Newsletter Fall 2017: Environmental Science & Ecology

Newsletter from the Department of Environmental Science and Ecology for Fall 2017. This newsletter highlights the sabbatical of Dr. Chris Norment, welcomes two new Assistant Professors, Dr. Courtney McDaniel and Dr. Michael Chislock and Visiting Assistant Professor Dr. Nathan Kleist. It shares the research activities of faculty and students, and updates from several alumni.https://digitalcommons.brockport.edu/env_news/1018/thumbnail.jp

Newsletter Spring 2018: Environmental Science & Ecology

Newsletter from the Department of Environmental Science and Ecology for Spring 2018. This newsletter highlights the phased retirement of Dr. Doug Wilcox, says goodbye to Visiting Assistant Professor Dr. Nathan Kleist, and shares the research activities of faculty and students, and updates from several alumni.https://digitalcommons.brockport.edu/env_news/1019/thumbnail.jp

Growth, Survival, and Body Composition of Yellow Perch Juveniles Fed Commercial and Experimental Diets

Two experiments were carried out to evaluate the efficacy of commercial and experimental diets on the survival, growth, and body composition of juvenile yellow perch Perca flavescens. In both experiments, fish were fed by hand four to five times a day at a restricted ration of up to 90% satiation for 51 d. In experiment 1, fish (initial weight, 87 6 24 mg) were fed three experimental diets (F1, F2, and a casein–gelatin-based diet) and one commercial diet (Kyowa 400B). In experiment 2, fish (initial weight, 174 6 56 mg) were fed four experimental diets (Kyowa 400B, INVE-NRD, a starter diet from BioOregon, and a starter diet from Purina). In both experiments, the growth performance of yellow perch juveniles was significantly affected by dietary treatments. In experiment 1, fish fed Kyowa 400B and the casein–gelatinbased diet grew significantly faster than those fed the F1 and F2 diets. However, survival was significantly lower in fish fed the casein–gelatin-based diet than in those fed the other dietary treatments. In experiment 2, fish fed the INVE-NRD diet exhibited the best growth performance. Survival was not affected by dietary treatments. In both experiments, the proximate composition of fish among dietary treatments reflected the proximate composition of the diet. Our results indicate that satisfactory growth of yellow perch juveniles can be achieved using commercial and experimental diets

Linking Egg Thiamine and Fatty Acid Concentrations of Lake Michigan Lake Trout with Early Life Stage Mortality

The natural reproduction of lake trout Salvelinus namaycush in Lake Michigan is thought to be compromised by nutritional deficiency associated with inadequate levels of thiamine (vitamin B1) in their eggs. However, mortality driven by thiamine deficiency (commonly referred to as early mortality syndrome [EMS]) is not the only significant cause of low lake trout survival at early life stages. In this study, we sought to better understand the combined effects of variable levels of thiamine and fatty acids in lake trout eggs on prehatch, posthatch, and swim-up-stage mortality. We sampled the eggs of 29 lake trout females from southwestern Lake Michigan. The concentrations of free thiamine and its vitamers (e.g., thiamine monophosphate [TMP] and thiamine pyrophosphate [TPP]) as well as fatty acid profiles were determined in sampled eggs. Fertilized eggs and embryos were monitored through the advanced swim-up stage (1,000degree-days). Three distinct periods of mortality were identified: prehatch (0–400 degree-days), immediately posthatch (401–600 degree-days), and swim-up (601–1,000 degree-days). Stepwise multiple regression analysis revealed (1) that cis-7-hexadecenoic acid in both neutral lipids (NL) and phospholipids (PL) correlated with prehatch mortality, (2) that docosapentaenoic acid in PL and docosahexaenoic acid in NL correlated with posthatch mortality, and (3) that total lipids, TPP, and palmitoleic acid in NL, linoleic acid, and palmitic acid in PL correlated with the frequency of EMS. These results indicate the complexity of early life stage mortality in lake trout and suggest that inadequate levels of key fatty acids in eggs, along with variable thiamine content, contribute to the low survival of lake trout progeny in Lake Michigan

Uptake and depletion of plasma 17α-methyltestosterone during induction of masculinization in muskellunge, Esox masquinongy: Effect on plasma steroids and sex reversal

