|Long Term Monitoring|
It is important for all potential Reef Check users to recognize that the core methods are meant to be flexible, and can be changed to meet local needs, within certain boundaries, and still be useful for the annual global assessment.
While the methods were designed for use by volunteer recreational divers, they have been used in many parts of the world by teams of scientists. The point is that the methods can and should be adjusted to match the ability level of the team members and management needs.
When major changes are made to the Reef Check methods, the team has two choices: either the team can extract the core data and submit them to Reef Check for inclusion in the global database and annual report (which is then provided to ReefBase), or the team can simply use them for their own analysis and management purposes.
While one goal of Reef Check continues to be to obtain annual reports on as many reef sites as possible, the latter option is reasonable when more than one survey is made per year at a given site. Please let us know about your surveys even if you don't submit data.
The three most important considerations for using Reef Check for long-term monitoring are taxonomic specificity, temporal and spatial replication. Team scientists are encouraged to add indicator organisms that may be of particular importance in their area. Adding taxonomic specificity, i.e. requiring species level identification of some organisms may also be useful. As more parameters and/or specificity are added to the core Reef Check methods, the designer must try to strike a balance between the need to obtain "useful" data, the ability of the volunteer team members, and the potential to bore or burn them out.
One reason for the success of Reef Check in over 80 countries and territories is that it is fun. The success of Reef Check depends on it remaining an enjoyable experience for volunteers. If more than a few additional species level identifications are added, pre-testing should be used to ensure that the volunteers are capable of identifying all organisms accurately.
The original Reef Check methods were designed to be carried out once per year at each site. This level of temporal replication is typically sufficient to characterize changes in reef corals and other sessile invertebrates. If there is sufficient manpower, this may be increased to twice per year to get a seasonal update.
For mobile invertebrates and reef fish, however, this frequency of replication is generally considered too low for a meaningful stock assessment at one site (but when repeated at many sites, the snapshot becomes very meaningful). It is important to recognize that the sample size used in one Reef Check survey is robust with respect to the parameters measured. Upper Arrow Butterfly Fish [Courtesy of R.Patzner] What allows the survey to be carried out quickly is that there are relatively few parameters measured and no temporal replicates.
To use Reef Check methods for long-term monitoring of fish and mobile invertebrates, additional temporal replicates should be made of the fish and invertebrate belt transects. A pilot study could be carried out to determine the variability of fish and invertebrate populations at a given location. A suggested rule of thumb would be to carry out three replicate surveys at each site (i.e. three repeat surveys of one transect deployment), and then to resurvey each site at quarterly intervals. If the taxonomic requirements are not increased too much, this higher intensity survey could still be accomplished by recreational divers.
The core methods include four spatial replicates along the transect line. Given the low taxonomic specificity in the methods (typically family level), these replicates are sufficient to capture variability within one site, and the overall 100 m length of the sample is robust. However, it is desirable to measure variability at several sites within "the area of interest." Thus for long-term monitoring within say, a 1 km wide bay, a set of three to five sites might be used.
The core methods include two transects with the deepest located at a maximum allowable depth of 12 m. The Reef Check program does not accept data obtained from deeper areas for two reasons: safety considerations and the fact that reefs do not extend below this depth in many parts of the world making regional and global comparisons difficult.
However, in areas where it is important to record information at greater depths, a third or forth transect could of course be surveyed and the information used locally. Although these data will not be included in the annual Reef Check report, they could be submitted directly to ReefBase.
Two papers can be downloaded on monitoring. Although they were written for Hawaii, they are relevant to all locations. To download these papers, click here.