Population dynamics of Siderastrea stellata Verrill, 1868 from Rocas Atoll, RN: implications for predicted climate change impacts at the only South Atlantic atoll

ABSTRACT Coral reefs are one of the most vulnerable ecosystems to ocean warming and acidification, and it is important to determine the role of reef building species in this environment in order to obtain insight into their susceptibility to expected impacts of global changes. Aspects of the life history of a coral population, such as reproduction, growth and size-frequency can contribute to the production of models that are used to estimate impacts and potential recovery of the population, acting as a powerful tool for the conservation and management of those ecosystems. Here, we present the first evidence of Siderastrea stellata planulation, its early growth, population size-frequency distribution and growth rate of adult colonies in Rocas Atoll. Our results, together with the environmental protection policies and the absence of anthropogenic pressures, suggest that S. stellata population may have a good potential in the maintenance and recovery in the atoll. However, our results also indicate an impact on corals' recruitment, probably as a consequence of the positive temperature anomaly that occurred in 2010. Thus, despite the pristine status of Rocas Atoll, the preservation of its coral community seems to be threatened by current global changes, such as more frequent thermal stress events.

Impact of upwelling events on the sea water carbonate chemistry and dissolved oxygen concentration in the Gulf of Papagayo (Culebra Bay), Costa Rica: Implications for coral reefs / Impacto de los eventos de surgencia en la química del carbonato del agua de mar y la concentración de oxígeno disuelto en el Golfo de Papagayo (Bahía Culebra), Costa Rica: Implicaciones para los arrecifes de coral

The Gulf of Papagayo, Pacific coast of Costa Rica, is one of the three seasonal upwelling areas of Mesoamerica. In April 2009, a 29-hour experiment was carried out at the pier of the Marina Papagayo, Culebra Bay. We determined sea surface temperature (SST), dissolved oxygen concentration, salinity, pH, and the partial pressure of CO2 (pCO2). The aragonite saturation state (Ωa) as well as the other parameters of the marine carbonate system such as the total dissolved inorganic carbon (DIC) and the total alkalinity (TA) were calculated based on the measured pH and the pCO2. The entrainment of subsurface waters raised the pCO2 up to 645 µatm. SSTs, dissolved oxygen concentrations decreased form 26.4 to 23.7°C and from 228 to 144 µmol l-1. Ωa dropped down to values of 2.1. Although these changes are assumed to reduce the coral growth, the main reef building coral species within the region (Pocillopora spp. and Pavona clavus) reveal growth rates exceeding those measured at other sites in the eastern tropical Pacific. This implies that the negative impact of upwelling on coral growth might be overcompensated by an enhanced energy supply caused by the high density of food and nutrients and more favorable condition for coral growth during the non-upwelling season.

El Golfo de Papagayo, costa Pacífica de Costa Rica, es una de las tres regiones de afloramiento estacional de Mesoamérica. Las características físicas y químicas del agua que aflora no habían sido estudiadas. Durante 29 horas en Abril 2009, se estudiaron la temperatura superficial del mar (TSM), la concentración de oxígeno disuelto, salinidad, pH y la presión parcial de CO2 (pCO2), en la Marina Papagayo, Bahía Culebra. Con base en las mediciones de pH y pCO2 se calculó el estado de saturación de la aragonita (Ω) y otros parámetros del sistema de carbonatos como lo es el carbono orgánico disuelto (COD) y la alcalinidad total (AT). Los resultados indican que el arrastre por convección del agua sub-superficial durante los eventos de afloramiento aumenta la pCO2 y disminuye la TSM, la concentración de oxígeno disuelto y Ω. Aunque se asume que estas condiciones reducen el crecimiento coralino, las principales especies constructoras de arrecife en la región de Papagayo (Pocillopora spp. y Pavona clavus) tienen las mayores tasas de crecimiento en el Pacífico Tropical Oriental. Esto posiblemente implica que el efecto negativo del afloramiento es compensado por el crecimiento durante la época de no afloramiento.

