Coastal amphipods from Bahía Málaga and Bahía Buenaventura, Eastern Tropical Pacific of Colombia / Anfípodos costeros de Bahía Málaga y Bahía Buenaventura, Pacífico Oriental Tropical de Colombia

Knowledge about the diversity of coastal amphipods in the eastern tropical Pacific, including the Pacific coast of Colombia, is scarce. We characterized amphipod diversity in Bahía Málaga (intertidal and subtidal rocky shores, and sandy beaches) and Bahía Buenaventura (intertidal rocky shores, mangrove roots, and sandy beaches), two important estuaries in the central Pacific coast of Colombia. Sixteen species in eleven families were found; Hourstonius baciroa, Leptocheirus rhizophorae, Leucothoe alata, Elasmopus ocoroni, Melita bousfieldi, and Neomegamphopus heardi represent new records for Colombia.

El conocimiento acerca de la diversidad de los anfípodos costeros en el Pacífico Oriental Tropical, incluyendo las costas del Pacífico de Colombia, es escaso. Por esto, caracterizamos la diversidad de anfípodos en Bahía Málaga (costas rocosas intermareales y submareales, playas arenosas) y Bahía Buenaventura (costa rocosa intermareal, raíces de manglares, playas arenosas), dos estuarios importantes de la costa central del Pacífico de Colombia. Se encontraron 16 especies en once familias, de las cuales Hourstonius baciroa, Leptocheirus rhizophorae, Leucothoe alata, Elasmopus ocoroni, Melita bousfieldi y Neomegamphopus heardi representan nuevos registros para Colombia.

Relating sinking and suspended microbial communities in the California Current Ecosystem: digestion resistance and the contributions of phytoplankton taxa to export.

We used 16S, 18S, plastid and internal transcribed spacer (for Synechococcus strains) sequencing to quantify relative microbial abundances in water-column samples and on sediment-trap-collected particles across an environmental gradient in the California Current Ecosystem (CCE) spanning a > 60-fold range of surface chlorophyll. Most mixed-layer dominant eukaryotes and prokaryotes were consistently underrepresented on sinking particles. Diatoms were the only phototrophic taxa consistently overrepresented. Even within this class, however, one genus (Thalassiosira) was a particle-enriched dominant, while a similarly abundant species was poorly represented. Synechococcus was significantly enriched on sinking particles at only one of four sites, but clade I was disproportionately abundant on sinking particles throughout the region compared with clade IV, the euphotic-zone co-dominant. The most abundant microbes on particles across the CCE were organisms with distributional maxima close to the sediment-trap depth (rhizarians), microbes associated with metazoans or sinking particles as a nutritional habitat (certain alveolates, Gammaproteobacteria) and organisms that resist digestive degradation of their DNA (Thalassiosira, Synechococcus). For assessing taxon contributions of phytoplankton to carbon export, our results highlight the need for sequence-based quantitative approaches that can be used to integrate euphotic-zone abundances, compute rates and account for taxon differences in preservation of sequence markers through trophic processing.

Spatial and temporal variations in Synechococcus microdiversity in the Southern California coastal ecosystem.

The Synechococcus cyanobacterial population at the Scripps Institution of Oceanography pier in La Jolla, CA, shows large increases in abundance, typically in the spring and summer followed, by rapid declines within weeks. Here we used amplicon sequencing of the ribosomal RNA internal transcribed spacer region to examine the microdiversity within this cyanobacterial genus during these blooms as well as further offshore in the Southern California coastal ecosystem (CCE). These analyses revealed numerous Synechococcus amplicon sequence variants (ASVs) and that clade and ASV composition can change over the course of blooms. We also found that a large bloom in August 2016 was highly anomalous both in its overall Synechococcus abundance and in terms of the presence of normally oligotrophic Synechococcus clade II. The dominant ASVs at the pier were found further offshore and in the California Current, but we did observe more oligotrophic ASVs and clades along with depth variation in Synechococcus diversity. We also observed that the dominant sequence variant switched during the peak of multiple Synechococcus blooms, with this switch occurring in multiple clades, but we present initial evidence that this apparent ASV switch is a physiological response rather than a change in the dominant population.