Oral administration of 17α-methyltestosterone (MT) was used to induce masculinization of sexually undifferentiated muskellunge, Esox masquinongy. Three groups of muskellunge (mean weight, 2.5 ± 0.6 g) were submitted to MT treatment (15 mg of MT/kg) for 60 days. An additional one group was used as a control (hormone-free diet). Food was distributed over a 10-h period by using automatic belt feeders. Blood was sampled in both control and treated fish at different intervals during and after feeding: before (0 h), at 3 h, 6 h, and cessation of feeding (10 h), and after a fast of 22 h (32 h). MT had no significant effect on growth and survival in muskellunge 6 months after the treatment. Concentrations of plasma MT increased during the feeding period and reached their maximum levels 6 or 10 h after starting feeding. This rapid increase of MT indicated a rapid absorption of this steroid. Plasma MT levels then declined and reached a radir by 22 h after cessation of feeding, suggesting that MT is rapidly metabolized and excreted. The profiles of plasma testosterone during the MT treatment did not differ significantly between control and MT-treated groups. During and after the MT treatment, the concentration of plasma testosterone did not differ significantly between control and MT-treated groups. Moreover, no sexual dimorphism of testosterone levels was observed. Six months after treatment, the sex ratio in MT-treated groups (33% males, 62% females, and 5% intersex) was opposite to control (70% and 30%, respectively) and differed significantly. This suggests that at 15 mg of MT/kg over 60 days, a paradoxical feminization took place.Salaries were partly provided by State and Federal Funds awarded to the Ohio Agriculture Research and Development Center, Wooster, OH, USA

Effects of Vitamin B1 (Thiamine) Deficiency in Lake Trout Alevins and Preventive Treatments

The objectives of this study were to examine the effect of thiamine immersion of fish from a population known for compromised survival as a result of early mortality syndrome (EMS) and to investigate the causeâ response relationship between thiamine concentration and lesions in tissues in swimâ upâ stage lake trout Salvelinus namaycush alevins. Lake trout eggs from 14 fish from Lake Michigan were artificially fertilized and the progeny divided into two groups based on the thiamine concentration (low (0.85 nmol/g)) in the unfertilized eggs. Progeny were treated or not with a thiamine solution (2,000 mg/L for 2 h) at hatching or the swimâ up stage. The survival of progeny in control groups at the swimâ up stage correlated with thiamine concentration. The low thiamineâ treated groups had significantly higher survival between the swimâ up stage (812.0 degreeâ days) and 16 d after swimâ up (963.3 degreeâ days) than the control groups; the survival of the high thiamineâ treated groups did not differ between treated and control fish, regardless of the treatment at hatching and the swimâ up stage. Control alevins that had low thiamine levels showed EMS, which resulted in 94.9â 100% mortality 16 d after the swimâ up stage. No pathological changes were observed in the brain, olfactory lobe, eye, liver, or muscle in alevins of high thiamineâ treated group. Glycogen deposits in the liver of alevins from the low control group were variable, no glycogen being observed in the hepatocytes of 7 of the 24 fish. We demonstrate that thiamine treatment at swimâ up enhances the survival of EMSâ affected lake trout relative to treatment at hatching.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141712/1/aah0290.pd

Molecular Markers of Yolk Sac Fry Development in Nine Families of Lake Trout

Salmonids in certain areas of North America and northern Europe suffer from reproductive disturbances manifested through the death of yolk sac fry. These disturbances are referred to as early mortality syndrome (EMS) in the Great Lakes region and M74 in the Baltic Sea. Both of these syndromes have been associated with reduced concentrations of thiamine in affected females and their eggs. However, large variations in signs and mortality, both within and between the individual syndromes, have been reported. Yolk sac fry mortality (M74) in Atlantic salmon Salmo salar has been shown to be associated with reduced DNA binding of the hypoxia-inducible transcription factor 1 (HIF-1), reduced production of vascular endothelial growth factor (VEGF) protein, decreased capillary density, and down-regulation of adult-type globin gene transcription (which is responsible for the protein part of adult hemoglobin). One of the main effects of all of these changes is reduced oxygen transport to the tissues of affected fry. In this study, the developmental patterns of HIF-1 DNA binding, VEGF protein expression, and adult-type globin gene transcription were analyzed in nine family groups of Lake Michigan lake trout Salvelinus namaycush. The results indicate that HIF-1 DNA binding and globin gene transcription increase from hatch to the end of yolk sac stage. Interindividual and between-family biological variations were detected, especially in VEGF protein expression and globin gene transcription. Our results demonstrate the possibility of using these molecular markers in investigating the etiology of EMS and making comparisons between the mechanisms of different salmonid yolk sac fry mortalities