Implications of coral harvest and transplantation on reefs in northwestern Dominica

In June, 2002, the government of Dominica requested assistance in evaluating the coral culture and transplantation activities being undertaken by Oceanographic Institute of Dominica (OID), a coral farm culturing both western Atlantic and Indo-Pacific corals for restoration and commercial sales. We assessed the culture facilities of OID, the condition of reefs, potential impacts of coral collection and benefits of coral transplantation. Coral reefs (9 reefs, 3-20m depth) were characterized by 35 species of scleractinian corals and a live coral cover of 8-35%. Early colonizing, brooders such as Porites astreoides (14.8% of all corals), P. porites (14.8%), Meandrina meandrites (14.7%) and Agaricia agaricites (9.1%) were the most abundant corals, but colonies were mostly small (mean=25cm diameter). Montastraea annularis (complex) was the other dominant taxa (20.8% of all corals) and colonies were larger (mean=70cm). Corals (pooled species) were missing an average of 20% of their tissue, with a mean of 1.4% recent mortality. Coral diseases affected 6.4% of all colonies, with the highest prevalence at Cabrits West (11.0%), Douglas Bay (12.2%) and Coconut Outer reef (20.7%). White plague and yellow band disease were causing the greatest loss of tissue, especially among M. annularis (complex), with localized impacts from corallivores, overgrowth by macroalgae, storm damage and sedimentation. While the reefs appeared to be undergoing substantial decline, restoration efforts by OID were unlikely to promote recovery. No Pacific species were identified at OID restoration sites, yet species chosen for transplantation with highest survival included short-lived brooders (Agaricia and Porites) that were abundant in restoration sites, as well as non-reef builders (Palythoa and Erythropodium) that monopolize substrates and overgrow corals. The species of highest value for restoration (massive broadcast spawners) showed low survivorship and unrestored populations of these species were most affected by biotic stressors and human impacts, all of which need to be addressed to enhance survival of outplants. Problems with culture practices at OID, such as high water temperature, adequate light levels and persistent overgrowth by macroalgae could be addressed through simple modifications. Nevertheless, coral disease and other stressors are of major concern to the most important reef builders, as these species are less amenable to restoration, collection could threaten their survival and losses require decades to centuries to replace. Rev. Biol. Trop. 58 (Suppl. 3): 111-127. Epub 2010 October 01.

En junio del año 2002 el gobierno de Dominica solicitó asistencia para evaluar el Instituto Oceanográfico de Dominica (OID), una operación de cultivo de corales del océano Atlántico y del Indo Pacifico para propósitos de restauración y comercio. Evaluamos las facilidades de cultivo del OID, la condición de los arrecifes y el impacto potencial de la recolección de corales y los posibles beneficios del transplante de colonias. Los arrecifes de coral (9 arrecifes de profundidades entre 3 y 20m se caracterizaban por 35 especies escleractíneos y una cobertura viva de coral entre 8 y 35%. Las especies que liberan larvas tales como Porites astreoides (14.8 % de todos los corales), P. porites (14.8%), Meandrina meandrites (14.7%) y Agaricia agaricites (9.1%) fueron los más abundantes, pero sus colonias eran pequeñas (promedio de 25cm de diámetro). El complejo de Montastraea annularis fue otro grupo dominante (20.8% de todos los corales) y sus colonias eran mayores (promedio de 70cm de diámetro). Entre todas las especies los corales habían perdido el 20% de sus tejidos, con un promedio de 1.4% por mortandad reciente. Las enfermedades de coral afectaron 6.4% de todas las colonias, con la incidencia mayor en Cabrits Oeste (11%), Bahía Douglas (12.2%) y el arrecife de Coconut Afuera (20.7%). Plaga blanca y la enfermedad de la banda amarilla causaron la mayoría de la pérdida de tejido vivo, especialmente en el complejo de M. annularis, con impactos localizados por caracoles coralívoros, sobre crecimiento por macroalgas, impactos de tormentas y sedimentación. Mientras los arrecifes parecen estar declinando substancialmente, los esfuerzos de restauración de OID no parecen entablar su recuperación debido a que las especies escogidas para transplantar con las mayores tasas de sobrevivencia incluyen especies que liberan larvas (Agaricia y Porites) que fueron abundantes en las restauraciones, al igual que los organismos potencialmente parasíticos (Palythoa ...

