Effects of Hatchery Rearing on the Structure and Function of Salmonid Mechanosensory Systems

This paper reviews recent studies on the effects of hatchery rearing on the auditory and lateral line systems of salmonid fishes. Major conclusions are that (1) hatchery-reared juveniles exhibit abnormal lateral line morphology (relative to wild-origin conspecifics), suggesting that the hatchery environment affects lateral line structure, perhaps due to differences in the hydrodynamic conditions of hatcheries versus natural rearing environments, and (2) hatchery-reared salmonids have a high proportion of abnormal otoliths, a condition associated with reduced auditory sensitivity and suggestive of inner ear dysfunction

Differences in Lateral Line Morphology between Hatchery- and Wild-Origin Steelhead

Despite identification of multiple factors mediating salmon survival, significant disparities in survival-to-adulthood among hatchery- versus wild-origin juveniles persist. In the present report, we explore the hypothesis that hatchery-reared juveniles might exhibit morphological defects in vulnerable mechanosensory systems prior to release from the hatchery, potentiating reduced survival after release. Juvenile steelhead ( Oncorhynchus mykiss ) from two different hatcheries were compared to wild-origin juveniles on several morphological traits including lateral line structure, otolith composition (a proxy for auditory function), and brain weight. Wild juveniles were found to possess significantly more superficial lateral line neuromasts than hatchery-reared juveniles, although the number of hair cells within individual neuromasts was not significantly different across groups. Wild juveniles were also found to possess primarily normal, aragonite-containing otoliths, while hatchery-reared juveniles possessed a high proportion of crystallized (vaterite) otoliths. Finally, wild juveniles were found to have significantly larger brains than hatchery-reared juveniles. These differences together predict reduced sensitivity to biologically important hydrodynamic and acoustic signals from natural biotic (predator, prey, conspecific) and abiotic (turbulent flow, current) sources among hatchery-reared steelhead, in turn predicting reduced survival fitness after release. Physiological and behavioral studies are required to establish the functional significance of these morphological differences

Assessing silver nanoparticles behaviour in artificial seawater by mean of AF4 and spICP-MS

The use of nanotechnology-based products is constantly increasing and there are concerns about the fate and effect on the aquatic environment of antimicrobial products such as silver nanoparticles. By combining different characterization techniques (asymmetric flow field-flow fractionation, single particle ICP-MS, UVeVis) we show that it is possible to assess in detail the agglomeration process of silver nanoparticles in artificial seawater. In particular we show that the presence of alginate or humic acid differentially affects the kinetic of the agglomeration process. This study provides an experimental methodology for the in-depth analysis of the fate and behaviour of silver nanoparticles in the aquatic environment

High variability in hair cell number within neuromasts.

<p>(A–C) Confocal images (brightest-point projections) of neuromasts double-labeled with anti-acetylated tubulin (red) and phalloidin (green), showing the kinocilia and hair bundles/cuticular plates, respectively. The phalloidin label also delineates overall neuromast architecture. (A) Three neuromasts from stitch S2 of a wild-origin fish, showing neuromast morphology and spacing. (B) Single SN from stitch S3 of a Lake Quinault hatchery fish, demonstrating the rounded morphology sometimes observed. In contrast, elongated SN were more typically noted, illustrated here by the S5 neuromast from a Cook Creek fish (C). (D) Average hair cell number for 4 randomly selected individuals (open circles) from each group for which complete data (SN in all four dissected ROIs S1–S4; range 3–21 SN per ROI) were available, and group means (filled circles, mean ± 1 SEM) for each ROI. There were no significant cross-group differences in hair cell number (<i>p</i>>0.05).</p

Differences in neuromast number across groups.

<p>(A) SN were clustered in one of six discrete ‘stitches’ or groupings, which we term for convenience in the present report S1–S6. Each of these stitches was treated as a region of interest for analysis of neuromast number. (B–E) Examples of DASPEI-labeled neuromasts from wild-origin juveniles (B–C) or Cook Creek hatchery fish (D–E). (B) Stitches S1–S2, showing how S2 intersects S1 near its midpoint, running anteroventrally toward the eye. Scale bar = 1 mm. (C) Low-magnification image of the left side of the head, showing the stitch around the naris (S3) and the stitch over the operculum (S4). The infraorbital canal (IC) is also labeled in this image. This canal was not clearly visible in all specimens so neuromast number was not quantified. Scale bar = 2 mm. (D) Stitch S3 (bordering a right-side naris) under higher magnification. Scale bar = 1 mm. (E) SN from stitch S5 (arrowheads), which sits atop the trunk canal (arrows). Trunk canal neuromasts are elongated in the rostrocaudal direction, while adjacent SN are oriented dorsoventrally. Scale bar = 1 mm. (F) Total neuromast number (summed across left and right sides) per fish (open circles) and per group (filled circles, mean±1 SEM, <i>n</i> = 10 fish per group). There were significant differences in neuromast number between groups (one-way ANOVA <i>F</i>_1,2 = 9.45, <i>p</i> = 0.001). (G) SN number comparisons within each ROI using one-way ANOVA followed by Tukey's post-hoc analysis. Individual and group data are plotted across ROIs. Statistical tests are summarized are in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0059162#pone-0059162-t001" target="_blank">Table 1</a>.</p

Statistical comparison of SN number across groups.

