Habitat and bycatch effects on population parameters of inshore lizardfish (Synodus foetens) in the north central Gulf of Mexico

We examined the effect of habitat and shrimp trawl bycatch on the density, size, growth, and mortality of inshore lizardfish (Synodus foetens), a nonexploited species that is among the most widespread and abundant benthic fishes in the north central Gulf of Mexico. Results of quarterly trawl sampling conducted from spring 2004 through spring 2005 revealed that inshore lizardfish are most abundant on sand habitat, but larger fish are more common on shell rubble habitat. There was no significant difference in fish density between habitats exposed to shrimp trawling on the open shelf versus those habitats within a permitted artificial reef zone that served as a de facto no-trawl area; this finding indicates that either inshore lizardfish experienced minimal effects from trawling or, more likely, that fish moved between trawled and nontrawled habitats. Exploitation ratio (bycatch mortality/total morality) estimates derived from catch curve analysis ranged from 0.43 inside the artificial reef zone to 0.55 outside the reef zone, thus indicating that inshore lizardfish are subject to significant fishing mortality in the north central Gulf of Mexico despite the lack of a directed fishery for the species. We infer from this result that effects of shrimp trawl bycatch may be significant at the population level for nonexploited species and that a broader ecosystem-scale examination of bycatch effects is warranted

Validation of a Predictive Model for Survival in Patients With Advanced Cancer: Secondary Analysis of RTOG 9714.

BackgroundThe objective of this study was to validate a simple predictive model for survival of patients with advanced cancer.MethodsPrevious studies with training and validation datasets developed a model predicting survival of patients referred for palliative radiotherapy using three readily available factors: primary cancer site, site of metastases and Karnofsky performance score (KPS). This predictive model was used in the current study, where each factor was assigned a value proportional to its prognostic weight and the sum of the weighted scores for each patient was survival prediction score (SPS). Patients were also classified according to their number of risk factors (NRF). Three risk groups were established. The Radiation Therapy and Oncology Group (RTOG) 9714 data was used to provide an additional external validation set comprised of patients treated among multiple institutions with appropriate statistical tests.ResultsThe RTOG external validation set comprised of 908 patients treated at 66 different radiation facilities from 1998 to 2002. The SPS method classified all patients into the low-risk group. Based on the NRF, two distinct risk groups with significantly different survival estimates were identified. The ability to predict survival was similar to that of the training and previous validation datasets for both the SPS and NRF methods.ConclusionsThe three variable NRF model is preferred because of its relative simplicity

Otolith Microchemical Fingerprints of Age-0 Red Snapper, Lutjanus campechanus, from the Northern Gulf of Mexico

Red snapper, Lutjanus campechanus, in the northern Gulf of Mexico (Gulf) are believed to constitute a single stock. However, tagging and genetics studies suggest there is little mixing between populations of red snapper in the northern Gulf, and little is known about mixing rates of adult fish. The long-term goal of our work is to determine if age-0 red snapper from different nursery areas have unique microchemical fingerprints in their sagittal otoliths, and if so, can the microchemical fingerprints at the core of adult otoliths be used to determine retrospectively nursery area of origin. Ultimately, we hope to use the microchemical fingerprints at the core of adult snapper otoliths to estimate adults\u27 mixing rates and movement patterns. In this study, the objective was to determine if age-0 red snapper collected from different northern Gulf nursery areas in summer and fall 1995 did contain unique microchemical fingerprints. Sagittal otoliths of age-0 red snapper collected off the coasts of Alabama/Mississippi, Louisiana, and Texas were analyzed using inductively coupled plasma atomic emission spectrometry (ICP-AES). Twelve elements in the sagittae of age-0 snapper were analyzed with ICP-AES. Of these, eight were put into a stepwise discriminant function analysis with the best-fitted model including Mg, Se, As, Fe, and AI, entered in that order (MANOVA, P \u3c 0.001). Cross-validated classification accuracies were 92% for Texas fish, 91% for Louisiana fish, and 92% for Alabama/Mississippi fish. Therefore, it appears that otolith microchemistry can be used to infer nursery area of age-0 red snapper. Future work will focus on (1) establishing the temporal stability of age-0 red snapper otolith microchemical fingerprints and (2) inclusion of analyses of age-structured samples from adult red snapper otolith cores to estimate their nursery area of origin and mixing rates

Movement of Red Snapper, Lutjanus campechanus, in the North Central Gulf of Mexico: Potential Effects of Hurricanes

