Thesis--Wisconsin. / Includes bibliographical references (leaves 55-59).

A systematic study was made of the genus Cottus, emphasizing the species of British Columbia. Some five thousand specimens from the Institute of Fisheries museum were used to construct distribution maps. Intensive examination before and after clearing and staining with alizarin or X-raying was made of 745 B.C. specimens and several exotic species. Color pattern, sex body proportions, prickles and the number of fin rays, lateral line pores, operculomandibular pores, caudal vertebrae, and preopercular spines were noted. Specific descriptions employing these characters were constructed. A new species found by Bailey is reported and described; philonips is synonomized with cognatus. Intraspecific variation in meristic characters showed modification with habitat, distance from the sea, altitude, latitude, populations and in some cases with sex. Interspecific comparisons revealed differences which were evaluated and made into a key of B.C. species. Supraspecific study showed the existence of three species groups having different counts of caudal vertebrae and other characteristics. A key is given to the species groups. / Science, Faculty of / Zoology, Department of / Graduate

The behaviour of two sympatric species of sculpins, Cottus asper and Cottus aleuticus, which occupy different microhabi-tats, was studied by the comparative method. The aim of the study was to determine some of the important behavioural adaptations to the differences in their microhabitats. C. asper occurs in areas of slow current and fine substrate and G. aleuticus in areas of fast current and coarse substrate. The posture, orientation to the current, and locomotary and feeding behaviour of the species were examined in the laboratory under different conditions of current and substrate. C. asper responds to a current by lying flat on the substrate. C. aleuticus also exhibits this posture on sand, but on a gravel substrate, raises the body, by spreading the pectoral fins. C. aleuticus adopts a parallel orientation to the current more frequently than a broadside orientation, but C. asper "prefers" the broadside position. However, both species assume the broadside position more frequently on sand than on gravel, and the parallel orientation more frequently on gravel than on sand. C. asper is a much poorer swimmer than C. aleuticus, especially in a current. C. aleuticus is much more active than C. asper at all times of day and under all conditions of current tested. C. asper is a lurking predator and takes food from the surface of the substrate. C. aleuticus is a more active feeder, and feeds by swimming to the water surface, by taking food from the substrate surface and by foraging in the crevices of the gravel. From laboratory observations it appears that C. aleuticus relies on sight in food detection to a greater extent than does C. asper. The findings of this study were compared with field observations and with previous studies of other cottid species. It was concluded from this that C. aleuticus’ posture, orientation to the current, and locomotory and feeding behaviour are a reflection of a more active way of life and are related to the special problems of life in a strong current. C. asper, however, is typical, both in behaviour and morphology, of bottom-dwelling, sedentary fish, of reclusive habits. / Science, Faculty of / Zoology, Department of / Graduate

Differential responses to water current and substrate, exhibited by populations of Cottus aleuticus and Cottus asper in the Little Campbell River, were studied both in the field and in experimental laboratory apparatus. Both broad-scale and local distributions of C. aleuticus and C. asper appear to be closely associated with available habitat. The slow moving areas of the lower river appear to provide adequate habitat for fry of both species. These fish have the least decided preferences for current and substrate conditions. As yearlings the two species show almost complete divergence of habitat choice with most C. asper inhabiting slow areas of the lower river and most C. aleuticus moving upstream to riffles and other areas of distinct current. As adults, C. asper inhabit areas of non-current, decreasing in numbers from mouth to source of the stream, coincident with a decrease in occurrence of pool environments. The upper river, which is entirely pool habitat, may have a reduced C. asper population due to isolation for six months of the year and suspected low oxygen concentrations. Cottus aleuticus yearlings and adults are found principally in the middle river where areas of current are present. Day and night collections reveal that yearling and adult C. aleuticus and adult C. asper are largely segregated into different microhabitats during daylight but may occupy similar areas during darkness. Formation of pool environments by tidal inundation of former current and non-current areas appears to allow fry of both species, previously largely segregated, to occupy similar areas regardless of time of day. Both species were found to feed principally at night as yearlings and adults. Responses of field fish displaced to habitats not normally occupied strongly suggests the importance of environmental factors in determining distribution and abundance and, in segregating the two species under natural conditions. Fish were given a choice of current and non-current areas in one series of laboratory experiments and coarse and fine substrates in another series. Tests were performed on fish taken directly from the field, on fish held in bare hatchery troughs for 60 days, and on fish exposed to simulated natural conditions of flow and substrate for 60 days. At current speeds of 45 centimeters per second, C. aleuticus fry (less than 40 millimeters) in the laboratory showed no preference for either current or non-current areas, while fish greater than 60 millimeters (yearlings and adults) tended to select current. Cottus aleuticus, at all size groups tested, preferred coarse rather than fine-textured substrate. In the field, C. aleuticus showed a preference for current and coarse substrate although fry often occupied areas of fine substrate and non-current when C. asper were absent or scarce. Cottus aleuticus, as yearlings and adults, were rarely found over fine substrate. In laboratory experiments C. asper generally preferred non-current to current and showed no substrate preference except fry which preferred coarse substrate. Fish between 80 and 100 millimeters showed no preference for either current or non-current areas in the laboratory. In the field, C. asper were rarely associated with current but were found over a wide range of fine and coarse substrate. When a choice of flow and substrate conditions were offered simultaneously, C. aleuticus preferred current and coarse substrate. C. asper showed no preference for either flow condition and had no substrate preference. There was no significant difference in a species response to flow and substrate when tested singly or in groups. Holding conditions (bare troughs and simulated natural conditions) did not change responses of either species from those outlined for fish tested directly from the field. Field and laboratory results suggest habitat segregation to be most pronounced in fish between 40 and 80 millimeters long. The relevance of these results to habitat segregation by the two species in a stream is discussed. Food, reproduction, fish associations and densities are also discussed as factors affecting spatial and temporal distribution of the species. / Science, Faculty of / Zoology, Department of / Graduate

