Depredación de coral vivo por peces en el Parque Nacional Natural Tayrona, Caribe colombiano

Este artículo se publicó en el Volumen 52, fascículo 4, correspondiente al mes de diciembre 2004. Por error de la imprenta la figura 1 presenta su imagen en tonalidades invertidas (negativo). Se adjunta la imagen impresa correctamente.

Widespread local chronic stressors in Caribbean coastal habitats

Coastal ecosystems and the livelihoods they support are threatened by stressors acting at global and local scales. Here we used the data produced by the Caribbean Coastal Marine Productivity program (CARICOMP), the longest, largest monitoring program in the wider Caribbean, to evidence local-scale (decreases in water quality) and global-scale (increases in temperature) stressors across the basin. Trend analyses showed that visibility decreased at 42% of the stations, indicating that local-scale chronic stressors are widespread. On the other hand, only 18% of the stations showed increases in water temperature that would be expected from global warming, partially reflecting the limits in detecting trends due to inherent natural variability of temperature data. Decreases in visibility were associated with increased human density. However, this link can be decoupled by environmental factors, with conditions that increase the flush of water, dampening the effects of human influence. Besides documenting environmental stressors throughout the basin, our results can be used to inform future monitoring programs, if the desire is to identify stations that provide early warning signals of anthropogenic impacts. All CARICOMP environmental data are now available, providing an invaluable baseline that can be used to strengthen research, conservation, and management of coastal ecosystems in the Caribbean basin.

Mid-term coral-algal dynamics and conservation status of a Gorgona Island (Tropical Eastern Pacific) coral reef

<span>A través del Sistema Nacional de Monitoreo de Arrecifes Coralinos en Colombia (SIMAC) se han colectado anualmente (1998-2004) datos de cobertura de corales y algas en 20 transectos de 10m localizados en dos profundidades de dos sitios del arrecife de La Azufrada, Isla Gorgona (costa Pacífica). En general, la cobertura coralina fue alta (55.1% - 65.7%) y la de algas baja (28.8% - 37.5%), con una significativa variación entre años, más notablemente en áreas someras. Las diferencias entre sitios tanto en cobertura de coral como de algas estuvieron presentes desde que comenzó el estudio y pueden ser explicadas por diferencias en estrés por sedimentación (escorrentía terrestre). Las diferencias entre las profundidades muy probablemente se deben a los efectos de exposiciones aéreas durante mareas bajas. Las exposiciones aéreas particularmente intensas y repetidas entre enero-marzo de 2001 explican la disminución de la cobertura de coral, y aumento de la de algas en áreas someras observadas más tarde ese año. Adicionalmente, el área somera del sitio norte parece ser negativamente afectada por el efecto combinado de la sedimentación y la exposición mareal. Sin embargo, una tendencia a la disminución de la cobertura coralina y aumento de la de algas desde 2001 en las áreas profundas de ambos sitios permanece sin explicación. Comparaciones con estudios previos indican que el arrecife de La Azufrada ha sido más elástico que otros arrecifes del Pacífico Oriental Tropical (POT). A pesar de las perturbaciones naturales recurrentes, la cobertura coralina en 2004 fue tan alta como la existente antes de 1982 en La Azufrada, y una de las más altas observadas en arrecifes coralinos saludables de la región del POT.</span>

Recent dynamics and condition of coral reefs in the Colombian Caribbean

Long-term monitoring data provide a basis to recognize changes in coral reef communities and to implement appropriate management strategies. Unfortunately, coral reef dynamics have been poorly documented at any temporal scale in the Southern Caribbean. Through the "National Monitoring System of Coral Reefs in Colombia" (Spanish acronym: SIMAC), we assessed 32 permanent plots at different depth levels in six reefs areas of the Colombian Caribbean from 1998 to 2004. Temporal trends in coral and algal cover were evaluated by repeated measures ANOVA. The model included the effect of depth levels (a fixed effect), monitoring plots (a random effect) as a nested factor within depths, and time (repeated factor). We found high spatial variability in major benthic components. Overall means indicated that algae were the most abundant biotic component in nearly all areas, ranging from 30.3% at Rosario to 53.3% at San Andrés. Live coral cover varied considerably from 10.1% at Santa Marta up to 43.5% at Urabá. Coral and algae cover per se are not always accurate reef indicators and therefore they need supplementary information. Temporal analyses suggested relative stability of coral and algal cover along the study but the causes for the observed trends were rarely identified. A significant decrease (p = 0.042) in coral cover was only identified for some monitoring plots in Tayrona-time x plot (depth level) interaction, and importantly, few coral species explained this trend. Significant increase (p = 0.005) in algal cover was observed over time for most plots in Rosario. Temporal trajectories in algal cover were influenced by depth-significant time x depth interaction-in San Andrés (increase, p = 0.004) and Urabá (decrease, p = 0.027). Algae trends were mainly explained by changes in algal turfs. Monitoring programs must focus on the mechanisms mediating the changes, in particular those concerning coral recovery and reef resilience in the current context of climate change.