Effect of severe hurricanes on Biorock Coral Reef Restoration Projects in Grand Turk, Turks and Caicos Islands

Artificial reefs are often discouraged in shallow waters over concerns of storm damage to structures and surrounding habitat. Biorock coral reef restoration projects were initiated in waters around 5m deep in Grand Turk, at Oasis (October 2006) and at Governor’s Beach (November 2007). Hemi-cylindrical steel modules, 6m long were used, four modules at Oasis and six at Governor’s Beach. Each project has over 1200 corals transplanted from sites with high sedimentation damage, and are regularly monitored for coral growth, mortality and fish populations. Corals show immediate growth over wires used to attach corals. Growth has been measured from photographs using a software program and is faster at Governor’s Beach. After hurricanes Hanna and Ike (September 2008) the Governor’s Beach structure was fully standing since the waves passed straight through with little damage, the Oasis structures which were tie-wired rather than welded had one module collapse (since been replaced with a new, welded structure). Hurricane Ike was the strongest hurricane on record to hit Grand Turk. Most cables were replaced following the hurricanes due to damage from debris and high wave action. The projects lost about a third of the corals due to hurricanes. Most of those lost had only been wired a few days before and had not yet attached themselves firmly. These projects have regenerated corals and fish populations in areas of barren sand or bedrock and are now attractive to snorkelers. High coral survival and low structural damage after hurricanes indicate that Biorock reef restoration can be effective in storm-impacted areas. Rev. Biol. Trop. 58 (Suppl. 3): 141-149. Epub 2010 October 01.

Con frecuencia no se favorece la creación de arrecifes artificiales en aguas someras debido a que se estima que las tormentas pueden producir daños en las estructuras y en el hábitat circundante. En las aguas de Grand Turk, a unos 5m de profundidad, se iniciaron proyectos de restauración de arrecifes coralinos en Oasis (octubre 2006) y en Governor’s Beach (noviembre 2007). Se utilizaron módulos de acero semicilíndricos, 4 en Oasis y 6 en Governor’s Beach. A cada proyecto se han trasplantado más de 1200 corales desde sitios con un elevado daño por sedimentación y se monitorean regularmente para evaluar crecimiento y mortalidad de los corales, así como la población de peces. Los corales muestran un crecimiento inmediato sobre los alambres utilizados para asegurar los corales. Este crecimiento se ha medido usando fotografías y un programa de computación y es más rápido en Governor’s Beach. Después de los huracanes Hanna e Ike (setiembre 2008), las estructuras en Governor’s Beach se mantuvieron erectas debido a que las olas pasaron a través de las mismas sin afectarlas, una de las estructuras en Oasis colapsó debido a que todas se amarraron con alambre en vez de soldarse (desde entonces se sustituyó con una nueva, soldada esta vez). El huracán Ike ha sido el más fuerte de los históricamente registrados que ha impactado Grand Turk. La mayor pare de los cables fueron reemplazados debido a daños causados por la acción de detritus y de las grandes olas. Los proyectos perdieron alrededor de un tercio de los corales debido a los huracanes. La mayoría de los corales perdidos habían sido amarrados a las estructuras unos días antes de los huracanes y consecuentemente no se habían adosado firmemente a las mismas. Estos proyectos han regenerado poblaciones de corales y peces en áreas inhóspitas de arena o roca y constituyen ahora una atracción para el buceo superficial. La alta tasa de supervivencia de corales y el bajo daño a las estructuras después de los huracanes indican que la tecnología Biorock para restauración de arrecifes coralinos es efectiva en áreas impactadas por tormentas.

Efecto de la herbivoría y coralivoría por peces en la supervivencia de corales trasplantados en el Caribe colombiano

Effect of herbivorous and corallivorous fishes on the survival of transplanted corals in the Colombian Caribbean. To examine the effects of herbivorous and corallivorous fishes on the survival of transplanted colonies of Montastraea annularis, Diploria labyrinthiformis and Porites astreoides, both transplanted and native colonies were full-cage enclosed and compared to open (uncaged) colonies, while caging effects were assessed with a partial-cage (roof treatment). To evaluate if transplant stress increased the corals availability to fish predation, comparisons of fish foraging intensity among transplanted versus native colonies were made. To determine the density of herbivorous and corallivorous fishes on the transplants area visual censuses were made. The transient herbivorous fishes (Scaridae and Acanthuridae) were the most abundant fishes, and the corallivorous fishes (mainly Chaetodontidae) were the scarcest. A negative effect of territorial herbivorous fishes on M. annularis transplants survival was observed, mainly early on the study. Fish foraging intensity was similar on transplanted and native colonies, but differed among coral species, being lowest on D. labyrinthiformis. Fast macroalgal growth inside full-cages due to reduced fish grazing was observed. This caused partial bleaching and partial mortality in some colonies, mainly of P. astreoides. No significant difference in healthy tissue percentages among full-cage and uncaged colonies on M. annularis and D. labyrinthiformis was found, while in P. astreoides there were evident differences. The results indicate a damselfish negative effect on transplants survival early on the study, which can change depending on the fish and coral species involved. Results also indicate a fish grazing positive effect, caused by the reduction of coral-algae competition pressure, mainly on P. astreoides. Parrotfishes seem to affect corals survival both negatively through direct biting, and positively by controlling algal growth. Overall, coral transplant success was almost unaffected by fish foraging activity although several differences among coral species were obvious in relation to colony shape. Additionally, the interaction among herbivorous fish grazing and coral-algae competition balance appear important in determining transplant survival. Rev. Biol. Trop. 55 (3-4): 825-837. Epub 2007 December, 28.

