摘要:

During the Yaloc 66 cruise of R/VYaquina, the vertical distribution of nutrients,pH alkalinity, apparent oxygen utilization, preformed phosphate, preformed nitrate, and specific alkalinity across the subarctic boundary near 170°W were studied. In addition to use of salinity to identify the subarctic boundary, the surface distributions of nutrients,pH, and preformed nutrients were found to be useful. Both the density-apparent oxygen utilization relationships and the specific alkalinity pattern indicated upward divergence of subsurface water having salinity greater than 34.0‰ on the north side of the boundary. A high specific alkalinity of about 0.129 immediately north of the boundary was probably due to the transport of upwardly diverged water having high specific alkalinity to near the boundary. Values for preformed phosphate and preformed nitrate gave supporting evidence that the origin of the salinity-minimum water located south of the boundary is in the subarctic region.

ISSN:0706-652X    

DOI:10.1139/f67-080

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

The size spectrum of particulate material in seawater can easily be expressed as total particle volume versus the logarithm of particle diameter. This appears to be the most informative way to present the data and it is also aptly suited to the classical divisions of nanno-, micro-, and macroplankton.A realistic measure of the volume of irregularly shaped particles such as phytoplankton chains could be made with a Coulter Counter. Particle volume measurements were in good agreement with estimates based on microscopic determination of particle diameter. There were also highly significant correlations between total particle volume, as indicated by the counter, and particulate carbon and nitrogen.

ISSN:0706-652X    

DOI:10.1139/f67-081

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

In a sample of 73 females of winter steelhead,Salmo gairdneriRichardson, from the 1965–66 spawning run in the Alsea River, Oregon, egg size and egg number were correlated with body length. Alsea steelhead produced approximately 32% fewer eggs than females from Trinity River, California, and 51% less than fish of similar size from Scott Creek, California.

ISSN:0706-652X    

DOI:10.1139/f67-082

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

The open water of two northern Wisconsin lakes was sampled for larval fish at night with fine-mesh conical townets. Those collected were identified to genus or species and enumerated. The majority of larval fish were captured in the limnetic region but a few never strayed from the littoral region.The seasonal changes of the limnetic species were similar for the two lakes and 3 years of study. Their abundance varied greatly from year to year but yellow perch, sunfish, and black crappies always dominated.

ISSN:0706-652X    

DOI:10.1139/f67-083

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

This study was undertaken to determine what part partial scaling and partial desliming might play in the survival of trout. Carbohydrate metabolism in these trout was studied and in addition, hemoglobin levels and red cell volumes were studied to serve as indicators of osmotic shifts of water.Increases in lactate were minimal and occurred during the first few hours of holding after the removal oftoof the scales. There were slight changes in hemoglobin levels and red cell volumes which appeared to coincide with activity as reflected by lactate levels. There was a three- to fourfold increase in the blood glucose level of partially scaled fish. Liver glycogen levels dropped toof the air-dipped control value for fish that had beenscaled and held in holding baskets for a period of 140 hr. Only one mortality occurred in all the experiments.The following conclusions were reached. Partial loss of scales or mucous does not result in the death of rainbow trout (Salmo gairdneri). Partial scaling or desliming of the fish was accompanied by a significant increase in blood glucose (p < 0.05).

ISSN:0706-652X    

DOI:10.1139/f67-084

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

During the parr–smolt transformation in Atlantic salmon, silvery materials were found beneath the scales (scale layer) and deep in the dermis adjacent to the muscle (skin layer). Both layers were thicker in smolts than in parr and both layers contained guanine and lesser amounts of hypoxanthine.Changes in levels of guanine, hypoxanthine, and the ratio between them (G/H) were measured from late December to late May on 2-year-old parr held in the laboratory under natural photoperiods and at temperatures varying from 6.0 in December to 9.5 C in late May. The change from parr to silvery parr during February and March accompanied sharp increases in guanine, hypoxanthine, and G/H values in the skin layer with less marked increases in the scale layer. The change from silvery parr to smolts during April and May accompanied sharp increases in guanine, hypoxanthine, and G/H values in the scale layer but no change occurred in the trend already established in the skin layer.Parr held all winter under stream conditions and examined in early April possessed purine levels and G/H ratios in the skin and scale layers comparable to those in laboratory fish during the previous December.Silvery parr captured migrating seaward in early June had purine levels and G/H ratios in the scale layer similar to those in laboratory smolts in late May but skin guanine values were much lower and the G/H ratio in the skin was extremely low.

