Coral Reef Restoration Handbook - Chapter 10 ppsx

Hudson has also worked to develop benthic organism transplanting techniques.12 Nearly every client funding a coral reef restoration effort where tourism is involved insists on aesthetic

Trang 1

Ecological Restoration

Jessica Tallman

CONTENTS

10.1 Introduction 193

10.2 Artificial Reefs 194

10.2.1 Materials of Opportunity 194

10.2.2 Purpose-Designed Reefs 195

10.2.3 Underwater Artists 199

10.3 Recommendations 200

Acknowledgments 202

References 203

10.1 INTRODUCTION

The beauty of coral reefs has appealed to the human psyche for centuries In the late 1800s, Alfred Russel Wallace described a coral reef as “one of the most astonishing and beautiful sights I have ever beheld The bottom was absolutely hidden by a continuous series of corals, sponges, actinae [sea anemones] and other marine productions, of magnificent dimensions, varied forms, and brilliant colours … It was a sight to gaze at for hours, and no description can do justice to its surpassing beauty and interest.”1 Beholding a relatively healthy coral reef, such as the one described by Wallace,

or the one pictured in Figure 10.1, can be like swimming amid a rainbow Slices of spectrum undulate in an enticing dance due to whirlpools of fish spiraling in parades of color and flashing their iridescent scales against the sunlight Coral growth forms the basis of this ecosystem, having developed for thousands of years into magnificent pinnacles, caverns, towers, and peaks Amid these castles one feels the only way to explore is to slip into a school of vibrant fish and glide alongside their finned rhythm Multitudes of people visit coral reefs to experience immersion in this world of abundant and color-infused marine life

Due to their beauty and biological bounty, coral reef ecosystems provide services to millions

of people Businesses based near reefs create millions of jobs and contribute billions of dollars in tourism-dependent revenue annually to the world’s coastal regions Unfortunately, the rapidly declining health of the world’s coral reefs is largely due to human use Some diving destinations have far exceeded their ecologically bearable capacity.2 Significant effects from tourism are espe-cially found on major reef-building hard corals.3 Yet marine-related tourism is the cornerstone of many national economies, and the loss of this revenue is too great to end reef-related activities in order to preserve coral reefs.4 The reefs of southeast Florida, alone, are deemed to have an asset value of $7.6 billion.5 Sustaining this industry that generates billions of dollars is dependent on maintaining existing reefs and rehabilitating the lost splendor of this fragile ecosystem

Every restoration project has a unique set of goals, and while it is hoped that biological success

is the top priority of all undertakings, aesthetics should also be of importance Incorporating beauty

2073_C010.fm Page 193 Tuesday, April 18, 2006 11:16 AM

Trang 2

194 Coral Reef Restoration Handbook

and viewer interest in project plans is profitable for tourism-dependent operations and also raises awareness of conservation issues Conversely, aesthetics increases recreational activities that can

be damaging to restoration efforts and therefore should not be incorporated into all restoration projects Where appropriate, however, increasing aesthetic beauty of the world beneath the waves enhances the experience of reefs for millions of people

10.2 ARTIFICIAL REEFS

Artificial reefs are major tools of reef restoration efforts Artificial reefs have been in use since the 1700s, when Japanese fishermen shaped bamboo into structures attractive to fish In 1830, artificial reefs were used in the United States for the first time off of South Carolina These reefs of pine boughs were also meant to attract fish Fish aggregative devices (FADs) are still very common uses

of artificial reefs; however, in the present day, artificial reefs may be used for many other reasons

as well For example, some artificial reefs are a means of generating tourism as they are created

to heighten interest and beauty for snorkellers and scuba divers Today, “materials of opportunity” such as oil rigs, sunken ships, vehicles, and railway tracks are dumped into the ocean, or their presence there is exploited With a greater environmental effort in mind, purpose-designed reefs sculpted out of concrete, limestone rocks, metal, or bamboo are more favored for building ecolog-ically sound reefs on which marine life and human visitor appeal can thrive

