Fundacion La Salle de Ciencias Naturales

Caracas A, Venezuela

Fundacion La Salle de Ciencias Naturales

Caracas A, Venezuela
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Suter E.A.,State University of New York at Stony Brook | Scranton M.I.,State University of New York at Stony Brook | Chow S.,State University of New York at Stony Brook | Stinton D.,State University of New York at Stony Brook | And 2 more authors.
Limnology and Oceanography | Year: 2017

Particles able to settle distances of approximately a meter in 1–2 h are undersampled in water traditionally collected in Niskin bottles. Gardner (Limnol Oceanogr, 22, 764–768, 1977) demonstrated that particles sink into the space below the spout of Niskin bottles on timescales relevant to sample processing. We examined this effect on measurements of microbial abundance, community composition, and transparent stainable particles across an oxygen-sulfide gradient in the Cariaco Basin. Within 1 h, modestly sized micro-aggregates (> 16 μm) were not detected in samples drawn from the spout, but were abundant in the waters below the spout. Total transparent exopolymer particles (TEP) and Coomassie stainable particles (CSP) were at least twice as abundant in the below-spout samples as in spout-collected water. Below-spout samples accounted for four times more total particle surface area per mL than spout samples. Approximately 10% of all microbes were particle-associated, which led to only small enrichments of total microbes in the below-spout samples. However, fluorescent in situ hybridization (FISH) revealed five of seven clades surveyed were significantly more enriched in water below the spout than total cells, indicating (1) a small bias when enumerating total particles and microbes from spout samples and (2) a very strong bias for particular phylogenetic groups that are more prevalent on particles than the total community. In particular, sulfate-reducing δ-proteobacteria were consistently enriched in below-spout samples collected at depths along the oxygen-sulfide transition. Abundance of this functional group has potentially been underestimated in the past. Consequently, microbial diversity results derived from Niskin bottle samples should be cautiously applied when interpreting biogeochemical cycling. © 2016 Association for the Sciences of Limnology and Oceanography

Rojas-Runjaic F.J.M.,Fundacion La Salle de Ciencias Naturales | Rojas-Runjaic F.J.M.,Grande Rio University | Guayasamin J.M.,Technological Amerindian University, Ambato
Check List | Year: 2015

Pristimantis myersi is a small Andean frog that inhabits paramos, sub-paramos and upper Andean forests at elevations between 2,900–3,275 m. It is known from about a dozen localities in the southern end of the Cordillera Central of the Colombian Andes. Herein, we report for the first time the presence of this species in Ecuador, based on ten specimens from three localities in the provinces of Imbabura and Sucumbíos. The species’ range is extended and a distribution map with the Ecuadorian records is provided. © 2015 Check List and Authors.

Armesto L.O.,Venezuelan Institute for Scientific Research | Armesto L.O.,University of Pamplona | Quilarque E.,Venezuelan Institute for Scientific Research | Rojas-Runjaic F.J.M.,Fundacion La Salle de Ciencias Naturales | Rojas-Runjaic F.J.M.,Grande Rio University
Check List | Year: 2015

Dendropsophus meridensis is a medium-sized treefrog endemic to the Cordillera de Mérida in the Venezuelan Andes. The geographic distribution of this species is poorly known, and only 10 localities known in the literature. Most of these localities do not have associated geographic coordinates and altitude. In this note we provide eight new locality records and a geographic distribution map of D. meridensis, based on field work, revision of Venezuelan museum collections, and species distribution modeling. Three of these new localities were found after performing species distribution modeling. Additionally, some comments on natural history and color variation are included. © 2015 Check List and Authors.

Bates N.R.,Bermuda Institute of Ocean Sciences | Bates N.R.,University of Southampton | Astor Y.M.,Fundacion la Salle de Ciencias Naturales | Church M.J.,University of Hawaii at Manoa | And 8 more authors.
Oceanography | Year: 2014

