Gorgona Island Research Articles

Asociación de la temperatura superficial del mar y la abundancia del Piquero Café (Sula leucogaster) según el estado de desarrollo en el Parque Nacional Natural Gorgona

La variación de las condiciones fisicoquímicas del mar puede influir en la distribución y la abundancia de las aves marinas al afectar la estructura trófica del ambiente pelágico. Por ello se pretendió evaluar la asociación entre la abundancia de tres estados de desarrollo (pollos, juveniles y adultos) del Piquero Café (Sula leucogaster etesiaca) y la variación de la temperatura superficial del mar (TSM) y su anomalía térmica (ANOM) en isla Gorgona, Pacífico colombiano. Estas tendencias fueron evaluadas por medio de correlaciones cruzadas y modelos lineales generalizados. En cada estado de desarrollo la abundancia presentó una tendencia diferente ante la variación de la TSM o ANOM. Se sugiere que dichas tendencias se deben a que el incremento de la temperatura del mar podría estar asociado con una menor abundancia y disponibilidad de recursos presa. Bajo estas condiciones, los adultos tienden a disminuir el esfuerzo invertido en el cuidado parental e, incluso, reducen el suministro de alimento a juveniles dependientes y pollos para aumentar su propia supervivencia. Es posible que estas tendencias hayan estado asociadas con un régimen reproductivo que les permita a los volantones alcanzar la independencia de los padres durante el periodo con mayor disponibilidad de alimento.

Aproximación a la dieta de Thalassoma lucasanum (familia Labridae) en el arrecife coralino de La Azufrada, isla Gorgona, Pacífico Oriental Tropical

El arcoíris de Cortés, Thalassoma lucasanum, es un pez arrecifal abundante en el Pacífico Oriental Tropical (POT). A diferencia de otras especies del género Thalassoma que son reconocidas por ser limpiadoras, en T. lucasanum este comportamiento es poco frecuente, ya que se alimenta principalmente de invertebrados mediante forrajeo. No obstante, la información sobre la ecología trófica de esta especie es limitada, especialmente en el POT. En este estudio se caracterizan los hábitos alimentarios de T. lucasanum en la isla Gorgona (POT) a partir del análisis de su contenido estomacal y se calcula su nicho trófico. Los moluscos fueron el principal recurso alimentario de T. lucasanum, siendo este el ítem de presa más importante y frecuente al ser encontrado en 100 % de los estómagos analizados (n = 5). En términos de biomasa, los crustáceos presentaron la mayor contribución a la dieta, con lo cual se posicionaron como el segundo ítem alimentario más importante. Otras presas incluyeron poliquetos, partes de peces y material calcáreo. Este estudio contribuye al conocimiento de la dinámica trófica de los ecosistemas arrecifales del POT.

Primer registro del pepino de mar garra de león Euapta godeffroyi Semper, 1868 (Holothuroidea: Apodida: Synaptidae) en la isla Gorgona, Pacífico colombiano

Los holotúridos corresponden a 20-25 % de todas las especies conocidas de equinodermos. En el Pacífico colombiano se han registrado 34 especies, de las cuales 11 lo han sido en la isla Gorgona. Este es el primer registro del pepino de mar garra de león Euapta godeffroyi en la isla. El espécimen fue recolectado mediante buceo autónomo en el submareal del parche coralino conocido localmente como El Arrecifito del Muelle, a una profundidad aproximada de 2 m. Tenía una longitud aproximada de 80 cm y entre 2 y 3 cm de diámetro. Los osículos de la pared del cuerpo corresponden básicamente a anclas y a placas de anclas; estas últimas presentan pequeñas ramificaciones en la base del eje central. El presente registro llena un vacío en la distribución de esta especie en el Pacífico Oriental Tropical.