Para investigar el efecto de los peces herbívoros y coralívoros en la supervivencia de colonias trasplantadas de Montastraea annularis, Diploria labyrinthiformis y Porites astreoides se encerraron colonias trasplantadas y nativas en jaulas y se compararon con colonias libres (control), mientras los efectos del encierro fueron evaluados con un tratamiento de techos. Para saber si el estrés debido al trasplante aumentó la vulnerabilidad de los corales a la depredación por peces, se comparó la intensidad de forrajeo por peces entre colonias trasplantadas y nativas. Se realizaron censos visuales para determinar las densidades de las poblaciones de peces herbívoros y coralívoros en la zona de trasplante. Los peces herbívoros móviles (Scaridae y Acanthuridae) fueron los más abundantes, los peces coralívoros (principalmente Chaetodontidae) fueron los más escasos. Se observó un efecto negativo de los peces herbívoros territoriales en la supervivencia de los trasplantes de M. annularis, principalmente al inicio del estudio. La presión de forrajeo fue similar en colonias trasplantadas y nativas, pero fue diferente entre especies, siendo D. labyrinthiformis la menos depredada. En los tratamientos de colonias protegidas en jaulas se observó un crecimiento acelerado de macroalgas debido a la reducción del forrajeo por peces herbívoros. Esto causó blanqueamiento parcial y mortalidad parcial en algunas colonias, principalmente de P. astreoides. En M. annularis y D. labyrinthiformis no se observaron diferencias significativas en los porcentajes de tejido sano de las colonias entre los tratamientos de jaulas y de control, pero sí en P. astreoides. Los resultados sugieren un efecto negativo de los peces herbívoros territoriales en la supervivencia de las colonias durante los primeros días del trasplante; este efecto puede variar dependiendo de las especies de peces y corales involucradas. Los resultados también indican un efecto positivo del forrajeo por peces, debido a la reducción de la presión competitiva alga-coral, sobretodo en P. astreoides. Los scáridos parecen afectar la supervivencia de los corales tanto de manera negativa, al morder en el tejido vivo, como de manera positiva al controlar el crecimiento de las macroalgas. En general, el éxito del transplante de coral fue poco afectado por la actividad de forrajeo de los peces, aunque algunas diferencias entre las especies de coral parecen estar relacionadas con la forma de las colonias. La interacción entre el forrajeo de peces hervíboros y el balance competitivo alga-coral puede ser importante en determinar la supervivencia al transplante.

Diversidad y abundancia relativa de corales, octocorales y esponjas en el Parque Nacional Jaragua, República Dominicana / Diversity and relative abundance of corals, octocorals and sponges at Jaragua National Park, Dominican Republic

The Jaragua National Park is located in a remote area to the SW coast of the Dominican Republic. Fishing and mining are the major human activities. The main reef formations of the Park include: (a) long bank reefs (spur and groove) growing as bands over the platform and running in a SW-NW direction at 12-25 m depth, (b) well developed, deep, fringing reefs at the platform edge (drop-off) areas which could extend from 10 to 45 m depth, and (c) small patch reefs and poorly developed coral-octocoral-sponge-algal communities in shallow platforms near shore, rocky bottoms, and over the submerged walls of the uplifted reef. Nine reef localities were surveyed between Cabo Beata and Bahia Honda using Scuba diving to inventory the diversity and relative abundance of scleractinian corals, octocorals and sponges. Fringing reefs were surveyed starting at the bottom (30 m) and swimming in a zig-zag pattern (50 m on each side) to shallower areas. Bank reefs were surveyed by swimming in zig-zag across the spur-groove formation along 500 m. Sponges were the most diverse group with 83 species in 50 genera followed by the scleractinian corals with 56 species in 26 genera and the octocorals with 47 species in 15 genera. New records included eight coral species, 29 octocoral species and 59 sponges. The diversity, species composition and abundance of particular groups varied across the different localities. Northern reefs within the park and the Los Frailes Island offshore had the highest live cover, relative abundance and diversity for the three groups. In general, the Jaragua National Park had the highest diversity of corals, octocorals and sponges reported for the Dominican Republic and rank amongst the highest reported for the northern Caribbean. It is recommended that the area be protected and that fishing activities be regulated or eliminated altogether.