Sustained observations provide critically needed data and understanding not only about ocean warming and water cycle reorganization (e.g., salinity changes), ocean eutrophication, and ocean deoxygenation, but also about changes in ocean chemistry. As an example of changes in the global ocean carbon cycle, consistent changes in surface seawater CO2-carbonate chemistry are documented by seven independent CO2 time series that provide sustained ocean observations collected for periods from 15 to 30 years: (1) Iceland Sea, (2) Irminger Sea, (3) Bermuda Atlantic Time-series Study (BATS), (4) European Station for Time series in the Ocean at the Canary Islands (ESTOC), (5) CArbon Retention In A Colored Ocean sites in the North Atlantic (CARIACO), (6) Hawaii Ocean Time-series (HOT), and (7) Munida in the Pacific Ocean. These ocean time-series sites exhibit very consistent changes in surface ocean chemistry that reflect the impact of uptake of anthropogenic CO2 and ocean acidification. The article discusses the long-term changes in dissolved inorganic carbon (DIC), salinity-normalized DIC, and surface seawater pCO2 (partial pressure of CO2) due to the uptake of anthropogenic CO2 and its impact on the ocean's buffering capacity. In addition, we evaluate changes in seawater chemistry that are due to ocean acidification and its impact on pH and saturation states for biogenic calcium carbonate minerals. © 2014 by The Oceanography Society. All rights reserved.

Black D.,State University of New York at Stony Brook | Thunell R.,University of South Carolina | Wejnert K.,University of South Carolina | Astor Y.,Fundacion la Salle de Ciencias Naturales
Geophysical Research Letters | Year: 2011

The burning of fossil fuels and deforestation have significantly increased atmospheric CO 2 levels, from ∼280 ppm prior to the industrial revolution to the present value of ∼390 ppm. Suess (1955) was the first to show that the carbon isotopic composition of the atmosphere is changing in response to the anthropogenic input of radiocarbon-dead, 13C depleted CO 2 from fossil fuel combustion. Here we report a high resolution planktonic foraminiferal δ 13C record from the Caribbean Sea for the last 300 years that clearly resolves the timing and magnitude of the marine 13C Suess effect associated with the oceanic uptake of anthropogenically derived CO 2. Cariaco Basin sediment trap and upper-most box core sediment δ 13C match both the trend and magnitude of observed δ 13C changes in atmospheric CO 2 over the last 15 years. The longer sediment record suggests the marine Suess effect to be-0.75 ‰ from pre-industrial values, with most of the change occurring since 1950, coincident with the rapid rise in atmospheric CO 2 noted in ice core and instrumental data. If the current anthropogenic CO 2 emission trend continues, extrapolating our marine δ 13C rate curve into the future suggests that the rate of marine δ 13C change caused by anthropogenic CO 2 will increase to-0.10 ‰ yr -1 by the end of this century, an increase of more than an order of magnitude from 1950 values. Copyright 2011 by the American Geophysical Union.

Astor Y.M.,Fundacion La Salle de Ciencias Naturales | Lorenzoni L.,University of South Florida | Thunell R.,University of South Carolina | Varela R.,Fundacion La Salle de Ciencias Naturales | And 6 more authors.
Deep-Sea Research Part II: Topical Studies in Oceanography | Year: 2013

We examined the variability of sea surface carbon dioxide fugacity (fCO2sea) and its relation to temperature at the Cariaco Basin ocean time-series location (10°30'N, 64°40'W) for the period from 1996 through 2008. Periods of warm (positive) and cold (negative) anomalies at the station were related to variability in coastal upwelling intensity. A positive temporal trend in monthly-deseasonalized sea surface temperatures (SST) was observed, leading to an overall increase of 1.13°C over 13 years. Surface fCO2sea displayed significant short-term variation (month to month) with a range of 330-445μatm. In addition to a large seasonal range (58±17μatm), deseasonalized fCO2sea data showed an interannual positive trend of 1.77±0.43μatmyr-1. In the Cariaco Basin, positive and negative anomalies of temperature and fCO2sea are in phase. An increase/decrease of 1°C coincides with an increase/decrease of 16-20μatm of fCO2sea. Deseasonalized fCO2sea normalized to 26.05°C, the mean Cariaco SST, shows a lower rate of increase (0.51±0.49μatmyr-1). Based on these observations, 72% of the increase in fCO2sea in Cariaco Basin between 1996 and 2008 can be attributed to an increasing temperature trend of surface waters, making this the primary factor controlling fugacity at this location. During this period, a decrease in upwelling intensity was also observed. The phytoplankton community changed from large diatom-dominated blooms during upwelling in the late 1990's to blooms dominated by smaller cells in the first decade of the 21st century. The average net sea-air CO2 flux over the study period is 2.0±2.6molCm-2yr-1 employing the Wanninkhof parameterization, and 2.1±2.5molCm-2yr-1 based on Nightingale's model. To further understand the connection between the changes observed in the Cariaco Basin, the relationships between interannual variability in the temperature anomaly with three modes of climate variability (AMO, NAO and ENSO) were examined. The correlations between SSTA and two of these climate modes (AMO and ENSO) only show very weak relationships, although they were significant. © 2013 Elsevier Ltd.

