Size, growth, and density data for shallow-water sea urchins from Mexico to the Aleutian Islands, Alaska, 1956-2016.

Size, growth, and density have been studied for North American Pacific coast sea urchins Strongylocentrotus purpuratus, S. droebachiensis, S. polyacanthus, Mesocentrotus (Strongylocentrotus) franciscanus, Lytechinus pictus, Centrostephanus coronatus, and Arbacia stellata by various workers at diverse sites and for varying lengths of time from 1956 to present. Numerous peer-reviewed publications have used some of these data but some data have appeared only in graduate theses or the gray literature. There also are data that have never appeared outside original data sheets. Motivation for studies has included fisheries management and environmental monitoring of sewer and power plant outfalls as well as changes associated with disease epidemics. Studies also have focused on kelp restoration, community effects of sea otters, basic sea urchin biology, and monitoring. The data sets presented here are a historical record of size, density, and growth for a common group of marine invertebrates in intertidal and nearshore environments that can be used to test hypotheses concerning future changes associated with fisheries practices, shifts of predator distributions, climate and ecosystem changes, and ocean acidification along the Pacific Coast of North America and islands of the north Pacific. No copyright restrictions apply. Please credit this paper when using the data.

Present-day oxidative subsidence of organic soils and mitigation in the Sacramento-San Joaquin Delta, California, USA.

Subsidence of organic soils in the Sacramento-San Joaquin Delta threatens sustainability of the California (USA) water supply system and agriculture. Land-surface elevation data were collected to assess present-day subsidence rates and evaluate rice as a land use for subsidence mitigation. To depict Delta-wide present-day rates of subsidence, the previously developed SUBCALC model was refined and calibrated using recent data for CO2 emissions and land-surface elevation changes measured at extensometers. Land-surface elevation change data were evaluated relative to indirect estimates of subsidence and accretion using carbon and nitrogen flux data for rice cultivation. Extensometer and leveling data demonstrate seasonal variations in land-surface elevations associated with groundwater-level fluctuations and inelastic subsidence rates of 0.5-0.8 cm yr-1. Calibration of the SUBCALC model indicated accuracy of ±0.10 cm yr-1 where depth to groundwater, soil organic matter content and temperature are known. Regional estimates of subsidence range from <0.3 to >1.8 cm yr-1. The primary uncertainty is the distribution of soil organic matter content which results in spatial averaging in the mapping of subsidence rates. Analysis of leveling and extensometer data in rice fields resulted in an estimated accretion rate of 0.02-0.8 cm yr-1. These values generally agreed with indirect estimates based on carbon fluxes and nitrogen mineralization, thus preliminarily demonstrating that rice will stop or greatly reduce subsidence. Areas below elevations of -2 m are candidate areas for implementation of mitigation measures such as rice because there is active subsidence occurring at rates greater than 0.4 cm yr-1.

L'affaissement des sols organiques dans le Delta de Sacramento-San Joaquin menace la durabilité du système d'approvisionnement en eau et de l'agriculture de la Californie (Etats-Unis d'Amérique). Des données d'altitude de la surface topographique ont été collectées dans le but d'estimer le taux d'affaissement actuel des sols et d'évaluer l'occupation des sols par des rizières en tant que moyen d'atténuation de l'affaissement des sols. Pour décrire les taux actuels d'affaissement des sols à l'échelle du Delta, le modèle SUBCALC développé précédemment a été affiné et calé grâce à l'utilisation des données récentes sur les émissions de CO2 et des variations d'altitude de la surface topographique enregistrées par des extensomètres. Les données de variations d'altitude de la surface topographique ont été évaluées par rapport aux estimations indirectes de l'affaissement du sol et de son accroissement basées sur les données de flux de carbone et d'azote au niveau des rizières. Les données d'extensiométrie et de nivellement montrent que les variations saisonnières de l'altitude de la surface topographique associées aux fluctuations des niveaux piézométriques et des taux d'affaissement inélastique du sol compris entre 0.5 et 0.8 cm an­1. Le calage du modèle SUBCALC indique une précision de ±0.10 cm an ­1 là où la profondeur de la nappe, la teneur en matière organique du sol et la température sont connues. Les estimations régionales de l'affaissement du sol sont compris entre <0.3 à >1.8 cm an­1. L'incertitude principale est la distribution de la teneur en matière organique du sol qui conduit à un lissage spatial dans la cartographie des taux d'affaissement des sols. L'analyse des données de nivellement et d'extensiométrie dans les rizières conduit à un taux d'accroissement estimé entre 0.02 et 0.8 cm an­1. Ces valeurs sont généralement en accord avec les estimations indirectes basées sur les flux de carbone et de la minéralisation de l'azote qui indiquent a priori que le riz stoppera ou réduira de manière substantielle l'affaissement du sol. Les zones d'altitude inférieure à ­2 m sont des zones candidates pour la mise en œuvre de mesures d'atténuation telles que la culture du riz car il s'y produit un affaissement du sol actif avec des taux supérieurs à 0.4 cm an­1.