El Parque Nacional Jaragua está localizado en un área remota al SW de la República Dominicana. La actividad humana se limita a pesquerías y minería. Las principales formaciones arrecifales incluyen (a) arrecifes de banco (montículo) creciendo sobre la plataforma en bandas paralelas, separadas por canales de arena y en dirección SE – NW, entre 12 y 25 m de profundidad, (b) arrecifes de franja profundos que se desarrollan en los bordes de la plataforma entre 10 y 45 m de profundidad, y (c) parches arrecifales y comunidades coralinas con poca o ninguna estructura arrecifal en áreas cercanas a la costa y plataformas someras. Nueve localidades fueron muestreadas intensivamente entre Cabo Beata y Bahía Honda mediante buceo autónomo. Se nadó en un patrón de zig-zag (50 m a cada lado) desde el fondo (30 m) hasta la zona somera en los arrecifes frangeantes. Se uso el mismo patrón pero a lo largo (por 500 m) cubriendo el ancho de las bandas en los arrecifes de montículo. Las abundancias relativas y la diversidad de corales escleractínidos, octocorales y esponjas se estimaron en estas bandas. Las esponjas presentaron la mayor diversidad con 83 especies en 50 géneros, seguidas por los corales escleractínidos con 56 especies en 26 géneros y los octocorales con 47 especies en 15 géneros. Nuevos registros para el área incluyen ocho especies de corales, 21 de octocorales y 59 de esponjas. La diversidad, abundancia y distribución de especies de cada grupo varió entre localidades. En general, las localidades del norte y la isla de Los Frailes mar afuera, mostraron las mayores diversidades y abundancias de los tres grupos. En general, el Parque Nacional Jaragua presenta las diversidades más altas de corales, octocorales y esponjas registradas para la República Dominicana y están entre las más diversas para el norte del Caribe. Se recomienda una protección integral del área que incluya una regulación substancial (o prohibición) de las actividades pesqueras.

The occurrence of black corals in Jamaican reef environments, with special reference to Stichopathes lutkeni (Antipatharia: Antipathidae)

The purpose of this study was to record the species of Antipatharia on Jamaican reefs and to carry out limited studies on densities and sizes of the common species.In addition,a cliff face created by dredging in 2002 provided the opportunity to study growth of newly settled colonies.Observations since 1998 and measurements since 2001 were made using SCUBA at depths down to 35 m.Seven species of Antipatharia were observed on steep coral reef escarpments below 25 m depth.The commonest species was the unbranched "wire coral " Stichopathes lutkeni .Other common species included the fan-shaped black corals Antipathes atlantica and A. gracilis .Frequently encountered species included commercially important A.caribbeana and a species with an unusual,scrambling growth form, A. rubusiformis.The other major commercial species in the Caribbean, Plumapathes pennacea ,and a cave-dwelling species,A.umbratica ,were rarely observed.Greatest black coral abundance occurred on steep slopes of hard substrata in low light intensity but exposed to the long-shore current. Combined densities of the commoner Antipatharia at 30 m deep at Rio Bueno on the north coast,ranged from 0.1 to 2.5 m-2 (eleven 10 m x 1 m belt transects,1-25 colonies per transect,68 colonies in total).Forty-six of the 68 colonies were S.lutkeni ,while nearby at Discovery Bay at 30-35 m,55 out of 59 colonies were S.lutkeni. There was a significant difference between the mean length of colonies in these two populations of S.lutkeni (100 cm and 80 cm,respectively),probably relating to habitat.A third population of S.lutkeni growing at 15-20 m deep on the recently dredged cliff had a much smaller mean length of 36.6 cm (n=27).The largest individual measured 83 cm long,indicating a minimum growth rate of the unbranched corallum of 2.1 mm per day

