of the structure, and then is scoured away underneath it until the structure settles, cracks, falls apart, and needs to be rebuilt. These structures protect what is behind them until they fall down, but they cause erosion in front of them and guarantee loss of sediment. All such structures are consequently ephemeral and will fall down sooner or later, depending on how large and strong they are.
 
This is well known to coastal engineers but most feel there is no alternative to impermeable solid walls, even though so called “porous” or “permeable” breakwaters, made of small distributed modules shaped like coral reefs, with holes within structures and passages between them, seem to protect shores with much less material and with greatly reduced reflection. But we could find no experimental or theoretical modeling literature on porous permeable structures like natural coral reef structures found by searching on Google Scholar. Most search results for porous breakwaters were for solid rock walls with crevices between stones rather than reef-like structures with a much greater range of pore and spacing sizes, capable of interacting with waves over larger wavelength ranges.
 
Coral reefs provide the most perfect natural shore protection, dissipating around 97% of incident wave energy by frictional dissipation [16]. Healthy reefs produce sand as well as protect it, and rapidly build beaches behind them. They are sand factories, generating vast amounts of new sand, largely remains of calcareous green and red algae. Every grain of white limestone sand on a tropical beach is the skeletal remains of a living coral reef organism. Once corals die from high temperatures, pollution, or disease, the previously growing and self-repairing reef framework starts to deteriorate and crumble from boring organisms that excavate the rock [17]. Because of the mass mortality of corals around the world caused by global warming [18-23], tropical beaches that were growing until recently have begun rapid erosion, and islands are washing away because of global sea level rise. 
 
Here we describe the results of a novel method of beach restoration—Biorock electric reef shore protection—which avoids the intrinsic physical flaws of hard reflective structures, and which grows beaches back at record rates at a lower cost, with less materials, and with much greater environmental benefits than seawalls. Biorock electric reefs are grown by low voltage electrolysis of sea water, which causes growth of limestone rock minerals dissolved in sea water over steel surfaces, which are completely protected from corrosion [24,25]. Biorock reef structures can be any size or shape, and are the only marine construction material that gets stronger with age and is self-repairing [26]. When grown slowly, less than 1-2 cm/year, this material is several times harder than Portland Cement concrete [25].
 
Biorock shore protection reefs are open mesh frameworks designed to permit water to flow through them, like coral reefs. The size and shape of the structures, and of the holes in them, determine their performance dissipating wave energy. The electricity needed for electrolysis is safe extremely low voltage (ELV) direct current provided by transformers, chargers, batteries, solar panels, wind mills, ocean current generators, or wave energy generators, depending on which source is most cost effective at the site [27].
 
Biorock reefs in Grand Turk survived the two worst hurricanes in the history of the Turks and Caicos Islands, which occurred three days apart and damaged or destroyed 80% of the buildings on the island [28]. Sand was observed to build up around the bases of Biorock reef structures. In contrast, concrete reef balls nearby caused such severe sand scour around and under them that they buried themselves into the sand, digging their own graves. Solid objects, by forcing bottom currents to accelerate as they diverge around them, cause erosion to a depth of about half the height of the structure, and about as wide as the structure height [29]. Biorock reefs, being permeable and porous to waves, had the opposite effect than reef balls, baffling waves, lowering their velocity, and causing sand deposition instead of erosion [30].
 
The first Biorock shore protection reef was built in front of a beach that had washed away at Ihuru Island, North Male Atoll, the Maldives, in 1997. Sand bags were being piled in front of trees and buildings that were falling into the sea, which the hotel thought they had no chance of saving. The Biorock reef was a linear structure parallel to the shore, 50 m long, about 5 m wide, and about 1.5 m high, built on eroded reef bedrock. The structure cemented itself solidly to the limestone bedrock with mineral growth. Waves were observed to slow down as they were refracted through the structure, dissipating energy by surface friction. Sand immediately began to accumulate on the shore line and under and around the reef, and the beach grew back naturally and rapidly in a few years, and stabilized with no further erosion, even though the 2004 Tsunami passed right over it [30]. Corals growing on the Biorock reef had 50 times (5000%) higher coral survival than the adjacent natural coral reef after the 1998 coral bleaching event [25]. For a decade after the bleaching event this resort had the only healthy reef full of corals and fishes in front of their beach in the Maldives. The hotel whose reef and beach were saved by the Biorock project turned the power off, with the result that the corals, no longer protected from bleaching by the Biorock process [31,32], suffered severe mortality in the 2016 bleaching event.
 
