Effect of Fish Size on the Reactive Distance of Bluegill (Lepomis macrochirus) Sunfish

1983 ◽  
Vol 40 (2) ◽  
pp. 162-167 ◽  
Author(s):  
James E. Breck ◽  
Michael J. Gitter
Keyword(s):  
Visual Acuity ◽  
Lepomis Macrochirus ◽  
Behavioral Measure ◽  
Eye Lens ◽  
Fish Size ◽  
Size Classes ◽  
Reactive Distance ◽  
Rate Of Increase ◽  
Lens Diameter ◽  
Cone Density

We hypothesized that visual acuity in fishes and thus reactive distance should increase with fish size; visual acuity depends on eye lens diameter and cone density in the retina, and eye lens diameter increases with fish size. Though cone density declines in larger fish, we expected this effect to be relatively small. We tested this hypothesis for a behavioral measure of visual acuity, the reactive distance of bluegill (Lepomis macrochirus) sunfish to zooplankton prey, in aquaria (375 L) for fish from 27 to 162 mm standard length. Reactive distance increased nonlinearly with fish size; the rate of increase in reactive distance slows in larger fish. For fish of a given size, reactive distance was dependent on prey size, but visual angle measured from the fish eye was nearly constant. Whereas lens diameter and visual acuity increase with fish size in bluegills, the acuity of larger fish is less than expected from eye lens diameter alone. This is probably a result of cone density decreasing with fish size, as has been found for other fishes. The observed fish-size-dependent differences in reactive distance imply very large differences in visual volumes and encounter rates with prey among size-classes of bluegills. Habitat segregation among bluegill size-classes may prevent the intense intraspecific competition for prey that would be expected, in part, from the superior visual acuity of larger fish.Key words: foraging, reactive distance, size-class interactions, bluegill, Lepomis macrochirus; predation, visual acuity, zooplankton

Isotopic characterization of lifetime movement by two demersal fishes from the northeastern Gulf of Mexico

2021 ◽  
Vol 657 ◽  
pp. 161-172
Author(s):  
JL Vecchio ◽  
JL Ostroff ◽  
EB Peebles
Keyword(s):  
Gulf Of Mexico ◽  
Continental Shelf ◽  
Life Histories ◽  
Linear Mixed Model ◽  
Trophic Position ◽  
Eye Lens ◽  
Outer Continental Shelf ◽  
Red Grouper ◽  
Lens Diameter ◽  
Isotopic Characterization

An understanding of lifetime trophic changes and ontogenetic habitat shifts is essential to the preservation of marine fish species. We used carbon and nitrogen stable isotope values (δ13C and δ15N) recorded within the laminar structure of fish eye lenses, reflecting both diet and location over time, to compare the lifetime trends of 2 demersal mesopredators. Tilefish Lopholatilus chamaeleonticeps inhabit burrows on the outer continental shelf, which results in exceptional site fidelity. Red grouper Epinephelus morio are spawned on the middle to outer continental shelf, move to the inner shelf for the juvenile period, and return offshore upon sexual maturity. Both species inhabit the eastern Gulf of Mexico, a region with a distinctive offshore-inshore gradient in background δ13C values. Within individual tilefish (n = 36), sequences of δ13C values and δ15N values had strong, positive correlations with eye-lens diameter, and strong correlations between the 2 isotopes (mean Spearman r = 0.86), reflecting an increase in trophic position with growth and little lifetime movement. In red grouper (n = 30), δ15N values positively correlated with eye-lens diameter, but correlations between δ15N and δ13C were weak (mean Spearman r = 0.29), suggesting cross-shelf ontogenetic movements. Linear mixed model results indicated strong relationships between δ15N and δ13C values in tilefish eye lenses but no convergence in the red grouper model. Collectively, these results are consistent with previously established differences in the life histories of the 2 species, demonstrating the potential utility of eye-lens isotope records, particularly for investigating the life histories of lesser-known species.

