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1.
Abstract

Rough and smooth skates (Dipturus nasutus (Banks 1841) and/), innominatus (Garrick &; Paul 1974)) were aged by counting growth bands on X‐rays of thick sections of vertebral centra. Band counts were imprecise, but there was no between‐reader bias. Age estimates were not validated. The oldest rough skate was 9 years old, but few were more than 6 years old. Females may live longer than males. The combined sexes von Bertalanffy growth curve was Lr = 91.3 (1 ‐ e?0.16[t + 1.20]). Half the males matured by c. 52 cm pelvic length (PL) and 4 years, and females by 59 cm PL and 6 years. The oldest smooth skate in the sample was 24 years, but longevity probably exceeds that. Females appear to live longer than males. The combined sexes von Bertalanffy growth curve was: Lt = 150.5 (1 ‐ e?0.095[t + 1.06]). Half the males matured by c. 93 cm PL and 8 years, and females by 112 cm PL and 13 years. Smooth skate are late maturing and long‐lived relative to other skates, whereas rough skate are early maturing with a moderate life span.  相似文献   

2.
Growth of the red gurnard, Chelidonichthys kumu (Lesson and Garnot), from Pegasus Bay, Canterbury, was measured during 1966–67. Otoliths were used as an indicator of fish growth; mean length‐at‐age data were obtained from back‐calculated fish lengths at the time of formation of successive annual rings in the otoliths. Growth in length was found to be adequately expressed by the von Bertalanffy growth equation :

lt = 52.0 [1 ‐ e0.406 (t‐o.291)]

(where lt is the fork length in cm at age t). The length: weight relationship was:

w = 78.56 × 10‐4 l 3.072

(where w is the weight in grams). From this relationship, growth in weight was described by the equation:

wt = 1469 [1 ‐ e‐0.406 (t‐0.291)]3.  相似文献   

3.
Abstract

Rates of coastal erosion and accretion for New Zealand are calculated for the period since early European colonisation. Methods used for calculating rates from cadastral plans, vertical aerial photographs and field measurements are described, evaluated, and illustrated with examples. The most natural reference line for measurements of shoreline changes and for defining the seaward boundary of land is the seaward limit of land vegetation. Measurements made from air photographs and plans at scales larger than 1:4000 have errors less than ± 1 m. As scales become small, errors increase proportionately. Along depositional shorelines, erosion and accretion generally occur at 0.5–4.0 m.y?1. Maximum erosion and accretion rates are 25.4 m.y?1 at North Kaipara Head and 68.9 m.y?1 at Farewell Spit respectively. Cliff recession generally occurs at 0.25 ‐ 1.0 m.y?1 with maximum rates of 2.25 m.y?1 for mudstone cliffs at Cape Tumagain and 3.46 m.y?1 for conglomerate cliffs at Ngapotiki.  相似文献   

4.
Squalus acutipinnis (previously included in S. megalops) individuals caught off the east, south and west coasts of South Africa were examined for siphonostomatoid copepod infection. Collected siphonostomatoids were fixed and preserved in 70% ethanol and studied under microscopes using both transmitted and incidental light. The copepods were identified and the host-parasite associations estimated by calculating their prevalence, mean intensity and mean abundance. The siphonostomatoids represented four families and six species, and included new host records for Nemesis sp., Lernaeopoda sp. and Eudactylina acanthii, and a new geographical record for E. acanthii. Squalus acutipinnis individuals were infected by relatively low loads of siphonostomatoids. The most commonly found species was Achtheinus pinguis, the only species found off all three coasts. There was no difference in the prevalence of A. pinguis in sharks sampled off the three coasts but the highest mean intensity was found on the East Coast followed by the West Coast. The overall prevalence of A. pinguis was 33.6%, and was an order of magnitude higher than that of the other siphonostomatoids recorded. At such low levels of infection it will thus be necessary to examine a large number of hosts to determine the biodiversity of siphonostomatoids and geographical differences in prevalence in South African waters.  相似文献   

