摘要:

Studies of large (about 125) samples of walleye (Stizostedion vitreum), northern pike (Esox lucius), white sucker (Catostomus commersoni), and lake whitefish (Coregonus clupeaformis) from each of four areas of Clay Lake, Ontario, a highly mercury-contaminated lake, have confirmed previous findings that the larger the fish, the greater the white muscle mercury concentration, within species, within populations. This relationship was statistically broken into separate age:concentration and growth:concentration partial regressions; older fish and faster growing fish were generally more contaminated, subject to the above species–area restrictions. However, the generally positive correlation between concentration and condition (as measured by relative heaviness of individuals within area–species samples) found in the previous study is here contradicted; relatively heavier fish tended to have lower Hg concentrations. Despite the relatively small size of the lake (about 11 × 2 km) analyses of multiple covariance indicated profound within-species differences between the samples from the four areas. However, there did not appear to be any obvious correlation between these differences and sediment mercury values.The various statistical relationships do not appear to be simple, first-order regressions; rather, there appear to be significant interactions between age and growth, and age and condition, which tend to change the partial slopes with age. The four species were distinctly different in most of their relationships.

ISSN:0706-652X    

DOI:10.1139/f74-218

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Groups of yellow perch (Perca flavescens) were acclimated to constant temperatures of 10 and 20 C. Acclimation temperatures were then abruptly reversed. Critical swimming speeds were determined prior to and following the temperature change at 24-h intervals. Adjustment (acclimation) of fish subjected to an increase in temperature was immediate. Fish subjected to a decrease in temperature required less than 24 h to regain maximum swimming capability.

ISSN:0706-652X    

DOI:10.1139/f74-219

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Adult worms recovered from naturally infected sockeye salmon (Oncorhynchus nerka) smolts provided the eggs for regeneration ofEubothrium salveliniin the laboratory. Of several copepods tested three species ofCyclopsproved to be successful intermediate hosts whereby infections were ultimately transmitted to sockeye fry. The parasite's life cycle is described. The rate of development within the intermediate host is shown to be related directly to temperature. It is also demonstrated that susceptibility of fry to infection diminishes as they exceed a certain size.

ISSN:0706-652X    

DOI:10.1139/f74-220

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Specific antibody production in response to an intraperitoneal injection ofA.salmonicidaendotoxin first occurred in juvenile coho salmon (Oncorhynchus kisutch) held at 6.7, 12.2, and 17.8 C at 4, 2 and 1 wk, respectively.Aeromonas salmonicidaendotoxin was antigenic to juvenile coho salmon at all doses between 1 and 5000 μg administered intraperitoneally with and without an aluminum hydroxide carrier.The endotoxin was nontoxic to juvenile coho salmon when 1–5000 μg was injected intraperitoneally and the fish held at temperatures from 6.7 to 17.8 C or when "free endotoxin" was administered by the intramuscular or intraperitoneal route.Aeromonas salmonicidaendotoxin was toxic to mice, however.

ISSN:0706-652X    

DOI:10.1139/f74-221

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

The antibody response of a population of juvenile coho salmon (Oncorhynchus kisutch) held at 12 C approached 100% following a single parenteral vaccination withAeromonas salmonicidacells emulsified in Freund's complete adjuvant. This response indicates that coho salmon behave as a homogeneous population with respect to immunological competence.Fish as small as 1.2 g produced antibodies as early as 4 wk after administration of this vaccine; high levels of antibody persisted for at least 1 yr after injection. This single vaccination provided juvenile coho salmon with protective immunity against furunculosis.

ISSN:0706-652X    

DOI:10.1139/f74-222

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

The critical swimming velocities of brook trout (Salvelinus fontinalis) following exposure to 150, 500, and 1500 μg/liter fenitrothion were 100, 83, and 70%, respectively, of the performance of control fish. This represented 35 and 60% decrease in power output, respectively, for the two higher concentrations.At step-test intervals longer than 15 min, the critical velocity (ca 4.5–5 lengths [L]/s) was reasonably constant. At shorter step-test intervals, the critical velocity increased rapidly to exceed 7 L/s at a step-test interval of 30 s. The cruising speed of control fish was estimated at 4.5 L/s.The influence of fenitrothion exposure on swimming speed is related to previous studies on sublethal effects of fenitrothion and to concentrations in streams resulting from insecticide spraying.

ISSN:0706-652X    

DOI:10.1139/f74-223

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Oxygen consumption attributable to apparent specific dynamic action (SDA) was measured in relation to feeding level and body weight in largemouth bass,Micropterus salmoides, forced to swim at 1.7 body lengths/s (BL/s). Apparent SDA rose curvilinearly with ration size, the coefficient increasing with weight of bass. For a ration of fixed percent body weight/day, apparent SDA increased curvilinearly with weight of bass, the rate being most pronounced at higher levels of food intake. Apparent SDA expressed in energy units as a percent of ration ingested did not differ significantly with weight of fish or meal size. The overall mean apparent SDA ±SDwas 14.19 ± 4.19% of the energy ingested. Time required for oxygen consumption to subside to pre-feeding levels increased with ration size and weight of bass.Over the range of swimming speeds from 1.4 to 2.5 BL/s, there were no differences in apparent SDA of similar size bass fed a ration of 4% body weight/day. Similarly, time for elevated levels of oxygen consumption to return to prefeeding rates was independent of swimming speed.

ISSN:0706-652X    

DOI:10.1139/f74-224

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

The total phosphorus budgets for a number of lakes in the Haliburton–Kawartha region of southern Ontario were measured over a 20-mo period. These data, combined with the lakes' morphometry and water budgets, were used to test a simple nutrient budget model similar to that proposed by Vollenweider (1969) purporting to predict the total phosphorus concentration in lakes. Except in the case of two very shallow lakes, the concentrations predicted by the model were very close to those measured in the lakes at spring overturn. Additional data from the literature supported the belief that this model could be used effectively for oligotrophic and mesotrophic lakes. Its value lies in the fact that quantitative changes in phosphorus loading can be interpreted in terms of changes in phosphorus concentration, which in turn, can be related to changes in parameters that reflect the lake's trophic state such as summer chlorophyllaconcentration.

ISSN:0706-652X    

DOI:10.1139/f74-225

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

The primary productivity of the benthic microflora was measured using in situ techniques. Primary productivity ranged from below 0.5 mg C m−2h−1in winter when the sampling area was covered with ice to nearly 57.0 mg C m−2h−1in August. This is 8 times the productivity of the ice algae and twice that of the phytoplankton.

ISSN:0706-652X    

DOI:10.1139/f74-226

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Swimming activity, aggressive behavior, and upstream orientation of yearling Atlantic salmon (Salmo salar) treated with 6.43 × 10−11 Mthyroxine were significantly lower than those of control fish injected with solvent alone. Two concentrations of triiodothyronine (7.43 × 10−11 M; 7.43 × 10−10 M) caused similar but less pronounced effects.Because similar behavioral modifications accompany smolt migration, we hypothesize that thyroid hormones may play a role in arousing migratory tendencies in Atlantic salmon.

ISSN:0706-652X    

DOI:10.1139/f74-227

出版商:NRC Research Press    

年代:1974

数据来源: NRC