Gorgona Island Research Articles

Vocal and genetic variation between a land-bridge island and mainland populations of the Black-crowned Antshrike (Thamnophilus atrinucha)

Island-mainland systems serve as natural laboratories for studying communication signals. We explored potential divergence in the song of the black-crowned antshrike between Gorgona Island, a land-bridge island off the Pacific coast of Colombia, and several mainland populations. We found that the perching song of this species, the so called loudsong, was distinctly different on Gorgona Island. This differentiation encompassed an increase in frequency bandwidth, a decrease in vocal performance, and a reduction in song duration. All are consistent with documented patterns of divergence observed in avian acoustic signals on oceanic islands. The observed distinctions in loudsong acoustics, including variations in frequency and temporal features, led to the inference that the population on Gorgona Island produces the least complex loudsong dialect across the entire species range. This pattern of how an innate vocalization manifests within a land-bridge island, which was connected to the mainland not long ago, lends support to the Character Release Hypothesis. To ensure an unbiased comparison, we considered genetic clusters and analyzed them by comparing ten acoustic signals between the land-bridge island and several mainland populations. Combined with the gene genealogy, this finding supports the validity of two geographic forms: Thamnophilus atrinucha atrinucha and Thamnophilus atrinucha gorgonae (island). However, they also reveal the existence of additional unrecognized dialects of loudsong that transcend current taxonomic classifications. We provide evidence that challenges the long-standing presumption suggesting minimal intraspecific geographic variation in the vocalization among non-vocal learning species.Significance statementSignificant evolutionary implications exist for an intriguing pattern of variation of the loudsong behavior in the Black-crowned Antshrike over a land-bridge island. Our gene tree does provide evidence of the enormous haplotypic diversity accumulated in the trans-Andean region long after the final uplift of the northern Andes. The acoustic divergence of the loudsong suggests substantial geographic variation within a non-vocal learning suboscine. Genetic and loudsong divergence on a land-bridge island add to document that evolution of acoustic traits may be relaxed in islands as compared to those observed on the species-rich mainland. The island-mainland system is one of the few definitive biogeographic contexts for understanding evolution of acoustic behavior.

First Record of Parasphaerosyllis malimalii (Polychaeta: Syllidae) from Gorgona Island (Colombian Pacific)

A new species of polychaete, Parasphaerosyllis malimalii (Syllidae), inhabiting coral colonies of Pocillopora spp. was described on Coiba Island (Pacific coast of Panama) by Capa et al. (2001a). To improve its description and provide additional ecological remarks, 73 specimens of P. malimalii, found in dead fragments of Pocillopora spp. in two research projects on bioerosion in Gorgona Island (Colombian Pacific coast), between March 1998 and December 1999, and June 2015 and August 2018, were examined and measured. The average (±SD) length (in mm) of the specimens from the first (n=38) and second (n=35) projects were 2.84 (0.42) and 8.86 (3.24) respectively. The largest specimen was collected in the second project and measured 15.4 mm. The pygidium of this species has a pair of cirri slightly thicker and longer than the parapodial cirrus. These polychaetes are mostly dead coral inhabitants, nesting in vacant galleries left by borers. With this record, the distribution range of P. malimalii is extended southward to Gorgona Island. We are confident that this species must inhabit other coral reefs in the area, so we propose that the distribution of this species must be circumscribed to the Tropical Eastern Pacific.

High-resolution imagery of the coral reefs of Gorgona Island, Colombian Pacific Ocean: An improved view for monitoring and research

The shape and size of a coral reef are both key factors influencing its ecology and biodiversity. These parameters play a fundamental role in the creation of specific habitats that support a rich biodiversity. They also greatly influence its resilience to climatic events and external influences. Here we present a practical example of photogrammetric reconstruction of the best developed coral reefs of the Colombian Pacific, located at Gorgona Island. Using unoccupied aerial vehicles (drones) and Geographic Information Systems (GIS), we produced high resolution orthophotomosaics and precise contour maps of four reefs and updated estimates of reef areas. We illustrate the improved accuracy of these maps in comparison with maps obtained from satellite imagery and conclude by highlighting the usefulness of drones to locate, measure, and monitor small coral reefs.