The second group of Biorock shore protection reefs were built at three eroding beach locations at Gili Trawangan, Lombok, Indonesia around 2010. These consisted of 4 to 6 separate reef modules designed to break waves up by slowing down separate portions of the wave front and driving the incoming wave front out of coherence, using less structural materials. The Biorock structures are shaped like an upside-down wave, which is optimal for dissipating wave energy, with no vertical surfaces to cause reflections, and so are called Biorock Anti-Wave structures (BAW). Although these structures were small, new beach growth was clearly visible at all sites within 8 months on Google Earth images [30]. One set of structures was of, and creation of a gap underneath it, so that it was on the way to falling down. One year later the gap underneath had completely filled in, and the sand had risen by about a meter to cover half the vertical wall height. The seawall on the neighboring property, built at the same time, but not protected by Bioorck, completely collapsed within a year [30]. The hotels whose beaches had been restored by the projects then turned the power off. Because the structures, no longer maintained, growing, or protected from rusting, are now collapsing, beach erosion has now resumed, with new sea walls being constantly built and falling down.
 
2. Materials and Methods
 
Pulau Gangga, North Sulawesi, Indonesia, has suffered progressive beach erosion. The index maps show its location on various scales (Figure 1a-d), and Google Earth images show the rapid erosion of the beach between 2013 and 2014 (Figure 2a,b). The site is outside the typhoon belt because it is close to the Equator, but it is affected by both the Australian and Indo-China Monsoons. From around December through May the winds and waves are usually from the southeast. A strong southward tidally-modulated current normally sweeps sand from north to south at the site.
 
The formerly wide sand beach had largely washed away by late 2015, leaving an erosion cliff about 1.36 m high along the shore, with trees falling into the sea, and beach pavilion buildings have had to be repeatedly torn down and moved inland. In front of the 200 m of severely eroded beach we built 48 Biorock Anti Wave reefs in a staggered design to dissipate wave energy before it hits the beach. The time of installation, January 2016, was just before the monsoon season when erosion takes place on this beach, and was done as fast as possible before waves made installation difficult.
 
48 Biorock Anti Wave reefs were deployed in the sea grass beds in front of the eroding beach in January 2016. They were arrayed in twelve groups of four, each group powered by a single power supply located 100 m away on land, connected by electrical cables dug into the sand (Figures 3 and 4a-d). They grow thickest at the bottom, and thinnest on top. The bottom 10-20 cm of the structures were always submerged at low tide, but above this they were exposed to the air for various periods, depending on the tidal cycle. Since structures grow only when and where submerged in salt water, the bottoms are always growing, while the top grows only when submerged, about half of the time. The gabion baskets were deployed in a grid pattern (visible from aerial images below) at low tide in shallow sand, seagrass, and coral rubble.
 
The resort had previously purchased gabion wire baskets for stones to make a breakwater, not knowing that these would quickly rust and fall apart. Because these were already available, they were incorporated into the core of the Biorock Anti Wave structures, because the Biorock electrolysis process prevents any rusting of the steel. The rocks are bound in place by growth of minerals over the mesh and by prolific growth of barnacles, oysters, and mussels, preventing rock shifting in heavy surge from breaking the gabion. There are both advantages and disadvantages to the use of rock gabions in Biorock shore protection structures, as they can cause scour by acting as a near solid wall, but they cause more rapid initial results slowing wave erosion than a more open structure that does not incorporate them. Gabions are not an essential part of the design, in fact not using them makes BAW units much faster and cheaper to construct and deploy. In this study gabions were used only for convenience as they had been previously bought and were already on site. Not to include rocks at all relies purely on the growth of a biological reef to provide long-term growing shore protection, instead of that provided by the rocks.
 
