Damage Assessment
An assessment can be done in a variety of ways and the method used depends on the reason for the assessment and project goals. Below is a list of quantitative and qualitative methods most often used for damage assessment by the Reef Ball Foundation.
Quantitative Measures
Area of Bottom Impacted
The area of impacted bottom is the simplest quantitative assessment method, and simply reflects the footprint of the damaged area. It is useful for rapid assessment and determining the logistics of the project, but it is an extremely poor estimator of the degree and severity of ecological impact in any but the most homogeneous of systems (e.g. sea grass systems, or sandy/rocky bottom habitats). The area of bottom impacted can be cheaply determined however, using simple observation with camera, measuring reel, solid graphite sketchbook and a mariner's chart.
Cubic Volume of Reef Habitat Lost
This method is also fairly easy to compute and is a better method than the simple calculation of area when describing damage to reef ecosystems. An accurate survey of the bathymetry (often by side scan or multi-beam sonar) of the impacted area must be conducted to generate a three dimensional map of the damaged area. This is thus a much more costly endeavor, but in some cases, can be done with the help of vessels (nearby the reef's location) of environmental organizations. Alternatively, a simplified version of this method can be accomplished by multiplying the original average height of the reef by the square footage/meters of the area of bottom impacted. This can be a bit complicated if the original height was highly variable or unknown. The approximation of maximum pre-incident relief can be important because impacts to taller, typically more mature coral reefs are much more severe than impacts to lower, typically younger reef systems, even when the footprint of the damage is the same. This measure, however, fails to consider the complexity of the reef lost and therefore cannot be used to estimate the amount of protective void space loss. This method can be enhanced by increasing the precision of data collected on the habitat types within the entire impacted area.
Reef Head Size and Density
Surveying adjacent, non-impacted areas can be useful to estimate the reef head size and density lost. This can be helpful in planning the proper levels of protective void space rehabilitation. Once you have calculated the approximate density and relief of nearby habitats, planned base modules can be built to approximate the complexity, density and size of the adjacent reef heads. In the case of coral reefs, this method can be enhanced with an independent analysis of certain high value coral species, particularly the large protective void space creating coral species.
Diversity of Coral, Fish, Invertebrates, and Other Impacted Species
If the project team has good monitoring capabilities, the most complete assessment method is an inventory of species diversity and population densities. For most reefs (especially coral reefs), this can be an extremely complex and time-consuming task, and it is probably only feasible to focus on the specific species that are judged most important in Step 1: Determine Goals. A number of scientific papers have been published which detail different methods of underwater visual census (UVC) which may be more or less appropriate for your specific project. However, a thorough discussion of these methodologies is beyond the scope of this manual.
Number of Coral Colonies Impacted
Some projects may only be concerned with coral. These might include, projects that are initiated because of coral damage, or projects addressing specific threatened coral species such as elkhorn (Acropora palmata) and staghorn (Acropora cervicornis). In these projects it is appropriate to focus solely on the coral of interest. By refining the focus of your monitoring efforts, resources can be devoted to categorization of coral heads by size or age estimates in order to more accurately focus rehabilitation efforts.
Semi-Quantitative Measures
These methods are based on quantitative techniques, but can include factors that vary for different reef species, or are more difficult to quantitatively estimate. Factors such as protective void space and biologically active surface area must be assessed differently if you are concerned with the protection of tiny creatures versus large ones. Nonetheless, these factors are critical to understanding meaningful rehabilitation. To be most useful, these analyses need to be tailored to your project goals. For example, if your interest is in juvenile fish production, protective void loss should be examined from a small fish perspective; whereas if you are looking at adult fish populations the analysis should be from an adult fish size perspective. Similarly, the biological surface area from the perspective of a lobster is different from the biological surface area for a tiny copepod. Tiny surface holes and wrinkles make a big difference for copepods but do not provide additional habitat for an adult lobster.