Comparative analysis of spatiotemporal trends in sea surface temperature in the major marine protected areas of the Eastern Tropical Pacific

The Eastern Tropical Pacific (ETP) is characterized by complex oceanographic dynamics that affect the regional sea surface temperature (SST), a key parameter driving marine ecosystems. To date no comparative studies have been conducted on the spatial and temporal variations of SST among the several marine protected areas in the ETP. The present study used remote sensing to evaluate the monthly, annual, and decadal variations in SST from 1982 to 2019 in Coiba National Park (Coiba), Cocos Island National Park (Cocos), Malpelo Fauna and Flora Sanctuary (Malpelo), Gorgona Island National Park (Gorgona), Galápagos Marine Reserve (Galápagos) and La Plata Island (La Plata). An overall increasing trend in SST was observed across all study sites, except for West Galápagos. A decrease in SST anomaly was observed from February through April at Malpelo, Coiba, Gorgona and La Plata. These observations are likely in response to the Humboldt Current and upwelling events in the Colombian Pacific Basin. Using a longer SST dataset is recommended to determine if the annual, monthly and decadal trends observed here are driven by local, regional or global processes. Consistent monitoring of SST trends is a strategic practice in understanding and planning for current and projected changes in the marine environment.

The survival of tracers of primordial mantle heterogeneity investigated through 142Nd/144Nd and 3He/4He isotope decoupling in the Gorgona Island lavas

While 142Nd/144Nd, 3He/4He, and 182W/184W isotope ratios are recognized and applied as tracers of primordial mantle heterogeneity, their distribution and reasons behind the extent of variability in the modern-day mantle remain unclear. Lavas associated with the Galapagos plume exhibit the steepest 3He/4He vs. μ182W isotope correlations and thus hold the potential to elucidate the processes involved in the preservation of isotope variability. Among the various eruptions suggested to be related to the Galapagos plume is Gorgona Island, which is geologically significant for their Phanerozoic komatiites. We report the first high precision 142Nd/144Nd isotope measurements for the Gorgona komatiites, as well as 3He/4He and major and trace element data for an array of lavas including komatiites, a picrite, a d-gabbro (“depleted”), and an e-basalt (“enriched”). The 142Nd/144Nd ratios of six komatiite samples are indistinguishable to within ±2.4 ppm (2σ) from the modern-day terrestrial mantle as sampled by most mid-ocean ridge and ocean island basalts. The 3He/4He values determined for the komatiites and a picrite are from 4.6 to 45.1 RA. Eight of the 3He/4He measurements are higher than the MORB average (8 ± 1 RA), and thus strongly point to a plume source sampling an undegassed reservoir. The RA value of 45.1 in particular ranks among the highest 3He/4He ratios measured to date at Gorgona Island and elsewhere, close to what is observed for Phanerozoic flood basalts from Baffin Island.Evaluation of the sources of the lavas using major and rare earth elements along with ε143Nd signatures suggest that the komatiites and picrites are derived from a depleted peridotite source. Meanwhile, the e-basalts are deduced to have been derived from a hybrid source consisting of roughly 8% pyroxenite to 92% peridotite. The inferred and calculated degree of pyroxenite in the sources of the different lava types align with the magnitude of 3He/4He ratios observed. Model calculations involving pyroxenite sources in the e-basalts, which are reported to exhibit 182W/184W isotope anomalies, attest to their survival, while analogous calculations with 142Nd/144Nd isotope ratios suggest homogenization occurring on a faster timescale. It is deduced that 182W/184W anomalies are likely to outlast mixing with recycled pyroxenite compared to 142Nd/144Nd and 3He/4He ratios. The decoupling of modern-day 142Nd/144Nd, 3He/4He, and 182W/184W isotope variabilities thus likely reflect the sensitivity each system has to different mantle processes that contribute to their preservation throughout time.