10.2.1 M ATERIALS OF O PPORTUNITY

Materials of opportunity are commonly sunk to form artificial, or “found,” reefs Many scientists believe artificial reefs made of surplus materials are ocean pollutants destroying marine habitat.6,7 Some found reef material contains substances that may be toxic to biota such as heavy metals in cables, paints, and alloys.8 Additionally, artificial reefs are often longlasting, if not permanent intrusions into the benthic habitat.9 Permanent structures with such repercussions have little, if any, ecological value Even if reefs made from materials of opportunity did not pose an ecological threat, they do little to restore coral cover They are also often inappropriate for providing fish recruits with necessary protection found in a complex habitat due to large open spaces and lack of small recesses within the structure Without fish, algae will likely grow to cover the structure, thus smothering coral recruits

FIGURE 10.1 A natural coral reef off of Discovery Bay, Jamaica (Joshua Idjadi, with permission).

2073_C010.fm Page 194 Friday, April 7, 2006 4:53 PM

Trang 3

Aesthetic Components of Ecological Restoration 195

As seen in Figure 10.2, reefs made of materials of opportunity can be unsightly People dive and snorkel in tropical waters to see splendor, not someone’s old Chevy parked where there could

be a flourishing reef Many dive operations, hotels, and other tourism-dependent businesses are opting for more ecologically sound artificial reefs In a study on visitor experience and perceived conditions for tourists of the Great Barrier Reef, natural conditions were overwhelmingly the most important influence on enjoyment.10 The ecological need to mimic natural conditions coincides with aesthetic desires of reef visitors The tourism value of found reefs falls far short of the alternatives, purpose-designed artificial reefs or increasing efforts to preserve naturally healthy reefs Found reefs contribute very little ecologically and more often than not, have negative impacts on the visual beauty of the ocean floor Improving upon these surplus material reefs with purpose-designed reefs will help to achieve not only ecological but aesthetic goals

10.2.2 P URPOSE -D ESIGNED R EEFS

There is a considerable demand for artificial reefs to be aesthetically pleasing from the moment they are first deployed It can, however, take decades for an artificial reef to look like and take on some

of the functions of a natural reef Researchers, however, have discovered methods to hasten the time

it takes for a dive site to be aesthetically intriguing Today, aquascapists design snorkel trails and transplant benthic organisms to artificial or damaged reefs, and underwater sculptors create topo-graphically diverse artificial reefs The present technology in ocean engineering and construction allows almost any restoration design to be implemented.11 With scientific basis, reefs can be con-structed that not only meet scientific objectives but also create a beautiful environment for visitors to experience Knowledge of successful and unsuccessful restoration methods allows for a multidisci-plinary approach and incorporation of goals that may have been overlooked when reef restoration was a science in its beginning Socioeconomic aims can now take on greater importance in restoration plans by creating beautiful reefs not only attracting marine life but also human visitors

Harold Hudson (aka “Reef Doctor”) of the Florida Keys National Marine Sanctuary has been researching restoration modules for years His research has resulted in a terrific example of an artificial reef built with biological goals as a top priority while being mindful of the aesthetic beauty

of a natural reef formation Along with the FKNMS, Hudson has created modules of preformed concrete casts Figure 10.3 shows an example of the units made of small limestone boulders, rebar, concrete, and sand The conglomerates form a medium able to take on a number of shapes In the case of the NOAA Wellwood restoration project, the casts mimic the spur-and-groove formation of the natural reef at the grounding site, thus mindful of the necessity to create maximum habitat for marine life

Hudson has also worked to develop benthic organism transplanting techniques.12 Nearly every client funding a coral reef restoration effort where tourism is involved insists on aesthetic components and natural aesthetics takes time Transplants can hasten the process and are utilized

2073_C010.fm Page 195 Tuesday, April 18, 2006 11:17 AM

Trang 4

in a number of restoration efforts using purpose-designed artificial reefs and damaged natural reefs

A major goal of transplanting is to reduce the time it takes for an artificial reef to take on some of the functions of a natural reef Transplanting also coincides with aesthetic goals as the reef mimics

a natural reef and thus speeds the attraction to humans Divers, like the one pictured in Figure 10.4, employ quick-setting cement to adhere hard and soft corals to reef substrate Bolting corals has also been relatively successful but unsightly.13 To further emulate the natural reef, the finished concrete surfaces of some modules have smaller rocks pressed into them or rocks secured with mortar Aesthetics are heightened with these methods by reducing concrete exposure Increasing the amount of exposed limestone surfaces, coral, sponges, and algae not only catalyzes biological recovery, it lessens the visually stressing sight of human damage