5.
The sandy substrate of Lake Taharoa (west coast, North Island, New Zealand ‐ 35°50'S, 173°41'E) is covered by communities of filamentous algae that extend from the exposed beach down to 21 m depth. The algae bind the sand to form crusts and mats which may break off as discrete plates. The dominant species are the blue‐greens Microcoleus, Nostoc, Phormidium, Lyngbya, Oscillatoria, Scytonema, Stigonema, Shizothrix, Calothrix, Dichothrix, Tolypothrix, and Anabaena, with occasional high concentrations of the desmid Cylindrocystis. Nitrogenase activity, measured by acetylene reduction, showed a wide range of rates (4–150 μmol C2H4 m‐2h‐1). Estimates of annual rates of nitrogen fixation by the Taharoa communities are comparable with those for periphytic blue‐green algae‐dominated systems reported elsewhere.  相似文献   

6.
为了研究烟曲霉次生代谢产物,我们采用硅胶柱层析、sephadex LH-20凝胶柱层析、半制备液相色谱等分离方法对来源于印度洋深海区的烟曲霉(Aspergillus fumigatus)的乙醇提取液进行系统的次生代谢产物分离,根据所分离得到的化合物的理化性质和波谱数据确定化合物的结构。共分离鉴定了15个化合物,其中11个二酮哌嗪类生物碱(diketopiperazine),4个喹唑啉类衍生物(fumiquinazoline),分别为:fumitremorgin B(1),13-oxofumitremorgin B(2),fumitremorgin C(3),12-hydroxyfumitremorgin(13),3-hydroxyfumiquinazoline A(14)和fumiquinazoline E(15)。分离得到的15个化合物,丰富了烟曲霉次生代谢产物的类型,为烟曲霉的开发利用提供了化学研究基础。  相似文献   

7.
Between 1957 and 1962, 4155 snapper, Chrysophrys auratus (Bloch & Schneider), were tagged and released at a number of sites in Victoria. By the end of June 1972, 210 had been recaptured, and knowing their lengths at release and recapture and the periods at liberty, we determined the von Bertalanffy growth parameters K and L 8 . The values (with 95% confidence limits) were: eastern stock ‐ K = 0.071 ± 0.040, L8 = 968 ± 325 mm; western stock ‐ K = 0.068 ± 0.023, L8 = 1079 ± 209 mm; combined stocks ‐ K = 0.062 ± 0.019, L 8 = 1119 ± 215 mm. No difference between the stocks was apparent when we compared the estimates of K and L 8 separately; however, when the estimates of K and L 8 were compared together, a Wilcoxon's test gave a significance probability of 1.5%, indicating a difference in growth rate between the stocks. For the range of lengths of snapper recaptured, this difference was evidently caused by faster growth of snapper from the western stock.  相似文献   

8.
Ciona intestinalis sp. A (Tunicata, Ascidiacea) is a marine invertebrate with a widespread distribution and high invasive potential, yet little is known about its ecology. Here, the macrodynamics of demographic and reproductive trends were first determined using archive data covering 2002–2012. Species abundance in the central Tyrrhenian Sea (Campania, Italy ‐ NW Mediterranean) displayed Poisson distribution across 2002–2008, massive die‐off in 2009/2010 and population recovery in 2011/2012. We defined the seasonal ranges of sea surface temperature in which sampling size, animal size and reproductive status reached their highest values. In 2003/2004, self and non‐self fertilization appeared to follow reverse trends across the year. The long‐term recording run here on Ciona intestinalis sp. A provides novel insights into its population biology and ecology, and represents a valuable tool for sampling management and research planning.  相似文献   