The core of each structure was a double gabion basket, 1 m × 1 m × 2 m with the long dimension parallel to the shore. These were placed on the shallow sea floor at predetermined sites, with the long axis parallel to the shore, and filled in with rounded river stones (largely in the 20-50 cm size range). At the start, the rocks had clean surfaces with nothing growing on them. The gabion baskets were overlain with standard welded steel mesh bars used in local construction, spacing 15 cm, dimensions about 2.1 m by 5.4 m. These sheets were curved into an arc to fit over the top of the gabion basket, with the long dimensions at right angles, so that the long axis of the arc was perpendicular to the shore, oriented into the waves coming over the shelf edge coral reef. They were welded across at the base with support rebars and vertical bars to strengthen them. Each unit was carried by four people at low tide, placed over a gabion basket and wired to it with hose clamps and binding wire. The growth of minerals over the steel cement it firmly to any hard rock bottom, and cement sediment around the bases on sand or mud, firmly attaching the structure to the bottom. The structures sit on the bottom under their own weight and that of the rocks they contain.
 
Beach profiles were measured using the U-tube water level measuring method [32]. They are estimated to be accurate vertically to about a millimeter, and horizontally to about a centimeter, by repeated measurements. The beach profile before the start of the experiment was estimated from photographs taken before and after from the same positions with common objects of known size in the images for scale. The accuracy of the pre-project beach profile estimate is thought to be about 10 cm vertically and one meter horizontally. Unfortunately, the apparatus for making rapid and accurate beach profiles was not built until September 2016, eight months after the start of the project. A second set of measurements was made in January 2017, a year after the start of the project, after a severe storm and at several more intervals since then. Initial beach profiles were estimated by measuring the height of the erosion cliff at the start of the project using the measured height of concrete foundations as a scale.

 

(a)
(b)
(c)
Figure 1. The site shown on Google Earth Images of the location of the project (red star) on decreasing scales: (a) Indonesia, (b) North Sulawesi, (c) Pulau Gangga
 
(a) 23 May 2013
(b) 4 January 2014
(c) 15 December 2014
(d) 4 August 2017
Figure 2. Erosion of the beach prior to the project. Google Earth images from 2013 (a) and 2014 (bshowing short term changes in the beach before the project, the last available image taken near low tide a year before the project began in early 2016 (c), and the first image after the project, taken near high tide 1.5 years after (d). Notice the cores of the Biorock Anti Wave modules as white spots in the seagrass off the regenerated beach. Beach erosion beyond the project near the pier at the south was caused by storm waves from the southeast and longshore drift sand blockage by the solid rock pier. Waves from the northwest shown in (c) are typical during erosion of this westward facing beach. Note the row of pavilions (dark spots) on the edge of the beach erosion scarp and brown dying trees with roots exposed in (c) and how in (d) the roofs are now hidden by new leaf canopies due to prolific tree leaf regrowth after sand buildup around their roots.
 
 
Figure 3. Soon after start of the project, at low tide (wide angle image). The tops of the reef restoration structures are clearly visible. The eroded curve is the area where the beach grew back.
 
 
(a)
(b)
(c)
(d)
Figure 4. Aerial views, oblique at low tide (a) and vertical at high tide (b) on 12 March 2017, fourteen months after the installation, showing the Biorock Anti Wave structures (dark spots in sea grass beds). The northern edge of the project, on the same day at high (c) and low (d) tides. The Red spot in the last image two images is the northern limit of the project.
 
 
3. Results
 
The speed of beach regrowth astonished local residents. The formerly concave beach, ending in an eroding cliff, is now convex in its profile and growing. Large trees that had been dying after sand washed away, exposing their roots to sea water, have leafed out new canopies since the sand built up around their roots.
 
By the time of the first beach profile measurements the eroded beach had almost completely grown back and the erosion scarp, 1.36 m tall, was reduced to about 10 cm. About 80% of the beach grew back in less than 3 months and has continued to grow ever since, even during strong storm conditions that in the past caused severe erosion. Over the course of a year the beach has increased in height by more than a meter, and in width by more than 15 m, over a two hundred meter length, a conservative estimate of an increase of beach sand volume of 3000 cubic meters. Most of the gains occurred in the first two months, but have continued since (Figure 5a-g).
 
