摘要:

Benthic infauna was collected at 37 stations in Puget Sound, in Juan de Fuca Strait, and off the northwestern coast of Washington during the summer of 1967, and at 18 additional stations off the southwestern coast of Washington during the summer of 1968. The crustaceans, lamellibranchs, and echinoderms were identified and counted, and the data were subjected to an analysis of affinity among stations, to Fager's recurrent group analysis, and to factor analysis for identification of the benthic communities and the groupings of benthic species in the investigated area.Trellis-diagrams of indices of affinity among the stations, based on the presence or absence of species, indicated four rather distinct groups of stations with specific geographic distributions or relations to certain sediment types. Fager's recurrent group analysis for the 36 most frequently occurring species resulted in eight groups and five species that were strongly associated with one or more of the recurrent groups. Most tests of interspecific relations among the species within the groups were not significant, and it was concluded that the analysis was only partly useful for delimiting species groups with ecological significance. The Q-mode of the factor analysis resulted in three groups of stations distributed in bands parallel to the coast, and each group of stations (community) could be recognized by its distinct sediment types or depth distribution. The R-mode of the factor analysis gave six groups of species with specific preferences of depths, sediment types, or geographic distribution. The results of the various techniques were compared, and their application in benthic synecology was discussed.

ISSN:0706-652X    

DOI:10.1139/f70-069

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

Laboratory experiments showed that sheets of polyethylene or a layer of sand placed on the surface of undisturbed lake mud reduce the loss of oxygen in the overlying water and greatly decrease the rate of release of phosphate, iron, and ammonium from the sediment. Polyethylene laid on disturbed mud produced the same effects, and it also reduced the rate of release of total ions as measured by electrical conductivity.Experiments with P32showed that phosphate moves readily through undisturbed mud, and that the movement is not a biotic process. We also found that phosphate and ammonium injected 4 cm below the mud–water interface move upwards into the water, and that this applies to both a rich calcareous mud and a poor acid peaty one.We concluded that early reports of little movement of phosphate through muds are erroneous, possibly because they are based on short experiments, and that there is a great potential store of nutrient salts in enriched muds. This would greatly delay recovery of lakes that have been rendered eutrophic by pollution, so we suggest that polyethylene sheet laid on the sediments of valued lakes may serve to rehabilitate them more rapidly.

ISSN:0706-652X    

DOI:10.1139/f70-070

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

Catches ofPandalus borealisby surface-to-bottom pot fishing in Kachemak Bay, Alaska, showed that this species was distributed in large numbers throughout the water column at night and suggested a diel vertical migration. The shrimp apparently left the vicinity of the bottom about dusk and returned about dawn; the apparent length of time they were off bottom was directly related to the length of the night. Bottom trawling clearly showed lower availability ofP.borealison bottom at night than during the day. Catches of shrimp by pot fishing and trawling indicated that smallP.borealishave a greater tendency to migrate vertically than the larger individuals.

ISSN:0706-652X    

DOI:10.1139/f70-071

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

The concentration of 15 trace elements was determined by activation analysis of samples of whole fish and fish livers from three of the Great Lakes: Michigan, Superior, and Erie. The average concentrations of 7 elements in 19 whole fish from 3 species were as follows: uranium, 3 ppb (parts per billion); thorium, 6 ppb; cobalt, 28 ppb; cadmium, 94 ppb; arsenic, 16 ppb; chromium, 1 ppm; and copper, 1.3 ppm. The average concentrations of 8 elements in 40 liver samples from 10 species of fish were as follows: uranium, −2 ppb; thorium, ≤ 2 ppb; cobalt, 40 ppb; copper, 9 ppm; zinc, 30 ppm; bromine, 0.4 ppm; arsenic, 30 ppb; and cadmium, 0.4 ppm. Other elements observed in most of the samples were: antimony, 5–100 ppb; gold, 2–5 ppb; lanthanum, 1–20 ppb; rhenium, 0.5–5 ppb; rubidium, 0.06–4 ppm; and selenium, 0.1–2 ppb.Trace element concentrations varied with species and lake. Uranium and thorium varied with species, but not for the same species from different lakes. The levels of copper, cobalt, zinc, and bromine varied little between species and lakes. The concentration of cadmium, arsenic, and chromium varied between species and with species between lakes.

ISSN:0706-652X    

DOI:10.1139/f70-072

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

Growth, density, and body size of the deposit-feeding amphipodHyalella azteca, and its food, epibenthic algae, and sediment microflora, were greatest in shallow-water areas of Marion Lake. The vertical distribution ofHyalellawas limited to the upper 2 cm of sediment cores. Highest concentrations of sedimentary chlorophyll and lowest concentrations of nondigestible ligninlike material also occurred at the sediment surface.In laboratory substrate-choice experiments,Hyalelladifferentiated between sediments with different concentrations of microorganisms, and growth depended upon the quantity of microflora in the diet. In Marion Lake, increased growth ofHyalelladuring June was independent of temperature and closely correlated with increased rates of epibenthic primary production.Egg production, related to body size in a nonlinear manner, began during May as growth rates increased. As a combined result of egg production and juvenile survival, the maximum density ofHyalellain Marion Lake was reached in August.