Effects of cadmium on the foraging behavior and growth of juvenile bluegill, Lepomis macrochirus

1995 ◽  
Vol 52 (8) ◽  
pp. 1630-1638 ◽  
Author(s):  
Miehael D. Bryan ◽  
Gary J. Atchison ◽  
Mark B. Sandheinrich
Keyword(s):  
Foraging Behavior ◽  
Standardized Test ◽  
Prey Capture ◽  
Prey Size ◽  
Cadmium Concentration ◽  
Control Level ◽  
Lepomis Macrochirus ◽  
Aquatic Organisms ◽  
Handling Time ◽  
Behavioral Measure

Standardized test protocols for assessing chemical hazards to aquatic organisms inadequately consider behavioral effects of toxicants; yet, organisms behaving abnormally in the wild have reduced growth, reduced fitness, and high mortality. We determined the chronic effects of cadmium (0, 30, 60, 120, and 240 μg∙L−1) on juvenile bluegill (Lepomis macrochirus) foraging behavior and growth rates in functional response experiments, each using different sized Daphnia as prey. Bluegill consumption rate increased with prey density. Cadmium-exposed fish initially attacked fewer prey per unit of time than unexposed fish, with subsequent recovery to control-level consumption rates determined by cadmium concentration and prey size. The degree of change (over time) in the number of Daphnia attacked per 30 s was the most consistently sensitive behavioral measure of sublethal stress in exposed bluegill; the lowest observed effect concentration (LOEC) was 37.3 μg Cd∙L−1. Effects on prey attack rates (attacks/30 s) were inversely related to prey size; cadmium had the greatest effect on bluegill foraging on the smallest prey. Cadmium had no effect on prey capture efficiency or handling time. Growth in bluegill length and weight was reduced (P ≤ 0.019) by all cadmium concentrations and was a more sensitive end point than were the foraging behaviors.

scholarly journals Sleep Deprivation Has No Effect on Dynamic Visual Acuity in Military Service Members Who Are Healthy

2013 ◽  
Vol 93 (9) ◽  
pp. 1185-1196 ◽  
Author(s):  
Matthew R. Scherer ◽  
Pedro J. Claro ◽  
Kristin J. Heaton
Keyword(s):  
Visual Acuity ◽  
Sleep Deprivation ◽  
Repeated Measures ◽  
Military Service ◽  
Intraclass Correlation ◽  
Vestibular Function ◽  
Service Members ◽  
Behavioral Measure ◽  
Dynamic Visual Acuity ◽  
Repeated Measures Design

Background The risk of traumatic brain injury (TBI) and comorbid posttraumatic dizziness is elevated in military operational environments. Sleep deprivation is known to affect a service member's performance while deployed, although little is known about its effects on vestibular function. Recent findings suggest that moderate acceleration step rotational stimuli may elicit a heightened angular vestibulo-ocular reflex (aVOR) response relative to low-frequency sinusoidal stimuli after 26 hours of sleep deprivation. There is concern that a sleep deprivation–mediated elevation in aVOR function could confound detection of comorbid vestibular pathology in service members with TBI. The term “dynamic visual acuity” (DVA) refers to an individual's ability to see clearly during head movement and is a behavioral measure of aVOR function. The Dynamic Visual Acuity Test (DVAT) assesses gaze instability by measuring the difference between head-stationary and head-moving visual acuity. Objective The purpose of this study was to investigate the effects of 26 hours of sleep deprivation on DVA as a surrogate for aVOR function. Design This observational study utilized a repeated-measures design. Methods Twenty soldiers with no history of vestibular insult or head trauma were assessed by means of the DVAT at angular head velocities of 120 to 180°/s. Active and passive yaw and pitch impulses were obtained before and after sleep deprivation. Results Yaw DVA remained unchanged as the result of sleep deprivation. Active pitch DVA diminished by −0.005 LogMAR (down) and −0.055 LogMAR (up); passive pitch DVA was degraded by −0.06 LogMAR (down) and −0.045 LogMAR (up). Limitations Sample homogeneity largely confounded accurate assessment of test-retest reliability in this study, resulting in intraclass correlation coefficients lower than those previously reported. Conclusions Dynamic visual acuity testing in soldiers who are healthy revealed no change in gaze stability after rapid yaw impulses and subclinical changes in pitch DVA after sleep deprivation. Findings suggest that DVA is not affected by short-term sleep deprivation under clinical conditions.

