Impact of humans on the flux of terrestrial sediment to the global coastal ocean   总被引：11，自引：0，他引：11  

Syvitski JP  Vörösmarty CJ  Kettner AJ  Green P 《Science (New York, N.Y.)》2005,308(5720):376-380

Here we provide global estimates of the seasonal flux of sediment, on a river-by-river basis, under modern and prehuman conditions. Humans have simultaneously increased the sediment transport by global rivers through soil erosion (by 2.3 +/- 0.6 billion metric tons per year), yet reduced the flux of sediment reaching the world's coasts (by 1.4 +/- 0.3 billion metric tons per year) because of retention within reservoirs. Over 100 billion metric tons of sediment and 1 to 3 billion metric tons of carbon are now sequestered in reservoirs constructed largely within the past 50 years. African and Asian rivers carry a greatly reduced sediment load; Indonesian rivers deliver much more sediment to coastal areas.  相似文献   

Detection of the first larval feeding in Crassostrea gigas, using the epifluorescence microscope     

Albert Lucas  Carlos Rangel 《Aquaculture (Amsterdam, Netherlands)》1983,30(1-4):369-374

The first larval feeding in Crassostrea gigas, detected by epifluorescence microscope, occurred 24 h after fertilization at 24°C and 30 h at 21°C. The amount of algal cells (Pavlova lutheri and Isochrysis galbana) necessary to have larvae with filled stomachs was estimated to be 800 cells per day at 24°C and 400 cells per day at 21°C.  相似文献   

Algal biomass accrual in relation to nutrient availability and limitation along a longitudinal gradient of a karst riverine system   总被引：1，自引：0，他引：1  

Penick  Mary D  Grubbs  Scott A  Meier  Albert J 《International Aquatic Research》2012,4(1):1-13

Textural property of surimi products is a prime factor in determining the acceptability of consumer as well as market value. Gelatin is one of the most popular biopolymers widely used in food industry as gelling agent with the unique textural properties. Therefore, the addition of gelatin along with the use of protein cross-linkers could be a means to modify the texture of surimi gel, which can fit the demand of consumers. Surimi from the threadfin bream (Nemipterus bleekeri) was added with bovine gelatin (BG) and bovine/fish gelatin mix (BFGM; 1:1, 2:1, 1:2, 4:1, and 1:4) at 10% protein substitution in combination with and without microbial transglutaminase (MTGase) at 1.2 units/g surimi. Textural properties, whiteness, expressible moisture content, protein pattern, and microstructure and sensory properties of gels were determined. When MTGase at 1.2 units/g surimi was incorporated, the increases in breaking force and deformation were noticeable in both surimi gels, with and without 10% BG added ( p < 0.05). On the other hand, surimi gels added with BFGM at all bovine/fish gelatin ratios had the higher breaking force and deformation, compared with that added with BG, when MTGase was incorporated. Addition of BG or BFGM lowered the expressible moisture content and whiteness of surimi gel ( p < 0.05). Based on SDS-PAGE, band intensity of myosin heavy chain and actin of surimi gel decreased when surimi gel was added with all gelatins, regardless of MTGase addition. The microstructure study revealed that surimi gel network became finer and denser with the addition of MTGase (1.2 units/g surimi), but the coarser and irregular structure was obtained when gelatin was incorporated. Gelatin, especially bovine/fish gelatin mix, at an appropriate level could be used as the protein additive in surumi gel in conjunction with MTGase in order to improve the textural and nutritive properties of the products.  相似文献   

Photoperiod manipulation for the reproductive management of captive wolffish populations: <Emphasis Type="Italic">Anarhichas minor</Emphasis> and <Emphasis Type="Italic">A. lupus</Emphasis>     

Bernard-Antonin Dupont Cyr  Helge Tveiten  Domynick Maltais  Grant W. Vandenberg  Nathalie R. Le François 《Aquaculture International》2018,26(4):1051-1065

This study provides new and practical information to implement the use of photoperiodic manipulation for the control of the sexual maturation of Canadian 6⁺ Atlantic wolffish (Anarhichas lupus) and 3⁺ first-time spawners spotted wolffish (Anarhichas minor) from Canadian and Norwegian populations. Wolffish reproductive cycle (gametogenesis and oocyte maturation and spermiation) was monitored for 23 consecutive months. Control groups were held under a 12-month simulated natural photoperiod and treatment groups under an 8-month compressed photoperiod. Plasma sex steroid concentrations (estradiol-17β and 11-ketotestosterone), oocyte diameter growth, and milt production were assessed monthly. For all groups under study, fish subjected to the compressed photoperiod spawned 2–6 months earlier than the controls. Complete out-of-shift cycle was not achieved based on the completion of two reproduction cycles, and this is briefly discussed. Photoperiod treatment induced temporal shifts in sex steroid profiles, which are the likely mediators of altered timing of ovulation/final maturation. Photoperiod has a strong influence on the timing of wolffish maturation and could be used as an efficient and inexpensive tool to secure wolffish reproduction operations (year-round supply of egg and milt and/or timing with optimal temperature regimes).  相似文献   

Energy acquisition and allocation to egg production in relation to fish reproductive strategies          下载免费PDF全文

Richard S McBride  Stylianos Somarakis  Gary R Fitzhugh  Anu Albert  Nathalia A Yaragina  Mark J Wuenschel  Alexandre Alonso‐Fernández  Gualtiero Basilone 《Fish and Fisheries》2015,16(1):23-57

Oogenesis in fishes follows a universal plan; yet, due to differences in the synchrony and rate of egg development, spawning frequency varies from daily to once in a lifetime. Some species spawn and feed in separate areas, during different seasons, by storing energy and drawing on it later for reproduction (i.e. capital breeding). Other species spawn using energy acquired locally, throughout a prolonged spawning season, allocating energy directly to reproduction (i.e. income breeding). Capital breeders tend to ovulate all at once and are more likely to be distributed at boreal latitudes. Income breeding allows small fish to overcome allometric constraints on egg production. Income breeders can recover more quickly when good‐feeding conditions are re‐established, which is a benefit to adults regarding bet‐hedging spawning strategies. Many species exhibit mixed capital‐ and income‐breeding patterns. An individual's position along this capital–income continuum may shift with ontogeny or in relation to environmental conditions, so breeding patterns are a conditional reproductive strategy. Poor‐feeding environments can lead to delayed maturation, skipped spawning, fewer spawning events per season or fewer eggs produced per event. In a few cases, variations in feeding environments appear to affect recruitment variability. These flexible processes of energy acquisition and allocation allow females to prioritize their own condition over their propagules' condition at any given spawning opportunity, thereby investing energy cautiously to maximize lifetime reproductive value. These findings have implications for temporal and spatial sampling designs, for measurement and interpretation of fecundity, and for interpreting fishery and ecosystem assessments.  相似文献   

Age-independent diameter increment models for mixed mountain forests     

Ciceu  Albert  Bronisz  Karol  Garcia-Duro  Juan  Badea  Ovidiu 《European Journal of Forest Research》2022,141(5):781-800

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