ISSN:0706-652X    

DOI:10.1139/f67-085

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

Counts of pyloric caeca and gill rakers were made on lake trout (Salvelinus namaycush) in three Algonquin Park lakes where the trout were dependent on plankton for food in varying degrees. In 798 trout from the three lakes, pyloric caeca counts ranged from 105 to 210 and varied with the size of trout. There was no association between numbers of caeca and type of food eaten.Gill raker counts were made on 930 lake trout. Numbers of rakers are not related to size or sex of lake trout in the sample. Gill raker counts ranged from 17 to 26 in the combined populations. An association exists between the numbers of gill rakers, their length, and the amount of plankton eaten by the lake trout. Accessory gill rakers on the medial surface of the gill arch are described. The number and development of these rakers were associated with the amount of plankton eaten by the lake trout.

ISSN:0706-652X    

DOI:10.1139/f67-086

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

Ogac Lake is the almost isolated head of a fiord, Ney Harbour, on the south coast of Frobisher Bay, N.W.T. Earlier knowledge of the lake is summarized, a brief account is given of expeditions to the lake in 1957 and 1962, and the scope of the studies is outlined.

ISSN:0706-652X    

DOI:10.1139/f67-087

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

Ogac Lake is the small (148 ha) landlocked head of a fiord with three distinct basins. It receives highest spring tides (maximal range 12 m, as high as 1.2 m above lake level) monthly during the open-water season through a narrow entrance. The predictable inflows displaced about one-quarter of the lake's volume in 1957. The lake is meromictic, fresh at the surface and 28‰ salinity at depth. Some 55 kg/m2salt lost in surface outflow in summer was more than restored by the tides by the end of 1957. Deep salinities did not change between 1951 and 1962. Vertical attenuation of light is adequately accounted for by chlorophyll alone. The lake is much warmer than the nearby sea. Temperature inversions are caused by cold tidal water and perpetuated by vertical stability. The gross annual heat budget in 1957 was 22,000 cal/cm2, about the same as in the nearby sea, but higher than in a freshwater lake. Heating from below a few meters to 30 m can be accounted for by radiation alone. About 20% of radiation reaching the bottom subsequently appeared as heat in the water immediately overlying the bottom, thus implying restricted horizontal transfer. Oxygen was absent below 25–32.5 m, which may approximate the compensation level in this and similar lakes. Oxygen differences between basins are partly controlled by morphometry. Distinct oxygen minima in 1957 were associated with temperature minima and caused by concentrations of zooplankton. Vertical distribution ofpH parallels that of oxygen. Specific alkalinities seem slightly higher than in normal seawater. Phosphate showed a distinct and stable minimum just above the anoxic layer and was as high as 14.3 μg-at/liter within that layer. Nitrate was relatively low and maximal just above the anoxic layer. Although nutrient levels seemed partly related to morphometry in the three basins, no evidence of nutrient enrichment of bottom water was found in late summer. The tides contribute negligible nutrients to the lake. The character of Ogac Lake compared with similar lakes derives from the great tidal amplitude and narrow connection with the sea, as well as from its small size and sheltered setting.

ISSN:0706-652X    

DOI:10.1139/f67-088

出版商:NRC Research Press    

年代:1967

数据来源: NRC

摘要:

The profundal benthic fauna of nine lakes lying along the margin of the Precambrian Shield in the Province of Manitoba was investigated during August 1963, and is described with particular attention to the midges (Diptera: Chironomidae).Comparison with a Scottish lake, similarly situated with respect to Precambrian rocks, showed no close agreement in the distribution of species of Chironomidae. This can be credited to differences in the Palaeozoic rocks adjoining the Precambrian.Chironomus tentansandC.decoruswere most numerous and most frequent at water depths up to 15 m whereasC.anthracinusandChironomussp. A were generally in water over 20 m.In Falcon, Reed, and Morton lakes,C.anthracinustended to be more successful where sediments contained appreciable amounts of allochthonous debris and to give way toChironomussp. A where sediments were autochthonous.

ISSN:0706-652X    

DOI:10.1139/f67-089

出版商:NRC Research Press    

年代:1967

数据来源: NRC