Protective Void Space Loss
Protective void space is the habitat that reefs create for fish. Just like trees create habitat for birds, providing them shade, hiding places, nesting sites and wind protection. The most critical function that coral (or any reef structure) provides to reef associated fish is protective void space. Protective void space is the area that protects fish (or other mobile marine life) from larger predators and provides shelter from energy-draining currents. All reef dwelling demersal fish species (as opposed to pelagic fish species) exhibit a certain degree of habitat fidelity, and need protective void space. The amount of protective void space provided by a reef helps to determine the carrying capacity for fish and other marine life of the reef. Reefs with higher carrying capacities for small fish will also support a larger number of pelagic predators which feed on reef associated fish species. Protective void space is created by reefs. A reef is defined as “a submerged ridge of rock or coral near the surface of the water” by the dictionary [Source: WordNet (r) 1.7] but for purposes of this manual it can be defined more loosely as rocks or outcroppings in the sea. Outcroppings can develop from coral branches and in the interior of the coral structures. The interior often contains holes and cavities of the eroded limestone. Outcroppings can also come from other biological organisms such as oysters and rocks can form from exposed hard bottom or other geological processes on the seabed.
When considering rehabilitation options, it is often useful to try to quantify that amount of protective void space that has been lost or is being created by the lost or degraded reef. To compute an EPVS, calculate the maximum foray distance in all directions, which can be further defined as resting, foraging, mating, high current, predator attack, or other foray category as needed for the specific analysis goals, and subtract the volume of the reef space (natural or artificial) that cannot be occupied by the species. It may be easier to understand the concept by thinking of a single artificial reef module place on an open bottom as in the first illustration.
Areas around the reef where eddies and back currents form also provide a type of protective void space that is especially important in areas where there are currents. During times of low current velocity, the void space expands to the greatest distance a particular fish is able to venture from safe cover and still return to cover safely if chased presuming the fish is in a foraging mode. Functional void space shrinks during storm events and times of high velocity currents. At these times, the void space is limited to interior cavities of the reef and areas close to the edges of larger reef structures where there is sufficient shelter from the force of the ocean to conserve energy. Rehabilitation of void space is particularly important to rehabilitating sustainable fisheries on coral reefs, and is often overlooked. It is rare to find demersal reef associated fish far from a protective void space, except when they are displaced, migrating, spawning or foraging in nearby sandy areas. Furthermore, mortality of fish at the time of transition from pelagic larvae to demersal juveniles is extremely high, and survival has frequently been shown in studies to be proportional to available habitat.
Larvae that settle onto unsuitable habitat have virtually 100% mortality, while larvae that are able to find some measure of protection have a higher probability of survival. Since many of these demersal site associated fish species exhibit density dependent mortality rates, and appear to be habitat limited in their production, any rehabilitation effort that fails to create protective void space may have little, if any effect on populations of these fish species.
In looking at reef ecosystems, one often needs a system wide EPVS understanding including distances between larger EPVS zones. This is where non-reef ecosystems such as sea grass beds and submerged mangrove roots can heavily interact with reef rehabilitation plans as they both offer specific types of EPVS even though they are not technically defined as reefs. There are many other non-reef features that create EPVS that should be considered in system wide views. EPVS can also be used to predict species inbalances. For example, let's assume your project includes the decommisioning and sinking of a large vessel or oil platform. Such projects are going to provide a lot of non-feeding and current protected foray. However, if a species is a sand forager or must travel to reef habitat for feeding it might be limited by specific EPVS types. Any project that deploys base materials higher than the average relief of the natural reefs in the area risks an imbalanced EPVS that can attract too many fish without providing all the needed EPVS sub-types and therefore should be undertaken only when there is sufficient low height structures nearby providing the needed foray(s). Note: Because of the powerful attraction features of very large EPVS (tall base structures), when EPVS balancing is not possible by either site selection or augmentation with additional low profile materials then we recommend classifying the structures as “Marine Protected Zones” and not allowing human harvesting of the marine life. Without this step, very large EPVS creation will likely contribute to a depletion rather than a supplement to marine resources in the area (harvestable resources such as fish). For example, providing one artificial reef module in the middle of the sand far away from any reef might provide EPVS for a species that never leaves the reef (such as an attached coral), but without nearby additional natural or artificial reefs the EPVS could be unsuitable for a species that obtains food from the fouling community (let's say a Parrot fish that eats coral) because the surface area of the individual module is too small to support the Parrot fish.