The beach growth in the first year was wider at the south than at the north. But there were interesting differences after a severe storm in early January, which caused some erosion of the southern end of the beach, while there was substantial growth of the central and northern sections. Since then the center and north have continued to grow, while the south has continued to erode slowly (Figure 6a-c).
 
(a) November 2015
(b) December 2015
(c) December 2015
(d) May 2016
(e) August 016
(f) November 2016
(g) January 2017
Figure 5. Before & after photos of beach taken at various times: (a) November 2015, beach looking north two months before start of project, tree falling into the sea and roots exposed at beach erosion scarp, (b) December 2015, one month before project, 1.36 m high erosion scarp and foundations of beach pavilions about to collapse near center of beach, (c) December 2015, one month before project, large old tree collapsing into the sea, leaves dying, roots exposed, (d) May 2016, 4 months after project installation, lower branches of fallen tree buried in new beach sand growth, roots buried, new growth, (e) August 2016, seven months after, (f) November 2016, ten months after, (g) January 2017, Twelve months after, soon after a severe storm, looking south. Most of the beach grew after the storm, even though this was the sort of event that had caused heavy erosion in the past. The south end, shown here, was worst affected.
 
 
(a)
(b)
(c)
Figure 6. Beach profiles, measured at different times for the north (a), center (b), and south (c). The Zero reference datum for the central profile is the top of the concrete pillar foundation at the left of the December 2015 photograph. A 1.36 m vertical cliff stood at what is now the zero distance, based on measurements from photographs. Dates of measurements: X and dashed line estimate from January 2016; KEY to symbols: B upward triangle, 21 September 2016; C square, 11 January 2017; D downward triangle, 11 March 2017, E circle, 10 July 2017.
 
There has been prolific growth of hard and soft corals all over the bases of the structures and in intervening areas (Figure 7a-e), prolific growth of sea grasses all around them, dense settlement and growth of barnacles, mussels, and clams on the rocks in the core of the BAW structures, and a rapid increase in juvenile fish and echinoderm populations. In addition, there has been prolific growth of sand-producing calcareous green and red algae around and between the structures.
 
(a)
(b)
(c)
(d)
(e)
Figure 7. Underwater images: One end of a Biorock Anti Wave structures at high tide soon after installation (a), growth of barnacles over smooth river stones inside the gabions (b), examples of rapid growth of corals, sea grasses, and other organisms under, over, and around their bases (ce).
 
Wave fronts are dissipated as they pass through the structures, breaking up the coherence of incoming wave fronts (Figure 8a-c). This dissipation behaves as refraction through permeable structures. But the wave interaction can include a reflective component once structures have grown to be solid with all pores filled in, or if the rock fill is too impermeable to transmit wave pressure through intervening spaces. In that case, sand-eroding scour will be caused, while purely refractive dissipation increases sand accumulation underneath and behind the structure. There is also a diffractive component caused by wave interaction with the metal structure spacing and lattice spacing, which appeared to damp waves at spatial scales that range from the spacing of the metal grid used (0.1 m), the size of the modules (1-5 m), and the spacing of the modules (roughly 10 m).
(a)
(b)
(c)
Figure 8. Diffraction of energy. Incoming wave energy dissipated by interaction with structure these photographs were taken in rapid succession, the middle picture appears brighter because of break in the clouds, and the photographer moved between the first two images. (a) approaching wave, (bwave starting to interact with mesh, (c) wave energy dissipated by friction.
 
4. Discussion
 
We are not aware of any other case in which a badly eroded beach has been grown back so uickly and naturally. In addition, the Biorock reefs have caused prolific growth of corals, barnacles, oysters, mussels, and seagrass, and created a juvenile fish habitat [30]. 
 