9.
The Po River runoff strongly affects the oceanographic and ecological characteristics of the Northern Adriatic Sea. Catalysed reported deposition ‐ fluorescence in situ hybridization (CARD‐FISH) analysis was employed to assess how the composition of the coastal bacterioplankton community is influenced by the river runoff in two different seasons (spring and autumn). Samples were collected from the water column along a coastal–offshore transect in the Northern Adriatic Sea at different depths. Four clone libraries were then constructed from coastal (0 m) and offshore waters (?65 m). Higher abundances of bacteria were recorded in coastal waters as compared with the offshore samples. This result was mainly due to the trophic state of the water column, and it was related to salinity. Particularly, Actinobacteria and Gammaproteobacteria were affected by the riverine inputs, whereas Bacteroidetes and Alphaproteobacteria showed only minor responses. This was particularly clear in the autumn sample, in which a clear difference between the coastal and the offshore samples was found due to a strong influence of the less saline river water with high nutrient concentrations. Analysis of 205 partial length 16S rRNA gene sequences indicated a high diversity with the dominance of Alphaproteobacteria, Bacteroidetes and Gammaproteobacteria mainly affiliated to coastal and marine bacterioplankton clades. Actinobacteria were also detected and, together with Gammaproteobacteria, strongly follow the freshwater intrusion. Overall, our results indicate that the seasonal difference in the Po River discharge greatly affects the bacterioplankton community. In spring we observed a smooth transition from coastal to open‐sea conditions owing to the more superficial freshwater plume. In autumn the deeper freshwater intrusion in the coastal site and thermal stratification offshore resulted in a marked difference between the coastal and offshore microbial communities.  相似文献   

10.

An analysis of the New Zealand whale stranding record by M. W. Bradyn. Science and Research Series 29. ISSN 0113–3713, ISBN 0–478–01278–6. Available from Department of Conservation, Wellington. Price: $15.00.

Fish quality control by computer vision, edited by L. F. Pau and R. Olafsson. Published by Marcel Dekker, Inc.  相似文献   

11.
For classical Hamiltonian with general form we find a new convenient way to obtain its normal coordinates, namely, let H be quantised and then employ the invariant eigen-operator (IEO) method (Fan et al. 2004 Phys. Lett. A 321 75) to derive them. The general matrix equation, which relies on M and L, for obtaining the normal coordinates of H is derived.  相似文献   

12.
在研究中国真马尾藻亚属SubgenusSargassum刺托组SectionAcanthocarpicae团徽托序亚组SubsectionGlomerulatae宾德系SeriesBinderiana宾德种群SpeciesGroupBinderia过程中,发现该种群新种3个,它们是中间马尾藻SargassumIntermediumTsengetLusp.nov.,模式标本于1975年5月15日由李伟新采自广西涸洲岛,模式标本号AST75-0594;琼海马尾藻SargassumqionghaienseTsengetLusp.nov,模式标本于1983年7月12日由陆保仁采自海南省琼海县沙,模式标本号CA83-0016;裂开马尾藻SargasumerumensTsengetLusp.nov,模式标本于1982年4月23日由陆探仁采自海南省三亚市鹿回头,模式标本号AST82-0413。模式标本均存于中国科学院海洋研究所植物标本室。  相似文献   

13.
Book reviews     

R. Donaghe, R. Chaney, and M. Silver, eds. 1988. Advanced Triaxial Testing of Soil and Rock, STP 977. Philadelphia: American Society for Testing and Materials. Hard Cover, 904 pp., 625 illus. $120.00.

Adrian F. Richards, ed. 1988. Vane Shear Strength Testing in Soils: Field and Laboratory Studies, STP 1014. Philadelphia: American Society for Testing and Materials. Hard Cover, 312 pp., 253 illus. $79.00.  相似文献   

14.
Abstract

Investigations aimed at obtaining knowledge about the environmental effects of mining aggregate from the sea bottom were carried out on the Stupsk Bank. Special attention was given to the magnitude and reach of changes of hydrologic conditions, in that to changes in concentration of matter suspended in sea water, and to dynamics of the sea bottomchange of bottom relief, resulting from both natural causes and from mining of the aggregate.  相似文献   

