摘要:

In Bedford Basin, Nova Scotia,Sagitta eleganshas two main generations per year, one in the spring and one in the fall. The biomass ofS.elegansper 100 m3of water was an order of magnitude greater in the Basin than that reported previously for St. Margaret’s Bay, N.S. The growth rate and the number of degree days needed to mature were similar to those found forS.elegansin St. Margaret’s Bay. Annual turnover rate forS.elegansin the Basin was 5.6 and yearly production was estimated at 27.0 kcal per year or 9.0% of the yearly copepod production. It was calculated that the species used 90.4 kcal per m2per year in respiration. The percentage of the total yearly production of copepods consumed byS.eleganswas estimated at 36%.

ISSN:0706-652X    

DOI:10.1139/f73-063

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

An integrated, quantitative method is described for the determination of chlorophylls and chlorophyll degradation products in freshwater phytoplankton and sediments. Prior to extraction, algal samples were concentrated by filtration through glass fiber filters while sediment samples were lyophilized. All materials were extracted in a mixture of acetone, methanol, and water (80:15:5) by ultrasonication in a glass extraction chamber refrigerated at −10 C. Extracts were filtered through solvent-resistent membrane filters, rather than centrifuged, and then fractionated without prior drying by reverse-phase thin-layer chromatography on oil-impregnated layers of kieselguhr G. Using three chromatographic systems consisting of different developing solvents and oil phases (triolein, parrafin oil, and castor oil), rapid, artefact-free separations of chlorophyllsa,b, andcand 18 of their derivatives were obtained. Individual pigments were estimated by direct, in situ thin-layer scanning with a filter fluorometer. The sensitivity and reproducibility of the procedure are ca. 2 ng and 11%, respectively. In routine operation, the method is fast and relatively simple, a complete analysis being accomplished in 1.5 hr.

ISSN:0706-652X    

DOI:10.1139/f73-064

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Creek chub (Semotilus atromaculatus) are omnivorous with a diet consisting of berries, insects, crayfish, noncyprinid fishes, and frogs. In 1971, in the Mink River, most spawning occurred between the middle and end of May in shallow (< 25 cm) fast-flowing (> 15 cm/sec) waters. Fecundity varied from 1146 to 7539 ova per female. In summer most chub in their 1st and 2nd years occupied moderately deep waters (< 50 cm) with little current (0–30 cm/sec), while most older chub occupied deeper waters. In autumn chub were most abundant in deep (> 50 cm) sheltered pools, where they overwintered.

ISSN:0706-652X    

DOI:10.1139/f73-065

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Cellular changes attributable to copper were observed in the mechanoreceptors of the lateral line canals in the head of adult mummichog (Fundulus heteroclitus) and Atlantic silverside (Menidia menidid). The epithelium of these canals was also altered inF.heteroclitus. In both species, lesions were observed in the olfactory organs, which included the chemoreceptive sites. These manifestations of copper poisoning were evident at all studied concentrations (0.5, 1.0, and 5.0 mg/liter) of the metal. InM.menidiadilation of blood vessels was apparent, and in five cases hemorrhage had occurred in the brain and in periorbital connective tissues.Renal lesions inF.heteroclitusexposed to 1.0 and 5.0 mg/liter of copper were apparent; these changes could not be identified inM.menidia. Hepatic changes were not detectable by light microscopy in either species following external exposures to copper. High concentrations of copper administered intraperitoneally toF.heteroclitusdid induce liver damage.Fry ofF.heteroclituswere more sensitive to copper than were the adults or their zygotes. The emergence of larval forms from the zygote, the time required for emergence, and their survival was impaired by the metal. Lesions were not evident in developing sensory areas of the lateral line or the olfactory systems in these immature forms.

ISSN:0706-652X    

DOI:10.1139/f73-066

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Sublethal effects of aerated neutralized, filtered, full bleach kraft mill effluent (BKME) on circulation and respiration of Pacific salmon were examined. Ventilatory water flow, oxygen uptake, cough frequency, and buccal pressure increased in a group of 19 sockeye salmon,Oncorhynchus nerka, 207–321 g, at 10.5 ± 0.5 C, upon initial exposure to sublethalBKMEconcentrations. The threshold concentration for these responses appreared to be around 20% of the 4 dayLC50 (static bioassay).Following overnight exposure toBKME, ventilatory volume, oxygen uptake rate, cough frequency, and oxygen utilization tended to approach pre-exposure levels, particularly at the higher sublethal contractions. Changing effluent toxicity, acclimation phenomena, or physiological adjustment are discussed as possible explanations for these results.Measures of arterial oxygen tension in sockeye salmon indicated that arterial tension declines rapidly and remains depressed following up to 24 hr exposure toBKME(33–47% of 4 dayLC50). On the average this decline represented a 20% decrease in oxygen saturation of the blood. Decreased arterial PO2may be due to mucous production at the gills and resulting gas diffusion problems, as well as abnormalities in ventilation. Reduction in scope for activity might result from impaired oxygen uptake at the gills. A similar response was observed in rainbow trout,Salmo gairdneri.