Biorock reefs can be any size or shape. Mineral growth extends up to the high tide mark. They can be built entirely subtidal, as at Ihuru, entirely exposed at low tide as at Gili Trawangan, or have only the tops exposed at low tide, as at Pulau Gangga. Since the structures grow only when submerged, those in the intertidal grow most on the bottom, and least on the top. The structures attach themselves solidly to bedrock, and cement loose sand around their bases. Whether the structures are entirely submerged or partially exposed affects their wave mitigating performance. Those that are fully submerged are never visible from shore and generate real coral reef communities or oyster and mussel reefs in muddier or colder waters. Those reefs located in the intertidal zone are visible at low tide, which may be aesthetically objectionable to those who want a clear ocean view from the beach, but they are more effective in protecting the shore if there is a storm during high tide, which would pass over deeper reef structures.
 
The size, shape, and spacing of the modules affect their performance, and cost. What is astonishing is that record beach growth was achieved with far less material and far lower cost than sea wall or a breakwater. Conventional reinforced concrete structures are made by first building a reinforcing bar frame, and the steel is a very small part of the total cost compared to cement, stone, wooden forms, and labor. Since steel in reinforced concrete structures invariably rusts, expands, and cracks the concrete, such structures have finite lifetimes, especially in salty coastal air. 
 
Biorock structural steel is completely protected from rusting, and the continuous growth of hard minerals makes it constantly stronger, and able to grow back first in areas that are physically damaged. The cost is far less than a reinforced concrete structure of the same size and shape, because instead of cement, rocks, labor, and wooden forms we simply provide an electrical supply instead. Estimates of Biorock reef costs range from $20-1290/m of shoreline depending on the size of the reef grown, while other methods range from $60-155,000/m, or 3-120 times more expensive [16]. The amount of electricity used is small, the entire Pulau Gangga beach restoration project uses about one air conditioner worth of electricity.
 
Shore protection provided by Biorock includes both production of new sand by prolific growth of calcareous algae around them, and physical protection from sand erosion by wave energy dissipation. The results of beach growth after the project was installed indicate that beach sand accumulation is a very dynamic function of wave and current interactions with reef structures. Biorock reef structures physically dissipate wave energy and reduce erosion at the shoreline, while also generating new sand. They should slow down transport of sand by north to south tidal currents at the site. That, and the interplay of the structures with waves coming from different directions, may explain why the unusual January 2017 storm seems to have transported sand in the reverse of the usual direction. Further measurements will reveal if this trend continues, or is reversed by sand production from increased calcareous algae growth around the structures.
 
Wave energy dissipation due to friction at the surface of the growing limestone minerals produced by the Biorock process is very quickly exceeded by the much larger, and rougher, surfaces provided by the prolific growth of corals, barnacles, sea grass, and all other living marine organisms as the structure becomes rapidly overgrown. The size, shape, and spacing of the structures, as well as the reef organisms growing on them, affect their performance as wave absorbers, and their designs can be readily changed by adding, or removing, sections as needed. Such structures can be designed to be oyster, mussel, clam, lobster, or fish habitat for highly productive and sustainable mariculture.
 
Biorock structures interact with waves over a very broad range of wavelengths, and are expected to produce wave diffraction on wavelength scales similar to the spacing of the structures—about 10 m—and over the spacing of the mesh—about 10 cm. Since the growing, self-repairing Biorock structures cannot be modelled by conventional hydrodynamic modeling schemes, it will be important to make physical measurements of wave energy around such structures to evaluate actual performance, and to optimize them for beach growth purposes.
 
The initial results of this project resulted in extraordinary beach growth, which could be improved with further experimentation under a wider range of conditions, and should be much more widely applied as a cost-effective beach restoration solution that uniquely restores marine ecosystem  services.
 