La subsidencia de los suelos orgánicos en el Delta de Sacramento-San Joaquín amenaza la sostenibilidad del sistema de suministro de agua y la agricultura en California (EE.UU.). Se recolectaron datos de elevación de la superficie del terreno para evaluar las tasas de subsidencia actuales y evaluar el cultivo de arroz como un uso de la tierra para la mitigación de la subsidencia. Se refinó y calibró el modelo SUBCALC desarrollado previamente para describir las tasas de la subsidencia en el ancho actual del Delta, usando los datos más recientes de las emisiones de CO2 y los cambios en la elevación de la superficie del terreno medidos con extensómetros. Se evaluaron los datos de cambio de la elevación de la superficie del terreno con respecto a las estimaciones indirectas de la subsidencia y la acumulación de carbono a partir de datos y el flujo de nitrógeno para el cultivo de arroz. Los datos de extensómetros y de nivelación demuestran variaciones estacionales en las elevaciones de la superficie terrestre asociados a las fluctuaciones del nivel del agua subterránea y tasas de subsidencia inelásticas de 0.5 a 0.8 cm año­1. La calibración del modelo SUBCALC indicó una precisión de ±0.10 cm año­1, donde son conocidas la profundidad del agua subterránea, el contenido de materia orgánica del suelo y la temperatura. Las estimaciones regionales de subsidencia varía de <0.3 a >1.8 cm yr­1. La principal incertidumbre es la distribución del contenido de materia orgánica en el suelo que resulta del promedio espacial en el mapeo de las tasas de subsidencia. El análisis de los datos de nivelación y extensómetro en los campos de arroz resultó en una tasa de acreción estimada entre 0.02 y 0.8 cm yr­1. Estos valores en general concuerdan con las estimaciones indirectas basadas en los flujos de carbono y nitrógeno, lo que demuestra en forma preliminar que la mineralización del arroz va a detener o reducir en gran medida la subsidencia. Las áreas por debajo de elevaciones de ­2 m son áreas examinadas para la implementación de medidas de mitigación, tales como el cultivo de arroz debido a que no hay lugar para un ritmo de subsidencia activa de más de 0.4 cm año­1.

A subsidência dos organossolos no Delta dos rios Sacramento-San Joaquin põe em risco a sustentabilidade do sistema de abastecimento de água e da agricultura do estado da Califórnia (EUA). Foram coletados dados de elevação da superfície do solo para estimar as taxas atuais de subsidência e avaliar o uso de cultivo de arroz para mitigar a subsidência. Para simular as taxas atuais de subsidência da região do Delta, o modelo SUBCALC, desenvolvido anteriormente, foi refinado e calibrado utilizando dados recentes de emissões de CO2 e mudanças na elevação do terreno obtidas com extensômetros. Os dados de mudança na elevação foram avaliados em relação a estimativas indiretas de subsidência e acreção, utilizando dados de fluxo de carbono e nitrogênio no cultivo de arroz. Os dados dos extensômetros e de nivelamento demonstraram variações sazonais de elevações do terreno, associados a flutuações do nível da água subterrânea e taxas de subsidência inelásticas que variam de 0.5 a 0.8 cm ano­1. A calibração do modelo SUBCALC indicou precisão de ±0.10 cm por ano­1, onde a profundidade das águas subterrâneas e o teor de matéria orgânica e temperatura do solo eram conhecidos. As estimativas regionais de subsidência variam de <0.3 a >1.8 cm ano­1. A principal incerteza nas estimativas de subsidência modeladas é a distribuição do conteúdo de matéria orgânica do solo. Porem, as taxas mapeadas de subsidência representam médias em áreas de solos mapeados com teor de materia organica semelhantes. Análises dos dados de nivelamento e dos extensômetros em campos de produção de arroz, resultaram em uma taxa de acreção estimada de 0.02 a 0.8 cm por ano­1. Estes valores geralmente concordam com estimativas indiretas baseadas em fluxos de carbono e a mineralização do nitrogênio, portanto, indicando que o cultivo de arroz ira parar ou reduzira significativamente o processo de subsidência. Áreas com elevação inferior a ­2 m são candidatas para a implementação de medidas de mitigação como o cultivo de arroz, por haver subsidência ativa ocorrendo com taxas superiores a 0.4 cm por ano­1.

Dispersion reduction in open-channel liquid electrochromatographic columns via pressure-driven back flow.