Diurnal Flying Activity of a Neotropical Bat (Saccopteryx leptura): Effect of Light Intensity, Temperature, and Canopy Cover

Nocturnal behavior is a critical life-history trait associated with the evolutionary success of bats. Avian predation, competition with birds, and hyperthermia may explain the origin of this behavior, but it is difficult to assess the validity of these hypotheses due to the rarity of diurnal activity in bats. In Gorgona National Natural Park, Colombia, the population of the lesser sac-winged bat (Emballonuridae: Saccopteryx leptura) has an unusual daylight flight activity, which provides an opportunity to learn about the origin of nocturnality in bats. We described the daylight activity of S. leptura in Gorgona Island and explored the influence of environmental factors at different spatiotemporal scales, potentially involved in this particular behavior. We registered the variation of light intensity and temperature across days, months, and different vegetation canopy covers and assessed their effects on the number of daylight flights. We found that the daytime activity of this insular population increases with vegetation cover, decreases with light intensity and temperature, and varies seasonally. These responses of flying activity to environmental temperature and light intensity seem to be related to avoiding the risk of overheating. Furthermore, bats were also active at night, and daytime flights included echolocation and feeding, which suggest that daytime activity complements but does not replace night-time activity. Consequently, our results provide empirical support for the notion that the nocturnality in bats can reflect the actions of avoiding overheating during the day.

The δ53Cr isotope composition of komatiite flows and implications for the composition of the bulk silicate Earth

Data on the chromium stable isotope composition of planetary reservoirs have the potential to provide information about core formation, partial melting and conditions of the Moon formation. In order to detect the small Cr isotopic differences between various reservoirs in the solar system, their compositions need to be precisely constrained. The current BSE value of δ53Cr = −0.11 ± 0.06‰ (Sossi et al., 2018) cannot resolve differences between achondrites, (Vesta δ53Cr = −0.17 ± 0.05‰) and chondrites (carbonaceous δ53Cr = −0.12 ± 0.05‰; ordinary δ53Cr = −0.11 ± 0.04‰). The composition of the bulk silicate Earth (BSE) is often used as a reference point for comparisons to other planetary reservoirs. However, past attempts to estimate the Cr isotopic composition of the BSE have been unable to provide a well-constrained BSE value. Traditional methods, using mantle peridotites, are affected by the susceptibility of Cr isotopes to fractionation during metasomatism. More recently, the Cr isotope composition of the BSE has been calculated using komatiites, in addition to mantle peridotites, to produce a more precise value (Sossi et al., 2018). In order to constrain the BSE composition to a higher precision, the δ53Cr of remarkably fresh komatiite lava flows from three localities, ranging in age from 2.7 Ga to 89 Ma, have been investigated in detail. These included the Tony's Flow in the Belingwe Greenstone Belt, Zimbabwe, the Victoria's Lava Lake in Fennoscandia, and komatiites from Gorgona Island in Colombia.In the komatiites studied, a range in Cr isotopic compositions was found, from δ53Cr = −0.16 ± 0.02 to −0.01 ± 0.02‰. We show that the high degrees of partial melting that produced the komatiites, did not result in Cr isotopic fractionation between the komatiitic melt and mantle residue. However, limited Cr isotopic fractionation is found to be a consequence of komatiite lava differentiation. For the lava flows with high Mg content and high Cr2+/ƩCrTOT (the molar ratio of Cr2+/(Cr2+ + Cr3+)), such as Tony's Flow and Gorgona, δ53Cr increases in the evolved portion of the magma during olivine fractionation due to the preferential inclusion of light Cr into olivine. Other flows with lower MgO content do not show this behaviour because a smaller fraction of the Cr is contained in olivine. The effects of fractional crystallisation must, therefore, be taken into account when calculating the Cr isotopic composition of the source of komatiite lavas.The weighted average of δ53Cr for the komatiite lavas analysed is −0.12 ± 0.04‰ (n = 5) and represents our best estimate for the Cr isotopic composition of the BSE. It agrees with the previous estimates, while providing an improvement to the uncertainty. There is no resolvable difference between this value and that of chondritic meteorites. Our data also indicate that the δ53Cr of the mantle has been constant since at least the Archean.