Another group utilizing the transplanting technique is the Reef Ball Foundation, Inc Reef Balls™ are concrete artificial reefs that now number over half a million throughout the world Aquascapists

of the Reef Ball Foundation Coral Team employ their creative and scientific backgrounds to cover reefs with coral, algae, and sponge transplants Reef Balls are designed to form the base of a reef system as any coral structure would Transplanted organisms are selected with specific traits for various ecological reasons such as compatibility, resistance to sedimentation, and fast growth rates Aesthetic selection of specific corals helps to create a design attractive to divers and snorkellers Colorizing a reef in designed schemes is carried out in much the same way a landscaper would sculpt grounds Thus, interesting topography and coloration patterns can be somewhat predetermined by transplanting, at least for the time being before successionary processes progress

FIGURE 10.3 A material primarily of concrete and limestone boulders allows designers to create modules that imitate natural coral reef topography (FKNMS/NOAA, with permission).

FIGURE 10.4 Transplanting live coral (FKNMS/NOAA, with permission).

Trang 5

The morphologies of Reef Balls are also designed to function as the natural bases of coral fossils and rock outcroppings Marine-friendly concrete is poured into fiberglass molds containing buoys In the standard design, a buoy is surrounded by various sizes of inflatable balls that, once removed, result in openings As with natural reefs, Reef Balls vary in shape, hole density, and texture This flexible technique allows for custom designs to be easily created Figure 10.5 and Figure 10.6 are examples of the diversity of forms into which Reef Balls can be molded There are 10 different sizes of Reef Balls and 20 different patterns More specific options are also available because patterns can be mixed and matched into endless combinations As reef visitors desire variation in topography, reef restoration efforts can increase aesthetics by including a range of Reef Ball™ morphologies

The Reef Ball Development Group, Ltd has created a number of purely aesthetic components that can be incorporated into their projects Reef Balls can be fashioned into blowholes, and lights can be added for a nighttime effect A project where visual impact was of top priority was the creation of an underwater sculpture park at Club Cozumel Carib The Reef Ball Development Group, Ltd taught cement artisans eco-safe construction methods to use in creating underwater art The structures were immediately attractive to human visitors and will develop into reefs that will hopefully grow to mimic some of the functions of a natural reef Due to the combination of creativity and aptitude for ecological restoration, Reef Balls are incredibly popular with marine tourism operations throughout the world

FIGURE 10.5 A standard Reef Ball ( www.reefball.com , with permission).

FIGURE 10.6 A layer cake Reef Ball ( www.reefball.com , with permission).

Trang 6

From the time they are first deployed, one of the most morphologically convincing purpose-designed reef types is the EcoReef® module purpose-designed by president Michael Moore Clients are drawn to the branching coral morphology of EcoReefs Modules look instantly organic, as seen in the picture of an EcoReef team installing the EcoReef modules in Figure 10.7 EcoReefs, Inc., has the ability to create many coral forms Efforts to date have been using the branching coral module, seen in Figure 10.8, while other morphologies continue to be researched Diving operations, hotels, and other tourism-dependent operations are finding this design to be an aesthetically favorable solution

The branching coral morphology is designed with both short- and long-term aesthetic goals in mind It has been seen through time, branching corals are among the first corals to recolonize a disturbed area.14 These pioneer species provide a large surface area for coral recruits to settle and protection for fish and invertebrates EcoReefs catalyze the reef successionary process and break down,

as would any branching coral, when other coral species take over Thus, the common EcoReef module

Trang 7

is an appropriate shape, considering a natural reef’s successionary process The reefs are not meant

to last hundreds of years as with other artificial reef modules As a naturally beautiful reef takes over, the EcoReef performs its duty as a substrate, functioning well both ecologically and aesthetically

An important function of the EcoReef modules is the ability to create a large ecological footprint

in a variety of areas Many artificial reefs are limited in their impact on the ecosystem because of their small size Eco Reefs can also be placed on slopes, a rare option for artificial reefs Eco Reefs not only create something immediately attractive, they do so over a large area no matter what the existing topography