To determine a simplified effective protective void space (EPVS value) for any species of a particular object (coral head, artificial reef module, etc.) simply monitor the maximum distance the species will venture away from the structure during normal reef-dwelling behavior during low current times. Monitor both the horizontal and vertical distances and then compute the volume of the area the species occupies. Then subtract the solid volume of the structure (if significant). If openings in the structure are too small for the species in question to penetrate, the structure should be considered to be solid for the purposes of this calculation. If there are very frequent high current velocity events, such as a reef at the entrance to an inlet where tidal or wind-driven currents may be strong, you may want to repeat the calculations during a high current event and use a weighted average of the two measurements based on how frequently the site in question experiences high versus low current conditions (for example, if current is high for 4 hours out of a 12 hour tidal cycle, multiply the EPVS calculated at low current level by .66 and the EPVS at high current by .33 and sum them to calculate the weighted average). The result of the computation will be the amount of protective void space created for that species, by the object studied, in the particular current climate studied. Such measurements of protective void space can be used to compare rehabilitation methods and estimate the relative potential success of the method for a particular reef species. For projects concerned with diversity or community health, and if you are using a diversity index (such as Simpsons, or Shannon-Weiner, Reef Check or other methods) the concept of EPVS can help you finetune your rehabilitation to get better results. For example, if you find your rehabilition is not providing enough habitat for Moray eels compared to the natural habitat you can add new EPVS or re-arrange your existing EPVS to better suit that species. Once the concept of EPVS is understood, a well-trained expert eye can approximate the amount and complexity of base material that must be used to rehabilitate a lost reef’s function fairly accurately, without performing these complex analyses. In many cases, your project may not have the resources to recover all the lost void space. In these cases, it is important to do whatever you can, and remember that some rehabilitation effort is usually better than none. Conversely, if your project has extra resources, or you’re not sure how much was lost, and need to allow a margin of safety, we are not aware of any cases where constructing more complexity than was lost has been detrimental to a system. In the worst case, adding more habitat than needed would lead to an inefficient use of that habitat by the resources provided you did everything correctly following the steps to avoid negative project consequences.
Biological Surface Area Loss
This is a theoretically quantifiable measure of the biologically active surface area lost during an event. While functional, and easy to understand, there are many complications associated with the calculation. The most important assumption regards the scale of detail with which area is measured. Rugosity and fine scale complexity at different size ranges are important to different organisms, so making an assumption about what is functional surface area depends on what the target species. If you are working with larger organisms, it may be adequate to make the assumption for calculation purposes that the surface is perfectly smooth. In this case, a standard CAD program can calculate the surface area, or one of many photo imaging analysis software packages can calculate surface area. On a real reef, however, surfaces are anything but smooth, so depending upon what scale you define the surface, the result changes greatly. For example, if you consider a piece of corrugated tin, if you were standing a mile away, you would probably measure area by simply multiplying length by width. Once you got closer, and could see the grooves, you might change your calculation to account for the additional area from each of the grooves. If you looked at the tin under a microscope, you would see many small pits and cracks, which would increase the surface area further! The same holds true for a coral colony or a patch reef. Once again, this also depends upon which marine creatures you are judging for habitat purposes. It might be appropriate to judge a surface on a millimeter scale if looking at copepods. It is probably better to look at a centimeter scale for coral settlement or to assume a totally smooth surface for adult coral base space. For this reason, it is impossible to compare calculations of area lost between different sites or events, but this tool can be quite useful for estimating the amount of impact when comparing areas within the same project as long as the resolution is kept the same for all computations.
