Volume 15. Article 1. Oceanography of Long Island Sound, 1952–1954.

https://elischolar.library.yale.edu/bulletin_yale_bingham_oceanographic_collection/1154/thumbnail.jp

Neural stem cells and the regulation of adult neurogenesis

Presumably, the 'hard-wired' neuronal circuitry of the adult brain dissuades addition of new neurons, which could potentially disrupt existing circuits. This is borne out by the fact that, in general, new neurons are not produced in the mature brain. However, recent studies have established that the adult brain does maintain discrete regions of neurogenesis from which new neurons migrate and become incorporated into the functional circuitry of the brain. These neurogenic zones appear to be vestiges of the original developmental program that initiates brain formation. The largest of these germinal regions in the adult brain is the subventricular zone (SVZ), which lines the lateral walls of the lateral ventricles. Neural stem cells produce neuroblasts that migrate from the SVZ along a discrete pathway, the rostral migratory stream, into the olfactory bulb where they form mature neurons involved in the sense of smell. The subgranular layer (SGL) of the hippocampal dentate gyrus is another neurogenic region; new SGL neurons migrate only a short distance and differentiate into hippocampal granule cells. Here, we discuss the surprising finding of neural stem cells in the adult brain and the molecular mechanisms that regulate adult neurogenesis

Do artificial nests simulate nest success of greater sage-grouse?

Artificial nests have been used to study factors affecting nest success because researchers can manipulate them more than natural bird nests. Many researchers have questioned the validity of generalizing the results from artificial nests onto naturally occurring nests. Other studies have assessed the validity of artificial nest studies by simultaneously comparing overall depredation or daily survival rates, depredation timing, predator species, or habitat characteristics of artificial and natural nests. To evaluate how well artificial nests simulated nest success of greater sage-grouse (Centrocercus urophasianus; hereafter, sagegrouse), we used the unique approach of monitoring artificial nests (n = 69) placed in the natural nest bowls of sage-grouse in southern Wyoming, USA, during 2010 to 2011. Brown chicken eggs were placed in natural sage-grouse nests 7 to 14 days after the hatch or depredation of natural sage-grouse nests to compare artificial nest fate to the fate of natural sage-grouse nests. As secondary objectives, we placed cameras next to a subset of artificial nests to identify which predator species were depredating nests, and we assessed the effects of corvid (black-billed magpie [Pica hudsonia] and common raven [Corvus corax]) density, nest-site characteristics (i.e., anthropogenic development, landscape variables, and microhabitat) date of depredation, and presence of a camera near nest bowls on the depredation rate of all artificial nests. We found that depredation of artificial nests paralleled the fate of natural sagegrouse nests. Depredations were more likely to occur earlier in the summer (June to early July rather than late July to early August). Depredation of artificial nests was negligible as time progressed past the typical sage-grouse nesting season, supporting the hypothesis of predators using a search image to detect eggs. We also found that shorter perennial grass height and greater magpie densities were positively associated with the depredation rates of artificial nests. Camera-recorded depredation events verified that 4 badgers (Taxidea taxus), 2 magpies, and 1 domestic cow depredated artificial nests. Artificial nests may give managers insight into the expected nest success rates of sage-grouse in areas of conservation interest. However, care must be taken regarding placement and timing of artificial nests for reliable conclusions to be drawn from artificial nest studies. Furthermore, identifying predators based on artificial nests likely leads to inaccurate assessment of local species composition of nest depredators

Evaluation of a Planning Methodology: Integrating Land Use Information in Water Quality Planning

The case study investigated was the 208 water quality planning conducted in the Ashley Valley, around Vernal, Utah. The region is expected to urbanize rapidly due to energy development on adjacent state and federal land. The water quality planning was being conducted in the absence of substantial prior land use planning. A method is developed in the thesis for evaluating plans and methodologies. The method utilizes preformulated evaluation criteria to analyze structure and function of the methdology, political context, informational inputs, limiting factors, trigger factors, causeeffect relationships, and impacts of methodology on planning recommendations. The criteria collected from the literature and agency guidelines are consolidated into an evaluation model. Data were collected through field interviews, on-site inspection, and examination of workplans, critical path charts and plan documents. The planning was well conducted overall. However, the water quality planning methodology did not maximize the utilization of land use information, nor did it integrate the available land use information into the analysis as fully as possible. Utilization of land use information could have been increased through greater emphasis on land use in the original workplan, more guidance to staff through specification of land use analysis subtasks, tighter coordination of staff, and consideration of a broader range of alternative scenarios. The cursory nature of the land use analysis limited the number of alternative land use patterns identified. This in turn limited the number of potential pollution sources identified. The local political context discouraged serious consideration of some alternative land use patterns, and the use of land use controls as a management strategy

Seasonal Responses of Filtration Rates to Temperature, Oxygen Availability, and Particle Concentration of the Freshwater Clam, Musculium partumeium (Say)