<p>Observed <i>p</i>-values for ANOVAs and post-hoc pairwise tests (Tukey's) assessing cross-group differences in SN number by anatomical region (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0059162#pone-0059162-g001" target="_blank">Fig. 1A</a>). Post-hoc tests were not conducted for S5 or S6, where the omnibus ANOVA demonstrated no main effect of group. Bolded values indicate significance at <i>p</i><0.05.</p

Sagittal otolith calcium carbonate composition.

<p>Transmitted light images of a normal (aragonite) sagitta from a wild-origin juvenile (left) and a crystallized (vaterite) sagitta from a Cook Creek hatchery fish (right). Scale bars in each image  =  1 mm. (B) Relative proportion of aragonite (black) and vaterite (gray) sagittae in fish from each population (wild <i>n</i> = 20 otoliths (10 fish×2 otoliths each), Cook Creek = 28 otoliths, Lake Quinault = 34 otoliths). Both groups of hatchery fish had a significantly higher proportion of crystallized otoliths than wild fish (Chi-square tests, <i>p</i> = 0.001).</p

Brain weight differs between groups.

<p>Normalized brain weight, expressed as the brain/body weight ratio, of 8 randomly selected individuals (open circles) from each group and means for each group (filled circles, mean ± 1 SEM). The inset shows a brain from a wild-origin juvenile with the olfactory bulbs removed. Scale bar = 2 mm.</p

Sullivan au solstice. Les Saisons Sullivan, de Françoise Sullivan et Marion Landry avec une postface de Louise Déry. Galerie de l’UQAM, 91 p.

The influence of monomeric and micellar concentrations of the cationic monomeric, dodecyltrimethylammonium bromide (DTAB), and the corresponding dimeric, bis(N, N-dimethyl-N-dodecyl) ethylene-1,2-diammonium dibromide (12-2-12), surfactants on the formation and transformation of amorphous calcium phosphate (ACP) was investigated. The combination of microscopy (AFM and TEM) and light scattering techniques (size and zeta potential measurements) enabled, for the first time, the simultaneous monitoring of the effect that additives exert on different length scales during CaP formation in solution - from prenucleation clusters and ACP particles to the crystalline phase. Depending on their aggregation state (monomers or micelles) and the geometry of the aggregate (spherical or elongated micelles), DTAB and 12-2-12 have exhibited different effects on the rate of ACP transformation, as well as on the morphology of the amorphous and crystalline phases. It was shown that the effect of surfactants on the precipitation process observed on the microscale could be a result of different pathways on the nanoscale. The obtained results may have implications for the understanding of the general mechanism of inorganic-organic interactions underlying the biomineralization processes, as well as for materials science

Differences in Lateral Line Morphology between Hatchery- and Wild-Origin Steelhead

Despite identification of multiple factors mediating salmon survival, significant disparities in survival-to-adulthood among hatchery- versus wild-origin juveniles persist. In the present report, we explore the hypothesis that hatchery-reared juveniles might exhibit morphological defects in vulnerable mechanosensory systems prior to release from the hatchery, potentiating reduced survival after release. Juvenile steelhead (Oncorhynchus mykiss) from two different hatcheries were compared to wild-origin juveniles on several morphological traits including lateral line structure, otolith composition (a proxy for auditory function), and brain weight. Wild juveniles were found to possess significantly more superficial lateral line neuromasts than hatchery-reared juveniles, although the number of hair cells within individual neuromasts was not significantly different across groups. Wild juveniles were also found to possess primarily normal, aragonite-containing otoliths, while hatchery-reared juveniles possessed a high proportion of crystallized (vaterite) otoliths. Finally, wild juveniles were found to have significantly larger brains than hatchery-reared juveniles. These differences together predict reduced sensitivity to biologically important hydrodynamic and acoustic signals from natural biotic (predator, prey, conspecific) and abiotic (turbulent flow, current) sources among hatchery-reared steelhead, in turn predicting reduced survival fitness after release. Physiological and behavioral studies are required to establish the functional significance of these morphological differences