Prey Detection in Cyprinids during Early Development

1989 ◽  
Vol 46 (6) ◽  
pp. 995-1001 ◽  
Author(s):  
Josef Wanzenböck ◽  
Fritz Schiemer
Keyword(s):  
Visual Acuity ◽  
Juvenile Fish ◽  
Rutilus Rutilus ◽  
Prey Detection ◽  
Roach Rutilus Rutilus ◽  
Fish Size ◽  
Video Recordings ◽  
Prey Location ◽  
Bleak Alburnus Alburnus ◽  
Zooplankton Prey

Larval and juvenile fish of roach (Rutilus rutilus L), bleak (Alburnus alburnus L), and blue bream (Abramis ballerus L.) were investigated weekly to define the ontogenetic development of prey detection capacities. Visual acuity was determined by measuring reactive distances for zooplankton prey for fish from 8 to 50 mm standard length using video recordings. Data of reactive distances, swimming speeds, and the characteristics of the visual field were combined to calculate prey location volumes. Prey location capacity increased exponentially with fish size which implies enormous differences in prey encounter rates among size classes of cyprinids. Distinct differences of prey location capacities occurred between species in the juvenile, planktivorous stages of the three cyprinids coinciding with the trophic differentiation of the adults.

scholarly journals Human foveal cone photoreceptor topography and its dependence on eye length

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Yiyi Wang ◽  
Nicolas Bensaid ◽  
Pavan Tiruveedhula ◽  
Jianqiang Ma ◽  
Sowmya Ravikumar ◽  
...  
Keyword(s):  
Visual Acuity ◽  
Adaptive Optics ◽  
Axial Length ◽  
Visual Angle ◽  
Cone Photoreceptor ◽  
Foveal Vision ◽  
Cone Mosaic ◽  
New Generation ◽  
Myopic Progression ◽  
Cone Density

We provide the first measures of foveal cone density as a function of axial length in living eyes and discuss the physical and visual implications of our findings. We used a new generation Adaptive Optics Scanning Laser Ophthalmoscope to image cones at and near the fovea in 28 eyes of 16 subjects. Cone density and other metrics were computed in units of visual angle and linear retinal units. The foveal cone mosaic in longer eyes is expanded at the fovea, but not in proportion to eye length. Despite retinal stretching (decrease in cones/mm2), myopes generally have a higher angular sampling density (increase in cones/deg2) in and around the fovea compared to emmetropes, offering the potential for better visual acuity. Reports of deficits in best-corrected foveal vision in myopes compared to emmetropes cannot be explained by increased spacing between photoreceptors caused by retinal stretching during myopic progression.

The Fish Size, Prey Size, Handling Time Relation in Several Sunfishes and Some Implications

1974 ◽  
Vol 31 (9) ◽  
pp. 1531-1536 ◽  
Author(s):  
Earl E. Werner
Keyword(s):  
Life History ◽  
Prey Size ◽  
Lepomis Macrochirus ◽  
Handling Time ◽  
Size Ratio ◽  
Exponential Equation ◽  
Fish Size ◽  
Natural Prey ◽  
Mouth Size ◽  
Time Relation

The relation between fish size, prey size, and handling time was determined for bluegill (Lepomis macrochirus) and green (L. cyanellus) sunfishes with both artificial and natural prey. When scaled by plotting handling time against the ratio of prey size to mouth size, the relation was quite general across fish size and species and is described by a modified exponential equation. Handling time increases [Formula: see text] fold as fish approach satiation. Curves of handling time/unit return define optimal prey size for fish of different size and/or species and illustrate comparative aspects of the breadth of diet for different sized sunfish. Certain life history features of the bluegill are interpreted on the basis of these curves. Optimal prey size occurs at a prey size to mouth size ratio of 0.59 regardless of fish size.

Effects of Light and Turbidity on the Reactive Distance of Bluegill (Lepomis macrochirus)

1976 ◽  
Vol 33 (12) ◽  
pp. 2845-2849 ◽  
Author(s):  
Gary L. Vinyard ◽  
W. John O’brien
Keyword(s):  
Lepomis Macrochirus ◽  
Substantial Reduction ◽  
Daphnia Pulex ◽  
Large Prey ◽  
Feeding Rates ◽  
Fish Feeding ◽  
Turbid Waters ◽  
Reactive Distance ◽  
Light Intensities

Changes in the reactive distance of bluegill (Lepomis macrochirus) to various sizes of Daphnia pulex were measured at light intensities ranging from 0.70 to 215.3 lx (0.065–20.0 ft-c) and at turbidities ranging from 1 to 30 Jackson Turbidity Units (JTU). Both reduced illumination and increased turbidity caused substantial reduction in the reactive distance of bluegill for all prey sizes, and particularly for large prey. This result should be considered in efforts to determine fish feeding rates in lakes, and may be particularly relevant to vertically migrating zooplankton, or those inhabiting more turbid waters.