Coral recruitment patterns in the Florida Keys

This study examines scleractinian zooxanthellate coral recruitment patterns in the Florida Keys to determine if differences in density or community composition exist between regions. From July to September 2002, nine patch reefs, three in each of the upper, middle and lower Keys, were surveyed for coral recruits (colonies <5 cm in diameter) using randomly placed quadrats and transects. Coral recruits were enumerated, measured, and identified to genus. Fourteen genera of corals were observed across all sites and ranged from five to 13 per site. Densities ranged from 6.29 +/- 1.92 (mean +/- SE) to 39.08 +/- 4.53 recruits m(-2), and there were significant site and regional differences in recruit densities. The density of recruits in the upper Keys was significantly lower than in the middle and lower Keys. In addition, the upper Keys were less diverse and had a different recruit size-frequency distribution. The majority of recruits were non-massive scleractinian species that contribute relatively little to overall reef-building processes, a finding that is similar to previous studies. Fewer recruits of massive species were found in the upper Keys compared to the middle and lower Keys. The recruitment patterns of the reefs in the upper Keys could potentially hinder their ability to recover from stress and disturbances

Transplantation of benthic species to mitigate impacts of coastal development in Jamaica

Maintaining regional competitiveness and economic viability for Port Bustamante - Kingston Harbour, Jamaica, required improved accessibility to "Post Panamax" (too large to pass through the Panama Canal) container vessels. Removal of the northern portion of the shallow coral reef at Rackham's Cay, which was partially obstructing the western end of the east ship channel, was proposed. This aesthetically valuable reef was used by local fishermen and comprises part of the declared Palisadoes - Port Royal Protected Area. The proposal to transplant certain of the benthic species was advanced to mitigate loss of viable reef components. Between December 2001 and February 2002, sixty thousand items, consisting of reef building massive and branching corals; gorgonians; urchins (Diadema and Tripneustes spp.) and Thalassia meristems were relocated. During dredging, sedimentation rates from suspended solids in the water column were 0.003 g/cm(2)/day at the control site and 0.008 g/cm(2)/day at the dredge site. Coral cover in the relocation area increased from 15% to 20% while bare substrate decreased from 27% to 21%. This paper documents the mitigation required; some factors controlling the ecology of Rackham's Cay reef, the methodology of the relocation process; and the level of post-dredging survivorship of relocated corals. Political and economic realities of some proposed developments often override ecological considerations. Transplantation of important marine benthic species although time consuming, technically challenging, and expensive, may be one way for developers and ecologists to achieve sometimes disparate goals. This project cost US$1.7 million. The "items" moved were neither unique nor endemic and remain vulnerable to natural and anthropogenic impacts. This project increased public awareness and interest regarding the ecological and economic importance of reef ecosystems. It is anticipated that future coastal and inland developments will benefit from the lessons taught by these mitigative interventions

Assessing the accuracy of acoustic seabed classification for mapping coral reef environments in South Florida (Broward County, USA)

The Atlantic coast of Broward County, Florida (USA) is paralleled by a series of progressively deeper, shore-parallel coral reef communities. Two of these reef systems are drowned early Holocene coral reefs of 5 ky and 7 ky uncorrected radiocarbon age. Despite the case of access to these reefs, and their major contribution to the local economy, accurate benthic habitat maps of the area are not available. Ecological studies have shown that different benthic communities (i.e. communities composed of different biological taxa) exist along several spatial gradients on all reefs. Since these studies are limited by time and spatial extent, acoustic surveys with the QTCView V bottom classification system based on a 50 kHz transducer were used as an alternative method of producing habitat maps. From the acoustic data of a 3.1 km(2) survey area, spatial prediction maps were created for the area. These were compared with habitat maps interpreted from in situ data and Laser Airborne Depth Sounder (LADS) bathymetry, in order to ground-truth the remotely sensed data. An error matrix was used to quantitatively determine the accuracy of the acoustically derived spatial prediction model against the maps derived from the in situ and LADS data sets. Confusion analysis of 100 random points showed that the system was able to distinguish areas of reef from areas of rubble and sand with an overall accuracy of 61%. When asked to detect more subtle spatial differences, for example, those between distinct reef communities, the classification was only about 40% accurate. We discuss to what degree a synthesis of acoustic and in situ techniques can provide accurate habitat maps in coral reef environments, and conclude that acoustic methods were able to reflect the spatial extent and composition of at least three different biological communities.