Site fidelity and movement of red snapper, Lutjanus campechanus, were estimated from a tagging study conducted off the coast of Alabama from March 1995 to January 1997. Red snapper were caught using rod and reel over nine artificial reef sites, with three reefs each located at 21-m, 27-m, and 32-m depths. During the study, 1,604 fish were tagged, and 174 recaptures were made of 167 individuals. On 4 October 1995, the eye of Hurricane Opal passed within 40 km of the artificial reef sites. When recaptures were stratified according to whether or not they were at liberty during Opal, storm effect was the most significant factor in predicting the likelihood of movement and magnitude of movement by tagged red snapper. Eighty percent of recaptured red snapper that were not at liberty during Opal were recaptured at their site of release. Fish that were at liberty during Opal, however, had a significantly higher likelihood of movement away from their site of release (P \u3c 0.001). These fish also moved significantly further than those that were not at liberty during Opal (P \u3c 0.001). Fish that were at liberty during Opal moved a mean distance (± SE) of 32.6 km (± 6.81), compared to a mean distance (± SE) of 2.5 km (± 1.10) for fish that were tagged and recaptured before Opal, and a mean distance (± SE) of 1.7 km (± 0.43) for fish that were tagged and recaptured after Opal. Heretofore, it has generally been accepted that adult red snapper demonstrate strong site fidelity and genetic homogeneity in the stock was hypothesized to result from larval drift or due to historic mixing on longer time scales. This study documents movement of adult red snapper on spatial scales that would facilitate stock mixing and implicates large-scale climatic events, such as hurricanes, as important factors in stock mixing dynamics

Metabolism of a tropical rainforest stream

Gradients in photosynthesis (P) and respiration (R) were measured on an unperturbed portion of the Rio Mameyes, a tropical stream in the Luquillo Experimental Forest, northeastern Puerto Rico. Rates of P, which were similar to those of streams in temperate-deciduous forests, were low in the heavily canopied headwaters (\u3c70 g O2 m−2 y−1) and were higher (453–634 g O2 m−2 y−1) in middle and lower reaches. Periphyton biomass did not show the expected increase as the canopy opened downstream, probably because of increasing herbivory in downstream reaches. Rates of R, which were much higher than in most temperate streams, also were lower in the headwaters (767 g O2 m−2 y−1) than in the middle and lower reaches (1550–1660 g O2 m−2 y−1). High rates of R and suppressed periphyton abundance caused annual P/R to be \u3c\u3c1 from headwaters to lower reaches. Results for the Rio Mameyes suggest that intense herbivory, which is favored by the presence of large herbivores and consistently high temperatures, may be more typical of tropical than temperate streams. Results also show that the tropical rainforest provides the stream with sufficient amounts of labile organic C to support high rates of respiration over long distances across the basin

Multispectral Imaging from Mars PATHFINDER

The Imager for Mars Pathfinder (IMP) was a mast-mounted instrument on the Mars Pathfinder lander which landed on Mars Ares Vallis floodplain on July 4, 1997. During the 83 sols of Mars Pathfinders landed operations, the IMP collected over 16,600 images. Multispectral images were collected using twelve narrowband filters at wavelengths between 400 and 1000 nm in the visible and near infrared (VNIR) range. The IMP provided VNIR spectra of the materials surrounding the lander including rocks, bright soils, dark soils, and atmospheric observations. During the primary mission, only a single primary rock spectral class, Gray Rock, was recognized; since then, Black Rock, has been identified. The Black Rock spectra have a stronger absorption at longer wavelengths than do Gray Rock spectra. A number of coated rocks have also been described, the Red and Maroon Rock classes, and perhaps indurated soils in the form of the Pink Rock class. A number of different soil types were also recognized with the primary ones being Bright Red Drift, Dark Soil, Brown Soil, and Disturbed Soil. Examination of spectral parameter plots indicated two trends which were interpreted as representing alteration products formed in at least two different environmental epochs of the Ares Vallis area. Subsequent analysis of the data and comparison with terrestrial analogs have supported the interpretation that the rock coatings provide evidence of earlier martian environments. However, the presence of relatively uncoated examples of the Gray and Black rock classes indicate that relatively unweathered materials can persist on the martian surface

Dendritic Chelating Agents. 2. U(VI) Binding to Poly(amidoamine) and Poly(propyleneimine) Dendrimers in Aqueous Solutions

