Monitoreo de la ictiofauna usando grupos taxonómicos superiores en el Parque Nacional Cabo Pulmo, México

Ichthyofauna monitoring using higher taxa in Cabo Pulmo National Park, México. The uses of biological indicators allow to save time, resources and staff efforts when monitoring programs are conducted. The reef fishes are among the species with biggest potential as indicators since they are conspicuous, easy to identify in the field and have ecological and economical importance. The objective of this study was to evaluate the usefulness of higher taxa to predict fish ecological indices in Cabo Pulmo reef. We generated multiple stepwise regression equations with species abundance data grouped at genera and family levels as factors, and using ecological indices (H´, J´, Δ*) as dependent variables. To test the efficiency of the models, the expected indexes were compared with those observed in the field during independent test surveys. Results showed that all models were highly significant, and the best fit occurred at genus level to H´, while those used for Δ*, based on family data level, were less precise. The proportion of variables required to apply prediction models of any ecological index never exceeded 41% of the total taxa (genera or families). In conclusion, the use of regression methods to determine higher taxa indicators is adequate and represents a good potential to be used in monitoring programs. In addition, the use of genera and families as indicators provide logistic benefits as training for monitors is less intense and expensive. Finally, the use of expected-observed comparisons to measure the quality of the evaluations can be useful for managers in order to interpret and communicate results of the scientific endeavors to the society, so they in turn can participate and help to improve and facilitate long-term monitoring at Cabo Pulmo National Park. Rev. Biol. Trop. 59 (2): 871-885. Epub 2011 June 01.

El uso de indicadores biológicos es una herramienta útil para la descripción de las comunidades y permite ahorrar recursos en programas de monitoreo. Con el fin de evaluar el potencial bioindicador de grupos taxonómicos superiores en el Parque Nacional Cabo Pulmo, México, se construyeron modelos de regresión múltiple por pasos con valores de abundancia agrupados a nivel género y familia como predictores, mediante el uso de variables dependientes, los índices ecológicos de diversidad (H’), equidad (J’) y distintividad taxonómica (Δ*). Posteriormente se compararon los resultados de los modelos contra los valores de los índices ecológicos observados en un muestreo independiente. Los resultados mostraron que todos los modelos fueron altamente significativos; los valores más altos del coeficiente de determinación se obtuvieron en las regresiones aplicadas a H’, mientras que las usadas por Δ* fueron las menos precisas. Los resultados sugieren que los modelos predictivos aquí generados son susceptibles de ser aplicados en un programa de monitoreo. Este estudio sugiere la implementación de un programa de monitoreo a largo plazo basado en bioindicadores de la estructura comunitaria de peces en el Parque Nacional Cabo Pulmo, el cual combine la precisión con la facilidad de obtención de datos.

Conservation status and spatial patterns of AGRRA vitality indices in Southwestern Atlantic Reefs

Coral reefs along the Eastern Brazilian coast extend for a distance of 800km from 12° to 18°S. They are the largest and the richest reefs of Brazil coasts, and represent the Southernmost coral reefs of the Southwestern Atlantic Ocean. Few reef surveys were performed in the 90’s in reef areas of Bahia State, particularly in the Abrolhos reef complex, in the Southernmost side of the state. A monitoring program applying the Atlantic and Gulf Rapid Reef Assessment (AGRRA) protocol was initiated in 2000, in the Abrolhos National Marine Park, after the creation of the South Tropical America (STA) Regional Node of the Global Coral Reef Monitoring Network (GCRMN) by the end of 1999. From that time up to 2005, nine reef surveys were conducted along the coast of the State of Bahia, including 26 reefs, with 95 benthic sites, 280 benthic transects, 2025 quadrats and 3537 stony corals. Eighteen of the 26 investigated reefs were assessed once and eight reefs of Abrolhos were surveyed twice to four times. The MDS ordination, analysis of similarity (ANOSIM, one way and two-way nested layouts) and similarity percentages (SIMPER) tests were applied to investigate the spatial and temporal patterns of reef vitality. Four indicators of the coral vitality: live coral cover, the density of the larger corals (colonies >20cm per reef site) and of the coral recruits (colonies<2cm per square meter), and the percentage of macroalgae indicate that the nearshore reefs, which are located less than 5km from the coast, are in poorer condition than the reefs located more than 5km off the coast. A higher density of coral colonies, lower macroalgal index, higher relative percent of turf algae and higher density of coral recruits in offshore reefs compared to the nearshore reefs are the conditions that contribute more than 80% to the dissimilarity between them. The offshore reefs are in better vital condition than the nearhore reefs and have a set of vitality indices more closely related to the Northwestern Atlantic reefs than the nearshore reef. These have been most severely impacted by the effects of direct human activities such as euthrophic waters associated with sewage pollution, higher sedimentation rates and water turbidity, inadequate use of the reefs and over exploitation of their resources. The implementation of a more effective coral reef monitoring program in Bahia is mandatory, in order to improve the strategies for protection and management efforts of the reefs. Rev. Biol. Trop. 58 (Suppl. 1): 1-31. Epub 2010 May 01.

Desde el año 2000 se inició un programa de monitoreo utilizando el protocolo AGRRA en el Parque Nacional Marino de Abrolhos en el marco de la creación del Nodo STA de la GCRMN. Entre 2000 y 2005 se realizaron varias evaluaciones en 26 arrecifes. Los patrones espaciales y temporales de la vitalidad de los arrecifes fueron estudiados mediante análisis de ordenación (MDS), similaridad (ANOSIM) y porcentajes de similaridad (SIMPER). La cobertura de coral vivo, la densidad de colonias grandes (>20cm) y de reclutas (<2cm) y la cobertura de macroalgas indicaron que los arrecifes ubicados a más de 5km de la costa presentan una mejor condición que aquellos ubicados a menos de 5km de la costa. Los arrecifes más alejados registraron una mayor densidad de colonias, un bajo índice de macroalgas, un relativo más alto porcentaje de coberturas algales y una más alta densidad de reclutas en comparación con los arrecifes más cercanos. Los arrecifes más cercanos a la costa han sido más severamente afectados por las actividades humanas. Por ejemplo, eutrofización de aguas (contaminación de aguas residuales), mayor sedimentación y turbidez del agua, mal uso de los arrecifes y sobreexplotación de sus recursos. La implementación de un programa integral de monitoreo en Bahia es urgente y obligatorio para mejorar las estrategias de protección y los esfuerzos de manejo de sus arrecifes.