Summit-to-sea mapping and change detection using satellite imagery: tools for conservation and management of coral reefs

Continuous summit-to-sea maps showing both land features and shallow-water coral reefs have been completed in Puerto Rico and the U.S. Virgin Islands, using circa 2000 Landsat 7 Enhanced Thematic Mapper (ETM+) Imagery. Continuous land/sea terrain was mapped by merging Digital Elevation Models (DEM) with satellite-derived bathymetry. Benthic habitat characterizations were created by unsupervised classifications of Landsat imagery clustered using field data, and produced maps with an estimated overall accuracy of>75% (Tau coefficient >0.65). These were merged with Geocover-LC (land use/land cover) data to create continuous land/ sea cover maps. Image pairs from different dates were analyzed using Principle Components Analysis (PCA) in order to detect areas of change in the marine environment over two different time intervals: 2000 to 2001, and 1991 to 2003. This activity demonstrates the capabilities of Landsat imagery to produce continuous summit-to-sea maps, as well as detect certain changes in the shallow-water marine environment, providing a valuable tool for efficient coastal zone monitoring and effective management and conservation

The structure and productivity of the Thalassia testudinum community in Bon Accord Lagoon, Tobago

The Thalassia testudinum dominated seagrass community in the Buccoo Reef/ Bon Accord Lagoon Marine Park, measures 0.5 km(2) and is part of a contiguous coral reef, seagrass bed and mangrove swamp system in southwest Tobago. 7 testudinum coverage, productivity and percent turnover rates were measured from February 1998 to February 1999 at four sample locations, while total T. testudinum biomass was measured at two locations in the lagoon from 1992-2002. Productivity and turnover rates varied spatially and seasonally. They were higher in the back-reef area than in the mangrove-fringed lagoon, and were lowest at locations near to a sewage outfall. 7 testudinum coverage ranged from 6.6% in the lagoon to 68.5% in the back-reef area while productivity ranged from 3.9 to 4.9 g dry wt m(-2) d(-1) . Productivity and percentage turnover rates were higher in the dry season (January-June) than in the wet season (July-December). Productivity ranged from 3.0 in the wet season to 5.0 g dry wt m2 d-' in the dry season while percentage turnover rates ranged from 4.2% to 5.6%. Total Thalassia biomass and productivity in Bon Accord Lagoon were compared to six similar sites in the Caribbean that also participate in the Caribbean Coastal Marine Productivity Program (CARICOMP). This seagrass community is being negatively impacted by nutrient-enriched conditions

Depredación de coral vivo por peces en el Parque Nacional Natural Tayrona, Caribe colombiano / Live coral predation by fish in Tayrona Nature National Park, Colombian Caribbean

Para estudiar uno de los agentes biológicos implicados en la mortalidad coralina en dos bahías del Parque Nacional Natural Tayrona (Caribe colombiano),se evaluó la depredación de coral vivo por peces mediante censos visuales y se determinó la incidencia de depredación en dos ambientes arrecifales (uno dominado por Colpophyllia natans y otro por Montastraea faveolata ) para dos épocas climáticas (lluvia y seca),examinando todas las colonias presentes en bandas permanentes (20 x 2 m).Sparisoma viride fue el depredador más importante por su frecuencia de mordisqueo y por el tamaño de los mordiscos.Los adultos de las fases terminal e inicial de S.viride lograron remover tejido vivo y parte de la matriz calcárea de M. faveolata, M.annularis ,Porites astreoides y C.natans , de las cuales esta última perdió mayor cantidad de tejido en área (3.51 cm2)y volumen (3.22 cm3)por mordisco. Al relacionar la densidad coralina (gr/cm3)de las especies depredadas con el volumen promedio removido por mordisco,se encontró una tendencia exponencial negativa (r2= 0.94),indicando que el alcance de los mordiscos está determinado por la densidad de los corales. Además,se estableció que no hay una clara relación entre en la incidencia de depredación y las estaciones climáticas en los ambientes estudiados.En las bahías de Chengue y Gayraca,la depredación de coral vivo es uno de los factores que está contribuyendo con la pérdida de tejido coralino y podría tener importantes consecuencias en la dinámica de estos arrecifes

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