Application of electrokinetic forces to drive the mobile phase diminishes analyte dispersion in open-channel liquid chromatographic columns due to minimization of shear in the flow field. However, the retentive layer coating the inner walls of such devices slows down the average convective velocity of solute molecules in its vicinity, inherently causing dispersion of analyte bands. In this article, we explore the possibility of reducing such dispersion in electrochromatographic columns by imposing a pressure-driven back flow in the system. Analysis shows that although such a strategy introduces shear in the flow field, the overall dispersion in the mobile phase is reduced. This occurs as the streamline velocity in such a system is greater near the channel walls than that in the center of the conduit, thereby allowing fluid dispersion to counteract wall retention effects. For an optimally chosen magnitude of the back flow, hydrodynamic dispersion of any target species in the mobile phase may be shown to diminish by a factor of 3 and 10/3 in a circular tube and a parallel-plate geometry, respectively. A similar reduction in slug dispersion is also realized in rectangular conduits for all aspect ratios. In trapezoidal geometries with large wedge angles or isotropically etched profiles, this reduction factor may attain values of 10 or greater.

Dispersion in large aspect ratio microchannels for open-channel liquid chromatography.

Solute dispersion in open-channel liquid chromatography is often dominated by transverse diffusion limitations in the mobile phase (Martin, M.; Guiochon, G. Anal. Chem. 1984, 56, 614-620) convecting the solute species. While such dispersion is known to scale with the square of the Peclet number based on the narrower dimension of the conduit, the proportionality constant may significantly vary with the aspect ratio of the channel geometry. In this article, we investigate the effect of channel sidewalls on axial dispersion in electrokinetically and pressure-driven chromatographic systems. The analysis presented here clearly identifies the contribution from flow, wall retention, and the interaction between the two to the overall slug dispersion in the mobile phase for any arbitrary channel geometry. The particular geometries that have been investigated in this work, however, are the rectangular and the isotropically etched profiles often employed in microanalysis systems. Further, the effectiveness of simple double-etched profiles proposed elsewhere (Dutta, D.; Leighton, D. T. Anal. Chem. 2001, 73, 504-513) to diminish the effect of channel sidewalls on Taylor-Aris dispersion has also been examined. Analysis shows that dispersion arising due to shear and wall retention, as well as the interaction between the two, may be significantly reduced in large aspect ratio microchannels for optimized channel geometries.

A low dispersion geometry for microchip separation devices.

Curved channel geometries introduced on microchip separation devices to achieve greater separation distances often lead to large analyte dispersion, degrading the performance of these systems. While such electrokinetic dispersion may be minimized by reducing the channel width around the curved region, alternative strategies involving larger channel curvatures may be promising as well, depending on the application. For example, Culbertson et al. (Anal. Chem. 2000, 72, 5814-5819) recently demonstrated the effectiveness of gentle spiral geometries in carrying out separations of small molecules. For moderate and large Peclet number systems, however, larger spiral geometries are necessary to diminish electrokinetic dispersion of solute slugs which may not conform to the needs of the microchip format. In this work, we investigate a modified spiral geometry with a wavy wall along the inner track of the channel. Analysis shows that such width profiling may significantly improve the performance of the spiral geometry, making the design effective for larger Peclet number or smaller radii systems. Numerical simulations performed to optimize these modified spirals suggest equating transit times along the inner and the outer track of the channel as a useful design criterion for minimizing electrokinetic dispersion. An analytical model has been formulated to derive the optimal channel parameters based on this criteria which compares well with the simulation results.

Comparison of growth and lipid composition in the green abalone, Haliotis fulgens, provided specific macroalgal diets.

Lipid composition of abalone was examined over a one-year interval. A feeding trial was designed to cover a full reproductive cycle in young adult green abalone, Haliotis fulgens, consisting of five diet treatments: the macrophytic algal phaeophyte Egregia menziesii, rhodophyte Chondracanthus canaliculatus, chlorophyte Ulva lobata, a composite of the three algae and a starvation control. The lipid class, fatty acid, sterol and 1-O-alkyl glyceryl ether profiles were determined for foot, hepatopancreas/gonad tissues and larvae. The major fatty acids were 16:0, 18:0, 18:1(n-7)c, 18:1(n-9)c, 20:4(n-6), 20:5(n-3) and 22:5(n-3), as well as 14:0 for abalone fed brown and red algae. 4,8,12-Trimethyltridecanoic acid, derived from algae, was detected for the first time in H. fulgens (hepatopancreas complex, 1.2-13.9%; larvae, 0.5% of total fatty acids). Diacylglyceryl ethers were present in larvae (0.6% of total lipid). The major 1-O-alkyl glycerols were 16:0, 16:1 and 18:0. Additionally, 18:1(n-9) was a major component in hepatopancreas/gonad and larvae. The major sterol was cholesterol (96-100% of total sterols). Highest growth rates were linked to temperature and occurred in abalone fed the phaeophyte E. menziesii (43 microm.day(-1), 56 mg.day(-1) yearly mean), an alga containing the highest levels of C(20) polyunsaturated fatty acids and the highest ratio of 20:4(n-6) to 20:5(n-3). This study provides evidence of the influence of diet and temperature on seasonal changes in abalone lipid profiles, where diet is most strongly related to body mass and temperature to shell length. The allocation of lipids to specific tissues in green abalone clarifies their lipid metabolism. These results provide a basis for improving nutrition of abalone in mariculture through formulation of artificial feeds.