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241.
Direct and indirect methods have been used to describe patterns of movement of fishes, but few studies have compared these
methods simultaneously. We used 20 years of trawl survey data and 1 year of acoustic telemetry data to evaluate the vertical
and horizontal movement patterns of spotted ratfish Hydrolagus colliei in Puget Sound, WA, USA. Densities of large ratfish (≥30 cm) were higher at the deepest depths trawled (70 m) during daylight
hours, whereas densities were similar across depth zones (to 10 m) at night. Acoustic tracking of ratfish showed distinct
diel patterns of movement and activity level; ratfish moved into shallow, nearshore habitats at night from deeper, offshore
habitats during the day and made ~3 times more moves at night than day in shallow habitats. Broader spatial patterns depended
on where ratfish were tagged: one tag group remained in one general location with few excursions, whereas a second tag group
moved within a 20-km band with some individuals moving >90 km. These data will help inform food web models’ abilities to quantify
interspecific interactions between ratfish and other components of their community. 相似文献
242.
Alexandra?ZieritzEmail author Gemma?Clucas Lauren?Axtmann David?C.?Aldridge 《Marine Biology》2012,159(4):863-872
When feeding on blue mussels (Mytilus edulis), oystercatchers (Haematopus ostralegus) either stab into the mollusc’s gaping valves or hammer through its dorsal or ventral shell. Whilst the selectivity of hammering
and stabbing oystercatchers for specific prey morphologies has been well studied, the way in which the effects of environment
on M.
edulis morphology can in turn affect feeding methods of H. ostralegus is very poorly understood. Based on morphological analyses on randomly selected shells from three intertidal zones, this
study failed to detect differences in morphology or distribution of dorsally and ventrally hammered shells but confirms the
finding of previous authors that hammering oystercatchers select thinner mussels than stabbing birds. Additionally, we show
that this difference in optimal prey morphology can lead to spatial patterns in oystercatcher feeding behaviour. Whilst at
the low intertidal and higher mid intertidal zones, characterised by comparatively thick shells, most empty shells had apparently
been stabbed, hammering was the dominant feeding behaviour at the lower mid intertidal zone, where shells were thinner. Preference
of hammering birds for smaller mussels was not ubiquitous. Sagittal shell shape was predominantly influenced by allometric
growth effects and had only minor effect on prey selection. All oystercatchers preferred less inflated mussels, with the degree
of shell inflation gradually increasing with higher intertidal elevation. Our results illustrate the importance of small-scale
patterns in prey ecophenotypes in determining the distribution and feeding dynamics of wading birds. 相似文献
243.
Combining field and laboratory work, this study investigated the reproductive cycle, aggregative behavior, spawning periodicity,
development and early growth of the sea star Henricia lisa living at bathyal depths off eastern Canada. Marked differences were found between individuals from ~1,300 and ~600 m deep.
The former had a male biased sex ratio and an aperiodic reproductive cycle, whereas the latter displayed an equal sex ratio
and a biannual breeding pattern. Furthermore, the maximum size was larger and female fecundity roughly five times higher in
shallower compared to deeper populations. In the tanks, aggregative behavior was recorded twice a year during the summer and
winter breeding periods. The onset of aggregations and spawning coincided with a temperature of 3–4°C. Males spawned first
and females typically responded inside 30–60 min. Between 12 and 20 eggs were retained to be brooded under the arched arms
of the female, whereas the remainder were broadcasted and developed without parental care. The fertilized eggs underwent a
first cleavage after 12 h, reached the brachiolaria stage in 1 month, became juveniles within 3–4 months and reached ~ 4 mm
in diameter after 14–17 months of growth. The embryos and juveniles developed at the same rate whether brooded or not, and
development of winter cohorts was typically slower due to lower prevailing temperatures. This study of H. lisa provides the first evidence of lecithotrophy in a seasonally breeding deep-sea echinoderm and of brooding in a deep-sea asteroid. 相似文献
244.
Nicholas L. Clesceri Sidney J. Curran Richard I. Sedlak 《Journal of the American Water Resources Association》1986,22(6):983-990
ABSTRACT: Export coefficients (kg/km2/yr) for dissolved ortho-phosphate (OP), total phosphorus (TP), total inorganic nitrogen (TIN), and total nitrogen (TN) were derived for watersheds in Wisconsin using data bases available for 17 basins from the U.S. Environmental Protection Agency — National Eutrophication Survey, U.S. Geological Survey, and the Wisconsin Department of Natural Resources. Three general land use categories, representative of most regions in Wisconsin, were established: forest, mixed, and agricultural. Data for the 17 basins indicated greater exports of OP. TP, TIN, and TN as the percentage of forest decreased and agriculture increased. These region-specific coefficients are compared to the values reported in the literature representing much broader areas of the U.S. 相似文献
245.