5. Conclusions
 
We have grown back severely eroded beaches naturally in months by growing Biorock electric reefs in front of them. These structures cost far less than sea walls or breakwaters and work on entirely different physical principles. They restore marine ecosystems as well as beaches. The exceptionally rapid growth of corals on them [31,33] provides additional shore protection, and the rapid growth of sand-producing calcareous algae on and around them produces new biological sand supplies. These structures can easily keep pace with global sea level rise because solid hard electrochemical minerals can be grown upwards at rates up to 2 cm/year—around 5 times faster than sea level rise—and grow still much faster when corals, oysters, mussels, and other calcareous organisms cover them. As a result, Biorock shore protection reefs quickly turn eroding beaches into growing ones, can protect entire islands and even grow new ones. Biorock is the most cost-effective technology for protecting eroding coasts, for restoring fisheries habitat, and is critically needed to save the low-lying islands and coasts now threatened by global sea level rise, and the billions of coastal people who will become climate refugees if global warming is not rapidly reversed [4,12].
 
6. Dedication
 
This paper is dedicated to the memory of the late Wolf Hilbertz, who first invented the Biorockprocess of growing minerals in the ocean in 1976, and who foresaw all its applications, including shore protection.
 
Acknowledgments: We thank the entire management and staff of Pulau Gangga Dive Resort and its parent company, Lotus Resorts, for their willingness to try new, better, more natural and effective approaches to shore protection. Lotus Resorts paid for all materials, equipment, domestic travel, and time. The authors thank them deeply for their willingness to pioneer innovative methods of shore protection. We also thank Lori Grace for providing funds for a round trip ticket to Indonesia for Thomas J. F. Goreau to construct the device to measure beach profiles. We thank the anonymous reviewers for their constructive suggestions that have improved the original draft.
 
Author Contributions: T.J.F.G. and P.P. conceived, designed, built, and installed the first four Biorock Anti Wave modules and connected them to power; P.P. then built and installed the rest. T.J.F.G. analyzed the data; contributed reagents/materials/analysis tools; and wrote the paper. Although they are not listed as authors, because they did not work on the projects in the water, the entire management and staff of Lotus Resorts, operators of Pulau Gangga Dive Resort, played absolutely crucial roles in the design, logistics, funding, advice, information, and support for the work described. T.J.F.G. is a co-inventor of the Biorock electric technology of marine ecosystem restoration.
 
Conflicts of Interest: The authors declare no conflict of interest.
 