Effects of seasonal upwelling on hydrography and mesozooplankton communities in a Pacific tropical cove off Colombia

Introduction: The effects of seasonal upwelling on the conditions of the water column and mesozooplankton communities are poorly understood in the coastal zones of the Eastern Tropical Pacific (ETP), despite the important role of upwelling events in the modulation of productivity in these zones.Objective:To evaluate the influence of seasonal upwelling over the Panama Bight on the structure of the water column and mesozooplankton communities in a tropical cove of the ETP. Methods:Hydrographic data and mesozooplankton samples were collected during four field campaigns in Ensenada de Utría (December 2011, February 2012, October 2013, and February 2013), an estuary located in the Northern Pacific coast of Colombia. Non-parametric and multivariate analyses were used to evaluate seasonal differences in the environmental and biotic variables. Results:Surface waters were warm (> 25 °C) and presented low salinities ( 33), and presented low dissolved oxygen concentrations (< 2.0 ml l-1) during the dry season (January - March), whereas the water column was homogeneous during the rainy season (April - December). Despite the seasonal changes in the environmental conditions, the expected enhancement in the productivity of the system during the dry season (i.e., higher biomass and abundance of the mesozooplankton) only occurred in February 2012. Contrary to expectations, ichthyoplankton abundance was higher during the rainy season, when the assemblage was dominated by the larvae of anchovy (Cetengraulis mysticetus) and an unidentified Gobiidae.Conclusions: The entrance of upwelled waters into Ensenada de Utría is an important factor modulating the seasonal changes observed in the water column. However, there is high interannual variability in the response of mesozooplankton communities to the upwelling events. Because upwelled waters are oxygen-depleted and more acidic, the entrance of upwelled waters into Ensenada de Utría could be causing physiological stress to the benthic and pelagic organisms inhabiting the deepest zones of the cove. This condition may worsen in the future given the predicted increase of deoxygenation and ocean acidification due to climate change.

Introducción: Los efectos de surgencias estacionales sobre la estructura de la columna de agua y las comunidades del mesozooplancton son pobremente entendidos en zonas costeras del Pacífico Oriental Tropical (POT), a pesar de la importancia que tienen los eventos de surgencia en modular la productividad en estas zonas. Objetivo: Evaluar los efectos de la surgencia estacional que ocurre en la Ensenada de Panamá sobre la columna de agua y las comunidades del mesozooplancton en una ensenada tropical del POT. Métodos: Los datos hidrográficos y las muestras de mesozooplankton fueron recolectados durante cuatro campañas de muestreo en la Ensenada de Utría (diciembre 2011, febrero 2012, febrero 2013, octubre 2013), un estuario ubicado en la costa norte del Pacífico colombiano. Las diferencias estacionales en las variables ambientales y bióticas se evaluaron mediante análisis no paramétricos y multivariados. Resultados: Las aguas superficiales fueron cálidas (> 25 °C) y presentaron bajas salinidades ( 33) y presentaron menores concentraciones de oxígeno disuelto (< 2.0 ml l-1) durante la época seca (enero - marzo), mientras que la columna de agua fue homogénea durante la época de lluvias (abril - diciembre). A pesar de los cambios estacionales en las condiciones ambientales, el incremento esperado en la productividad del sistema durante la época seca (i.e., mayor biomasa y abundancia del mesozooplancton) sólo se observó durante febrero 2012. Contrario a lo esperado, la abundancia del ictioplancton fue mayor durante la época de lluvias, periodo en el que el ensamblaje estuvo dominado por un Gobiidae sin identificar y la carduma (Cetengraulis mysticetus). Conclusión: La entrada de aguas de surgencia a la Ensenada de Utría es un factor importante que modula los cambios estacionales observados en la columna de agua. Sin embargo, la respuesta de las comunidades del mesozooplancton ante los eventos de surgencia presentó alta variabilidad interanual. Considerando que las aguas de surgencia son reducidas en oxígeno y más acídicas, la entrada de aguas de surgencia a la Ensenada de Utría podría estar causando estrés fisiológico a los organismos bentónicos y pelágicos que habitan las zonas más profundas de la ensenada. Esta condición podría volverse más severa en el futuro considerando las predicciones que sugieren un incremento de la desoxigenación y acidificación del océano debido al cambio climático.

