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2020

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Articles 31 - 35 of 35

Full-Text Articles in Aquaculture and Fisheries

Direct And Indirect Effects Of Sex Steroids On Gonadotrope Cell Plasticity In The Teleost Fish Pituitary, Romain Fontaine, Muhammad Rahmad Royan, Kristine Von Krogh, Finn-Arne Weltzien, Dianne M. Baker Jan 2020

Direct And Indirect Effects Of Sex Steroids On Gonadotrope Cell Plasticity In The Teleost Fish Pituitary, Romain Fontaine, Muhammad Rahmad Royan, Kristine Von Krogh, Finn-Arne Weltzien, Dianne M. Baker

Biological Sciences Research

The pituitary gland controls many important physiological processes in vertebrates, including growth, homeostasis, and reproduction. As in mammals, the teleost pituitary exhibits a high degree of plasticity. This plasticity permits changes in hormone production and secretion necessary to meet the fluctuating demands over the life of an animal. Pituitary plasticity is achieved at both cellular and population levels. At the cellular level, hormone synthesis and release can be regulated via changes in cell composition to modulate both sensitivity and response to different signals. At the cell population level, the number of cells producing a given hormone can change due to …


Bigheaded Carp Spatial Reproductive Dynamics And Population Genetics In Large River Tributaries, Samuel J. Schaick Jan 2020

Bigheaded Carp Spatial Reproductive Dynamics And Population Genetics In Large River Tributaries, Samuel J. Schaick

Masters Theses

Fisheries managers are devoting considerable effort, time, and funding towards limiting the spread of invasive Bighead and Silver (bigheaded) Carp. A better understanding of factors that influence spatial patterns of bigheaded carp reproduction can help fisheries managers prevent their spread. To examine factors that influence spatial patterns of reproduction, we sampled ichthyoplankton using drift nets and larval push nets in three tributaries of the Illinois and Wabash Rivers March-September 2016-2018. We compared relative abundances of bigheaded carp eggs and larvae among tributaries using catch per unit effort (CPUE). Abiotic data were analyzed from individual study tributaries and pooled among tributaries …


Diet Of A Recently Reintroduced River Otter (Lontra Canadensis) Population In Taos County, New Mexico, Gabriela Alexandra Wolf-Gonzalez Jan 2020

Diet Of A Recently Reintroduced River Otter (Lontra Canadensis) Population In Taos County, New Mexico, Gabriela Alexandra Wolf-Gonzalez

Theses and Dissertations--Forestry and Natural Resources

North American river otters (Lontra canadensis), native to every U.S. state and Canada, experienced extensive population decreases and range reduction until the mid-20th century as a result of overexploitation and habitat loss during European colonization. The last known river otter in New Mexico was killed on the Gila River in 1953, although unverified reports continued thru 2008. After a nearly 60-year absence from New Mexico, 33 adult river otters were reintroduced to the Rio Pueblo de Taos in the northern part of the state between 2008-2010; however, they were not subsequently monitored or studied. I characterized diet of …


Spatial And Temporal Genetic Structure Of Winter-Run Steelhead (Oncorhynchus Mykiss) Returning To The Mad River, California, Steven R. Fong Jan 2020

Spatial And Temporal Genetic Structure Of Winter-Run Steelhead (Oncorhynchus Mykiss) Returning To The Mad River, California, Steven R. Fong

Cal Poly Humboldt theses and projects

Distinct populations of steelhead in the wild are in decline. The propagation of steelhead in hatcheries has been used to boost population numbers for recreational fisheries and for use in conservation. However, hatchery breeding practices of steelhead can result in changes in genetic structure. I investigated the genetic structure of winter-run steelhead (Oncorhynchus mykiss) returning to the Mad River, California, where a hatchery has been used enhance production for recreational fisheries since 1971. Genetic variability in Mad River steelhead was evaluated using 96 single nucleotide polymorphisms (SNPs) among 4203 individuals, including the Mad River and nearby locations, and …


The Effects Of Light Level And Temperature On Freshwater Microbial Biomass, Production, Enzyme Activity, And Community Composition, Joel Bonney Jan 2020

The Effects Of Light Level And Temperature On Freshwater Microbial Biomass, Production, Enzyme Activity, And Community Composition, Joel Bonney

Master's Theses and Doctoral Dissertations

Algae can stimulate the production of heterotrophic microbes in periphyton communities, but the synergistic effects of light and temperature on this phenomenon are not well understood and have implications on carbon cycling and energy flow. We employed recirculating mesocosms held at different temperatures and light levels and filled with Typha litter and attached microbes to assess these effects. Heterotrophic microbial production was greater in the presence of light, as were some periphytic enzyme activities. Few response variables increased in a near-linear fashion with ascending temperature, suggesting different temperature optima. The strength of heterotrophic microbial production responses to algal photosynthesis did …