Physiological responses of Pocillopora corals to upwelling events in the Eastern Tropical Pacific

Upwelling events can change the sea water conditions within few hours during several months on a seasonal regimen. These events are predicted to intensify due to climate change, exposing shallow benthic organisms to hypoxia and thermal stress, among other extreme conditions. Some coral reefs in the Eastern Tropical Pacific (ETP) recurrently experience upwelling events. Coral reefs off Gorgona Island, Colombia, are exposed to lower oxygen concentrations (3.0 - 3.7 mg O2 L-1) and lower temperatures (17 - 24°C) from mid-January to mid-April, when upwelling develops, compared to the rest of the year (4.9 ± 0.7 mg O2 L-1, 28.4 ± 0.3°C, mean ± SD). While no visible signs of stress have been reported for corals during upwelling, it can be hypothesized that corals would be negatively affected by these changes. Therefore, the objectives of this study were to (1) identify the effects of temperature and hypoxia on the metabolic rate (MO2) of Pocillopora corals under lab conditions, and (2) to examine the changes in skeletal growth and Symbiodiniaceae density of Pocillopora in the field between upwelling and non-upwelling seasons. Findings revealed that MO2 was significantly reduced by 20% at 24°C and significantly increased by 10% at 32°C compared to 28°C. During the upwelling season, Pocillopora corals exhibited a 52% increase in Symbiodiniaceae density, but the growth rate decreased by 50% compared to the non-upwelling season. Fast changes in water conditions during the upwelling strongly affects the metabolism of Pocillopora corals. Although conditions during upwelling were not lethal, they compromised the energy of the coral for their vital functions, indicating that upwelling pushes them toward their physiological limit. Consequently, predicted increases in upwelling events in combination with ocean warming and deoxygenation may be particularly critical for upwelling-exposed corals and the reefs they build in the Eastern Tropical Pacific.

Spatiotemporal variability of oxygen concentration in coral reefs of Gorgona Island (Eastern Tropical Pacific) and its effect on the coral Pocillopora capitata.

Dissolved oxygen concentration (DO) is one of the main factors limiting benthic species distribution. Due to ocean warming and eutrophication, the ocean is deoxygenating. In the Eastern Tropical Pacific (ETP), deep waters with low DO (<1 mg L-1) may reach coral reefs, because upwelling will likely intensify due to climate change. To understand oxygen variability and its effects on corals, we characterize the Spatio-temporal changes of DO in coral reefs of Gorgona Island and calculate the critical oxygen tension (P crit) to identify the DO concentration that could represent a hypoxic condition for Pocillopora capitata, one of the main reef-building species in the ETP. The mean (±SD) DO concentration in the coral reefs of Gorgona Island was 4.6 ± 0.89 mg L-1. Low DO conditions were due to upwelling, but hypoxia (<3.71 mg L-1, defined as a DO value 1 SD lower than the Mean) down to 3.0 mg O2 L-1 sporadically occurred at 10 m depth. The P crit of P. capitata was 3.7 mg L-1 and lies close to the hypoxic condition recorded on coral reefs during the upwelling season at 10 m depth. At Gorgona Island oxygen conditions lower than 2.3 mg L-1 occur at >20 m depth and coincide with the deepest bathymetric distribution of scattered colonies of Pocillopora. Because DO concentrations in coral reefs of Gorgona Island were comparably low to other coral reefs in the Eastern Tropical Pacific, and the hypoxic threshold of P. capitata was close to the minimum DO record on reefs, hypoxic events could represent a threat if conditions that promote eutrophication (and consequently hypoxia) increase.

Disruptive coloration and behavior facilitate camouflage of blue‐spotted cornetfish against complex coral reef bottoms

AbstractAvoiding recognition involves the use of extraordinary strategies, among which camouflage is the most common. Crypsis, a usual form of camouflage, involves, among many other strategies, disruptive coloration that uses marks that disguise the contours of creatures to hide it. Fish that live on coral reefs have developed several cryptic strategies to avoid the risk of detection. The blue‐spotted cornetfish,Fistularia commersonii, presents a pattern of dark bands that give the perception of disruptive coloration; however, this strategy has not been characterized for this fish. This study was conducted on the eastern coral reefs of Gorgona Island National Natural Park (Colombia). To confirm whetherF. commersoniipresents a disruptive pattern, photographs, and videos in situ of the individuals were taken, in addition to recording aspects of their behavior during changes in coloration. After strict selection, different images were processed and evaluated using three different visual systems (potential predator, potential prey, and human) to calculate the GabRat metric, that is detect consistent to inconsistent edges of a pattern. The images analysed and the observations indicate that this species displays a disruptive pattern that is used more frequently in the reef flat and during alert states, either in the presence of a possible predator or during the search for food.