Estructura de la comunidad y distribución vertical de la macrofauna de fondos blandos en isla Gorgona, Pacífico Colombiano / Community structure and vertical distribution of the soft bottom macrofauna on Isla Gorgona, Colombian Pacific

Soft bottoms are important in marine ecosystems but their ecology have been less studied in the tropics than in temperate areas. This article describes the temporal, spatial, and vertical distribution of the community structure of subtidal soft bottom macrofauna on Isla Gorgona, Colombian Pacific. Samples were collected in March and June 2011 by corers at 10m depth at five points around the island. Seventy-three species were recorded; polychaetes (55%) and crustaceans (30%) were the dominant groups in number of individuals. The community structure assessed by classification and ordination analysis did not change temporarily, but it shows differences between sampling points, due to the structure of the substrate. The highest abundances of macrofauna were recorded at points with dominance of fine particles (Farallones). However, another point with a similar substrate (Planchón) showed low abundance, apparently due to bioturbation exerted by the fish Heteroconger sp. The presence of Heteroconger sp. in El Planchón could also affect the vertical distribution of the macrofauna, where their relative abundance was homogeneous across the analyzed layers (1-2-3-4-5-10cm). In the other four sites, the abundance of the macrofauna was mainly limited to the first two centimeters of the sediment. Playa Blanca and Remanso showed substrates composed mainly of gravel, recording at the last sampling point the lowest richness, diversity and abundance. Rev. Biol. Trop. 62 (Suppl. 1): 169-188. Epub 2014 February 01.

Resumen Se evaluó la variación temporal, espacial y vertical de la estructura comunitaria de la macrofauna de fondos blandos submareales en isla Gorgona, Pacífico colombiano. Las muestras fueron colectadas en marzo y junio de 2011 mediante descorazonadores a 10m de profundidad en cinco puntos alrededor de la isla. Se registraron un total de 73 especies; poliquetos (55%) y crustáceos (30%) fueron los grupos dominantes en número de individuos. La estructura comunitaria evaluada mediante análisis de clasificación y ordenación, no varió temporalmente, pero si presentó diferencias entre puntos de muestreo, al parecer relacionada con la estructura del sedimento. Las mayores abundancias de la macrofauna se registraron en puntos con dominancia de partículas finas (Farallones), pero en otro punto con sustrato similar (Planchón), la abundancia fue baja, al parecer por la bioperturbación ejercida por el pez Heteroconger sp. La presencia de Heteroconger sp. en el Planchón posiblemente afectó la distribución vertical de la macrofauna, ya que en este último punto la abundancia relativa fue homogénea entre las capas analizadas (1-2-3-4-5-10cm). En los otros cuatro sitios, la abundancia de la macrofauna estuvo limitada principalmente a los primeros dos centímetros del sedimento. En Playa Blanca y Remanso el sustrato fue principalmente gravoso, registrándose en el último punto la menor riqueza, diversidad y abundancia.

Fitoplancton y zooplancton en el área marina protegida de Isla Gorgona, Colombia, y su relación con variables oceanográficas en estaciones lluviosa y seca / Phytoplankton and zooplankton on the marine protected area of Gorgona Island and its relationship with hydrographic variables during the rainy and dry seasons