Qualitative Measures
Loss of Reef Functions
There are a number qualitative indices used to define loss. Some commonly cited losses include:
- Fishery Resource
- Recreational Value
- Erosion Control
- Ecological Function
- Biodiversity
Sometimes, the most important things to consider cannot be measured quantitatively. This may be because of lack of resources or expertise to carry out appropriate quantitative analysis, or it may be because the factor being considered is difficult to put into numbers. That does not make these measures any less important. While qualitative measure often cannot be defended precisely, they are still useful for discussion and debate of rehabilitation options. However imprecise the measures may be, they do represent real issues that are often very important, and sometimes qualitative concerns can over-ride recommendations which arise from quantitative analysis. Not surprisingly, many rehabilitation efforts are decided upon using qualitative rather than quantitative analysis methods. Hopefully, as rehabilitation science continues to increase, more and better quantitative analysis tools will become widely available which will facilitate better analytical decision-making. Until that time, however, we must often work with what we have, and make decisions based on the best information available at the time.
Expert opinion
Many grassroots organizations are best served by expert opinion. As mentioned earlier, there are a great many factors that go into rehabilitation projects, and it is impossible to go into depth on all of them in a manual of this scope. For this reason, it is best to consult experts when a situation stretches beyond the knowledge of your team. There may be excellent local scientists or consultants available to share their opinion, or formal governmental assessment teams designed for this purpose. You may call upon the Reef Ball Foundation to help you find or to provide experts. If resources are very low, sometimes an expert can provide an opinion without a site visit, especially if necessary local information such as underwater video or digital photographs can be gathered in advance and shared via the world wide web. A true expert opinion can be quite valuable, but the opinion is only as good as the expert! If you decide to use expert opinion, be sure to select experts that you can trust. If you need a second opinion, please feel free to contact us. When choosing an expert, make sure they have local experience or pair experts with knowledgeable locals to facilitate better recommendations. Whatever method(s) you choose for damage assessment, it is helpful for you to document the entire process as thoroughly as possible, including taking measurements before any rehabilitation has started so that when you make rehabilitation efforts you will be able to measure your success (or lack thereof).
Coarse of action
To determine the coarse of action, a working timeline is required. Is the situation an emergency that requires immediate attention to rescue coral that have been damaged? Or, is it a case of a long-term reef loss where you hope to make long-term rehabilitation efforts? Perhaps there are specific weather constraints, or seasonal limitations such as monsoon or hurricane seasons that the project must work around. All of these things need to be considered when building a timeline When coral are imperiled or injured, immediate action is required in order to temporarily stabilize the situation while work plans are being designed. To accomplish this, it may be necessary to create a temporary "disaster nursery". If that is the case, proceed through this manual far enough to determine if you will be stabilizing mature or large coral colonies, or if you will be using genetic coral rescue (propagation and planting) methods. In most projects of an emergency nature, a combination of both is the best approach, given sufficient resources. Once these decisions have been made, a nursery protocol can be designed and implemented. Once the situation has been stabilized, more time is available to re-evaluate the situation and complete a more detailed work plan (see the next heading, creating a temporary disaster nursery for a quick introduction).
Assuming your project is not an emergency response, the season of the year can be an important variable. Artificial reefs can be built year round, but are best deployed during calmer seas. Coral propagation and planting cannot typically be done when water temperatures exceed 30°C (86°F). In fact, the best time to plant a coral fragment is when you are entering a cooler season because the fragments don’t have to deal with as much algae growth, bleaching events or lower oxygen levels; that are associated with higher water temperatures. In climates with distinct wet and dry seasons, it can be best to plant when you are entering a dry season because rain and run-off can impact coral health and reduce the efficiency of divers and propagation efforts. However, mature or large coral colonies can generally be re-stabilized year round because to wait might mean colony loss. In tropical areas, seasons for algae growth and temperature changes may not follow a seasonal pattern, so it is important to understand local conditions in order to make the right rehabilitation choices. Often, just knowing when the coral mass spawns in your area will give you the information about when it is optimal to plant fragments. Ideal planting times are typically within a few months following coral spawning events. If you are planning on deploying base substrate without any coral planting, then it is best to place your modules immediately after the spawn in order to maximize natural coral recruitment. If you deploy at other times, you need to insure good herbivore coverage (e.g. long spiny sea urchins, Diadema antilarum, or Turbo Snails (also known as turban snails), Turbo fluctuosa, or other similar species in order to reduce competition to young coral recruits.