Relationship between sea surface temperature and the nesting of the Olive Ridley sea turtle Lepidochelys olivacea (Testudines: Cheloniidae) in Gorgona Island, Colombian Pacific

Introduction: Lepidochelys olivacea is the most abundant sea turtle in the Colombian Pacific and oceanographic conditions at the Eastern Tropical Pacific may have an effect on its reproductive behavior Objective: To assess the relationship between reproductive aspects of L. olivacea nesting at Gorgona island and sea surface temperature at local and regional scales. Methods: Monthly mean data of reproductive attributes associated with nesting females, nests, eggs and hatchlings were established using records from Gorgona’s National Natural Park nesting monitoring and were correlated (cross-correlations) with SST of Gorgona island and Panama Bight, and with the temperature variability of the El Niño 1+2, El Niño 3, El Niño 3.4 and El Niño 4 regions, their thermal anomalies, and the ONI and SOI indexes. Significant correlations were included in a Generalized Additive Model. Results: Highest inverse correlation since maximum correlation is 1 was established between visits to the beach, number of nesting females, number of nests, clutch size, incubation days and hatching success and Niño 1+2 region with a lag of 12 months, whereas egg diameter, egg weight, straight carapace length and width and weight of hatchlings were correlated with Niño 4 anomaly, SOI and ONI indexes. It was also found that there is a non-linear tendency to decrease number of nesting females, number of nests, clutch size, egg diameter and egg weight with regional positive anomalies. Conclusions: Nesting attributes of L. olivacea in Gorgona correlate mainly with variations in regional SST, being low at high sea surface temperatures the year prior to nesting (12-month lag).

Distribution and species diversity of freshwater crabs of the family Pseudothelphusidae in Colombia (Crustacea: Decapoda: Brachyura)

The study of Colombian freshwater crabs has advanced significantly, but species records are scattered across different museums and research institutions. Assuming that museum collections incorporate valuable information in estimating species diversity, a database was organized on the 94 known species of family Pseudothelphusidae, which includes 568 records from 1853 to 2019 in continental Colombia and Gorgona Island. The natural regions of Colombia (Amazonian, Andean, Caribbean, Orinoquian, Pacific) were further subdivided into 75 natural sub-regions according to habitat types used by freshwater crabs. Sub-regions were (i) ranked in terms of species richness, with respective species reported in each sub-region listed accordingly, and (ii) classified into a scale of five categories on the basis of a geometric biodiversity index combining species richness and Simpson index. Species accumulation curves are presented to estimate the current status of knowledge about the diversity of the Colombian pseudothelphusids. Although the available data are not standardized for an adequate assessment of relative abundance, since they are influenced by sampling efforts and natural sub-regions are of different sizes and characteristics, the present study may be useful in future ecological and biogeographic research, as well as for conservation purposes.

VALIDACIÓN E IMPLEMENTACIÓN DE UNA HERRAMIENTA OPERACIONAL PARA EL PRONÓSTICO DE MAREAS EN EL PACÍFICO COLOMBIANO (CASO DE ESTUDIO ISLA GORGONA)

Las mareas son los procesos más regulares que se presentan en los océanos, producto del movimiento periódico de ascenso y descenso del nivel del mar. Esta clase de proceso hidrodinámico a escala local en zonas costeras e insulares es de gran importancia, debido a que las islas pequeñas juegan un papel muy importante para la pesca, el turismo y actividades socioeconómicas en general. En La isla Gorgona situada en el Pacífico Colombiano, es de gran importancia comprender la dinámica mareal, ya que sus alteraciones a nivel regional y local controlan en gran medida los atributos particulares de la biota de Gorgona, la cual tiene un impacto en los procesos ecológicos que moldean la diversidad marina del parque, afectando las actividades socioeconómicas de la isla. Es por esto, que el presente trabajo tiene como objetivo determinar el régimen mareal en la Isla Gorgona (Cauca), identificando las principales componentes armónicas que ejercen mayor influencia en la zona; y el régimen medio del nivel del mar, a partir de modelación numérica y datos medidos in-situ.