Unexpected coexistence of two species of garden eels (Heteroconger klausewitzi and Heteroconger pellegrini) in a colony at Gorgona Island, Colombia

Unexpected coexistence of two species of garden eels (Heteroconger klausewitzi and Heteroconger pellegrini) in a colony at Gorgona Island, Colombia

The Gorgona island, Colombia, earthquake of 10 September 2007 (Mw 6.8); rupture process and implications on the seismic hazard in the region

The subduction zone in southern Colombia and northern Ecuador has been the site of significant events in the area that broke the great 1906 earthquake in Ecuador. The 2007 earthquake on Gorgona Island is located within this area, presenting a normal-type focal mechanism and a moment magnitude Mw 6.8. This event is due to the compressive stresses exerted on the continental plate of South America by the Nazca oceanic plate. We performed a kinematic inversion source process of the Gorgona earthquake. Our results show the main slip patch at the hypocenter and a secondary slip release deeper at SW on the fault plane, which agrees with the location of aftershocks; the source time function obtained reflects these energy releases with a total duration of 15 s. We also analyzed the stress state field in this region using the focal mechanism of its early aftershock sequence, obtaining an extensive regime with an azimuth Shmin of 108° and NW-SE direction. The average interseismic coupling in this convergent margin zone is not so high as in the southern areas. Nevertheless, observations of this kind of seismicity and GPS studies in the upper plate of a subduction zone are essential in understanding earthquake cycles and, perhaps, in anticipating slip distributions in future subduction events.

The Italian wall lizard, Podarcis siculus campestris, unexpected presence on Gorgona Island (Tuscan Archipelago)

We here report the unexpected presence of the Italian wall lizard (Podarcis siculus campestris) on Gorgona Island, in the Parco Nazionale Arcipelago Toscano (Tuscan Archipelago, Tyrrhenian Sea, Tuscany, Central Italy). Field observations were carried out in 2020 confirming its presence on the island, where it had never been reported before. We recorded 37 GPS points of the species in three major areas of Gorgona (with 50 lizard records) and about 180 visual counts regarding all age classes (newborns, juveniles and adults). The species was found in the urban area (site of state prison) and in two grassy and bushed areas, around and along olive tree plantations. Seven individuals were captured and their tails were used to assess the sequence variation of the mitochondrial CYB gene. Biometrical parameters were also evaluated for six of these individuals. We detected three distinct CYB haplotypes that were compared to Podarcis siculus CYB sequences available in public databases. They resulted identical or phylogenetically closest to those found in mainland Tuscany. One haplotype, found in three specimens, was identical to one previously detected at Orti Bottagone (WWF Oasis in Piombino), while the other two haplotypes were most similar to haplotypes reported in the Giannella peninsula and Pisa, respectively.

Daytime diet of the lesser sac-winged bat (Saccopteryx leptura) in a Colombian Pacific Island

Insectivorous bats represent more than half of all the Chiropterans of the world. Although they are important stabilizers of insect populations within their habitat due to their feeding habits, just few studies have been focused on the diet of insular bat species. The lesser sac-winged bat, Saccopteryx leptura, is widely distributed in the new world tropics, but little is known about its prey selection. In this study we determined the diet composition of the population of S. leptura from Gorgona Island, Colombia, using stomach and intestinal content samples. We focused our research on their atypical daytime feeding behavior to evaluate differences in prey selection considering two main factors: 1) plant canopy cover and 2) bat sex. We found prey representatives of nine orders of insects, with Hymenoptera, Coleoptera and Hemiptera as the most consumed according to their abundance and volume percentage. We identified two new records at genus level in S. leptura´s diet, Camponotus (Formicidae) and Trigona (Apidae). In general terms, we did not find differences in the diet between canopy covers nor sexes. However, when analyzing the consumed percentage volume by order, there were significant differences in consumption of Psocoptera in both factors. Our results suggest that S. leptura has an opportunistic diet, as they tend to feed on prey of a wide range of sizes, usually the most abundant and available in the environment.