Coral diseases and bleaching on Colombian Caribbean coral reefs

Since 1998 the National Monitoring System for the Coral Reefs of Colombia (SIMAC) has monitored the occurrence of coral bleaching and diseases in some Colombian coral reefs (permanent stations at San Andres Island, Rosario Islands, Tayrona, San Bernardo Islands and Urabá). The main purpose is to evaluate their health status and to understand the factors that have been contributing to their decline. To estimate these occurrences, annual surveys in 126 permanent belt transects (10 x 2m) with different depth intervals (3-6 meters, 9-12 meters and 15-18 meters) are performed at all reef sites. Data from the 1998-2004 period, revealed that San Andrés Island had many colonies with diseases (38.9 colonies/m2), and Urabá had high numbers with bleaching (54.4 colonies/m2). Of the seven reported coral diseases studied, Dark Spots Disease (DSD), and White Plague Disease (WPD) were noteworthy because they occurred in all Caribbean monitored sites, and because of their high interannual infection incidence. Thirty five species of scleractinian corals were affected by at least one disease and a high incidence of coral diseases on the main reef builders is documented. Bleaching was present in 34 species. During the whole monitoring period, Agaricia agaricites and Siderastrea siderea were the species most severely affected by DSD and bleaching, respectively. Diseases on species such as Agaricia fragilis, A. grahamae, A. humilis, Diploria clivosa, Eusmilia fastigiata, Millepora complanata, and Mycetophyllia aliciae are recorded for first time in Colombia. We present bleaching and disease incidences, kinds of diseases, coral species affected, reef localities studied, depth intervals of surveys, and temporal (years) variation for each geographic area. This variation makes difficult to clearly determine defined patterns or general trends for monitored reefs. This is the first long-term study of coral diseases and bleaching in the Southwestern Caribbean, and one of the few long-term monitoring studies on coral diseases worldwide.

Temporal patterns in coral reef, seagrass and mangrove communities from Chengue bay CARICOMP site (Colombia): 1993-2008

Few monitoring programs have simultaneously assessed the dynamics of linked marine ecosystems (coral reefs, seagrass beds and mangroves) to document their temporal and spatial variability. Based on CARICOMP protocol we evaluated permanent stations in coral reefs, seagrass beds and mangroves from 1993 to 2008 in Chengue Bay at the Tayrona Natural Park, Colombian Caribbean. Overall, the studied ecosystems showed a remarkable stability pattern over the monitoring period. While there were annual variations in coral reefs (coral cover) and mangroves (litterfall) caused by hurricane Lenny in 1999, particular trends in seagrass (leaf area index and leaf productivity) appear to reflect the natural variability in this ecosystem. We suggest that monitoring sites at the three marine ecosystems had in general a healthy development in the last 16 years. Our results are critical to locally improve the management strategies (Tayrona Natural Park) and to understand the long-term dynamics of closely associated marine ecosystems in the Caribbean.

SIMAC: development and implementation of a coral reef monitoring network in Colombia