Seasonal filtration rates of a pond population of the freshwater pisidiid clam, Musculium par­tumeium (Say), were assessed by measuring the clearance of 2.02 µ.m latex beads from suspension and expressed in terms of FR = a(AFDW}b where FR = filtration rate (ml H20 · hr- 1 ) , AFDW = mg ash-free dry weight of a whole clam and a and b are constants. The a-values ( = FR of a 1-mg AFDW clam} vary seasonally with the highest rates corresponding to periods of maximum growth and reproduction in the spring and fall. Changes in b reflect the influence of body size on the weight-­specific rates (FR/AFDW). Seasonally a and b are inversely related. Therefore. seasonal increases in FR are proportionately greater for smaller clams. The 0,0 of FR is between 2-3 during the winter and decreases to 1.0 during the summer (temperature insensitivity) when clams are relatively inactive. At 20°c under aerobic conditions FR decreases as the concentration of suspension increases over a range of= 1.38-40 mg. · 1-1 with the FR for 1-mg AFDW clams going from 4.8 to 0.5; this minimum FR is maintained at higher concentrations. The amount of filtrate cleared (µ.g · clam- 1 • hr-1) initially increases as concentration increases (to = 13 mg -1 • I) then decreases before increasing again at concentrations\u3e =30 mg · I - 1• Ingestion must be less at higher concentrations since pseudofeces are produced at concentrations \u3e 22 mg · 1-1• Under anaerobic conditions FR is uniformly low at all concentrations. Seasonal responses of FR are assessed in terms of temperature. oxygen availability and particle concentration, and interpreted in terms of the interaction of growth, reproduction and population dyna­mics. These data have been integrated for 1-m2 of pond substrate. It is suggested that M. partumeium probably supplements filter-feeding with other mechanisms of energy intake such as deposit-feeding

High connectivity among locally adapted populations of a marine fish (Menidia menidia)

Author Posting. © Ecological Society of America, 2010. This article is posted here by permission of Ecological Society of America for personal use, not for redistribution. The definitive version was published in Ecology 91 (2010): 3526–3537, doi:10.1890/09-0548.1.Patterns of connectivity are important in understanding the geographic scale of local adaptation in marine populations. While natural selection can lead to local adaptation, high connectivity can diminish the potential for such adaptation to occur. Connectivity, defined as the exchange of individuals among subpopulations, is presumed to be significant in most marine species due to life histories that include widely dispersive stages. However, evidence of local adaptation in marine species, such the Atlantic silverside, Menidia menidia, raises questions concerning the degree of connectivity. We examined geochemical signatures in the otoliths, or ear bones, of adult Atlantic silversides collected in 11 locations along the northeastern coast of the United States from New Jersey to Maine in 2004 and eight locations in 2005 using laser ablation inductively coupled plasma mass spectrometry (ICP-MS) and isotope ratio monitoring mass spectrometry (irm-MS). These signatures were then compared to baseline signatures of juvenile fish of known origin to determine natal origin of these adult fish. We then estimated migration distances and the degree of mixing from these data. In both years, fish generally had the highest probability of originating from the same location in which they were captured (0.01–0.80), but evidence of mixing throughout the sample area was present. Furthermore, adult M. menidia exhibit highly dispersive behavior with some fish migrating over 700 km. The probability of adult fish returning to natal areas differed between years, with the probability being, on average, 0.2 higher in the second year. These findings demonstrate that marine species with largely open populations are capable of local adaptation despite apparently high gene flow.This work was funded by the National Science Foundation (grant OCE-0425830 to D. O. Conover and grant OCE- 0134998 to S. R. Thorrold) and the New York State Department of Environmental Conservation

Progress Report: Effects of Condensed Corn Distillers Solubles on Steer Performance and Carcass Composition

Condensed, corn, distillers solubles provides an effective energy supplement for finishing cattle across a number of finishing systems

Microhabitat Selection for Nesting and Brood-Rearing by the Greater Sage-Grouse in Xeric Big Sagebrush

Understanding selection of breeding habitat is critical to conserving and restoring habitats for the Greater Sage-Grouse (Centrocercus urophasianus), particularly in xeric landscapes (≤25 cm annual precipitation). We monitored radio-marked female sage-grouse in south-central Wyoming in 2008 and 2009 to assess microhabitat use during nesting and brood rearing. For each model we grouped variables into three hypothesis sets on the basis of the weight of support from previous research (a priori information). We used binary logistic regression to compare habitat used by grouse to that at random locations and used an information-theoretic approach to identify the best-supported models. Selection of microhabitat for nests was more positively correlated with mountain big sagebrush (Artemisia tridentata vaseyana) than with Wyoming big sagebrush (A. t. wyomingensis) and negatively correlated with cheatgrass. Nesting hens also selected microhabitats with greater litter cover. Microhabitat for brood-rearing had more perennial grass and sagebrush cover than did random locations. Microhabitat variables most supported in the literature, such as forb cover and perennial grass cover, accounted for only 8% and 16% of the pure variation in our models for early and late brood rearing, respectively. Our findings suggest sage-grouse inhabiting xeric sagebrush habitats rely on sagebrush cover and grass structure for nesting as well as brood-rearing and that at the microhabitat scale these structural characteristics may be more important than forb availability. Therefore, in xeric sagebrush, practices designed to increase forb production by markedly reducing sagebrush cover, as a means to increase sage-grouse productivity, may not be justified

Progress Report: Pasture Finishing of Beef Steers Using Contemporary Feedlot Protocols

Environmental regulations in Iowa can place animal population restrictions on a given site. This study explores the possibility of finishing cattle in a remote pasture location to handle an overflow of animals and yet remain in compliance with environmental mandates