Creating temporary "Disaster Nurseries"
In an emergency situation where a large number of imperiled corals have been damaged and need to be rescued in order to preserve the genetics of corals impacted by the disaster or to temporarily stabilize some of the most important adult coral heads for later re-stabilization, divers can create a temporary disaster nursery. These nurseries are designed to keep the coral healthy long enough to build and deploy appropriate artificial substrate (or to prepare the natural bottom); and to form a coral team with the necessary supplies to complete the rehabilitation.
If you have had Rapid Response Training and already have your Coral Disaster Response Kit on site then may be able to skip this step (see Appendix A). Even so, a disaster nursery may be a wise option to protect the most important coral colonies. Most disaster nurseries are designed to keep corals coral healthy for a few weeks or months, although occasionally, it may be necessary to hold corals in a temporary nursery for up to a year. The objective of a disaster nursery is to get the coral safely into conditions that minimize the risk of damage from waves, shifting sediments and the possibility of being buried by sand. The disaster nursery must provide stability so that currents or waves cannot further damage the coral. This type of nursery can be very simple welded steel frames made from rebar or angle iron with wire mesh attached to the frame to serve as attachment points as shown in Figure 2. There are a variety of other possibilities for construction of temporary disaster nurseries and the exact choice will most likely depend on the specific local conditions.
The shape is often triangular or tetrahedral, so that it can be deployed from a boat into a protected area, and will always land upright without additional effort. Deployment is best over a sandy bottom because it minimizes damage to natural fauna and facilitates anchoring, which is recommended if the nursery will be needed for more than a few weeks or if storms are expected before the corals will be relocated to a permanent emplacement. The nursery site should be as close to the original location as possible. If the original location is impractical, a site with similar water conditions (depth, light, salinity, temperature) should be found for the nursery. Screw anchors (Figure 2) are often used as temporary anchors because they are inexpensive, readily available, and screw into the seafloor easily.
There are many other anchoring options for temporary nurseries. The anchoring system to be used depends on the bottom type and the strength of waves and currents in the area. When in doubt, it is best to use the strongest anchors available within the resources allowed by the project. For genetic coral rescue projects, it is optimal to make at least 3 fragment plugs from each adult coral colony that is impacted. If possible, create multiple separate temporary nurseries, which allows preservation of coral genetic lines in case a storm or some other unforeseen situation destroys one of the nurseries.
It is important to carefully document the entire process, to facilitate scientific record keeping and documentation. The easiest way to accomplish this is to use digital still photography and a monitoring frame to record the donor colony and the fragmented coral saved. A monitoring frame allows you to calculate the size of the coral colony by referencing to a known grid, and also makes photographing easier, because it fixes the focal length. In this regard, be sure to use the same camera for each monitoring and to make sure the zoom feature is turned off or all the way zoomed out. It is best to work methodically over the site, consistently documenting your progress. Most disaster nursery rescue teams will develop some protocols including which coral are the highest priority for rescue, documentation procedures (often critical when there are liability issues) and handling techniques. Later sections in this guide will provide guidance on developing these protocols.
Following your protocols, attach the coral to the wire mesh using the zip tie method with plastic electrical ties or low-grade steel wire. Ensure that no colonies are touching and allow for growth or shifting of colonies, depending upon the length of expected nursery stay. Look for the healthiest coral possible and do not place any diseased coral in the nursery. The sheltered area under and around the nursery is a suitable place to store smaller adult colonies (such as softball or smaller brain coral) that need to be re-attached by hydrostatic cement methods. Coral that comes from deeper locations than the nursery depth are at risk of being sunburned during their nursery period, but these corals can be put inside the wire frames to reduce the risk of sunburn. Adult colonies that will ultimately be re-stabilized can usually be left where they are located, but they may need to be repositioned so that the polyps and their associated zooxanthellae can photosynthesize. If the adult colonies must be moved, it may be better to try to organize the emergency movement and re-stabilization as one process. This may require professional assistance, as this type of work is likely beyond the scope of grassroots organizations unless they have been trained in advance and have experience dealing with mature or large coral colonies.
