Based on what has been feasible in previous years, the Biomonitoring Program will undertake full-scale of monitoring of approximately 430 sites, with site selection based.
Field Study Sites
In a normal year the Biomonitoring Program will undertake full-scale of monitoring of approximately 430 sites, spanning a range of conditions from large rivers to tiny brooks, pristine wilderness sites to heavily impacted streams, sea level to 200 m. altitude with site selection based on the following criteria:
Reference Sites: These comprise an assortment of sites representing the “best” (least altered by human activity) sites in a variety of stream categories. Data from these sites is used to establish standards applied in monitoring and interpreting results from other sites.
Fixed Stations : We have now accumulated enough information to be able (in Costa Rica) to designate several fixed stations, to be monitored annually as a barometer of general conditions in Talamanca.
Local requests : Local interest is always a priority for us in selecting monitoring sites. To the greatest degree possible we try to honor requests for monitoring services from local individuals, communities or conservation groups.
Educational sites : A few individual sites have been and will continue to be monitored in conjunction with specific schools; others simply correspond well to pedagogical needs.
Perceived changes or threats : Some sites will be selected because of perceived changes (for better or worse) or threats. Factors under this category range from restoration projects to fish kills.
Relation to protected areas : Our work area includes several Protected Areas such as the Hitoy/Cerere Biological Reserve and Gandoca/Manzanillo Wildlife Refuge in Costa Rica and the Palo Seco Forest Reserve and San San/Pondsak Wetland of International Importance in Panama, but of particular significance is the huge La Amistad International Peace Park, a World Heritage Site which constitutes a major biodiversity “Hot Spot”. One of the most important developments during the life of the ANAI Stream Biomonitoring Program has been the emergence of the threat to biodiversity through elimination of diadromous species above dams, including in La Amistad and other protected areas. For this and other reasons we have increasingly factored relation to proposed dam sites and the boundary of La Amistad into our site selection process.
Benthic Macroinvertebrate Surveys
To collect fish we use electrofishing equipment complemented with a variety of fishing nets. Depending on the size and characteristics of a river, the team consists of between 3 and 9 people the majority are normally volunteers. Volunteers are essential to the work we do not only in practical and economic term, but because including local volunteers is part of the biomonitoring project´s environmental education objective. It usually takes three to four hours to complete a sample. Fish are identified by species, counted, examined for illnesses, parasites and other anomalies before being returned to the water.
Based on the results of the sample, we calculate a score, or Index of Biotic Integrity (IBI) for each site. According to the score, complemented by the knowledge and professional judgement of ANAI staff, a bioclass rating is assigned (Excellent, Good, Fair, Poor and Very Poor). The lowest possible score is 12. A score of 60 (Excellent) corresponds to a river that has not been altered by humans. Key aspect of the information used to determine the Index of Biotic Integrity include:
- Number of native species found
- Trophic level (place in the food chain) of the species encountered
- Habitat requirements (where species live in the aquatic system)
- Tolerance of contamination
Since 2008 we have also been involved in development of a Visual Index of Biotic Integrity (IBIVI), calculated on the basis of instream inventories, using facemask and snorkel. This method greatly facilitates participation and eventual “ownership” of the biomonitoring process by rural communities.
Development and refinement of fish-based biotic indices for Talamanca, and the humid tropics in general, is an open-ended process in which the ANAI team occupies a leadership position. In 2010 we concluded that we had accumulated a sufficient body of data to permit a more rigorous statistical analysis of much of our data. This is reflected in recently revised indices, but further improvement is to be expected.
As a consequence of our concerns about hydro dam proposals in the Greater Talamanca region diadromous animal (those obliged to move between marine and fresh water environments in order to complete their life cycles) have become a major focus of conservation concern in Bocas del Toro and Talamanca. An inescapable conclusion is that barriers to diadromous behavior would cause massive damage to ecosystems and fisheries anywhere in the region. This in turn places the role of rivers and streams as altitudinal biological corridors in the spotlight. We have been able to derive reliable estimates of the relative importance of diadromous fish and shrimp at different sites without recourse to full-scale quantitative sampling, such as is necessary for calculation of IBI.
For the foreseeable future much of our work will focus on diadromy and conservation of riverine corridors.
Benthic Macroinvertebrate Monitoring
Monitoring of benthic (bottom dwelling) macroinvertebrates, chiefly insects, is the most traditional method of stream biomonitoring, based on identifying samples of benthic organisms and applying indices similar to those described above for fish. Staff and volunteers normally carry out macroinvertebrate samples at each site monitored, applying the BMWP-CR index which officially establishes criteria recognized by the government of Costa Rica. For a more detailed account of our macroinvertebrate monitoring methods, see
We are also working to refine our macroinvertebrate assessment methodology to more closely correspond to the special characteristics of the Talamancan environment. An important emphasis at this time is the study of diadromous shrimp, which constitute a major component of the macroinvertebrate assemblage in most of our streams, but are little studied.
Physical Habitat Assessment
The third component of our routine monitoring procedure is assessment of the quality of physical habitat at the site using a variant of the USDAStream Visual Assessment Protocol (SVAP) adapted to the conditions of Talamanca. SVAP is a user-friendly, extremely low-cost method which permits observers, after less than an hour of training, to derive an SVAP score, on a scale of 1 to 10 by analyzing factors such as
*Condition of the riparian vegetative buffer.
* Degree of sedimentation.
* Abundance and condition of habitat features such as pools and riffles
* Nearby sources of organic pollution
* Barriers to fish movement.