Epipelagic copepods of Gorgona Island, Tropical Eastern Pacific: Taxonomy, size range, and sexual proportion

Copepod species present the greatest diversity of marine zooplankton in tropical systems worldwide. This study aimed to increase knowledge in biodiversity by providing a comprehensive species checklist, distribution, size range, and sexual proportion of copepods associated with the epipelagic environment around Gorgona Island, Eastern Tropical Pacific. Zooplankton samples were obtained in oblique tows from 40 m depth to the surface, using a bongo net with 300μm mesh size from a total of six sampling trips between 2010 and 2016. A total of 73 copepod species belonging to 22 families associated with the epipelagic environment of Gorgona Island were recorded. Seasonal differences in sexual proportion were observed for 32 species. The assemblage was composed mainly of small-sized families, such as Corycaeidae, Euterpinidae, Oncaeidae, and Paracalanidae. The species with greatest relative abundance were Euterpina acutifrons, Subeucalanus pileatus, Ditrichocorycaeus andrewsi, Oncaea clevei, and Paracalanus parvus, which together comprised 61.8% of total copepod relative abundance throughout the study. Non-parametric estimates of species richness for the present study suggested a sampling efficiency above 90%. This study represents the first taxonomic record of epipelagic copepods for Gorgona Island, generating 41 new records for the Colombian Pacific and it increases the distribution of Bestiolina similis, Lubbockia marukawai, Oithona brevicornis and Sapphirina sinuicauda in the Eastern Tropical Pacific, which until now, were registered only in tropical areas of the Central Pacific and Indian Ocean, and in temperate areas of the Northeast Pacific.

Molecular identification of Haemosporidia in avian endemics of Gorgona Island within a context for the eastern tropical Pacific region

Island bird populations and their obligate blood parasites are of interest for understanding the accumulation of biodiversity and the evolutionary relationship with their mainland congeners. We examined avian Haemosporidia cytochrome b gene among terrestrial birds on Gorgona Island National Park, Colombia. Three Haemoproteus haplotype groups found on Gorgona Island have a higher genetic similarity to Haemoproteus found in the eastern tropical Pacific than those documented in Africa, Asia, Europe and Oceania. Two of the haplotype groups on the island are generalists in terms of infecting multiple hosts and their wide geographical distribution within the eastern tropical Pacific region, a third Haemoproteus haplogroup appears endemic to Gorgona Island. The overall prevalence of haemosporidian parasites is 57,9% for birds on Gorgona island, which is higher than local reports of prevalence documented in other archipelagos or the mainland. The island population of Cyanerpes cyaneus gigas seems to be the most susceptible to Haemoproteus infection when compared to Thamnophilus atrinucha gorgonae and Coereba flaveola gorgonae. Our findings support an ubiquitous pattern of endemism among organisms including avian haemosporidian parasites on Gorgona Island and also highlight the potential exposure of island bird populations to avian malaria.

Coral reef restoration in the Eastern Tropical Pacific: feasibility of the coral nursery approach

Due to the worldwide degradation of coral reefs, the active restoration of these ecosystems has received considerable attention in recent decades. This study investigated (1) the feasibility of using coral nurseries for restoration projects, (2) the minimum size required for a Pocillopora damicornis (Pocilloporidae) coral fragment to survive and grow in a nursery, and (3) the optimal transplant size of a fragment when transplanted to a degraded reef at Gorgona Island (Colombian Pacific). For this investigation, 230 fragments were transplanted directly to El Remanso reef, and another 150 fragments were maintained in in situ nurseries. Every 2 months, the length, weight, and survival of the fragments were recorded. After growing for 134 days in the nurseries, the 52 surviving fragments were transplanted to El Remanso reef, and after 5 months, the same variables were measured. Among the nursery‐reared fragments, the largest (4 to <8 cm) had the highest survival and growth rates, whereas among the directly transplanted fragments, the smallest fragments (<2 cm) had the highest survival and growth rates. However, the nursery‐reared fragments acquired greater structural complexity (arborescent morphology), and they were all alive 156 days after transplantation and presented a maximum linear growth rate of over 2 cm, which was higher than that of the directly transplanted fragments. Apparently, the arborescent morphology acquired during the nursery period provides advantages to the colonies that favor greater success when transplanted. Therefore, nursery‐reared fragments of P. damicornis between 2 and 4 cm are the most appropriate for use in restoration projects.

