Physically‐mediated variations in production, standing stock and distribution of plankton have a significant impact on the growth and survival of larval fishes in Shelikof Strait. We integrate descriptions of mechanisms that control the distribution and regional production of planktonic organisms with mechanisms that influence survival of early life history stages of marine fish, especially the locally abundant walleye pollock, Theragra chalcogramma. The timing of the spring phytoplankton bloom is more variable than the regular appearance of pollock larvae, and is affected by variability in the winter to spring storm season transition, stratification in the Alaska Coastal Current (ACC), and cloudiness. The spring bloom occurs first in the ACC, fuelling local production of copepod nauplii, the main prey item of early larval pollock. Shelikof Strait zooplankton standing stock is higher in the ACC than the surrounding Coastal Water (CW) throughout the spring. This is the result of local production as well as regional production which occurs upstream of the strait. Mesoscale features associated with the ACC (fronts, meanders, and eddies) determine the distribution of plankton through physical convergence, and reduced dispersion and transport. Evidence for enhancement of planktonic production in these features is lacking. Thus the ACC plays a strong role in determining plankton production, standing stock, and distribution in the Shelikof region. The strength of the relationship among plankton, planktonic production, larval pollock growth and survival, and fisheries recruitment is variable. The plankton is only one of several key variables that affect eventual recruitment to the pollock fishery.
The objectives of this study were to determine a breed-specific vertebral heart scale (VHS) range for the dachshund and compare results to the established reference range of 9.7 ± 0.5, calculate inter-observer variability, and correlate VHS with echocardiography. Fifty-one normal dachshunds had radiographs and an echocardiogram performed. Five observers measured VHS to the nearest 0.25 vertebra. The data was analyzed using one-way analysis of variance, Wilcoxon Rank Sum test, Mann-Whitney rank sum test, calculation of reference and confidence intervals, Spearman rank-order correlations, and generation of intra-class correlations and confidence intervals. P < .05 was considered significant. The median for right lateral VHS was significantly larger than left (10.3 [range 9.25-11.55] versus 10.1 [range, 8.7-11.31], p < .0001). VHS for females was significantly larger than for males (left: 10.56 [9.2-11.31] versus 9.74 [8.7-10.88] and right: 10.8 [9.5-11.55] versus 9.99 [9.25-10.8], p = .0002). Observer consistency was high with an intra-class correlation coefficient of 0.95. No significant correlation was found between left atrial echocardiographic parameters and VHS. Results indicate normal dachshunds have a median VHS above the published generic canine reference range, and VHS can be reliably performed by observers with varying degrees of clinical experience.
A nine-month-old male Labrador retriever was admitted for a progressive gait abnormality. The owner had observed thoracic limb incoordination, which was more obvious at exercise and had gradually worsened over two months.Physical and orthopedic examinations were normal. Ataxia was noted of the trunk and limbs on neurologic evaluation. Conscious proprioceptive deficits were present in all limbs but were most pronounced in the thoracic limbs, where the toe nails were obviously worn. Cranial nerve function and spinal reflexes were normal. Spinal hyperesthesia was not detected.These abnormalities were consistent with a Cl-C5 spinal cord lesion. Differentials included congenital vertebral malformations, vertebral instability, syringomyelia and other intramedullary spinal cord defects, arachnoid cyst, inflammatory central nervous system disease, caudal cervical spondylomyelopathy and intervertebral disc disease.Complete blood cell count, serum biochemical analysis and urinalysis were normal. Cerebrospinal fluid collected from the lumbar region was normal. *Isowe (lopamidol injection 41 %), Squibb Diagnostics, Bristol-Myers College of Veterinary Medicine, Pullman WA 99 164-7060.Squibb Company, Princeton, NJ, 08543.
Previous research has suggested that free‐ranging mourning doves (Zenaida macroura) may ingest spent lead pellets, succumb to lead toxicosis, and die in a relatively short time (i.e., an acute lead toxicosis hypothesis). We tested this hypothesis by administering 157 captive mourning doves 2–24 lead pellets, monitoring pellet retention and short‐term survival, and measuring related physiological characteristics. During the 19‐ to 21‐day posttreatment period, 104 doves that received lead pellets died (deceased doves) and 53 survived (survivors); all 22 birds in a control group survived. Within 24‐hr of treatment, blood lead levels increased almost twice as fast for deceased doves compared to survivors (F1,208 = 55.49; P < 0.001). During the first week, heterophil:lymphocyte (H:L) ratios increased twice as fast for deceased doves than with survivors (F1,198 = 23.14, P < 0.001). Posttreatment survival differed (χ2 = 37.4, P < 0.001) among the 5 groups of doves that retained different numbers of pellets, and survival ranged from 0.57 (95% CI: 0.44–0.74) for doves that retained ≤2 lead pellets 2 days posttreatment compared to 0.08 (95% CI: 0.022–0.31) for those doves that retained 13–19 lead pellets on 2 days posttreatment; significant differences existed among the 5 groups. After controlling for dove pretreatment body mass, each additional lead pellet increased the hazard of death by 18.0% (95% CI: 1.132–1.230, P < 0.001) and 25.7% (95% CI: 1.175–1.345, P < 0.001) for males and females, respectively. For each 1‐g increase in pretreatment body mass, the hazard of death decreased 2.5% (P = 0.04) for males and 3.8% (P = 0.02) for females. Deceased doves had the highest lead levels in liver (49.20 ± 3.23 ppm) and kidney (258.16 ± 21.85 ppm) tissues, whereas controls showed the lowest levels (liver, 0.08 ± 0.041 ppm; kidney, 0.17 ± 0.10 ppm). For doves dosed with pellets, we observed simultaneous increases in blood lead levels and H:L ratios, whereas packed‐cell volume (PCV) values declined. Our results support an acute lead toxicosis hypothesis. Although further research is necessary to investigate the magnitude of lead shot ingestion and toxicosis in mourning doves, we recommend that management agencies initiate development of a long‐term strategic plan aimed at implementing a nontoxic shot regulation for mourning dove hunting.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.