摘要:

The devastation and recovery of the zooplankton communities were studied in conjunction with the application of rotenone to two mountain lakes in Jasper National Park. Crustacean plankters were absent for about 6 months after treatment, but rotifers and net phytoplankton were never completely absent. All crustacean species except one reached prerotenone abundance in about 3 years, probably the minimum time for recovery in these lakes.The speed of recovery is likely related to fecundity, time of reproduction, and the presence of resistant stages.Diaptomus sicilishad not reached reproductive maturity when rotenone was applied, and it was the last species to recover to its original numbers.Some species not found in samples before application were found in small numbers afterwards, probably due in part to movement from the littoral into the limnetic zone. In both lakes, blooms of small cladocerans after treatment were soon supplanted by increases in large cladoceran numbers. Most variations in composition and abundance after rotenone were likely due to changes in competition and predation pressures rather than to changes in environmental factors or to direct effects of rotenone.

ISSN:0706-652X    

DOI:10.1139/f70-159

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

Gastric juice of lobster hydrolyzed the following substrates: triolein (enzymic activity: lipase), tributyrin ("lipase"), Azocoll(R)(proteinase), TAME and BAEE ("trypsin"), ATEE ("chymotrypsin"), HPLA ("carboxypeptidase A"), DNA (deoxyribonuclease), RNA (ribonuclease),p-nitrophenyl-phosphate (phosphatase), andp-nitrophenyl-N-acetyl-β-glucosaminide (chitobiase). (The quotation marks signify that the substrate specificities are typical of the quoted enzymes of mammalian or microbial origin. The spectra of specificities, however, of these enzymes and the corresponding enzymes of lobster are not necessarily identical.) Very low activities were found against RBB-starch (amylase)p-nitro-phenyl-α-(and β)-glucopyranoside(α- and β-glucosidase),p-nitrophenyl-β-galactopyranoside (β-galactosidase), and chitin azure (chitinase). No activities corresponding to phospholipase (lecithin), carboxypeptidase B (benzoylglycyl-L-arginine), elastase, glycylglycine dipeptidase, or leucine aminopeptidase were found.Gel filtration of gastric juice proteins on Sephadex(R)G-100 yielded estimates of molecular weights, among them: chitobiase 100,000; phosphatase 80,000; lipase 43,000; DNase 33,000; "trypsin" and ribonuclease 25,000; and two proteinases with optima aroundpH 4 and 8 and the low molecular weight of 12,500; proteolytic activity atpH 4 was also associated with the molecular weights 25,000 and 50,000.In ion-exchange chromatography, enzymes were eluted from DEAE-cellulose in the following sequence of increasing anionic character: chitobiase, proteinase (pH 4), proteinase (pH 8), lipase, "carboxypeptidase A," DNase, phosphatase, and "trypsin" and "chymotrypsin."Of the principal enzymes, only one (chitobiase) had its optimum at thepH 5 normal for lobster gastric juice. The lipase had an optimalpH around 7, phosphatase near 9, and "trypsin" near 8; proteolytic activity shows a maximum atpH 7–8 and another maximum, unusual for Crustacea, atpH 4.Much of the protein of gastric juice could not be connected with any enzymic activity. The proportion of nonactive protein seemed to increase with starvation of the animals. We found no evidence for the occurrence of zymogens.

ISSN:0706-652X    

DOI:10.1139/f70-160

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

Of 17 amino acids and other organic compounds tested at high concentration, 13 elicited feeding and walking responses in lobsters significantly greater than those elicited by seawater controls, but only 7 of 29 were stimulatory at low concentrations (alanine, beta alanine, glutamic acid, proline, succinic and malic acids, and tyrosine). Fourteen of 15 mixtures of 2–9 amino acids were stimulatory. There may have been potentiation in mixtures with cysteine HCl, lysine, glycine HCl, and methionine and antagonism in some with alanine and arginine. Freshly prepared seawater extracts of cod, shrimp, and lobster muscle were more stimulatory than any of the compounds or mixtures.Male lobsters responded more frequently to water from a tank with a recently moulted mature female lobster than to water from a tank with a nonmoulted mature female or a moulted or a nonmoulted male. It is possible that moulted females release a sex attractant (pheromone).

