Diver video documenting coral injuries. Photo courtesy of NOAA.

Accurate quantification and documentation of vessel-inflicted coral injuries is critical to the success of any legal claims or actions taken against boaters responsible for injuries. It also provides the foundation for the selection of primary restoration techniques and is important to the development of associated monitoring plans.

The basic elements of an assessment are essentially the same for all incidents, although the size, shape, and location of reef injuries vary considerably. The Coral 312 Program assessment protocol includes the following steps:

1. Field assessment.
2. Application of injury recovery trajectories.
3. Application of an ecological service-scaling model.

Field Assessment

Delineating the Site

The injury site is marked with visual reference aids, primarily buoys and/or stakes made of PVC pipe, steel rebar, or steel rod stock, that provide parameters for further assessment and make relocation of the site easier. Injury features are then numbered so that all future restoration and monitoring efforts will correspond to the correct area. This can be achieved either by hammering into the reef substrate metal stakes or spikes with numbered heavy plastic or stainless steel number tags attached, or by affixing tag-bearing monuments composed of Portland cement to the reef (using Portland cement as the bonding agent).

Once the site has been appropriately marked, a transect measurement is taken to determine distances, serve as a referencing tool for assessing key features of the site, and aid in future restoration and monitoring efforts. A master transect line is laid centrally through the length of the injury site, usually along the longest axis, starting at the beginning of the inbound path and terminating at the end of the final resting place. In some cases where the injuries are scattered or the injury path is long or large, multiple baseline transects must be established.

Mapping with a differential global positioning system (GPS). For smaller groundings in shallow water, GPS coordinates of the grounding site are acquired, including the location of the endpoints of the path the vessel traveled and datapoints associated with significant features of the injury. From these measurements, the injury area can be calculated.

Mapping with the fishbone method. Because GPS is unable to provide precise measurements in deep water, deeper injuries are mapped using what is known as the fishbone method. This method generates a map of the injury area that resembles a fish skeleton. A measuring tape is fastened at an appropriate increment (usually 1 meter) along the master transect (the backbone of the fish), and a perpendicular measurement from the transect line to the edge of the injury (a rib of the fish) is taken. This procedure is repeated on the other side of the transect, and the measurements and corresponding incremental positions along the transect are recorded. The resulting measurements are then fed into a computer program (Canvas^®) that creates a scaled polygon of the injury and calculates its area.

Aerial photography. When injuries are large and geometrically complicated, it is often difficult and time consuming to measure the area onsite because of the physical limitations of diving and/or logistical complications. In these cases, aerial photography can be used to estimate the injury area. Prior to photographing the site, a number of GPS-positioned targets are placed onsite for photographic reference. Helicopters or small planes can then fly over the grounding area and photo document the site. These photos are digitized so the outlines of the injury area(s) can be digitally traced and area calculations made.

The damage to the coral habitat is determined by comparing pre- and post-injury conditions. Pre-injury conditions are determined by observing undisturbed areas immediately adjacent to the injury, called reference or control sites.

Photo and/or video documentation of both the injured area and reference site(s) is used to establish the species richness and percentage of coral cover at each site. Following along the transect, continuous digital video footage of the injury is taken. The field of view of the housed camcorder may not encompass the breadth of injury, and it may be necessary to slowly pan from one side of the injury to the other as the transect line is followed.

Software enables these video transects to be digitally rectified and collaged together to form a digital image map of the site. Photo quadrats can then be used to estimate percent cover and calculate relative species abundance.

Application of Injury Recovery Trajectories

Once the field data have been collected, Florida Keys National Marine Sanctuary (FKNMS) biologists review the data and assess how long it will take each injury type to fully recover by determining the shape, or trajectory, of the recovery over time. These recovery trajectories depend on the species of coral affected, the type and degree of injury, any primary restoration to be implemented, and the type of environment in which the injury occurred. Biologists use data from the literature, field observations, and their best professional judgment to develop these trajectories.

Application of an Ecological Service-Scaling Model

Although many coral injuries addressed by the Coral 312 Program are ultimately restored through primary restoration and are expected to eventually recover to their pre-injury conditions, the public and the environment must be adequately compensated for the resource services lost between the time of the injury and the time of full recovery.