15.
Fish stocks associated with seamounts may be particularly susceptible to overexploitation. From January to July 2001, the Spanish Oceanographic Institute (IEO) conducted an experimental fishing survey entitled ‘Palguinea-2001’ on the seamounts of the Sierra Leone Rise. Beryx splendens (commonly called alfonsino) is the main commercial demersal fish associated with this area. The aim of this study was to investigate the effects of a demersal longline fishery targeting B. splendens on the previously unexploited small Machucambo Seamount over a short time-scale, and also to consider trends in pooled catch rate at another four seamounts. During 110 fishing days at Machucambo, a total catch of 207 tonnes of B. splendens was taken with a fishing effort of 1 309 070 hooks. A spectral analysis and red-noise spectra procedure (REDFIT) algorithm was used to identify the red-noise spectrum from the gaps in the observed time-series of catch per unit effort by weight. Our results show the potential impact of longline fishing pressure on an unexploited ecosystem – after approximately 50 fishing days, the stock appeared to decline substantially, as reflected by a marked drop in catch per unit effort. The apparent rapid decline of the stock might be related to the small size and the virgin state of the Sierra Leone seamounts. The results could be extrapolated to similar small seamounts elsewhere.  相似文献   

16.
Abstract

The influence of temperature on the acute toxicity of a technical formulation (86%) and pure formulation (99%) of pentachlorophenol (PCP) to less than 24‐h‐old Simocephalus vetulus neonates was determined with 48‐h static toxicity tests. The technical grade PCP was significantly more toxic to S. vetulus than the pure PCP (P < 0.05). Sensitivity of S. vetulus to technical PCP also significantly increased with temperature (P < 0.05), but a significant temperature effect was not found with the pure PCP. The mean 48‐h LC50 values for neonates exposed to technical PCP were 140 and 199 μg l?1 at 22°C and 16°C, respectively, and for those exposed to pure PCP were 262 and 304 μg l?1, respectively.  相似文献   

17.
Abstract

Cone resistance and laboratory strength measurements have been compared for stiff overconsolidated clays from five oil and gas fields in the North Sea. The clays considered are glacial in origin. The best agreement between cone resistance and laboratory strength is found by using an Nk factor equal to 17 in the formula

qc = Nk . Su + γZ.

The study shows that the cone gives highly reproducible results, whereas there is a considerable scatter in the laboratory strength determinations. When making use of CPTs for preliminary design, the authors recommend assuming an Nk of 15–20, depending on the type of problem under consideration.  相似文献   

18.
Abstract

The stability of trenches for buried submarine pipelines (TBSPs) during excavation and/or prior to backfilling has not received enough attention in the literature. In this study, the undrained stability of TBSPs in horizontal and inclined seabeds with shear strengths increasing linearly with depth is investigated using the lower and upper bound finite element limit analysis (FELA). The surcharge due to excavated soils and trenching machines is reasonably considered. Extensive parametric studies are performed on the trench slope angle β, normalized width of trenching machine L/H, dimensionless strength gradient Hk/su0 and the volume ratio R (for inclined seabed only) of the excavated soil stacked on the upside and downside of trenches. The actual results are accurately bracketed by the computed upper and lower bound solutions. For the trench with horizontal seabeds, the maximum stability can be obtained under β?=?70°–80°. For inclined seabeds, the global stability of TBSPs roughly reaches peak value for different combinations of L/H and β when R?=?0.15–0.3.  相似文献   

19.
ABSTRACT

The tetrasporophytic ‘Trailliella’ stage of the red algal genus Bonnemaisonia is reported for the first time from the Southern Hemisphere. Here we describe a bloom of the tetrasporophyte of B. hamifera from the mouth of the Waikouaiti River, Karitāne, South Island, where it occurred as thousands of free-floating tufts up to 1?cm wide in shallow water, accumulated in windrows on sand banks and beaches, and in the water column at depths of 10–12?m on the adjacent open coast. Gametophytic stages have not yet been found in New Zealand. The material collected to date is strictly vegetative, and reproduction occurs via fragmentation. The identity of the New Zealand samples as B. hamifera was confirmed by both morphology and rbcL sequencing. The abundance and floating dispersal of B. hamifera suggests that it is invasive and will become widely distributed in New Zealand.  相似文献   

20.
ABSTRACT

The sinking of the MV Rena on Astrolabe Reef (Otaiti) in the Bay of Plenty, New Zealand, resulted in the release of oil and ship debris, including dangerous goods carried as cargo. Two key questions of concern to the public and environmental managers were posed immediately: what was the impact of the Rena oil spill and how long would it take for the marine environment to recover? The research that began immediately after the ship grounded provided answers, as documented in this special issue.  相似文献   

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