Effects of an experimental short-term cortisol challenge on the behaviour of wild creek chub Semotilus atromaculatus in mesocosm and stream environments

2013 ◽  
Vol 82 (4) ◽  
pp. 1138-1158 ◽  
Author(s):  
A. Nagrodski ◽  
K. J. Murchie ◽  
K. M. Stamplecoskie ◽  
C. D. Suski ◽  
S. J. Cooke
1984 ◽  
Vol 62 (8) ◽  
pp. 1548-1555 ◽  
Author(s):  
Pierre Magnan ◽  
Gérard J. FitzGerald

When brook charr, Salvelinus fontinalis Mitchill, are in allopatry in oligotrophic Québec lakes, they feed largely on macrobenthic invertebrates. However, when brook charr cooccur with creek chub, Semotilus atromaculatus Mitchill, they feed largely on zooplankton. In the present study, laboratory experiments showed that creek chub were more effective than brook charr in searching for hidden, patchily distributed prey. The searching efficiency of an individual chub feeding in a group was improved through social facilitation. In contrast, the high level of intraspecific aggression observed in brook charr prevents the formation of such feeding groups. In the laboratory, brook charr were able to displace creek chub from the food source because of interspecific aggression. Data are presented showing that chub are morphologically better adapted than charr to feed on benthos (subterminal orientation of the mouth and protrusible premaxillae), while the charr are better adapted than chub to feed on zooplankton (gill raker structure). Differences in feeding behaviour, morphology, and relative abundance between these species appear to be important in the observed niche shift of brook charr in nature.


1994 ◽  
Vol 72 (4) ◽  
pp. 721-730 ◽  
Author(s):  
Shaun P. Collin ◽  
M. Ather Ali

The topography of Nissl-stained cells within the retinal ganglion cell layer is examined in two closely related freshwater teleosts from the family Cyprinidae. Regardless of the close phylogenetic relationship and the sympatric habitats of the two species, pronounced differences in the number and position of areas of increased cell density are observed in their retinae. in the creek chub, Semotilus atromaculatus, a midwater crepuscular feeder, three retinal specializations or areae centrales are identified in the dorsonasal, nasal, and temporal regions of the retina. In the cutlips minnow, Exoglossum maxillingua, a benthic diurnal feeder, two areae centrales are identified in temporal and nasal retina. The upper limits of the spatial resolving power of each species are calculated from the spacing of cells within the ganglion cell layer. Differences in the arrangement of isodensity contours appear to reflect the symmetry of each species' visual environment. The development and significance of up to three visually acute zones are discussed.


1977 ◽  
Vol 55 (5) ◽  
pp. 843-846 ◽  
Author(s):  
P. M. Powles ◽  
Douglas Parker ◽  
Ronald Reid

No difference in growth rate occurred between two study streams, but male creek chub grew more rapidly than females, to a maximum reached at 7 years of age. Walfords were as follows: y = 4.8 TL + 0.810x, females; y = 3.5 TL + 0.792x, males. The length–weight relationship, W = −3.609 + 2.925 log L (TL), derived in the fall, was, as expected, somewhat below the spring relationship from an Illinois study. Kawartha creek chub M50 values were 6.0 TL ± 0.83 cm (males) and 6.54 ± 0.18 cm (females). Relative or apparent fecundity (fall egg count) was F = 71.9 + 136W and total or absolute fecundity (just before spawning) was virtually similar to other areas at F = 61.6 + 91.8W.


1989 ◽  
Vol 67 (6) ◽  
pp. 1372-1379 ◽  
Author(s):  
Jiří Lom ◽  
Sherwin S. Desser ◽  
Iva Dyková

One hundred and twenty-six fish of eight species, taken from Lake Sasajewun, Ontario, were examined for protozoan parasites. Detailed descriptions are given for Sphaerospora diminuta Li and Desser from the pumpkinseed, Lepomis gibbosus, and for Goussia degiustii Molnar and Fernando from the common shiner, Notropis cornutus. Oocysts of G. degiustii are pleomorphic and exhibit low tissue specificity. Goussia freemani Molnar and Fernando from the kidney of N. cornutus is tentatively synonymized with Goussia leucisci Shulman and Zaika. Two new species of Sphaerospora are described: Sphaerospora paulini n.sp. from the renal tubules of creek chub, Semotilus atromaculatus, with spherical spores 8.1 (8.0–8.5) μm in diameter, containing ovoid polar capsules 2.8 (2.5–3.4) × 2.6 (2.5–3.0) μm, and polar filament with 4–5 coils; and Sphaerospora hankai n.sp. from the renal tubules of the brown bullhead, Ictalurus nebulosus, with subspherical spores 6.1 (5.4–6.6) × 6.0 (5.4–6.5) μm, unequal subspherical polar capsules (larger, 2.8 (2.5–3.1) × 2.7 (2.3–2.9) μm; smaller, 2.4 (2.1–2.6) × 2.0 (1.9–2.2) μm), and polar filament with 4–5 coils in larger capsule, 3–4 coils in smaller capsule. Eimeria patersoni n.sp. is described from the kidney, spleen, and liver of L. gibbosus. Oocysts are subspherical (11.9 × 10.6), sporocysts ellipsoidal (10.4 (9.9–11.2) × 3.5 (2.6–4.0) μm), and sporozoites stubby (3.6 × 2.0 μm); sporocyst residuum has 1–3 large granules.


1966 ◽  
Vol 44 (5) ◽  
pp. 821-824 ◽  
Author(s):  
Alex Dechtiar

A new species of monogenetic trematode, Octomacrum semotili, on the gills of the creek chub, Semotilus atromaculatus, is described. This is the fourth species in the genus Octomacrum Mueller, 1934.


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