References
 
1.      Pilkey, O.H.; Neal, W.J.; Bush, D.M. Coastal erosion; In Coastal Zones and Estuaries. Encyclopedia of Life
Support Systems (EOLSS); UNESCO: Paris, France, 1992.
2.      Dieng, H.B.; Cazenave, A.; Meyssignac, B.; Ablain, M. New estimate of the current rate of sea level rise
from a sea level budget approach. Geophys. Res. Lett. 2017, doi:10.1002/2017GL073308.
3.      Nieves, V.; Marcos, M.; Willis, J.K. Upper-Ocean Contribution to Short-Term Regional Coastal Sea Level Variability along the United States. J. Clim. 2017, 30, 4037-4045.
4.      Goreau, T.J. Global biogeochemical restoration to stabilize CO2 at safe levels in time to avoid severe climate\change impacts to Earth’s life support systems: Implications for the United Nations Framework Convention on Climate Change. In Geotherapy: Innovative Technologies for Soil Fertility Restoration,  Carbon Sequestration, and Reversing Atmospheric CO2 Increase; Goreau, T.J., Larson, R.G., Campe, J.A., Eds.; CRC Press: Boca Raton, FL, USA, 2014.
5.      Levitus, S.J.; Antonov, I.; Boyer, T.P.; Baranova, O.K.; Garcia, H.E.; Locarnini, R.A.; Mishonov, A.V.; Reagan, J.R.; Seidov, D.; Yarosh, E.S.; et al. World ocean heat content and thermosteric sea leve change (0-2000 m), 1955-2010. Geophys. Res. Lett. 2012, 39, L10603, doi:10.1029/2012GL051106.
6.      Gebbie, G.; Huybers, P. The Mean Age of Ocean Waters Inferred from Radiocarbon Observations: Sensitivity to Surface Sources and Accounting for Mixing Histories. J. Phys. Oceanogr. 2012, 42, 291-305.
7.     Goreau, T.J. Balancing atmospheric carbon dioxide. Ambio 1990, 19, 230-236.
8.     Goreau, T.J. Tropical ecophysiology, climate change, and the global carbon cycle. In Impacts of Climate Change on Ecosystems and Species: Environmental Context; Pernetta, J., Leemans, R., Elder, D., Humphrey, S., Eds.; International Union for the Conservation of Nature: Gland, Switzerland, 1995; pp. 65-79.
9.      Rohling, E.J.; Grant, K.; Bolshaw, M.; Roberts, A.P.; Siddall, M.; Hemleben, C.; Kucera, M. Antarctic temperature and global sea level closely coupled over the past five glacial cycles. Nat. Geosci. 2009doi:10.1038/NGEO557.
10.     Koenigswald, W.V. Mammalian faunas from the interglacial periods in Central Europe and their stratigraphic correlation. In The Climate of Past Interglacials; Sirocko, F., Claussen, M., Sanchez Goñi, M.F., Litt, T., Eds.; Elsevier: Amsterdam, The Netherlands, 2006; pp. 445-454.
11.     Koenigswald, W.V. Discontinuities in the Faunal Assemblages and Early Human Populations of Central and Western Europe During the Middle and Late Pleistocene. In Continuity and Discontinuity in the Peopling of Europe: One Hundred Fifty Years of Neanderthal Study, 101 Vertebrate Paleobiology and PaleoanthropologyCondemi, S., Weniger, G.-C., Eds.; Springer Science + Business Media B.V.: Dordrecht, The Netherlands, 2011.
12.     Goreau, T.J. The other half of the global carbon dioxide problem. Nature 1987, 328, 581-582.
13.     Munk, W.H.; Traylor, M.A. Refraction of Ocean Waves: A Process Linking Underwater Topography to Beach Erosion. J. Geol. 1947, 55, 1-26.
14.     Wiegel, R.L. Oceanographical Engineering; Dover: New York, NY, USA, 1992.
15.     Schiereck, G.J. Introduction to Bed, Bank, and Shore Protection: Engineering the Interface of Soil and Water; VSSD: Delft, The Netherlands, 2006.
16.      Ferrario, F.; Beck, M.W.; Storlazzi, C.D.; Micheli, F.; Shepard, C.C.; Airoldi, L. The effectiveness of coral reefs for coastal hazard risk reduction and adaptation. Nat. Commun. 2014, doi:10.1038/ncomms4794.
17.      Goreau, T.F.; Goreau, N.I.; Goreau, T.J. Corals and Coral Reefs. Sci. Am. 1979, 241, 124-136.
18.      Goreau, T.J. Testimony to the National Ocean Policy Study Subcommittee of the United States Senate Committee on Commerce, Science, and Transportation, S. HRG. 101-1138: 30-37; US Government Printing Office: Washington, DC, USA, 1991
19.     Hayes, R.L.; Goreau, T.J. The tropical coral reef ecosystem as a harbinger of global warming. World Resour. Rev. 1991, 3, 306-322.
20.     Goreau, T.J.; Hayes, R.L.; Clark, J.W.; Basta, D.J.; Robertson, C.N. Elevated sea surface temperatures correlate with Caribbean coral reef bleaching. In A Global Warming Forum: Scientific, Economic, and Legal Overview; Geyer, R.A., Ed.; CRC Press: Boca Raton, FL, USA, 1993; pp. 225-255.
21.      Goreau, T.J.; Hayes, R.L. Coral bleaching and ocean “hot spots”. Ambio 1994, 23, 176-180.
22.      Goreau, T.J.; Hayes, R.L. Global coral reef bleaching and sea surface temperature trends from satellite-derived Hotspot analysis. World Resour. Rev. 2005, 17, 254-293.
23.      Goreau, T.J.; Hayes, R.L.; McAllister, D. Regional patterns of sea surface temperature rise: Implications for global ocean circulation change and the future of coral reefs and fisheries. World Resour. Rev. 2005, 17, 350- 374.
24.      Hilbertz, W.H.; Goreau, T.J. Method of Enhancing the Growth of Aquatic Organisms, and Structures Created Thereby. U.S. Patent No. 5,543,034, 6 August 1996.
25.      Goreau, T.J.; Hilbertz, W. Marine ecosystem restoration: Costs and benefits for coral reefs. World Resour. Rev. 2005, 17, 375-409.
26.      Goreau, T.J. Marine electrolysis for building materials and environmental restoration. In ElectrolysisKleperis, J., Linkov, V., Eds.; InTech Publishing: Rijeka, Croatia, 2012; pp. 273-290.
27.      Goreau, T.J. Marine ecosystem electrotherapy: Practice and theory. In Innovative Technologies for Marine Ecosystem Restoration; Goreau, T.J., Trench, R.K., Eds.; CRC Press: Boca Raton, FL, USA, 2012.
28.      Wells, L.; Perez, F.; Hibbert, M.; Clervaux, L.; Johnson, J.; Goreau, T. Effect of severe hurricanes on Biorock coral reef restoration projects in Grand Turk, Turks and Caicos Islands. Rev. Biol. Trop. 2010, 58, 141-149.
29.      Shyue, S.-W.; Yang, K.-C. Investigating terrain changes around artificial reefs by using a multi-beam  echosounder. ICES J. Mar. Sci. 2002, 59, S338-S342, doi:10.1006/jmsc.2002.1217.
30.     Goreau, T.J.; Hilbertz, W.; Azeez, A.; Hakeem, A.; Sarkisian, T.; Gutzeit, F.; Spenhoff, A. Restoring reefs to grow back beaches and protect coasts from erosion and global sea level rise. In Innovative Technologies for Marine Ecosystem Restoration; Goreau, T.J., Trench, R.K., Eds.; CRC Press: Boca Raton, FL, USA, 2012.
31.     Goreau, T.J. Electrical stimulation greatly increases settlement, growth, survival, and stress resistance of marine organisms. Nat. Resour. 2014, 5, 527-537, doi:10.4236/nr.2014.510048.
32.      Andrade, F.; Ferreira, M.A. A Simple Method of Measuring Beach Profiles. J. Coast. Res. 2006, 22, 995-999, doi:10.2112/04-0387.1.
33.      Goreau, T.J.; Cervino, J.; Polina, R. Increased zooxanthellae numbers and mitotic index in electrically stimulated corals. Symbiosis 2004, 37, 107-120.
 