Ugueto G.N.,Biscayne Boulevard and 556 | Velozo P.,Venezuelan Institute for Scientific Research | Sanchez L.E.,Venezuelan Institute for Scientific Research | Villapol L.A.B.,Ministerio de Poder Popular para El Ambiente | And 3 more authors.
Check List | Year: 2013

The occurrence of Gymnophthalmus lineatus in Venezuela is established for the first time based on a specimen collected on Las Aves Archipelago. We also document the first records of Phyllodactylus ventralis from Los Frailes Archipelago, Amphisbaena alba from Isla de Margarita, and report the occurrence of Thecadactylus cf. rapicauda on Las Aves Archipelago. Additionally we expand the distribution of the snake Leptophis ahaetulla on Isla de Margarita and report the third specimen known from that island. We also present information on the lepidosis and coloration for all species when pertinent. © 2013 Check List and Authors.

Montes E.,University of South Florida | Muller-Karger F.,University of South Florida | Thunell R.,University of South Carolina | Hollander D.,University of South Florida | And 4 more authors.
Deep-Sea Research Part I: Oceanographic Research Papers | Year: 2012

Surface-tethered particle interceptor traps (PITs) were deployed at 50 and 100m (1-3 days) on ten occasions in the Cariaco Basin between March 2007 and November 2009 to measure the settling fluxes of biogenic particles at 50m (the base of the euphotic zone-Ez) and 100m. Fluxes at these two depths were compared to concurrent fluxes estimated with moored sediment traps at 150, 225 and 410m from the CARIACO Ocean Time-Series program. We measured particulate organic carbon (POC), particulate organic nitrogen (PON), calcium carbonate, biogenic silica and terrigenous material concentrations in samples collected with both the drifting and moored traps. We also estimated the fluxes of foraminifera shells and coccolithophore cells at 50 and 100m using drifting traps samples. Surface chlorophyll a and primary production observations during each sampling period were examined to quantify the relationship between the magnitude and geochemical composition of the vertical flux and overlying production. Surface chlorophyll a concentrations and primary production rates were highest during months of upwelling (2.58-1.35mgm -3 and 3.6-1.4g Cm -2d -1, respectively). The fluxes of POC, PON, calcite and silica measured during the upwelling season (December-May) were typically higher than during the period of non-upwelling (August-November), when surface waters are more strongly stratified. POC fluxes measured with the drifting traps (50 and 100m) varied between 0.95 (upwelling) and 0.14gm -2d -1 (non-upwelling), compared with those from the moored traps (150, 225 and 410m) which ranged from 0.21 to 0.01gm -2d -1. Similarly, the fluxes of biogenic opal in the upper 100m ranged from 1.12 and 0.18gm -2d -1, and those at greater depths varied from 0.27gm -2d -1 during upwelling to values near zero during stratification periods. The fluxes of POC, PON, calcite and silica in the upper 100m decreased by an order of magnitude at the depth of the oxic-anoxic interface (>200m). The sinking organic matter collected with the floating traps within the upper 100m was significantly correlated with surface chlorophyll a concentrations (r=0.68, p<0.05) as a result of close coupling between the flux of biogenic particles and primary production. In contrast, there was no clear relationship between surface chlorophyll/primary production and fluxes measured below 150m depth. © 2012 .