The role of palash mul arka aschotana in kaphaja timira and kaphaja kacha w.s.r. immature cataract

2019 ◽  
Vol 7 (02) ◽  
Author(s):  
Swati Sarwade
Keyword(s):  
Developing Countries ◽  
Visual Acuity ◽  
Side Effects ◽  
Direct Effect ◽  
Eye Lens ◽  
Progressive Decrease ◽  
Single Drug ◽  
The World

     Blindness results due to numerous causes, Cataract is one of them , it is also major cause of blindness in tropical and developing countries all over the world due to direct effect on eye lens.      In view of ayurved literature Kaphaja timira and kaphaja kacha is a dreadful disease of eye lens mentioned in drishtigat roga vidyaniya addhyay .     The disease shows gradual –progressive decrease in vision. Ayurved literature have recorded single drug and compound formulation for treatment of Timir, Kacha (Imm.cat.) as Chakshushya or Netrya (sight ,vision improving) so that Palasha a Chakshushya drug in the form of  arka, which is kaphahara is taken for the treatment of same and results are noted according to CRF and improvement in visual acuity and disappearance of symptoms are statistically analyzed. Results are significant and no side effects of arka are seen.

Influence of scleral lens haptic zone design on lens fit in patients with different scleral toricity

2021 ◽  
pp. 53-56
Author(s):  
N.A. Bakalova ◽  
◽  
O.A. Zhabina ◽  
S.V. Listratov ◽  
S.V. Avetisov ◽  
...  
Keyword(s):  
Visual Acuity ◽  
Key Words ◽  
Contact Lens ◽  
Retrospective Review ◽  
Correct Choice ◽  
Patient Records ◽  
Stabilization Method ◽  
Lens Diameter ◽  
The Mean ◽  
Corneal Diameter

In our practice, we often encounter the issue of centering and stabilizing scleral contact lens (SCL) in the patient's eye. This is due to the fact that the haptic part of the SCL rests on the scleral conjunctiva, which itself is toric. Рurpose. To analyze possibilities of stabilizing scleral and mini-scleral lenses in patients with different scleral toricities. Material and methods. This study was a retrospective review of 17 patient records (34 eyes); 9 patients were male and 8 female. The mean age of the patients was 38 ± 12 years. Results. The horizontal visible iris diameter amounted to 11.85 ± 0.52 mm (11.0 to 12.5 mm). All patients previously underwent fitting of SCLs for correction of ametropia. Lens diameter was chosen based on the corneal diameter, while the shape of the patient's sclera determined stabilization method. This work describes a method for determining scleral toricity. An adequate fit of spherical SCLs was not achieved in patients with toric sclera; however, the correct choice of a stabilization method made it possible to achieve congruence of the lens edge with the scleral surface in all four quadrants and obtain a high visual acuity in all patients included in the study, regardless of the lens diameter. Conclusion. Stabilization of SCLs provided a safe and comfortable wearing experience. Key words: scleral lenses, mini-scleral lenses, lens edges, scleral conjunctiva, toric periphery, limbus

scholarly journals Congenital Aniridia: Clinic, Genetics, Therapeutics, and Prognosis

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Pedro Calvão-Pires ◽  
R. Santos-Silva ◽  
F. Falcão-Reis ◽  
A. Rocha-Sousa
Keyword(s):  
Gene Expression ◽  
Visual Acuity ◽  
Prognostic Factors ◽  
Clinical Characteristics ◽  
Rare Condition ◽  
Posterior Segment ◽  
Eye Lens ◽  
Pax6 Gene ◽  
Congenital Aniridia ◽  
Foveal Hypoplasia

Congenital aniridia is a rare condition related to a deficiency in the PAX6 gene expression, which may occur as a result of a family inheritance or a sporadic occurrence. Additionally, this condition may occur as an isolated ocular phenotype or in association with a systemic syndrome. The most common abnormality is iris hypoplasia; however, a panocular disease which also affects the cornea, anterior chamber of the eye, lens, and the posterior segment with presence of optic nerve and foveal hypoplasia is also evident. The development of keratopathy, glaucoma, and cataract is frequent and its presence has implications in the patient’s visual acuity. Managing aniridia is challenging since the focus is on treating the previously mentioned disorders, and the outcomes are often disappointing. In this paper, we shall review the epidemiology, pathophysiology, and clinical characteristics of patients with aniridia. We shall also make a review of the therapeutic options for the several conditions affecting this syndrome and consider the genetics and prognostic factors.

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