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1.
Age‐ or length‐structured stock assessments require reliable life history demographic parameters (growth, mortality, reproduction) to model population dynamics, potential yields and stock sustainability. This study synthesized life history information for 84 commercially exploited tropical reef fish species from Florida and the U.S. Caribbean (Puerto Rico and the U.S. Virgin Islands). We attempted to identify a useable set of life history parameters for each species that included lifespan, length at age, weight at length and maturity at length. Key aspects of the life history synthesis were development of: (a) a database that characterized study details including sampling region, biological and statistical methods, length range of sampled individuals, sample size, capture gears and sampling time frame; (b) reproducible procedural criteria for parameter identification for a given species; and (c) a reliability metric for each parameter type. Complete life history parameter sets were available for 46 species analysed. Of these, only 16 species had parameter sets meeting the highest standards for reliability, highlighting future research needs. 相似文献
2.
Rob M. Stevens Gordon Harvey Scott Norton William Frahn 《Agricultural Water Management》2011,101(1):62-70
Wetting plant foliage with saline irrigation increases the uptake of toxic ions Na+ and Cl−. Over three consecutive seasons, Colombard vines grafted on Ramsey rootstock were irrigated with saline water (EC 3.5 dS/m) by over-canopy sprinklers during any one of the first three of the four annual growth stages: bud burst to full bloom (treatment BB-FB), full bloom to veraison (treatment FB-V), and veraison to harvest (treatment V-H). At other times, vines received non-saline water (EC 0.5 dS/m) as did the control. Seasonal average soil salinities remained relatively constant over the trial. In contrast, the concentrations of Na+ and Cl− in one-year old wood and grape juice more than doubled. In treatments FB-V and V-H the average yield over the three seasons was reduced by up to 15%. Results were compared with those obtained in an earlier study which was undertaken in the same vineyard with the same treatments applied via dripper. With drippers, the maximum reduction in the average yield over three seasons was 2%. Saline sprinkling caused rises in Na+ and Cl− concentrations of fruit, leaf lamina and one-year-old wood that were at least 7-fold, 5-fold and 2-fold greater, respectively, than the rises caused by application of the same treatments with drip. Progressive seasonal rises in the concentrations of Na+ and Cl− in these tissues were due in part to carryover of salt added in previous seasons; with saline sprinkling the magnitude of these carryovers was 4-fold greater than those with saline drip irrigation. With saline water, vignerons can reduce losses by using irrigation systems which do not wet the foliage. 相似文献
3.
Singleton Megan P. Thode Andrea E. Sánchez Meador Andrew J. Iniguez Jose M. Stevens Jens T. 《Landscape Ecology》2021,36(12):3429-3449
Landscape Ecology - Spatial patterns of high-severity wildfire in forests affect vegetation recovery pathways, watershed dynamics, and wildlife habitat across landscapes. Yet, less is known about... 相似文献
4.
To understand nitrous oxide (N2O) emissions from terrestrial ecosystems it is necessary to understand the processes leading to N2O production. Here, for the first time, results are presented which identify in situ the processes of N2O production in a temperate grassland soil. A small portion of the nitrogen (N) applied in the summer to the grassland soil was rapidly transported below the main rooting zone (>20 cm) and resulted in large N2O productions at depths of 20-50 cm. Preferential pathways must have been responsible for this movement because the soil conditions were not conducive to leaching by piston flow. The N2O was entirely produced by nitrate (NO3−) reduction which was surprising because the bulk soil was aerobic. Therefore, reduction processes can operate during times of the year when it is least expected and cause large N2O concentrations deep in the soil profile. 相似文献
5.
Habitat mapping at the scale at which marine protected areas are designed and managed is essential for assessment of, and design for, representation. Most habitat mapping studies rely solely or in part on abiotic surrogates for patterns of biodiversity. The utility of abiotic variables in predicting biological distributions at the local scale (10 s of km) was tested in a remote video survey of macrobenthos in Moreton Bay, Australia. Habitat classifications of the same set of 41 sites based on 6 abiotic variables and abundances of 89 taxa and bioturbation indicators were compared using correlation, regression and ordination analyses. The concepts of false homogeneity (abiotically similar but biologically distinct) and false heterogeneity (abiotically distinct but biologically similar) were defined to describe types of errors associated with using abiotic surrogates to construct habitat maps, and quantified using two separate methods. Overall, the best prediction by abiotic surrogates explained less than 30% of the pattern of biological similarity. Errors of false homogeneity were between 20% and 62%, depending on the methods of estimation. Predictive capability of abiotic surrogates at the taxon level was poor, with only 6% of taxon/surrogate correlations significant. Abiotic variables did not discriminate sufficiently between different soft bottom communities to be a reliable basis for mapping. These results have implications for the widespread use of abiotic surrogates in marine habitat mapping to plan for, or assess, representation in marine protected areas. Little confidence can be placed in marine habitat classifications based solely or largely on abiotic surrogates without calibration by rigorous biological surveys at the appropriate scale. Therefore, it is questionable whether marine protected areas designed on this basis can have measurable benefits for conservation. 相似文献
6.