Thesis (M. Sc.)--York University, 1997. Graduate Programme in Biology. / Typescript. Includes bibliographical references (leaves 295-307). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL:http://wwwlib.umi.com/cr/yorku/fullcit?pMQ27344.

A comparative phylogenetically independent contrast (PIC) analysis was employed to investigate the adaptive role of traits involved in hypoxia tolerance in sculpins, a group of closely related fish species that live in the nearshore marine environment. I demonstrated that there was a tight correlation between critical oxygen (O₂) tension (P-crit) and the distribution of species across an environmental gradient. Species of sculpins with the lowest P-crit inhabit the 0₂ variable intertidal zone, while species with higher P-crit inhabit the O₂ stable subtidal zone. Low P-crit values in sculpins were associated with enhanced O₂ extraction capacity, with three principal traits accounting for 83% of the variation in P-crit: low routine O₂ consumption rate (MO2 ), high mass specific gill surface area and high whole cell hemoglobin-oxygen (Hb-0₂) binding affinity. Variation in whole cell Hb-O₂ binding affinity was strongly correlated with the intrinsic affinity of Hb for O₂ and not to differences in the concentration of the allosteric Hb modulators ATP and GTP. When environmental O₂ dropped below a species' P-crit, some species of sculpins behaviorally responded to the severe hypoxia by performing aquatic surface respiration (ASR) and aerial emergence. Although intertidal sculpins consistently performed these behaviors, the clustering of these species into a single phylogenetic Glade did not allow us to draw conclusions regarding the relationship between ASR, aerial emergence and P-crit using PIC analysis. Three species of sculpins, which were chosen because of their low, medium and high P-crit values, exhibited dramatically varied mortality rates when exposed to severe hypoxia equivalent to 40% of their respective P-crit. Although ATP turnover rates were similar between the three species in the initial two hours of hypoxia exposure, the differences in the ability of the three species to survive severe hypoxia appeared to be associated with the concentration of on-board liver glycogen and the degree of liver glycogen depletion. However, when liver glycogen was assessed in twelve species of sculpins at normoxia and compared with P-crit, there was nosignificant PIC correlation between P-crit and liver glycogen. Overall, I have shown that there is a clear relationship between P-crit and the distribution of sculpins along the nearshore environment and that this is primarily related to differences in O₂ extraction capacity. When O₂ tensions are well below their P-crit, there are dramatic differences in behavioral, physiological and biochemical responses among these species of sculpins.