A smaller footprint with excellent potential for aesthetic grandeur is the mineral accretion method first proposed by Dr Wolf Hilbertz in 1976.15 Hilbertz developed the method of in situ

formation of semiartificial substrate by electrolysis When a conductive material, such as steel mesh, is connected to a DC power supply, magnesium and calcium minerals precipitate upon the material This accreted material consists mainly of calcium carbonate that has chemical properties similar to reef limestone The matrix can be morphed in a multitude of shapes As with most restoration projects, the structure can be integrated into the natural topography of nearby reefs Reef organisms benefit from a variety of morphologies from tunnels creating whirlpools that increase food availability to nooks and overhangs offering protection As with limestone boulders, Reef Balls and EcoReefs, coral fragments can be rescued from damaged reef areas and placed on the conductive material to help speed the coral cover of the reefs Mineral accretion is very compatible with the desire of some reef projects to be aesthetically interesting

Dr Peter van Treeck and Dr Harold Schuhmacher of the University of Essen are among a number of researchers currently exploring the possibilities of mineral accretion Van Treeck and Schuhmacher believe that many underwater coastal activities do not require coral reefs.16 Any three-dimensional structure may be sufficiently attractive to the dive tourists upon whom many economies with reef-lined coasts are dependent The University of Essen’s Department of Hydrobiology has developed a concept for the installation of attractive recreation areas for divers as a way of lessening the impact of divers on natural destinations Save COral REefs (SCORE) modules are metal structures with platforms The researchers aim to place these in unobjectionable areas such as sand flats Van Treeck and Schuhmacher hope these underwater parks will meet the aesthetic desires of divers while lessening biological degradation of natural reefs

10.2.3 U NDERWATER A RTISTS

A number of professional artists are celebrating the world’s marine environment Ocean-inspired sculptures form reefs for the purpose of creating art while attempting to mimic some of the ecological functions of a natural reef Some provide an interesting structure, helping to lessen the amount of human traffic to natural reefs, while others are specifically designed to increase habitat for marine organisms All are creative approaches, enticing visitors to explore the underwater environment

In 1992, artist Ann Lorraine Labriola produced Stargazer, the world’s largest underwater sculptured reef Stargazer is 200 ft long, 70 ft wide and 10 ft high It is located 5 miles off the coast of Key West, Florida, between Rock Key and Sand Key Ten steel pieces each weighing as much as 6 tons and as long as 168 ft are welded together to form Stargazer The structure is anchored

to the ocean floor 22 ft below the ocean surface When seen from the air, Stargazer points southwest toward the Sand Key Lighthouse Labriola’s piece is a symbol of movement, honoring early mariners who navigated by the stars Stargazer was immediately attractive to visitors after its installation with its holes cut in the pattern of a star constellation The sculpture has since attracted more permanent life with a diverse accumulation of marine organisms encompassing the structure Stargazer has grown to be a much-loved reef system among divers and snorkellers

An angel is watching over the reefs off of Nassau, Bahamas The Angel of Harmony, the wings

of which are pictured in Figure 10.9, was created by Dave Caudill Caudill is a sculptor from

Trang 8

Louisville, Kentucky who also forms land sculptures, many with an open-weave construction of stainless steel rods Both above and below the water’s surface, Caudill aims to integrate natural beauty with artistic form He hopes his Angel of Harmony will eventually become one with the seabed and viewers will have to ask Is this a man-made or natural form? A few years after installation, the Angel of Harmony has taken on a full spectrum of colors, encrusted in corals, sponges, and algae Marine organisms are especially attracted to the hollow steel cylinders that form the wings of the sculpture Sea creatures dart in and out of these pipes covered with marine growth People can also be found circling the angel Located in 14 ft of water, the Angel of Harmony

is easily accessed by people who enjoy the sculpture, many playfully mimicking the form by striking an angel pose The Angel of Harmony is an enticing attraction to the coast of Nassau, augmenting the beauty of nearby natural coral patch reefs

