Final Preferendum Research Articles

Physiological and Ecological Correlates of Preferred Temperature in Fish

Fishes released from constraints of their previous thermal history tend to limit thermal exposure to a narrow range of temperatures. Thermoregulatory behavior (final preferendum) is a stable characteristic of each species studied, suggesting strong regulation by natural selection. However, the adaptive significance of the final preferendum has not been documented for most species. Species with wide geographic distributions, such as bluegill sunfish and largemouth bass exhibit constant laboratory final preferenda regardless of their geographic origin or thermal histories. This apparent evolutionary anomaly of the final preferendum requires further study. It is no longer adequate to describe responses of fish to thermal gradients, rather falsifiable hypotheses concerning adaptive relations between thermoselection, and physiological, biochemical, life-history and genetic correlates must be developed and tested experimentally.

Behavioral thermoregulation by Ammocoete larvae of the sea lamprey (Petromyzon marinus) in an electronic shuttlebox

Ammocoete larvae of the sea lamprey Petromyzon marinus, a member of the primitive vertebrate class Agnatha, were tested for thermoregulatory behavior in an electronic shuttlebox (ichthyotron). The final preferendum derived from pooled data for 24 individually tested ammocoetes was characterized by a mean of 13.6 ± 0.17 (s.e.m.)°C, a mode and median of 140°C, and a range of voluntarily occupied temperatures from 10–19°C over a 3-day period.

Behavioural thermoregulation in Rana pipiens tadpoles

1. 1.|The mean preferred temperature (final preferendum) of Rana pipiens tadpoles in an electronic thermoregulatory shuttlebox was 27.9°C. 2. 2.|The daytime modal preferendum was 28°C, while the nocturnal mode was 27°C; mean preferenda did not differ significantly between night (28.1°C) and day (27.8°C). 3. 3.|The tadpoles exhibited a bimodal pattern of preferred temperature with equal nocturnal and diurnal peaks (28.8°C), and minima at the transition from scotophase to photophase (27.1°C) and from photophase to scotophase (27.4°C); our data do not indicate whether this pattern is an endogenously controlled rhythm.

The Preferred Temperatures of the Brown Bullhead, Ictalurus nebulosus, with Reference to its Orientation to the Discharge Canal of a Nuclear Power Plant

Brown bullheads acclimated to temperatures between 3.5 and 28 C and tested in a thermal gradient trough usually preferred water temperatures above their respective acclimation temperatures. Fish tended to gravitate toward higher temperatures the longer they remained in the gradient; final preferendum was 27.3 C. Laboratory results are consistent with observed movements of Connecticut River brown bullheads into the thermal discharge canal of a power plant during autumn. It appears from both laboratory and field studies that a “temperature trap” keeps bullheads in the warm discharge canal during winter. However, brown bullheads leave the canal in spring sooner than would be predicted from temperature preference data alone.

The final thermal preferendum of fishes: Shuttling behavior and acclimation overshoot

The concept of final preferendum is reexamined in light of data concerning acclimation in a cyclic thermal regime. Because of ‘Shuttling behavior’ to temperatures above and below the mean preferendum, and because of faster acclimation ‘upward’ than ‘downward’, which result in acclimation to a temperature exceeding the mean of the cycle, a fish may finally gravitate to a preferendum which does not equal acclimation temperature. It is suggested that a distinction be made between the ‘crossover-point’ preferendum, where preference and acclimation are equal, and the ‘ultimate’ preferendum to which a fish will ultimately gravitate.

Circadian rhythm of preferred temperature in the bowfin Amia calva, a primitive holostean fish

1. 1. In an electronic thermoregulatory shuttlebox, the bowfin exhibits an endogenous circadian rhythm of preferred temperature, with a peak of 32.0°C during the day and a minimum of 28.8°C at night. 2. 2. The 24-hr mean preferred temperature (final preferendum) is 30.5°C; the diurnal mean is 31.3°C and the nocturnal mean is 29.6°C 3. 3. There is no clear rhythm of locomotor activity evident in this species; diurnal and nocturnal activity do not significantly differ as measured by two independent methods.