A comparative phylogenetically independent contrast (PIC) analysis was employed to investigate the adaptive role of traits involved in hypoxia tolerance in sculpins, a group of closely related fish species that live in the nearshore marine environment. I demonstrated that there was a tight correlation between critical oxygen (O₂) tension (P-crit) and the distribution of species across an environmental gradient. Species of sculpins with the lowest P-crit inhabit the 0₂ variable intertidal zone, while species with higher P-crit inhabit the O₂ stable subtidal zone. Low P-crit values in sculpins were associated with enhanced O₂ extraction capacity, with three principal traits accounting for 83% of the variation in P-crit: low routine O₂ consumption rate (MO2 ), high mass specific gill surface area and high whole cell hemoglobin-oxygen (Hb-0₂) binding affinity. Variation in whole cell Hb-O₂ binding affinity was strongly correlated with the intrinsic affinity of Hb for O₂ and not to differences in the concentration of the allosteric Hb modulators ATP and GTP. When environmental O₂ dropped below a species' P-crit, some species of sculpins behaviorally responded to the severe hypoxia by performing aquatic surface respiration (ASR) and aerial emergence. Although intertidal sculpins consistently performed these behaviors, the clustering of these species into a single phylogenetic Glade did not allow us to draw conclusions regarding the relationship between ASR, aerial emergence and P-crit using PIC analysis. Three species of sculpins, which were chosen because of their low, medium and high P-crit values, exhibited dramatically varied mortality rates when exposed to severe hypoxia equivalent to 40% of their respective P-crit. Although ATP turnover rates were similar between the three species in the initial two hours of hypoxia exposure, the differences in the ability of the three species to survive severe hypoxia appeared to be associated with the concentration of on-board liver glycogen and the degree of liver glycogen depletion. However, when liver glycogen was assessed in twelve species of sculpins at normoxia and compared with P-crit, there was nosignificant PIC correlation between P-crit and liver glycogen. Overall, I have shown that there is a clear relationship between P-crit and the distribution of sculpins along the nearshore environment and that this is primarily related to differences in O₂ extraction capacity. When O₂ tensions are well below their P-crit, there are dramatic differences in behavioral, physiological and biochemical responses among these species of sculpins.

Thesis (M.S.)--University of Nevada, Reno, 2006. / "December, 2006." Includes bibliographical references (leaves 30-34). Online version available on the World Wide Web.

A comparative phylogenetically independent contrast (PIC) analysis was employed to investigate the adaptive role of traits involved in hypoxia tolerance in sculpins, a group of closely related fish species that live in the nearshore marine environment. I demonstrated that there was a tight correlation between critical oxygen (O₂) tension (P-crit) and the distribution of species across an environmental gradient. Species of sculpins with the lowest P-crit inhabit the 0₂ variable intertidal zone, while species with higher P-crit inhabit the O₂ stable subtidal zone. Low P-crit values in sculpins were associated with enhanced O₂ extraction capacity, with three principal traits accounting for 83% of the variation in P-crit: low routine O₂ consumption rate (MO2 ), high mass specific gill surface area and high whole cell hemoglobin-oxygen (Hb-0₂) binding affinity. Variation in whole cell Hb-O₂ binding affinity was strongly correlated with the intrinsic affinity of Hb for O₂ and not to differences in the concentration of the allosteric Hb modulators ATP and GTP. When environmental O₂ dropped below a species' P-crit, some species of sculpins behaviorally responded to the severe hypoxia by performing aquatic surface respiration (ASR) and aerial emergence. Although intertidal sculpins consistently performed these behaviors, the clustering of these species into a single phylogenetic Glade did not allow us to draw conclusions regarding the relationship between ASR, aerial emergence and P-crit using PIC analysis. Three species of sculpins, which were chosen because of their low, medium and high P-crit values, exhibited dramatically varied mortality rates when exposed to severe hypoxia equivalent to 40% of their respective P-crit. Although ATP turnover rates were similar between the three species in the initial two hours of hypoxia exposure, the differences in the ability of the three species to survive severe hypoxia appeared to be associated with the concentration of on-board liver glycogen and the degree of liver glycogen depletion. However, when liver glycogen was assessed in twelve species of sculpins at normoxia and compared with P-crit, there was nosignificant PIC correlation between P-crit and liver glycogen. Overall, I have shown that there is a clear relationship between P-crit and the distribution of sculpins along the nearshore environment and that this is primarily related to differences in O₂ extraction capacity. When O₂ tensions are well below their P-crit, there are dramatic differences in behavioral, physiological and biochemical responses among these species of sculpins. / Science, Faculty of / Zoology, Department of / Graduate

The lower British Columbia mainland waterways are inhabited by two races of the prickly sculpin Cottus asper Richardson. One race lives in the lower part of rivers or in estuaries and spends at least part of its life, particularly during the spawning season, under tidal influence. This race is the "coastal". The other race, called "inland", is confined entirely to fresh water where it is found in scattered, more or less isolated populations. By investigating the effects of ambient salinity on the oxygen consumption and on the utilization of injected radioiodine, it was found that salinity profoundly effects the iodine metabolism and, to a lesser degree, standard metabolic rates of the fish. In fresh water the thyroids of both races appear relatively quiescent but with increasing salinity, particularly in hyperosmotic environment, there is a marked increase in thyroid uptake of tracer iodine and also in the levels of circulating thyroid hormone. The inland fish demonstrate a greater ability than coastal fish to retain iodide in fresh water, and in sea water their thyroids appear more active. The inland fish also have a lower oxygen consumption in fresh water than do coastal fish. Viewed together, the results lead to the conclusion that the inland fish, with respect to their osmoregulating ability, show genetic divergence from the coastal forms. The latter probably more closely resemble the ancestral form. / Science, Faculty of / Zoology, Department of / Graduate