ISSN:0706-652X    

DOI:10.1139/f70-161

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

Yellow phosphorus was lethal to seawater-maintained brook trout and smelt at concentrations as low as 0.5 μg/liter. Trout that were exposed to low concentrations of yellow phosphorus (0.5 and 7.0 μg/liter) for 50 or more hours turned red and showed signs of extensive hemolysis. At death, all trout that had been exposed to 104 μg/liter yellow phosphorus and lower had hematocrits that were significantly lower than those of the controls.

ISSN:0706-652X    

DOI:10.1139/f70-162

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

Juvenile sockeye salmon (Oncorhynchus nerka) were injected with the infectious hematopoietic necrosis (IHN) virus, and tissue samples from the anterior kidney, spleen, liver, intestine, and pyloric caeca of moribund fish were prepared for electron microscopy. Bullet-shaped virus particles measuring 158 × 90 mμ were observed in the hematopoietic tissues of the anterior kidney and spleen. Virus particles were also observed in the outer connective tissues of the pancreas or pyloric caeca, or both. No virus was found in the intestine or liver. The healthy appearance of erythrocytes, reticular cells, and endothelial cells in necrotic areas of the spleen and anterior kidney, and the absence of lymphocytes in these areas, suggested that lymphocytes might be one source of the virus.

ISSN:0706-652X    

DOI:10.1139/f70-163

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

Precipitins in albino rainbow trout serums were demonstrated by gel diffusion after a single parenteral exposure to the soluble antigens ofAeromonas salmonicida. The fraction of the serum containing antibody activity against the presented antigens was shown by immunoelectrophoresis to be in the nonmigrating region. This corresponded to the beta-2 fraction of rabbit serum. An antibody-containing component comparable with rabbit gamma globulin was not detected.

ISSN:0706-652X    

DOI:10.1139/f70-164

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

Feeding and filtration rates of four species of copepods (Pseudocalanus minutus,Temora longicornis,Oithona similis, andAcartia tonsa) from Bras d'Or Lake and Morrison's Pond, Cape Breton Island, N.S., were measured in the laboratory with natural populations of phytoplankton. Adult copepods ingested all sizes of flagellates (1–15 μ in maximum dimension) but 5–15-μ cells were removed most efficiently.Ceratiumsp. andChaetocerossp., principal spring and winter forms, were not utilized. Feeding rate declined as the number of animals per liter and the duration of the experiment increased. Estimates of feeding rates in nature were derived by extrapolation from the results of laboratory experiments. A comparison of estimates of mean summer primary production at the depths of maximum photosynthesis and daily zooplankton food intake suggested that, at those depths, zooplankton in Bras d'Or Lake consumed all the average daily production whereas 66% was removed in Morrison's Pond. The remaining production in Morrison's Pond probably contributed to the support of large rotifer and ciliate populations not found in Bras d'Or Lake. Natural concentrations of flagellates were more than sufficient to meet copepod respiratory energy requirements under laboratory conditions.