Induction of Gynogenesis in Muskellunge With Irradiated Sperm of Yellow Perch Proves Diploid Muskellunge Male Homogamety

Diploid gynogenesis was induced in muskellunge Esox masquinongy using UV-irradiated muskellunge sperm as the first step in producing monosex females. In this approach, we have to rely on negative controls as an indirect reference for sperm genetic material destruction. In the first experiment, equal proportions of gynogenetic females and males were produced. Negative controls, UV-irradiated sperm without heat shock, yielded some normal hatching larvae, described as spontaneous diploids. In the second experiment, muskellunge eggs were activated using sperm from yellow perch. Because hybrids between these species are not viable, we produced unambiguous gynogens. When UV-irradiated yellow perch sperm was used to inseminate muskellunge eggs, haploids resulted (22.5% ± 2.8% survival to the eyed stage). To produce diploid gynogens, a heat shock of 31°C was applied to inseminated eggs 20 min after activation for a duration of 6 min. This process yielded several hundreds of gynogens for rearing. Several treatments of masculinizing hormone, 17 α-methyltestosterone (MT), were carried out. Fish were dissected and gonads examined histologically for sex determination. Gynogens produced using yellow-perch sperm confirmed the presence of males in the control group, whereas the MT bath treatment (400 μg/liter) resulted in the production of fish with ovotestis. These results provide evidence for male homogamety in muskellunge and imply that a change of strategy is needed to produce monosex populations.Funding for this project was provided by the Federal Aid in Sport Fish Restoration Program (F-69-P, Fish Management in Ohio), administered jointly by the U.S. Fish and Wildlife Service and the Ohio Division of Wildlife

Reproductive Cycle and Plasma Levels of Sex Steroids in Female Eurasian Perch Perca Fluviatilis

From April 1995 to April 1996, the annual reproductive cycle of the Eurasian perch Perca fluviatilis was studied at the Fishfarming Lindre Center (Moselle, France). At monthly intervals (at intervals of 10 days during the periovulatory period), 5 females were caught and dissected. From sampled organs, the gonado-, hepato- and viscerosomatic indexes (GSI, HSI, VSI) were calculated, oocyte diameters (OD) and the plasma levels of testosterone (T), 17P-estradiol (E2), 17,20P-dihydroxy-4-pregnen-3-one (17,2Op-P) and protein-phosphorus (PPP) were measured. After the sexual resting period observed from May to August (GSI \u3c 1 %, OD \u3c 200 urn, VSI = 4-6 %), oogenesis began in September when the water temperature decreased from 26.4 to 14.1 “C. The GSI increased progressively until mid March (15 %), then rapidly until spawning (25 %, OD = 850 urn) which occurred in April (14- 15 “C). The plasma levels of T, E,, 17,2Op-P and PPP were low during the sexual resting period. E, and PPP levels increased significantly at the onset of the oogenesis in September, then the E, level raised abruptly in November (3-4 ng mL-‘). In December, the T level increased rapidly to 15-20 ng . mL-’ The testosterone, E, and PPP levels remained very high until spawning, indicating the existence of active vitellogenesis. The highest HSI (2.1-2.2 %) recorded in winter confirmed this. During the periovulatory period, a peak of E, (4 ng . mL-‘) appeared, whereas T level diminished. In this study, 17,2Op-P levels remained low (0.2-0.6 ng mL-‘) and relatively constant. No 17,2Op-P peak was observed during the periovulatory period. Sampling at 10 day intervals was probably inadequate to specify the hormonal variations related to the final oocyte maturation and the ovulation. 0 Ifremer-Elsevier, Paris