Significant coral reef decline has been observed in Colombia during the last three decades. However, due to the lack of monitoring activities, most of the information about health and changes was fragmentary or inadequate. To develop an expanded nation-wide reef-monitoring program, in 1998 INVEMAR (Instituto de Investigaciones Marinas y Costeras: "Colombian Institute of Marine and Coastal Research") designed and implemented SIMAC (Sistema Nacional de Monitorco de Arrecifes Coralinos en Colombia: "National Monitoring System of Coral Reefs in Colombia") with the participation of other institutions. By the end of 2003 the SIMAC network reached more than twice its initial size, covering ten reef areas (seven in the Caribbean and three in the Pacific), 63 reef sites and 263 permanent transects. SIMAC monitoring continued without interruption until 2008 and should persist in the long-term. The SIMAC has a large database and consists basically of water quality measurements (temperature, salinity, turbidity) and a yearly estimation of benthic reef cover, coral disease prevalence, gorgonian density, abundance of important mobile invertebrates, fish diversity and abundance of important fish species. A methods manual is available in the Internet. Data and results of SIMAC have been widely circulated through a summary report published annually since 2000 for the Colombian environmental agencies and the general public, as well as numerous national and international scientific papers and presentations at meetings. SIMAC information has contributed to support regional and global reef monitoring networks and databases (i.e. CARICOMP, GCRMN, ReefBase).

Bacterial communities associated with the mucopolysaccharide layers of three coral species affected and unaffected with dark spots disease

Dark spots disease (DSD) is a relatively new coral disease that has become one of the most prevalent afflictions in the Caribbean Sea. To partially characterize bacterial communities associated with DSD, carbon utilization patterns of bacterial strains isolated from the surface mucopolysaccharide layers of healthy and DSD-affected Montastraea annularis , Montastraea faveolata , and Siderastrea siderea were compared with each other and with bacterial strains isolated from the water column by using cluster analysis. Differences between healthy and diseased corals were found and were greatest for M. annularis than for the other species. A metabolic group of bacteria similar to Vibrio carchariae was found to be unique to diseased samples. Inoculation experiments on healthy corals did not result in the development of disease signs. However, our results support the hypothesis that stress (in this case disease) alters the normal microbiota in the coral surface mucopolysaccaride layers. Studies are continuing to determine the pathogenic agent(s) responsible for DSD.

[Live coral predation by fish in Tayrona Nature National Park, Colombian Caribbean]

Live coral predation by fish was evaluated in two bays of the Tayrona National Natural Park (Colombia), as a possible biological agent causing coral mortality. Visual censuses were used to identify the most important predator. Predation incidence was determined by examining all colonies present in permanent belt transects (20 x 2 m) in two reef environments (one dominated by Colpophyllia natans and the other one by Montastraea faveolata), for two climatic seasons (rainy and dry seasons). The parrotfish Sparisoma viride was the most important predator due to its biting frequency and bite size. S. viride adults of the initial and terminal phases, removed live tissue and part of the calcareous matrix of M. faveolata, M. annularis, Porites astreoides and C. natans, of which, the last one lost a major amount of tissue per area (3.51 cm2) and volume (3.22 cm3) per bite. A negative exponential tendency (r2=0.94), between coral density and volume removed was found, indicating that the coral density determines the bite's damage. There is no clear relationship between predation incidence and climatic seasons at the sites studied. At Chengue and Gayraca bays, live coral predation is one of the factors contributing to coral tissue loss and could have important consequences on the dynamic of these reefs.

[Reef fishes community structure in 4 atolls of the San Andrés - Providencia Archipelago (Southwestern Caribbean)]

In 1994 and 1995, 131 visual censuses of reef fishes were made using the stationary sampling method in Courtown, Albuquerque, Serrana and Roncador, four atolls of the Archipelago of San Andrés and Old Providence in the Southwestern Caribbean. Fish species and their abundances were recorded in four geomorphologic zones: lagoon, windward barrier reef, windward terrace and forereef terrace. A total of 98 species were censused; the most abundant were Chromis cyanea (14%), Clepticus parra (14%) and Stegastes partitus (10%). The most abundant families were Pomacentridae (37%), Labridae (28%) and Scaridae (10%). Analysis of similarities showed that differences between zones were greater than differences between atolls, but lagoon and forereef terrace were not significantly different. Cluster and ordination analysis confirmed these results; in addition, the ordination analysis placed the groups according to depth and wave-exposure gradients, suggesting that these two physical variables were responsibles for the clustering. Differences in equitability and species richness appear also due to these variables. Inverse analysis showed in each group few characteristic species, then the differences between zones were due specially to dominance of some species. The dominant trophic categories were planktivorous and herbivorous that were significantly different between zones. In shallow zones (shallow lagoonal patch reefs) and high wave-exposed zones (winward barrier reef) dominated herbivorous fishes, while in deeper zones (terraces and deep lagoonal patch reefs) planktivorous were more abundant.