The lawsonite-glaucophane blueschists of Elba Island (Italy)

Evidence for high-P blueschist-facies metamorphism was found in metabasites embedded in calcschists of Eastern Elba Island (Northern Apennines, Italy). Study of immobile trace elements (REEs and HFSEs) in the metabasites indicates an affinity with T- and E-MORBs, and they are interpreted as sill or dykes intruded in the western margin of the Adria continental plate. The minerals are heterogeneously distributed in the rock, constituting mafic and Ca-Al-rich microdomains inherited respectively from the magmatic pyroxene- and plagioclase-rich zones of the original doleritic rock. The peak pressure paragenesis consisted of lawsonite, aegirine-omphacite, glaucophane and chlorite. Former rhombic prisms of lawsonite have been replaced by pseudomorphic clinozoisite (0.1 mm in size) with inclusions of Ms. ± Ab ± Qz. The inclusions are preferentially oriented parallel to one of the diagonals of the basal rhombic sections, indicating that the two diagonals were not crystallographically equivalent. This implies that the protocrystals were orthorhombic prisms with {110} faces, which is the case of lawsonite. The different compositions shown by white mica and epidote in the pseudomorphs (muscovite and Fe3+-poor clinozoisite) and in the matrix (phengite and Fe3+-rich epidote) also suggest the former presence of Mg- and Fe-poor lawsonite in these rocks. Thermodynamic modelling, using the THERMOCALC software and dataset, suggests that metabasites experienced a clockwise P-T path from the lawsonite-blueschist to epidote-blueschist subfacies, down to greenschist facies. The estimated peak pressure conditions are P ≥ 1.6 GPa and 450 < T < 500 °C. Glaucophane grew mainly during the lawsonite-to-epidote transition and is dated at 19.8 ± 1.4 Ma by the 40Ar/39Ar method. This evolution is interpreted in terms: (i) intrusion of basic magmas in carbonatic and pelitic sediments (post-late Cretaceous, pre-Oligocene), (ii) subduction (Oligocene), (iii) collision (early Miocene: 19.8 ± 1.4 Ma), (iv) exhumation and granite intrusion (middle-late Miocene), favored by extensional tectonics. We underline that the eastern part of Elba Island belongs to a blueschist-facies belt that extends from Gorgona Island, in the northwest, to Argentario and Giglio Island in the southeast, so many of the conclusions of this study can be extended to the whole of this belt.

Taxonomic identity of an insular population of sac-winged bat Saccopteryx (Chiroptera: Emballonuridae)

Insular populations can differ from their continental counterparts since they are subject to particular pressures, biotic and abiotic, that can lead to variations in morphology and behavior; thus, the use of external characters may complicate taxonomic identification of insular populations. Even though the bat assemblage of Gorgona Island is a conservation target, there has been controversy about the taxonomic identity of bats from this Colombian National Natural Park. Specifically, our goal was to determine the taxonomic identity of the population of the sac-winged bat (genus Saccopteryx) resident in Gorgona, which have the peculiarity of having diurnal activity. Thus, we assessed differences among populations using morphometrics (traditional and geometric) and echolocation calls. Additionally, since the species of Saccopteryx involved have different mating systems, we assessed roosting association of Gorgona population as a surrogate for mating system. Despite the variation in skull morphometrics and echolocation calls among populations, Gorgona population was more similar to S. leptura than to S. bilineata. Besides, evolutionary allometry was significant, but size explained a small proportion of shape differences among populations. Finally, roosting association of Gorgona population suggests a monogamous mating system such as in S. leptura. We conclude that Saccopteryx from Gorgona corresponds to S. leptura. In addition, biogeographic history and geographic isolation of the island suggest that this population may have differentiated from their mainland counterparts through founder effect, genetic drift and/or adaptation to the local biotic and abiotic environmental conditions.