 © 2017 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution 

Electrical Stimulation Greatly Increases Settlement, Growth, Survival, and Stress Resistance of Marine Organisms

Thomas J. Goreau
Global Coral Reef Alliance, Cambridge, USA Email: goreau@bestweb.net
Received 23 May 2014; revised 26 June 2014; accepted 5 July 2014
Copyright © 2014 by author and Scientific Research Publishing Inc.
This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/

Abstract
Increasing stress from global warming, sea level rise, acidification, sedimentation, pollution, and unsustainable practices have degraded the most critical coastal ecosystems including coral reefs, oyster reefs, and salt marshes. Conventional restoration methods work only under perfect condi- tions, but fail nearly completely when the water becomes too hot or water quality deteriorates. New methods are needed to greatly increase settlement, growth, survival, and resistance to envi- ronmental stress of keystone marine organisms in order to maintain critical coastal ecosystem functions including shore protection, fisheries, and biodiversity. Electrolysis methods have been applied to marine ecosystem restoration since 1976, with spectacular results (Figures 1(a)-(c)). This paper provides the first overall review of the data. Low-voltage direct current trickle charges are found to increase the settlement of corals 25.86 times higher than uncharged control sites, to increase the mean growth rates of reef-building corals, soft corals, oysters, and salt marsh grass— an average of 3.17 times faster than controls (ranging from 2 to 10 times depending on species and conditions), and to increase the survival of electrically charged marine organisms—an aver- age of 3.47 times greater than controls, with the biggest increases under the most severe envi- ronmental stresses. These results are caused by the fundamental biophysical stimulation of natu- ral biochemical energy production pathways, used by all organisms, provided by electrical stimu- lation under the right conditions. This paper reviews for the first time all published results from properly designed, installed, and maintained projects, and contrasts them with those that do not meet these criteria.

Electrical Stimulation Greatly Increases Settlement, Growth, Survival, and Stress Resistance of Marine Organisms