We studied the variation in abundance and biomass of plankton in the pelagic environment of Gorgona during October 2010 (rainy season) and March 2011 (dry season), and evaluated their correlation with hydrographic features of temperature, salinity, dissolved oxygen and transparency. Surface waters during both periods were warmer (>26°C) and with low salinity values (<31). At 30m during October the waters were homogeneous, while during March the waters were colder (<18°C), saltier (>34) and presented low oxygen concentrations (<3.0ml/l). 61 genera of phytoplankton and 30 zooplankton groups were identified, with greater values of phytoplankton genus and zooplankton abundance and biomass during March than in October. Bacteriastrum, Chaetoceros, Coscinodiscus, Guinardia, Rhizosolenia and Skeletonema were the phytoplankton genera most frequent in both sampling periods. Copepods were the dominant group of zooplankton, followed by chaetognaths and appendicularia in both periods. Zooplankton biomass was positively associated with surface temperature, salinity at 10m, and transparency of water column, and negatively associated with surface and 30m dissolved oxygen. Rev. Biol. Trop. 62 (Suppl. 1): 117-132. Epub 2014 February 01.

Se estableció la variación en la abundancia y biomasa del fitoplancton y zooplancton en el ambiente pelágico de isla Gorgona durante octubre 2010 (época lluviosa) y marzo 2011 (época seca), y se evaluó su grado de correlación con las condiciones hidrográficas de temperatura, salinidad, oxígeno disuelto y transparencia. Las aguas superficiales en los dos periodos fueron cálidas (>26°C) y de bajas salinidades (<31). A 30m las aguas en octubre fueron homogéneas, mientras que en marzo fueron frías (<18°C), salinas (>34) y con bajas concentraciones de oxígeno (3.0ml/l). Se registraron 61 géneros de fitoplancton y 30 grupos de zooplancton, con mayores valores para la riqueza de géneros y abundancia del fitoplancton, y para la abundancia y biomasa del zooplancton en marzo que en octubre. Bacteriastrum, Chaetoceros, Coscinodiscus, Guinardia, Rhizosolenia y Skeletonema fueron los generous de fitoplancton más frecuentes durante ambos periodos de muestreo. Para el zooplancton los copépodos fueron el grupo dominante, seguido por los quetognatos y las apendicularias. Adicionalmente, la biomasa del zooplancton presentó una asociación positiva significativa con la temperatura superficial, la salinidad a 10m y la transparencia, y negativa con la concentración de oxígeno disuelto en superficie y a 10m.

Regional diversity of Amphipoda in the Caribbean Sea / Diversidad regional de Amphipoda en el Mar Caribe

The order Amphipoda is one of the most diverse within Peracarids, and comprises 6 950 described marine species. Amphipod research in the Caribbean Sea began in the late 1 800s, but has increased significantly since 1 980. In this study, we analized the amphipod biodiversity (Caprellidea, Gammaridea, Hyperiidea, and Ingolfiellidea) of the Caribbean Sea. For this, we compiled available data on species diversity of marine amphipods (data bases: WoRMS and OBIS and published species lists) into a comprehensive taxonomic list by country for the ecoregions of the Caribbean. Additionally, we analized the relative contribution of each country to regional diversity and the rate of discovery of new species. The Caribbean amphipod fauna is composed of 535 species within 236 genera and 73 families for the higher taxon. The Western Caribbean ecoregion holds the largest diversity (282 species), while the Eastern Caribbean recorded the lowest one (73). Mexico and Venezuela recorded the largest number of species with 266 and 206, respectively. Twelve countries had less than 50 species. The richest suborder is the Gammaridea with 381 species followed by the suborder Hyperiidea with 116. From the total of 535 amphipod species reported for the Caribbean region, 218 have the Caribbean as the holotype locality, and 132 are endemic (about 25% of the total). Areas of higher diversity seem to be concentrated along the Mexican Caribbean, Cuba and the Northern coast of South America (Venezuela-Colombia); however, such pattern is most likely reflecting local collection efforts and taxonomic expertise rather than actual distribution. Knowledge of amphipod species is mostly limited to shallow, near-shore waters, with little information available on the deep sea fauna. Regional research priorities for this group should be focused on completing shallow water coastal inventories of species in Central America and the Greater and Lesser Antilles. In addition, sampling the deep sea ecosystems should follow along with other particular habitats such as anchialine cave systems. It is also neccessary to increase ecological research efforts, mainly in some speciose suborders, including the Caprellidea and Hyperiidea, known to exhibit high diversity in other tropical localities. Rev. Biol. Trop. 61 (4): 1681-1720. Epub 2013 December 01.