Coralivoría del gasterópodo Jenneria pustulata (Ovulidae: Pediculariinae) en dos arrecifes coralinos del PNN isla Gorgona

Coral reefs are very important and highly biodiverse ecosystems that are exposed to various stressors, including biological ones, such as parasitism and corallivory – the direct consumption of coral tissue by a predator. Knowledge on the effects of corallivory on the coral reefs in the Colombian Pacific is poor. Therefore a study was set up to quantify the abundance of and the corallivory rate by the snail Jenneria pustulata in La Azufrada and Playa Blanca coral reefs (Gorgona Island, Colombia). Snails were manually sampled from the underside of Pocillopora sp. colonies and measured in situ to determine their size structure for each reef. To measure possible damage caused by corallivory, several snails were kept under controlled laboratory conditions for 24 h. Snail sizes and corallivory varied significantly between reefs (P=0.0001; P«0.001). Snails from Playa Blanca were larger than snails from La Azufrada, while corallivory was higher in La Azufrada than in Playa Blanca. Although corallivory rates by J. pustulata are smaller than rates reported for other predators in different coral species, it is recommended to continue this kind of investigations in order to increase the knowledge on biological dynamics of this species and to understand how they affect the reefs at Gorgona Island.

Evidencia de reclutamiento coralino producto de reproducción sexual, en Isla Gorgona, Pacífico Tropical Oriental

We present evidence of coral sexual recruitment, which has typically been low in the Eastern Tropical Pacific, on coral reefs and rocky sites of Gorgona Island, Colombia, and for the first time in the Colombian Pacific. With data obtained by thoroughly examining natural substrates, coral juveniles of at least ten species were found at ten out of 19 sites surveyed during scuba diving explorations performed around the island between 2010-2017; however, no corals were found on settlement plates of five different materials. The two most abundant coral species found as juveniles were Porites panamensis and Pocillopora sp., occurring at mean densities of 5.7 ± 4.7 and 0.07 ± 0.11 colonies m-2 (± SD), respectively, and with mean colony-sizes of 2.3 ± 0.9 cm and 3.5 ± 1.0 cm (± SD), respectively. These results indicate that, even though settlement plates do not seem to be as useful to study coral recruitment in the region as they are elsewhere, coral recruitment derived from the sexual reproduction of a diverse set of species is an active process at Gorgona Island.

Growth and survival of Pocillopora damicornis (Scleractinia: Pocilloporidae) coral fragments and their potential for coral reef restoration in the Tropical Eastern Pacific

ABSTRACTTransplantation of coral fragments is a common procedure for the restoration of degraded coral reefs. In the Tropical Eastern Pacific (TEP), the branching coral Pocillopora damicornis is the main reef-builder, and it frequently propagates through natural fragmentation; it is therefore a candidate for restoration efforts in this region. To evaluate the usefulness of P. damicornis for reef restoration in the TEP, fragments of three lengths were used: small (1–2 cm), medium (4 cm) and large (7 cm). Fragments of these three sizes were attached on the back-reef, reef flat and reef crest of La Azufrada reef (Gorgona Island, Colombian Pacific). Coral length, width, weight, and survival were followed during 119 days. Furthermore, skeletal density, linear extension and calcification rates of each coral fragment were obtained to evaluate the growth rates as a function of initial size and position on the reef. The overall fragment survival rate was 83.5%, but small fragments survived less, particularly on the back reef, than medium or large fragments. Fragment growth was greatest on the reef flat, whereas medium and large fragments grew faster than small ones. The overall mean of skeletal density, linear extension and calcification rates were 1.70 gCaCO3 cm−3, 1.89 cm yr−1 and 3.16 gCaCO3 cm−2 yr−1, respectively. These growth rates were comparable to those of other reef-building coral species in the world. Growth and survival rates of P. damicornis coral fragments found in this study, suggest that successful and low-cost restoration of TEP coral reefs is feasible using this species.