Daily and monthly ichthyoplankton assemblages of La Azufrada coral reef, Gorgona Island, Eastern Tropical Pacific

The description of the daily and seasonal variation of the species composition and abundance on the early stages of fishes in coral reefs can lead to a better understanding of fish population dynamics in these ecosystems, because settlement and recruitment processes depend on larval fish supply. Daytime and nighttime samples of ichthyoplankton were collected through circular surface tows using a bongo net between October 2010 and November 2011 at La Azufrada, the largest coral reef on the Colombian Pacific coast, located in Gorgona Island. A total of 2,171 fish larvae representing 87 species in 42 families were identified. The most important species by their frequency of occurrence and density were Anisotremus sp., Cetengraulis mysticetus, Bregmaceros bathymaster, and Gobiidae sp.4. Daytime and nighttime samples showed variations in the composition of the assemblage, with a greater number of species at night, evidencing short-scale variations over a diel cycle. On the other hand, environmental parameters such as oxygen, salinity, pH, temperature, and zooplankton biomass were also measured; however, none of them had a strong relationship with the larvae assemblage structure throughout the year. In conclusion, this study suggests that night conditions had a higher effect over the ichthyoplanktonic species found in La Azufrada coral reef than the observed changes in the environmental parameters.

Temporal changes in the epipelagic copepod assemblage at Gorgona Island, Colombian Eastern Tropical Pacific ocean

Temporal variations in the hydrographic conditions of the Eastern Tropical Pacific (ETP) can modulate the assemblage structure of marine organisms, including copepods. While this taxonomic group has been widely recognized as important in the energy flow of the pelagic environment, fundamental ecological aspects are still unknown particularly possible relationships with oceanographic variations that have been described for ETP. In this paper, we evaluated the intra-annual and interannual variation of structure, richness, diversity, and similarity of the epipelagic copepod assemblage of Gorgona Island (Colombian ETP) based on samples collected during six oceanographic campaigns carried out between 2010 and 2016. We found significant changes in the oceanographic conditions and abundance of copepods between periods and years. Seven significant clusters were identified: five for each sampled period and two for the period of October 2010. Ditrichocorycaeus andrewsi, Oncaea clevei, Paracalanus parvus, and Subeucalanus pileatus were the species with the greatest contribution to group formation. Our results suggest that the intra-annual changes in the assemblage of epipelagic copepods recorded in Gorgona Island are a consequence of the displacement of the Intertropical Convergence Zone throughout the ETP during the year. This is due to the fact that during the periods of March they respond to the entry of subsurface waters from the Ensenada de Panama, and during the periods of October respond to the increase of the continental runoff on the pelagic environment of Colombian ETP.

First functional and proteomic analysis of Bothrops asper snake venom from Gorgona Island - Colombia, and its comparative characterization with two Colombian Southwest ecoregions

Bothrops asper envenoming is a public health problem in tropical regions of Latin America. Bothrops asper has spread until Gorgona Island in the Pacific Colombian Ocean, but its biochemical venom characterization is poorly known. Thus, to increase knowledge on Bothrops species venoms, we developed for the first time the proteomic analysis using a shotgun approach and performed functional evaluations relevant to its toxicity and compared with two Colombian Southwest ecoregions from the Pacific and Western sides. Besides, we evaluated two antivenoms produced in Colombia (INS and PROBIOL) against three B. asper venom ecoregions through the ELISA approach and first-generation antivenom against B. asper from Gorgona Island. The protein components of B. asper from Gorgona Island were assigned to nine known protein families, sharing a conserved compositional pattern with B. asper from the pacific ecoregion. The RP-HPLC and in vitro activity suggest a phenotypic congruence in the expression of PLA2s and metalloproteinases between the B. asper snake venom from Gorgona Island and pacific, but inversely to the Western ecoregion. Additionally, the antivenoms immunoreactivity against the three B. asper lineage venoms was different. The INS displayed higher titers than PROBIOL against all the venoms and exhibited the most effective immunocapturing capacity against the individual components of snake venom from Gorgona Island. The results of this investigation suggest that B. asper from Gorgona Island displayed similar clinical manifestations concerning the Pacific ecoregion, and the immunoreactivity by antivenoms could be used after B. asper envenomation in Gorgona Island, using one of them preferably.