ISSN:0706-652X    

DOI:10.1139/f73-067

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Ten years research on metabolic rates and swimming speeds of sockeye salmon (Oncorhynchus nerka) ranging in weight from 2 to 2000 g, at temperatures from 2 to 24 C, is reviewed and summarized. Analysis of weight–slope relations (bvalues) at three temperatures, using log–log transformations, provided an overall mean of 0.88 for standard metabolism and 0.99 for active metabolism. A previously determined semilog equation for temperature effect on standard metabolic rate (at approximately 50 g) was supported by supplementary data at 2 C. Predictive graphic models in the form of isopleths of metabolic rates and critical swimming speeds in relation to weight, length, and temperature are depicted. These provide a composite presentation useful in estimating the metabolic rate and maximum sustained speed for any size and temperature.

ISSN:0706-652X    

DOI:10.1139/f73-068

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

A new species of marine triclad turbellarian,Sabussowia wilhelmiisp. nov., is described from the Pisquid River, Prince Edward Island, Canada. This represents the first occurrence of the genus and of the subfamily Cercyrinae of the Procerodidae in North America. The genus is discussed and a key to the known species is provided. A detailed discussion of the status ofVortex warreniof Girard andProcerodes warreniof Wilhelmi is given. The identity of the former cannot be ascertained. The latter could be aSabussowiaspecies, but, in the absence of fully mature material, this question cannot be resolved. Both names are regarded as nomina dubia, and the suppression of the genusFoviaof Girard is recommended.

ISSN:0706-652X    

DOI:10.1139/f73-069

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Red blood cell counts and hematocrits of juvenile coho salmon were unaltered by 12-hr exposure to neutralized kraft pulp mill effluent, although hematocrits were decreased by exposure for 25 days. The number of circulating immature erythrocytes increased in effluent-exposed fish in both the 12-hr and 25-day exposures. The number of circulating small lymphocytes decreased markedly after 12-hr exposure. However, following the prolonged exposure, the number of small lymphocytes returned to normal, while the number of circulating neutrophils increased.The level of plasma glucose increased in fish exposed to effluent for 12 hr, and decreased in fish exposed for 25 days. Liver glycogen was not altered significantly during either exposure period.No pathological changes attributable to exposure to kraft pulp mill effluent were observed in the tissues examined, including the spleen, kidney, gill, interrenal gland, skin epithelium, and thyroid gland.Results are discussed in terms of a stress response.

ISSN:0706-652X    

DOI:10.1139/f73-070

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

The two reciprocal F1hybrids of brook trout (Salvelinus fontinalis) and lake trout (S.namaycush) had similar times to death on exposure to several lethal high temperatures for a series of acclimation temperatures. These hybrids resembled the brook trout, the more resistant parent, more than the lake trout. The F2hybrids were intermediate in resistance to the parent species, and the backcrosses intermediate between the F2hybrids and the respective parents. After acclimation to 5 and 10 C, F2’s and backcrosses arising from the F1hybrid of brook trout maternal origin were consistently higher in resistance than the F2and backcrosses arising from the F1hybrid of lake trout maternal origin. After acclimation to 20 C and above, differences associated with the maternal origin of the F1hybrid were not found.The number of effective factors segregating was estimated using the techniques of variance component analysis. A genetic model with two codominant factors was found to fit the data for 5 and 10 C acclimation, and one with five factors and dominance of the brook trout factors was found to fit the data for the higher acclimation temperatures.

ISSN:0706-652X    

DOI:10.1139/f73-071

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

A number of regression situations in fish and fishery biology are examined, in which both of the variates are subject to error of measurement, or inherent variability, or both. For most of these situations a functional regression line is more suitable than the ordinary predictive regressions that have usually been employed, so that many estimates now in use are in some degree biased. Examples are (1) estimation of the exponent in the weight:length relationship, where almost all published values are somewhat too small; and (2) estimating the regression of logarithm of metabolic rate on log body weight of fish, where the best average figure proves to be 0.85 rather than 0.80. In the very common situation where the distribution of the variates is non-normal and open-ended, a functional regression is the most appropriate one even for purposes of prediction. Two ways of estimating the functional regression are (1) from arithmetic means of segments of the distribution, when computed symmetrically; and (2) from the geometric mean of one predictive regression and the reciprocal of the other. The GM regression gives a more accurate estimate when it is applicable; it is appropriate in all situations where the variability is mainly inherent in the material (little of it due to errors of measurement), or where the measurement variances are approximately proportional to the total variance of each variate; and it is the best estimate available for short series with moderate or large variability even when neither of these conditions applies. When error in X results solely from the measuring process the predictive regression of Y on X is also the functional regression if observations of X are not taken at random but rather have pre-established values, as is usual in experimental work. The uses of the various regressions are summarized in Table 8.

ISSN:0706-652X    

DOI:10.1139/f73-072

出版商:NRC Research Press    

年代:1973

数据来源: NRC