Lorenzoni L.,University of South Florida | Toro-Farmer G.,University of South Florida | Varela R.,Fundacion La Salle de Ciencias Naturales | Guzman L.,Fundacion La Salle de Ciencias Naturales | And 3 more authors.
Remote Sensing of Environment | Year: 2015

The spectral absorption coefficient of marine phytoplankton provides information on phytoplankton community structure, biomass, and general physiological conditions. These variables are necessary for understanding and predicting ocean productivity, carbon fluxes, underwater light propagation, water quality, and for assessing marine photochemical processes. The Cariaco Basin, located on the continental shelf of Venezuela in the southeastern Caribbean Sea, is the site of the CARIACO Ocean Time-Series project. Since 1995, CARIACO has collected bio-optical (hyperspectral inherent and apparent optical properties - IOPs and AOPs, respectively), biogeochemical and ecological observations to characterize local ecosystem variations in response to regional and global changes in climate. We examine phytoplankton taxonomic and pigment time series data collected by this program between 2006 and 2012 to understand how seasonal changes in these parameters relate to bio-optical data (i.e., absorption spectra). TChla and accessory pigments varied seasonally in response to changes in the phytoplankton community composition, with higher concentrations of microphytoplankton (>. 20. μm; 45%) during upwelling (December-April) than during the rainy season (16%; May/June-October/November). Picophytoplankton (<. 2. μm) dominated during the rainy season (66%). The absorption properties also exhibited seasonal variations. Diagnostic pigments could not be identified in a quantitative way using derivative analysis of phytoplankton absorption, likely because of overlapping of absorption spectra among the pigments present. The POC:TChla ratio at CARIACO was variable and dependent on bulk carbon (not necessarily related to phytoplankton) and the functional groups present at any given time, underscoring the fact that using a fixed ratio of POC:Chla in biogeochemical models can lead to large uncertainties in carbon budgets from coastal zones. High POC:TChla was associated with microphytoplankton size class (diatoms), while picophytoplankton (cyanobacteria) exhibited lower ratios. These results contribute to furthering our understanding of coastal phytoplankton dynamics and how they relate to optical signatures. © 2015.

Lorenzoni L.,University of South Florida | Hu C.,University of South Florida | Varela R.,Fundacion La Salle de Ciencias Naturales | Arias G.,Fundacion La Salle de Ciencias Naturales | And 2 more authors.
Continental Shelf Research | Year: 2011

Bio-optical properties of marine waters of the Cariaco Basin (southeastern Caribbean Sea) were assessed monthly between 1995 and 2005 as part of the CARIACO Ocean Time Series program. Temporal changes in light quality and penetration were caused by seasonal variation in the concentration of three major optical constituents, namely phytoplankton, detrital particles, and colored dissolved organic matter (CDOM). All constituents showed higher absorption coefficients during the upwelling season (January-May) compared to the rainy season (June-November). Both the absorption coefficient due to CDOM (a g(440)) and due to phytoplankton (a ph(440)) had similar contributions to total absorption of light during the upwelling season (a ph(440)=0.062±0.042m -1, a g(440)=0.065±0.047m -1). In contrast, a g(440) dominated light absorption during the rainy season (a ph(440)=0.017±0.011m -1, a g(440)=0.057±0.031). This led to an overestimate in SeaWiFS-derived chlorophyll concentrations during the rainy season, of between 7% and 45%. The detrital component, a d(440), typically showed the smallest contribution (a d(440)=0.021±0.014m -1 during upwelling and 0.007±0.001m -1 during the rainy season). There was no clear relationship between the various optically active components in time. During the upwelling season the chlorophyll-specific absorption coefficient, aph (440), was nearly half the value observed during the rainy season due to changes in the package effect (explaining ~40% of the variability) and in accessory pigment composition as a result of species succession (explaining ~60% of the variability). The euphotic zone depth (depth of the 1% photosynthetic active radiation (PAR) level) was typically shallower during the upwelling season (36.7±12.3m) than during the rainy season (47.9±13.5m) due to the onset of a shallower and stronger phytoplankton bloom. During upwelling, the highest chlorophyll-a concentrations (Chl>1mgm -3) were observed in the upper 25m with primary production rates exceeding 1800mgCm -2d -1. During the rainy season, a deep chlorophyll maximum (DCM, concentrations between 0.2 and 0.8mgm -3) was observed between 35 and 55m, with low (<0.2mgm -3) Chl concentrations above this depth and primary production values of ~990mgCm -2d -1. The DCM occurred immediately above the seasonal thermocline and around the 1% PAR light level. During the upwelling season, no DCM was observed. © 2011.

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