Robots Versus Humans: Automated Annotation Accurately Quantifies Essential Ocean Variables of Rocky Intertidal Functional Groups and Habitat State

Standardized methods for effectively and rapidly monitoring changes in the biodiversity of marine ecosystems are critical to assess status and trends in ways that are comparable between locations and over time. In intertidal and subtidal habitats, estimates of fractional cover and abundance of organisms are typically obtained with traditional quadrat-based methods, and collection of photoquadrat imagery is a standard practice. However, visual analysis of quadrats, either in the field or from photographs, can be very time-consuming. Cutting-edge machine learning tools are now being used to annotate species records from photoquadrat imagery automatically, significantly reducing processing time of image collections. However, it is not always clear whether information is lost, and if so to what degree, using automated approaches. In this study, we compared results from visual quadrats versus automated photoquadrat assessments of macroalgae and sessile organisms on rocky shores across the American continent, from Patagonia (Argentina), Galapagos Islands (Ecuador), Gorgona Island (Colombian Pacific), and the northeast coast of the United States (Gulf of Maine) using the automated software CoralNet. Photoquadrat imagery was collected at the same time as visual surveys following a protocol implemented across the Americas by the Marine Biodiversity Observation Network (MBON) Pole to Pole of the Americas program. Our results show that photoquadrat machine learning annotations can estimate percent cover levels of intertidal benthic cover categories and functional groups (algae, bare substrate, and invertebrate cover) nearly identical to those from visual quadrat analysis. We found no statistical differences of cover estimations of dominant groups in photoquadrat images annotated by humans and those processed in CoralNet (binomial generalized linear mixed model or GLMM). Differences between these analyses were not significant, resulting in a Bray-Curtis average distance of 0.13 (sd 0.11) for the full label set, and 0.12 (sd 0.14) for functional groups. This is the first time that CoralNet automated annotation software has been used to monitor “Invertebrate Abundance and Distribution” and “Macroalgal Canopy Cover and Composition” Essential Ocean Variables (EOVs) in intertidal habitats. We recommend its use for rapid, continuous surveys over expanded geographical scales and monitoring of intertidal areas globally.

A new species of Leucostethus (Anura, Dendrobatidae) from Gorgona Island, Colombia.

We describe a new species of Leucostethus from Gorgona Island, a small (13 km2) island located 35 km from the Pacific coast of southern Colombia. The new species most resembles L.argyrogaster and L.fugax from western Amazonia at 340–870 m elev. in Peru and Ecuador, with which it shares pale ventral coloration and orange suffusion of the axilla, groin and concealed surfaces of the hind limb, but it is most closely related to L.bilsa from ca. 340 km SW in the southern Chocó at 420–515 m elev., northwestern Ecuador. We report miniscule white spots on the posteroventral surface of the thighs of the new species and, on the basis of our preliminary assessment of their taxonomic distribution, hypothesize that their presence is a synapomorphy of Dendrobatoidea with subsequent losses in a few groups. Given the apparent restriction of the new species to Gorgona Island, it is Vulnerable according to IUCN Red List criteria. In addition to naming the new species, we also propose the following new combinations: L.alacris (Rivero and Granados-Díaz, 1990) comb. nov., L.dysprosium (Rivero and Serna, 2000) comb. nov., and L.yaguara (Rivero and Serna, 1991) comb. nov.

A new species of pikeblenny (Blenniiformes: Chaenopsidae: Chaenopsis) from the tropical eastern Pacific and a key to all species.