Behavioral thermoregulation in the rock bass, Ambloplites rupestris

Rock bass thermoregulating in an electronic shuttlebox exhibited a modal final preferendum of 30°C (range 26–34°C, midpoint 30°C, median 29°C, mean 29.4°C). This species did not exhibit any significant difference between day and night, either in preferred temperature or in locomotor activity.

Influence of Acclimation Temperature on Preferred Temperature in the Rainbow Trout Salmo gairdneri

Abstract The relation of preferred temperature to acclimation temperature of 29 rainbow trout 15 months old was examined during summer. Fish were acclimated to 5, 10, 15, 20, and 25 C, respectively, and tested individually in an electrically controlled shuttlebox device. Body temperatures monitored by a radiothermometer ingested by the fish closely approximated occupied temperatures to within 0.2 C. No significant differences were found in preferred temperature over the acclimation range studied. The calculated final preferendum was 11.3 C. Fish regulated environmental and body temperature with the same precision as they selected temperature in a spatial gradient.

Responses of Young California Grunion, Leuresthes tenuis, to Gradients of Temperature and Light

In a laboratory temperature gradient, young California grunion, Leuresthes tenuis, exhibited a final modal preferendum of 25 C, 7 C lower than the final preferendum of young L. sardina from the Gulf of California. No circadian rhythms in thermal preference were found, and the final preferendum was unaffected by acclimation temperature. Like L. sardina, young L. tenuis were strongly attracted to bright light (10,000 lux). In a simultaneous opposed gradient of temperature and light, the fish spent more time at the preferred temperature than at the preferred light intensity. The laboratory results are discussed in relation to observed field distribution and geographic range.

Thermal preference in relation to salinity in the threespine stickleback, Gasterosteus aculeatus L., with an interpretation of its significance

Thermal preferences were determined in spacious thermal gradients of fresh water and sea water (32‰ salinity (S))for acclimations of 5, 15, and 25 °C in sea water, for samples of threespine stickleback Gasterosteus aculeatus L. Preferred temperatures increased through acclimations of 5–25 °C, with those for the freshwater tests being about 2 °C lower at each acclimation. Final preferenda were 16 and 18 °C for freshwater tests and seawater tests, respectively. The final preferendum in such haloplastic species is defined as the highest obtainable preferendum that equals acclimation temperature. A later series of disjunct preference determinations in approximately isosmotic water (10.5‰ S) for subjects acclimated to 7, 15, and 20 °C yielded mean values of 17.7, 18.2, and 18.7 °C, respectively. A final preferendum has not been designated since the samples were of separate origins. A parallel exists between these responses and the response of this and other haloplastic species in the determination of upper lethal temperatures. The immediate cause appears to be differentials in metabolic loading occasioned by l stresses.

Responses of a Freshwater Sculpin (Cottus cognatus gracilis) to Temperature

Temperature tolerance, avoidance, and preference of a freshwater sculpin, Cottus cognatus gracilis, are described for fish acclimated to constant temperatures ranging from 5 to 20 C. Critical thermal maxima varied from 23.5 C for fish acclimated to 5 C, to 29.4 C for fish acclimated to 20 C. Incipient upper lethal temperatures ranged from 18.5 C to 23.5 C. The ultimate upper lethal temperature was approximately 26.5 C. Avoidance temperatures ranged from 15.2 C at 5 C to 21.5 C at 15 C. Preferred temperatures for 5 C- and 15 C-acclimated fish were 9 and 12 C, respectively, and the final preferendum was about 10 C.

Preferred Temperature of Yearling Lake Trout, Salvelinus namaycush

Preferred temperatures were determined for yearling lake trout acclimated to 5, 10, 15, and 20 C. Acclimation temperature had virtually no effect on preferred temperature. The final preferendum was 11.7 C, which is about 2 degrees C warmer than the temperature at which lake trout are most commonly caught in thermally stratified lakes.