Chelating agents are widely employed in many separation processes used to recover uranyl [U(VI)] from contaminated aqueous solutions. This article describes an experimental investigation of the binding of U(VI) to poly(amidoamine) [PAMAM] and poly(propyleneimine) [PPI] dendrimers in aqueous solutions. We combine fluorescence spectroscopy with bench scale ultrafiltration experiments to measure the extent of binding and fractional binding of U(VI) in aqueous solutions of these dendrimers as a function of (i) metal−ion dendrimer loading, (ii) dendrimer generation, (iii) dendrimer core and terminal group chemistry, and (iv) solution pH and competing ligands (NO_3^−, PO_4^(3−), CO_3^(2−), and Cl^−). The overall results of this study suggest that uranyl binding to PAMAM and PPI dendrimers in aqueous solutions involves the coordination of the UO22+ ions with the dendrimer amine, amide, and carboxylic groups. We find significant binding of U(VI) to PAMAM dendrimers in (i) acidic solutions containing up to 1.0 M HNO_3 and H_3PO_4 and (ii) in basic solutions containing up to 0.5 M Na_2CO_3. However, no binding of U(VI) by PAMAM dendrimers is observed in aqueous solutions containing 1.0 M NaCl at pH 3.0. These results strongly suggest that PAMAM and PPI dendrimers can serve as high capacity and selective chelating ligands for U(VI) in aqueous solutions

3-D Structural Modeling of Humic Acids through Experimental Characterization, Computer Assisted Structure Elucidation and Atomistic Simulations. 1. Chelsea Soil Humic Acid

This paper describes an integrated experimental and computational framework for developing 3-D structural models for humic acids (HAs). This approach combines experimental characterization, computer assisted structure elucidation (CASE), and atomistic simulations to generate all 3-D structural models or a representative sample of these models consistent with the analytical data and bulk thermodynamic/structural properties of HAs. To illustrate this methodology, structural data derived from elemental analysis, diffuse reflectance FT-IR spectroscopy, 1-D/2-D ^1H and ^(13)C solution NMR spectroscopy, and electrospray ionization quadrupole time-of-flight mass spectrometry (ESI QqTOF MS) are employed as input to the CASE program SIGNATURE to generate all 3-D structural models for Chelsea soil humic acid (HA). These models are subsequently used as starting 3-D structures to carry out constant temperature-constant pressure molecular dynamics simulations to estimate their bulk densities and Hildebrand solubility parameters. Surprisingly, only a few model isomers are found to exhibit molecular compositions and bulk thermodynamic properties consistent with the experimental data. The simulated ^(13)C NMR spectrum of an equimolar mixture of these model isomers compares favorably with the measured spectrum of Chelsea soil HA

Dendritic Anion Hosts: Perchlorate Uptake by G5-NH_2 Poly(propyleneimine) Dendrimer in Water and Model Electrolyte Solutions

Perchlorate (ClO_4^-) has emerged as a major groundwater and surface water contaminant in the United States. Ion exchange (IX) is the most widely used technology for treating water containing lower concentrations of perchlorate (<100 ppb). However, a major drawback of IX is the need for frequent regeneration or disposal of the perchlorate-laden resins. As a first step toward the development of high-capacity, selective and recyclable dendritic ligands for the recovery of perchlorate from aqueous solutions by dendrimer filtration, we tested the hypothesis that dendrimers with hydrophobic cavities and positively charged internal groups should selectively bind ClO_4^- over more hydrophilic anions such as Cl^-, NO_3^-, SO_4^(2-), and HCO_3^-. We measured the uptake of ClO_4^- by the fifth generation (G5-NH_2) poly(propyleneimine) (PPI) dendrimer with a diaminobutane core and terminal NH_2 groups in deonized water and model electrolyte solutions as a function of (i) anion−dendrimer loading, (ii) solution pH, (iii) background electrolyte concentration, and (iv) reaction time. The ClO_4^- binding capacity of this dendrimer is comparable to those of perchlorate-selective IX resins. However, its ClO_4^- binding kinetics is faster and reaches equilibrium in ∼1 h. Note also that only a high pH (∼9.0) aqueous solution is needed to release more than 90% of the bound ClO_4^- anions by deprotonation of the dendrimer tertiary amine groups. The overall results of this study suggest that dendritic macromolecules such as the G5-PPI NH_2 dendrimer provide ideal building blocks for the development of high-capacity, selective and recyclable ligands for the recovery of anions such as perchlorate from aqueous solutions by dendrimer enhanced filtration