Lloyd R. Stark William R. Wenerick Frederick M. Williams S. Edward Stevens Jr. Paul J. Wuest 《Water, air, and soil pollution》1994,75(3-4):405-420
Four volumes of spent mushroom compost were exposed to synthetic coal mine drainage (pH 3.5, 48 mg L?1 Fe, 22 mg L?1 Mn) under oxidizing conditions (Eh 300 to 400 mV) at a relatively high rate of flow. After 15 days, the compost lost its ability to elevate pH, to lower the redox potential, to lower outlet iron concentrations, and to lower manganese concentrations, with larger volumes retaining more Fe and H+, but less Mn. Estimated retention maxima per liter of spent mushroom compost were 281 μeq H+, 5.56 g Fe, and 0.15 g Mn. These values are similar to those reported elsewhere for peat. The ‘saturated’ compost was then mixed and exposed to mine water in order to eliminate ‘dead zones’ in the compost. Subsequently, the compost was re-exposed to synthetic mine water (pH 4.0, 60 mg L?1 Fe, O mg L?1 Mn) under a much lower flow rate and less oxidizing regime for a period of 114 days. Under the low flow regime, iron was first exported from the compost as reducing conditions were established, and then retained on a stable basis. In addition, Eh was lowered and pH was elevated by the compost. On a net basis, the capacity of the compost to retain iron was increased and apparently stable under the decreased flow conditions. 相似文献
7.
Stevens JF Taylor AW Clawson JE Deinzer ML 《Journal of agricultural and food chemistry》1999,47(6):2421-2428
The fate of three prenylated flavonoids of the chalcone type, xanthohumol, desmethylxanthohumol, and 3'-geranylchalconaringenin, was monitored with LC/MS-MS from hops (Humulus lupulus L.) to beer in two brewing trials. The three prenylchalcones were largely converted into their isomeric flavanones, isoxanthohumol, prenylnaringenins, and geranylnaringenins, respectively, in the boiling wort. Losses of prenylflavonoids were due to incomplete extraction from the hops into the wort (13-25%), adsorption to insoluble malt proteins (18-26%), and adsorption to yeast cells (11-32%) during fermentation. The overall yield of xanthohumol, after lagering of the beer and largely in the form of isoxanthohumol, amounted to 22-30% of the hops' xanthohumol. About 10% of the hops' desmethylxanthohumol, completely converted into prenylnaringenins, remained in the beers. 3'-Geranylchalconaringenin behaved similarly to desmethylxanthohumol. Solubility experiments indicated that (1) malt carbohydrates form soluble complexes with xanthohumol and isoxanthohumol and (2) solubility does not dictate the isoxanthohumol levels of finished beers. 相似文献
8.
Clarke JD Riedl K Bella D Schwartz SJ Stevens JF Ho E 《Journal of agricultural and food chemistry》2011,59(20):10955-10963
Increased consumption of cruciferous vegetables such as broccoli may reduce the risk of various cancers. Myrosinase is required to convert dietary glucosinolates from broccoli into bioactive isothiocyanates. We evaluated isothiocyanate excretion profiles in healthy subjects who consumed broccoli sprouts or broccoli supplement (no myrosinase) with equivalent glucosinolate content. Urinary metabolites of two major isothiocyanates, sulforaphane and erucin, were measured by liquid chromatography coupled with tandem mass spectrometry. Peak excretion of sulforaphane and erucin was higher and occurred sooner in subjects who consumed broccoli sprouts as compared to subjects who consumed the supplement. A subject-dependent shift in the ratio of urinary sulforaphane to erucin metabolites was observed in both groups, indicating conversion of sulforaphane to erucin. Lower histone deacetylase activity was observed in the peripheral blood mononuclear cells only in subjects consuming sprouts. Fresh broccoli sprouts differ from broccoli supplements in regards to excretion of isothiocyanates and bioactivity in human subjects. 相似文献
9.
10.
Meadowfoam ( Limnanthes alba) is an oilseed crop grown in western Oregon. The seed meal has potential value as a biopesticide due to glucosinolate degradation products and phytoecdysteroids, a group of polyhydroxylated triterpenoids with potent activities as arthropod molting hormones. Liquid chromatography in combination with tandem mass spectrometry operated in the precursor ion mode revealed the presence of four ecdysteroid glycosides in meadowfoam seed meal. The carbohydrate sequence and the identity of the ecdysteroid aglycones, ponasterone A and 20-hydroxyecdysone, were determined by product ion scanning. Ecdysteroids were detected in the negative ion mode as [M + formate] (-) ions, which yielded [M - H] (-) and alpha-cleavage fragments with retention of hydroxyl groups in MS/MS experiments (not seen in the positive ion mode), allowing the determination of the number of hydroxyl groups in the side chain and in the steroid ring system. MS/MS of glycoside ions ([MH] (+) or [M + formate] (-)) provided carbohydrate sequence information. 相似文献