The genus Chaenopsis presently includes 10 species, four in the eastern Pacific and six in the western Atlantic. Five individuals of an undescribed species of this genus were obtained at Gorgona Island in the eastern Pacific of Colombia, in depths between 3 and 5m. This new species differs from all the Eastern Pacific species in an array of traits including meristic, coloration and morphometric characters. Chaenopsis celeste new species differs from its only sympatric species, C. deltarrhis, in having fewer pectoral rays, fewer dorsal spines and more dorsal-fin soft rays and anal-fin elements. This new species is found over shallow sandy, rubble and small rocks bottoms from Costa Rica to Colombia.

Gross calcium carbonate production in Eastern Tropical Pacific coral reefs (Gorgona Island, Colombia)

The production and accumulation of carbonate reef framework is the positive component of reef development. The main organisms participating in this process are corals and crustose coralline algae (CCA) because their combined calcareous skeletons construct and help to consolidate reef frameworks. We assessed the contribution (i.e. gross production) of corals and CCA to the calcium carbonate (CaCO3) budget of the 2 largest and most developed reefs of Gorgona Island (Pacific coast of Colombia). On each zone (back reef [BR], reef flat [RP], reef front [RF], and reef slope [RS]) of these reefs, we measured substrate rugosity, coral (Pocillopora spp.) and CCA cover, colony density for corals, skeletal density for CCA, and growth rates for the estimation of CaCO3 production rates. Pocillopora spp. corals contributed 93.1% of the total carbonate production, while CCA supplied the remaining 6.9%. CaCO3 production was higher at Playa Blanca reef, although CaCO3 production in the RF of La Azufrada (12.31 kg m-2 yr-1) was higher in comparison to the RF at Playa Blanca (8.45 kg m-2 yr-1). Otherwise, CaCO3 production was higher in all other reef zones (BR, RP, RS) of Playa Blanca, although only significantly higher in the BR (2.25 kg m-2 yr-1 at Playa Blanca against 0.29 kg m-2 yr-1 at La Azufrada). The RF contributed the most CaCO3, mainly due to its high live coral cover and rapid coral growth. Although the contribution of CCA is low, they are key for reef stability. CaCO3 production rates reported here (2.86 and 3.80 kg m-2 yr-1 in La Azufrada and Playa Blanca, respectively) are within the limits reported for Eastern Tropical Pacific reefs, and raise hope for the continued existence of coral reefs in an era of increasing threats to this ecosystem.

A new species of Leucostethus (Anura: Dendrobatidae) from the Cordillera Mache-Chindul in northwestern Ecuador, with comments on similar Colostethus and Hyloxalus.

We describe a new species of dendrobatid frog, Leucostethus bilsa sp. nov., using molecular, morphological, and acoustic evidence. We also comment on the taxonomic status of four similar Hyloxalus and Colostethus. We provide an updated phylogeny of Leucostethus that corroborates previous hypotheses of relationships of nine species. Phylogenetic analysis using mitochondrial (i.e., 7095 bp of combined data from NADH1, NAHD2, cytochrome c oxidase I, cytochrome b and 12S-16S rRNA) and seven nuclear genes (i.e., 4739 bp) indicate a close relationship of L. bilsa to an undescribed species from Gorgona Island, Colombia, both of which apparently diverged in the Pliocene about 3 million years ago with about 6.25% (i.e., 146/2335 bp) differences for the section of 12S-16S mitochondrial fragment. Leucostethus bilsa is diurnal and riparian, characterized by distinctive bright mustard-yellow flash marks in the axillar and groin regions, posterior belly, and in the hindlimbs, the presence of dark gray lower labial stripe or marks, sexual dimorphism in ventral pattern, and by having male uniparental care. We describe its osteology and the male advertisement call, which is a series of peep notes. Osteological microCT images of representatives of each of the Colostethinae genera reveal a number of intriguing characters that may prove to be useful in phylogenetic studies. In terms of its distribution, Leucostethus bilsa is currently known only from a very small area within the Reserva Biológica Bilsa, located within the Cordillera Mache-Chindul in the Chocoan region of northwestern Ecuador, which was a Pliocene-Pleistocene refugium. This region is highly threatened with habitat degradation and remains as the last surviving refuge for a forest community known for a high proportion of endemic species of both flora and fauna.