ISSN:0706-652X    

DOI:10.1139/f70-073

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

The addition of 10–50 ppm of several transition metal ions rapidly decreased the extractable protein content of blended fish muscle. The most active metals were Cu++and Cr++followed by Sn++and Cd++. Other ions tested, Ce++, Zn++, Ni++, Co++, Fe++, Fe+++, V++, and Mn++, brought about relatively little or no change in extractable protein nitrogen (EPN) values. Effects of the metals differed with muscle from different species. Lean fish were more susceptible than either fatty fish or shellfish. Of all the species tested the metals had the least effect on scallops. A limited number of tests indicated that fish that were badly emaciated through starvation were more susceptible to the metal-induced change than normal individuals of the species.Addition of certain amino acids, notably cysteine, histidine, glutamic acid, and tryptophane, protected the muscle against metal-induced reduction of EPN. With lean fish, the amino acids that protected the muscle against metal-induced change in the protein also protected it against metal-induced oxidation of the lipids; with fatty fish, protection against rancidity was somewhat less; the invertebrates seemed to be normally protected against both without the addition of amino acids. This natural immunity of marine invertebrate muscle to changes induced by the addition of heavy metal ions may in part be attributed to their normally high content of free amino acids.

ISSN:0706-652X    

DOI:10.1139/f70-074

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

Displacement of 42 mature cutthroat trout (Salmo clarki) from their spawning tributaries to the open water of Yellowstone Lake in the summers of 1966 and 1968 and following them ultrasonically up to 13.5 hr and 11.8 km indicated that those that homed used a compass mechanism rather than search or true navigation to find shore and then followed the shoreline to the home stream. Vision was unnecessary for homing. For many of the fish whose movements showed no consistent pattern, the transmitters failed prematurely.Of 29 nonanesthetized trout tracked from a point northwest of their home streams, six moved generally eastward to shallow water, turned south, and followed the shoreline toward the home streams, three being followed all the way home. Six moved generally south or southeast and progressed toward their home streams entirely in open water, one being followed home. Three moved inappropriately for homing but were less than 2 km from the release point when tracking was ended. Fourteen moved randomly or did not move enough or were not tracked long enough to establish a pattern.Of five anesthetized-blinded trout, two moved eastward and then south along the shoreline, one moved south in open water, and the other two did not show a consistent pattern. Of four anesthetized-control trout, two moved eastward and then south along shore, one being followed home; one moved inappropriately and the other did not establish a pattern.Of four nonanesthetized trout tracked from a point southwest of their home stream, three moved east and then north along shore toward the home stream, one being followed home; the fourth moved north in open water.Current directions may have influenced the initial orientations.Swimming speeds ranged from 0.0 to 46.2 cm sec−1in open water and from 8.5 to 82.3 cm sec−1along shore. Average along-shore speed (36.6 cm sec−1) was greater than average open-water speed (22.9 cm sec−1). Blinded trout swam at about the same speeds (average 22.6 cm sec−1) as control trout (average 27.0 cm sec−1) and nonanesthetized trout (average 23.3 cm sec−1).

ISSN:0706-652X    

DOI:10.1139/f70-075

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

In laboratory tests, lobsters (Homarus americanus) did not avoid bleached kraft mill effluent (BKME) at concentrations up to 20%. BKME or fresh water introduced 50 cm upstream from resting lobsters did not elicit behavioural responses. Lobsters may have detected at least two (acetic acid and NH4OH) of six toxic or malodorous materials but did not avoid any of them. Based on these results, it seems unlikely that exposure to dilute solutions of BKME in nature would have immediate, direct effects on movement of lobsters.

ISSN:0706-652X    

DOI:10.1139/f70-076

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

Two sonic methods for estimation of abundance of fish stocks, the echo integrator and the digital counter methods, were compared on single and schooling fish in the Lofoten area of Norway during March 1969. Good correlation was obtained between the two systems for both situations, but the slopes of the regressions of integrated values on the digital counter differed significantly between low and high density fish concentrations. This suggests that the two systems treated the echo information differently, but nevertheless maintained a linear relation between themselves over a wide range of counts.

ISSN:0706-652X    

DOI:10.1139/f70-077

出版商:NRC Research Press    

年代:1970

数据来源: NRC

摘要:

Comparing numbers of spat obtained in opaque tanks with those from transparent tanks where time of illumination was varied, indicated that setting of mature larvae ofCrassostrea virginicaGmelin is encouraged by darkness and partially inhibited by light.

ISSN:0706-652X    

DOI:10.1139/f70-078

出版商:NRC Research Press    

年代:1970

数据来源: NRC