The paper examines characteristics of science parks in the face of employment decline, raising doubts about the scale of their success. The paper re‐examines previous research on the existence and causes of long waves of economic growth and decline and concludes that if these are not generated by innovations in production, then it should not be surprising that science parks have not lived up to expectations. 相似文献
246.
Nicholas Budd 《Natural resources forum》1995,19(2):99-106
Exporters of raw materials and commodities in developing countries depend on the availability of hard currency pre-export financing and the adoption of pricing policies which meet the requirements of the international marketplace to produce and market their products in an efficient manner. The author has identified a number of structural obstacles which impede access both to international financing and to price risk management tools which could be overcome through relatively simple modifications in export regulations, currency controls, insurance regulations and in laws concerning title to goods. 相似文献
247.
Hong?ZhengEmail author Yoshitaka?Nitta Isamu?Yokota 《Journal of Material Cycles and Waste Management》2004,6(2):153-161
In this article, the systems for the collection and intermediate processing of used beverage cans (UBCs) are compared and analyzed, focusing on the time taken and the cost of processing, the energy consumption, and the emissions of CO2, SO
x
, and NO
x
, during the process. We found that cases where the UBCs were crushed in the discharging process gave better results, and how the UBCs were collected was the most important factor. It was more desirable to treat UBCs in one place than in two places. When the transportation distance was longer, the pressed form of UBCs was more convenient. When the transportation distance was short, the original form, the crushed form, and the shredded form of UBCs were all suitable. That is, the contribution of the transportation process to the evaluation was large when the transport distance was long, and the contribution of the treatment process was large when the transport distance was short. 相似文献
248.
Seung-Hwan?LeeEmail author Tsutomu?Ohkita 《Journal of Polymers and the Environment》2004,12(4):203-210
Ring-opening polymerization of cyclic esters (-caprolactone, -valerolactone, and l-lactide) onto liquefied biomass (LB) was conducted to obtain the polyester-type polyol and to regulate the characteristics of LB. IR and 1H-NMR spectra of the obtained polyol showed that the polymerization was successfully conducted in the presence of acid catalyst, which is used in liquefaction. The molecular weight (Mw), hydroxyl value, and viscosity were controllable by changing the reaction conditions. Polyester-type polyurethane foams with a wide range of properties were prepared from the obtained polyol with the appropriate combinations of foaming agents. 相似文献
249.
Abdul G.?LiewEmail author Azni?Idris Abdul A.?Samad Calvin H.K.?Wong Mohd S.?Jaafar Aminuddin M.?Baki 《Journal of Material Cycles and Waste Management》2004,6(1):41-47
Bricks produced from sewage sludge in different compositions were investigated. Results of the tests indicated that the sludge proportion is a key factor in determining the brick quality. Increasing the sludge content results in a decrease in brick shrinkage, bulk density, and compressive strength. Brick weight loss on ignition was mainly due to the contribution of the contained organic matter from the sludge being burnt off during the firing process, as well as inorganic substances found in both clay and sludge. The physical, mechanical, and chemical properties of the bricks that were supplemented with various proportions of dried sludge from 10 to 40wt% and generally complied with the General Specification for Brick as per the Malaysian Standard MS 7.6:1972, which dictates the requirements for clay bricks used in walling in general. A standard leaching test method also showed that the leaching of metals from the bricks is very low. 相似文献
250.
Masahiro?ShimadaEmail author Takahiko?Iida Kensuke?Kawarada Yoshifumi?Chiba Toshihiro?Mamoto Takayuki?Okayama 《Journal of Material Cycles and Waste Management》2004,6(2):111-118
We have previously manufactured activated carbon using waste paper board, which was prepared by adding 8% phenol resin adhesive to torn waste newspaper and hot-pressing. In this study, the pretreatment process of the raw material was simplified; the waste paper was extruded to form granules. The activated carbon was manufactured by the carbon dioxide activation method using the granules as the raw material. The properties of the activated carbon were evaluated based on the pore structure, the iodine adsorption number, and the adsorption of toluene vapor in a sealed chamber. The activated carbon, which was manufactured at an activation temperature of 1100°C and a treatment time of 60min, exhibited a specific surface area of 1241m2/g and an iodine adsorption number of 1120mg/g. These results were similar to those obtained for two commercially available activated carbons. The extent of toluene vapor adsorption by this activated carbon was similar to that observed for the two commercial activated carbons over a period of 130min. 相似文献