Influence of Temperature and Salinity Acclimation on Temperature Preferenda of the Euryhaline Fish Tilapia nilotica

When Tilapia nilotica was acclimated to temperatures of 15–35 C and salinities of 0–30‰ in a vertical gradient tank, maximum temperature preferenda occurred at acclimation temperatures of 20 and 25 irrespective of salinity. Preferenda declined as acclimation temperature was increased above 25 C and, except at 0 and 7.5‰, declined as acclimation temperature was decreased below 20 C. The pattern of the relation between final temperature preferenda and salinity was similar to that reported between oxygen consumption for a given sustained swimming speed and salinity. The final preferendum was lowest at 15‰, close to the isosmotic salinity of T. nilotica, and highest at the extremes, 0 and 30‰. Final temperature preferenda are in general agreement with optimum temperatures reported for growth, reproduction, and swimming performance.

Thermal Acclimation and Temperature Selection in Atlantic Salmon, Salmo salar, and Rainbow Trout, S. gairdneri

The selected temperature for Atlantic salmon and rainbow trout, as determined in a horizontal gradient, increases with acclimation temperature over the acclimation range 5–20 C for salmon and 10–20 C for trout. The final preferendum for salmon is about 17 C. The results for rainbow trout suggest that the type of gradient used, i.e. vertical or horizontal, has a marked influence on the experimentally determined relation between acclimation temperature and selected temperature.

PREFERRED TEMPERATURE OF RAINBOW TROUT (SALMO GAIRDNERI RICHARDSON) AND ITS UNUSUAL RELATIONSHIP TO ACCLIMATION TEMPERATURE

The modal preferred temperatures of rainbow trout acclimated to 5 °C, 10 °C, 15 °C., and 20 °C. were determined photographically to be 16 °C, 15 °C., 13 °C, and 11 °C., respectively. The final preferendum was 13 °C. The phenomenon of decreasing preferred temperature with increasing acclimation temperature has not been reported for any other species of fish.

The Preferred Temperature of Fish and their Midsummer Distribution in Temperate Lakes and Streams

Laboratory studies of preferred temperature with yellow perch (Perca flavescens) are compared with results from 21 other species. These show that temperature, if acting alone, can determine the distribution of fish in laboratory apparatus. Factors such as light, conditioned responses related to feeding routines, and social behaviour can interfere with the expression of the response to temperature. Subdued lighting conditions were necessary in the experiments with Oncorhynchus, Salvelinus and Coregonus, whereas full daylight was required in experiments with Perca flavescens.The level of thermal acclimation influences the range of temperature preferred. In general the preferred temperature is considerably higher than the acclimation temperature at low thermal acclimations, but this difference decreases up to the final preferendum, where both coincide. The final preferendum and the relation between acclimation and preferred temperature is characteristic for the species. The shape of the resulting curve may have some value in interpreting observations of fish mortalities and distribution in nature. The final preferendum of the yellow perch from the present work was 24.2 °C., from other work using older fish it was 21.0 °C.Summer field observations of yellow perch in Lake Nipissing, Costello Lake and Opeongo Lake in Ontario, showed average thermal distribution of 19.7 °C., 21.0 °C. and 21.2 °C. respectively. This agrees well with 20.8 °C. observed for four Wisconsin lakes. Oxygen depletion reported for Tennessee Valley reservoirs, distribution of primary prey species of lake trout in New York waters, and other factors, have been shown to modify the thermal distribution in nature. Differential sex response to temperature may be important in the perch. Field observations of thermal distributions for other species are also presented.A comparison of the laboratory and field data shows good agreement with fish having colder final preferenda: Salvelinus fontinalis, Salvelinus namaycush, Salvelinus hybrid and Coregonus clupeaformis. Fish with warmer final preferenda, such as Micropterus salmoides, Micropterus dolomieu and Lota lota lacustris, showed higher temperatures in the laboratory than was shown by field observations. Young Perca flavescens showed similar results, but experiments with older perch showed excellent agreement between laboratory results and held observations. The lack of agreement between laboratory results and field observations is attributed to age differences; laboratory experiments being performed with young fish and held observations being made on older fish.

TEMPERATURE SELECTION OF THE CARP (CYPRINUS CARPIO LINN.)

The selected or preferred temperatures of the carp were determined for six acclimation temperatures. At 10 °C., 15 °C., 20 °C., 25 °C., 30 °C., and 35 °C. acclimation the selected temperatures were 17 °C., 25 °C., 27 °C., 31 °C., 31 °C., and 32 °C. respectively. The final preferendum of carp was found to be 32 °C.