Bauhinia proboscidea (Fabaceae: Cercidoideae), a new species from Costa Rica and Panama, with notes on B. beguinotii, B. gorgonae and B. pansamalana

Bauhinia proboscidea, a new species from Costa Rica and Panama, is described and illustrated, and compared to the closely related B. pansamalana of southern Mexico, Guatemala and Honduras. It is also compared with B. beguinotii, with which has been confused in herbaria. Bauhinia gorgonae, endemic to Gorgona Island in Colombia and which has been classified as a variety of B. beguinotii, is here considered a separate species. A key to the Neotropical species of Bauhinia with three fertile stamens is provided. Some observations on the morphology and reproductive biology of B. proboscidea are presented. Global-level assessments of the conservation status according to IUCN Red List criteria indicate that B. proboscidea and B. beguinotii (which was previously assessed using some misidentified records) should both be considered as species of Least Concern (LC), B. gorgonae should be considered as Endangered (EN), and B. pansamalana should be considered Not Threatened (NT). Country-level conservation assessments are also provided for all four species. The homology of the “intrastipular spines” of Bauhinia is briefly discussed.

First record of Echinothrix calamaris (Echinoidea: Diadematidae) in the Colombian Pacific

BackgroundThe occurrence of Echinothrix calamaris Pallas, 1774 is reported for the first time in Colombia.ResultsThree specimens of Echinothrix calamaris were collected in two fringing reefs (La Azufrada and Playa Blanca) at Gorgona Island. The specimens now lie in the Echinoderm Collection of the Marine Biology Section at Universidad del Valle (Cali, Colombia).ConclusionsThis finding constitutes a range extension towards the Tropical Eastern Pacific, with only one previous record from Cocos Island. The list of Echinoids from the Pacific coast of Colombia now comprises 30 species.

New record of Hyachelia tortugae Barnard, 1967, an amphipod epibiont on green turtles Chelonia mydas (LINNAEUS, 1758) from Gorgona island (colombian pacific)

Objectives: Characterize the amphipods collected in esophageal lavages of the green turtle Chelonia mydas (Linnaeus, 1758). Scope: Increase the characterization of diversity of a poorly known group, but of great importance in benthic environments, in Colombia. Methodology: Amphipods were collected from esophageal lavages carried out on 77 green turtles between February and December 2012 at Gorgona Island, Colombian Pacific. Main results: We report the occurrence of the amphipod Hyachelia tortugae Barnard, 1967, a species that lives exclusively as an epibiont of sea turtles, for the first time for the Colombian Pacific. Three H. tortugae individuals occurred in two of the analyzed turtles. The hyperiid amphipods Paralycaea gracilis Claus, 1879, Schizoscelus ornatus Claus, 1879, and Parascelus sp. were also collected in the esophageal contents of the turtles. Conclusions: This study highlights that systematic studies should be carried out to characterize the associated fauna in sea turtles in the Colombian Pacific.

Evaluación del potencial electrogénico de sedimentos costeros de la playa La Azufrada, isla Gorgona

El presente trabajo exploratorio, evaluó la respuesta electrogénica de sedimentos costeros colectados en la Playa La Azufrada en la Isla Gorgona; se comparó con la respuesta electrogénica de lodos y aguas provenientes del lago de la microestación del Departamento de Biología del Campus Universitario Meléndez de la Universidad del Valle. Los sustratos fueron evaluados en celdas de combustible microbianas (MFC por su nombre en inglés) mediante curvas de densidad de potencia. Los sustratos ambientales fueron utilizados como inoculo y único sustrato energético. Al finalizar los ensayos, se realizó microscopía electrónica a los ánodos de las MFC. Se reportaron valores de densidad de potencia máximas de 3.1 mW/m2 en el día 19 de operación para el caso de las MFC alimentadas con sedimentos de lago y de 0.67 mW/m2 en el día 15 para el caso de los sedimentos marinos. Las observaciones mediante microscopía electrónica muestran diferencias en la formación de la biopelícula de los dos ambientes. Los ánodos de las MFC alimentadas con sedimentos marinos mostraron una formación de biopelícula insipiente. Los ensayos demuestran que los sedimentos marinos colectados presentan actividad electrogénica, lo cual abre la posibilidad de realizar estudios sobre las poblaciones bacterianas electrogénicas y las aplicaciones que puedan tener las MFC en estos ambientes