Bronze sculptures are another means of artistically enhancing the seafloor They provide little biological habitat yet serve an ecological purpose Not only do they encourage divers and snorkellers

to visit marine areas, thus raising awareness of marine issues, they also create an exciting attraction for divers while they improve their buoyancy skills Inexperienced divers can have a ruinous impact

on natural reefs Oceanic Voyagers created by Dale Evers and Mermaid by Simon Morris are some

of the most loved underwater sculpture installations in the Cayman Islands These works compel visitors to seek the beauty of the underwater world that has inspired their artists to create these pieces Bronze sculptures are a valuable and beautiful union between art and ocean

10.3 RECOMMENDATIONS

Many believe the design of a reef should be attractive to visitors from the very first days of a restoration effort without depending on coral growth or fish population to create an appealing environment.17 Designers of reefs take into account a variety of considerations to heighten the interest of a dive site Naturalness, nonrepetitive topography, and diversity and abundance of species are high on the list of visitor wishes Familiar species, such as Acropora spp corals, are also key ingredients in the mix of an ecosystem visitors will perceive as healthy and attractive

It is hard to improve upon the beauty of a natural reef like the one in Figure 10.10 A natural appearance is a goal for many restoration efforts Using the percent of live coral cover as a measure

of marine environmental quality, a study in Roatan, Honduras looked at the correlation of reef attributes with scuba diving behavior.18 The study found that marine environmental quality is a significant predictor of dive site visitation Thus, reefs that mimic the beauty of nature are a likely success with eco tourists Many restoration efforts include ecological goals of creating topographies similar to those of reefs before damage occurred This is in line with aesthetic desires of divers and snorkellers, who seek naturalness in their eco tourism destinations Limestone modules have

FIGURE 10.9 Dave Caudill’s Angel of Harmony ( www.caudillart.com , with permission).

Trang 9

proven to be excellent means to achieve similar topography to that of natural reefs EcoReefs, as seen in Figure 10.11, mimic the branching form of corals that divers consider a classic shape and associate with high-quality snorkeling and diving sites.6 Molding concrete and transplanting benthic organisms also aid in restoring natural appearance

Multidimensional and nonrepetitive habitats are a great attraction of reefs and can be achieved

by variation of reef structures Modules such as EcoReefs and Reef Balls are available in such an assortment of forms, they can create a multitude of shapes across the ocean floor Using mineral

FIGURE 10.10 A topographically diverse reef off of Discovery Bay, Jamaica (Joshua Idjadi, with permission).

Trang 10

accretion methods, an entire underwater village could be built For tourist divers, the more interesting the structure, the greater likelihood of the success as a dive site.8 Both natural-looking and purely aesthetic reefs that are topographically diverse will pique the interest of visitors With today’s techniques, a designer’s creativity is the only constraint on possible morphologies

High coloration is a guaranteed aesthetic success Transplanting can quickly infuse a reef with color Creativity can abound in patterns of colorful biota As coloration can also serve as visual cues, transplanting specific colors can help to steer divers away from more fragile areas and preserve the beauty of natural reefs Transplanted biota become a living palette for marine restoration “artists”

to beautify underwater restoration projects

Technology has no doubt advanced to a state where reef restoration projects can combine aesthetics and scientific techniques Ecological restoration performed by scientists in conjunction with artists can create a reef that satisfies the aesthetic objectives so many tourism-dependent operations require With so much of conservation driven by tourism dollars, aesthetics are an objective that should be considered in many restoration efforts No longer do sunken materials of opportunity need to be considered in many restoration projects These junk reefs tend to permanently structure a reef in an unnatural and unsightly way such as the tire reef in Figure 10.12 Purpose-designed artificial reefs are far more attractive and much more compatible with ecologically sound reef rehabilitation projects Purpose-designed artificial reefs and mitigation to damaged natural reefs are intelligent approaches to ecological restoration that can create visual excitement for divers While natural beauty is by far the greatest attraction under the surface of our water world, technology

is allowing us to replace some of the brilliance that has vanished beneath the ocean’s surface

ACKNOWLEDGMENTS

I would like to thank Todd Barber, Michael Moore, Dave Caudill, Nadav Shashar, Sue Wells, and Ann Lorraine Labriola for their time spent talking with me I am also grateful to Joshua Idjadi, and The Florida Keys National Marine Sanctuary for their help in acquiring images

Định dạng
Số trang	11
Dung lượng	4,17 MB