ISSN:0706-652X    

DOI:10.1139/f70-165

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

Water chemistry in southern Ontario lakes is determined primarily by surface and bedrock geology and the impact of cultivation. In areas of uniform bedrock, elevation and lake size are shown to be important. Total dissolved solids give a poor indication of the electrolyte content of lakes, because of the varied geology. Four main lake types are recognised: (1) base-poor lakes, frequently dystrophic, found on the Precambrian shield; (2) moderately base-rich lakes, in the Bancroft–Rideau lakes region, related to the frequent occurrence of more easily weathered rocks; (3) base-rich lakes found in the limestone region south of the shield, and receiving abundant drainage from cultivated land; and (4) base-rich lakes with high levels of magnesium draining from Silurian dolomitic limestone bedrock and dolomite-rich glacial tills.Phytoplankton populations were found to be related in part to the chemical composition of lake waters. Certain species such asTabellaria flocculosaand to a lesser extentAsterionella formosaandDinobryon divergenswere associated mainly with base-poor lakes; a far larger number of species, includingSynedra acus,Pediastrum duplex, Scenedesmus quadricauda,Cyclotella meneghiniana,Synedra ulna, andCyclotella kutzingiana, were significantly associated with base-rich conditions.An association diagram for all the species found in the lakes showed several groupings, mostly of species that prefer base-rich conditions. Few species confined to base-poor lakes were found to form associations. Apparent associations between oligotrophic species and species known to prefer eutrophic lakes can be explained by the fact that nutrients were depleted at the time of the survey.

ISSN:0706-652X    

DOI:10.1139/f70-166

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

An artificial incubation method employing filtered river water and a gravel substrate was compared with natural propagation in a test on pink (Oncorhynchus gorbuscha) and chum (O.keta) salmon, at Hooknose Creek, King Island, B.C. At time of migration, about 70% of the hatchery pink fry were similar to the wild fry in stage of development; the remainder were immature. A similar but less pronounced difference occurred in the chum. Average rates of development were the same in the hatchery and the creek for each species. These two phenomena combined resulted in the hatchery fry of both species migrating, on the average, from 1 to 2 weeks earlier than the wild fry.Growth during incubation was the same in hatchery and creek, i.e., no loss of potential size occurred in this hatchery environment. Survivals in the hatchery were higher than in the creek, but were less than expected on the basis of experiments carried out elsewhere. Hatchery pink fry showed a lower variability in mean lengths and weights than did creek fry, possibly in response to greater homogeneity of the incubational environment. Chum fry from the last part of the creek runs showed evidence of postemergent growth in fresh water.

ISSN:0706-652X    

DOI:10.1139/f70-167

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

An analysis of variance model for phytoplankton distribution is described, which allows the partition of the variance of chlorophyll observations into effects due to differences between stations, to differences between replicate samples at the same station, and to handling and analytical error. When the model was applied to observations of chlorophyll made in St. Margaret's Bay, N.S., it was found that, on the average, the variance between replicate samples on the same station was of the same magnitude as the analytical error variance. Significant differences were revealed between stations even at densities as high as 10 stations per 0.0625 sq miles. As the sampling area was increased (but the number of stations kept constant), the between-station variance rose rapidly, to a density of 10 stations per sq mile, after which it remained relatively constant. The maximum value of the between-station component of the variance was about 10 times the average for the between-replicate component. Heterogeneity of plankton distribution gave rise to coefficients of variation (logarithmic) up to 70% for single observations of chlorophyll concentration, for which the analytical technique has a precision of better than 10%.Analysis of chlorophyll samples taken at closely spaced stations (0.1 miles apart) along an 8-mile transect revealed considerable variability in distribution. Autocorrelation analysis of the data showed the presence of plankton patches 0.5–1.5 miles in diameter. Coherence analysis provided some evidence for correlation between the distribution of chlorophyll and of temperature and salinity. The dominant frequency in coherence spectra was −3 cycles/mile. Comparison of the autocorrelation function for chlorophyll with those for temperature and salinity indicated the influence of both deterministic and random processes on the chlorophyll distribution.Measurements taken at nine stations during the course of a plankton bloom showed that although there were differences between the stations, the time variation in chlorophyll concentration followed broadly the same course at all the stations. The variation between stations in total quantity of chlorophyll in the water column was small enough to indicate that measurements taken at a single station would be quite adequate to study major seasonal trends.

ISSN:0706-652X    

DOI:10.1139/f70-168

出版商:NRC Research Press    

年代:1970

数据来源: NRC