El orden Amphipoda es uno de los más diversos dentro de los Peracáridos. Las investigaciones sobre este orden en el Mar Caribe se iniciaron a finales de los años 1800, incrementándose significativamente a partir de 1980. En este estudio se analizó la biodiversidad de los anfípodos (Caprellidea, Gammaridea, Hyperiidea e Ingolfiellidea) en el Mar Caribe, compilándose los registros de especies citadas en las diversas ecorregiones del área, tanto en publicaciones como a través de bases de datos (WoRMS y OBIS). Se listan un total de 535 especies pertenecientes a 236 géneros y 73 familias. La ecorregión del Caribe Occidental presentó la mayor riqueza específica (282), mientras que el Caribe Oriental presentó el menor valor (73). México y Venezuela presentaron el mayor número de especies registradas (266 y 206, respectivamente), mientras que doce países presentaron menos de 50. Los Gammaridea fueron el grupo más diverso con 387 especies, seguido de los Hyperiidea (116 especies). Hasta el presente, se han descrito 218 especies nuevas en aguas del Caribe, de las cuales 132 son endémicas. Las áreas con mayor diversidad de anfípodos se concentraron a lo largo del caribe Mexicano, Cuba y la costa norte de Sur-América (Venezuela-Colombia); sin embargo, este patron refleja más bien un mayor esfuerzo en la recoleccion de estos organismos y una mayor experticia taxonómica, que un patron específico de distribución del grupo. En general, el conocimiento del grupo se limita a las aguas someras, con muy poca información sobre zonas profundas. En este sentido, las prioridades de investigación regional en este grupo, debe enfocar un mayor esfuerzo en la costa de Centro América y las Antillas Mayores y Menores. Así mismo, es necesario aumentar las recolecciones en aguas profundas y otros ecosistemas particulares como los anquialinos. Por último, es importante aumentar las investigaciones taxonómicas y ecológicas de los taxones que presentan mayor diversidad.

Regional diversity of amphipoda in the Caribbean Sea.

The order Amphipoda is one of the most diverse within Peracarids, and comprises 6950 described marine species. Amphipod research in the Caribbean Sea began in the late 1800s, but has increased significantly since 1980. In this study, we analized the amphipod biodiversity (Caprellidea, Gammaridea, Hyperiidea, and Ingolfiellidea) of the Caribbean Sea. For this, we compiled available data on species diversity of marine amphipods (data bases: WoRMS and OBIS and published species lists) into a comprehensive taxonomic list by country for the ecoregions of the Caribbean. Additionally, we analized the relative contribution of each country to regional diversity and the rate of discovery of new species. The Caribbean amphipod fauna is composed of 535 species within 236 genera and 73 families for the higher taxon. The Western Caribbean ecoregion holds the largest diversity (282 species), while the Eastern Caribbean recorded the lowest one (73). Mexico and Venezuela recorded the largest number of species with 266 and 206, respectively. Twelve countries had less than 50 species. The richest suborder is the Gammaridea with 381 species followed by the suborder Hyperiidea with 116. From the total of 535 amphipod species reported for the Caribbean region, 218 have the Caribbean as the holotype locality, and 132 are endemic (about 25% of the total). Areas of higher diversity seem to be concentrated along the Mexican Caribbean, Cuba and the Northern coast of South America (Venezuela-Colombia); however, such pattern is most likely reflecting local collection efforts and taxonomic expertise rather than actual distribution. Knowledge of amphipod species is mostly limited to shallow, near-shore waters, with little infonnation available on the deep sea fauna. Regional research priorities for this group should be focused on completing shallow water coastal inventories of species in Central America and the Greater and Lesser Antilles. In addition, sampling the deep sea ecosystems should follow along with other particular habitats such as anchialine cave systems. It is also neccessary to increase ecological research efforts, mainly in some speciose suborders, including the Caprellidea and Hyperiidea, known to exhibit high diversity in other tropical localities.