Non-Crisis Timelines: Project Management
If your project is not in crisis, you will need to produce a written timeline with at least the most important milestones that must occur to keep your project on track. A simple calendar may do for small projects whereas more complicated projects will benefit from using commercially available project management software. Ideally, choose one that, at a minimum, produces simple Gantt charts. The complexity of your projects will probably determine what level of technology is appropriate. Professional project management programs, such as Microsoft Project have heavy learning curves but offer more features. Some simple program such as, PlanBee, are available at little or no cost and minimize learning requirements but don't have features for very complex projects).
Determining number, and sizes of modules
The next step in the process is to determine the number and size distribution of modules required. There are many ways to estimate this, and the easiest way to do so is to use the data collected during the Damage Assessment. The basic goal of this step is to determine the amount of substrate necessary mimic the nearby natural reefs that are providing the functions you are trying to rehabilitate. So, if the damaged site a widely scattered patch reef with small coral heads, you may want to scatter small clusters of modules throughout the selected area, while if the damaged site is a contiguous fringing reef, perhaps the best rehabilitation method is to use a long thin line of modules. Remember, if you are planting coral, that your project may take many years to reach its final form. When designing the pattern of modules, envision the final results of your project, and account for growth rates and expected sizes of the adult colonies.
It is best to concentrate your efforts on the appropriate module density and size to achieve your goals not on the total number of modules. In most projects, the total number of modules is more likely to be determined by the available resources or permitting restrictions, rather than by rehabilitation goals. Unfortunately, in many cases, your conservation goals are likely to call for more modules than you can afford or have space for.
Several measures can be used to quantitatively estimate the appropriate density and sizes for artificial reef modules. Some if these methods include a survey to determine average number and size of coral heads per unit area, or more sophisticated EPVS measurement analysis. Look back on the data collected in the Damage Assesment. Much of this data can be used here to estimate your project’s needs. Expert opinion is also appropriate. Local reef users often have an impressive understanding of the requirements needed to rehabilitate specific reef functions. EPVS analysis can give you an idea for an optimal layout of reef substrate. This analysis tends to be rather species specific since usable void space varies greatly by size and functional group of a species. Therefore, this method is only appropriate when your goals are focused on specific species or functional group.
Gathering Budget and Resources
Nearly all rebuilding or rehabilitation efforts are constrained by money, time or other resources. The amount of resources you have available may depend on a grant, a court settlement, a corporate budget or on donations and volunteers. Whatever your resources may be, carefully document any constraints or opportunities that might change the budget or availability resources.
As with any project, having more resources will allow you to do a better job, but is it almost always possible to make some positive impacts even with a minimal budget and resources. Usually your resource budget will limit your rehabilitation options or project scope, but other times you may be able to increase the impact of your project by doing more of the work yourself or with volunteers, while retaining your original project scope. Sometimes, there are timeline constraints combined with budgetary limitations. For example, you may have an annual rehabilitation budget or an on-going revenue stream that can be directed to the project. In this case, you may have to look at solutions providing on-going efforts, instead of a specific project. We see many projects where a grant funds the initial set-up and training as one project, but the on-going rehabilitation work is funded locally. In almost all damaged coral projects, limited resources are cited as the number one reason for the lack of rehabilitation efforts or ineffective actions. This is one of the main reasons the Reef Ball Foundation has focused on developing rehabilitation options that are cost-efficient, and methods that can be employed by grassroots organizations. Working alone, governmental agencies and scientific groups usually consume too many resources to do cost-effective rehabilitations. These organizations need the linkages to community resources and volunteers provided by grassroots organizations to be able to bring together teams that can be more cost-effective. On the other hand, grassroots organizations that work alone often lack specific required technologies and scientific methods, the ability to obtain permits, and an ability to think outside of the box in their area of specialty. Once again, teamwork will help to increase your budget and resources to accomplish the project goals.
After reading this manual, it is our hope that the next time someone or something destroys your favorite reef that you will feel empowered to take action regardless of your budget or resources; and will build a team that can affect successful rehabilitation.
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Disclaimer
This information was Reef Ball's Draftguide document.
