The Olive Tree, Vol. 16 Number 1, 2008

The Spring 2008 issue of The Olive Tree features articles about library projects, collections, technological innovations, and events at Fogler Library, University of Maine.

Ice Layers as an Indicator of Summer Warmth and Atmospheric Blocking in Alaska

Samples were collected from a snow pit and shallow urn core near Kahiltna Pass (2970 m a.s.l.), Denali National Park, Alaska, USA, in May 2008. The record spans autumn 2003 to spring 2008 and reveals clusters of ice layers interpreted as summertime intervals of above-freezing temperatures. High correlation coefficients (0.75-1.00) between annual ice-layer thickness and regional summertime station temperatures for 4 years (n=4) indicate ice-layer thickness is a good proxy for mean and extreme summertime temperatures across Alaska, at least over the short period of record. A Rex-block (aka high-over-low) pattern, a downstream trough over Hudson Bay, Canada, and an upstream trough over eastern Siberia occurred during the three melting events that lasted at least 2 weeks. About half of all shorter melting events were associated with a cut-off low traversing the Gulf of Alaska. We hypothesize that a surface-to-bedrock core extracted from this location would provide a high-quality record of summer temperature and atmospheric blocking variability for the last several hundred years.

Use of Electroshock for Euthanizing and Immobilizing Adult Spring Chinook Salmon in a Hatchery

This study evaluated the use of electroshock as in alternative to traditional techniques for immobilizing and euthanizing hatchery fish. We used a commercially available electroanesthesia unit at the U.S. Fish and Wildlife Service's Carson National Fish Hatchery (Carson, Washington) to euthanize adult spring Chinook salmon Oncorhynchus tshawytscha and to son and collect gametes of fish at maturation. During euthanization by electroshock, the response of each fish was observed, Muscular and vertebral hemorrhaging wits quantified, and electrical settings were optimized accordingly. During gamete collection, fish were either electroshocked or exposed to tricaine methanesulfortate (MS-222); hemorrhaging, egg viability. egg size and quantity, and resultant fry quality were examined for each treatment group. Electroshocked fish had a higher likelihood Of injury during gamete collection than did fish exposed to MS-222. On average, each electroshocked fish had less than two hemorrhages oil both fillets examined. The size of each hemorrhage was less than 0.10% of the fillet surface. Fecundity and egg and fry quality were not affected by either immobilization method. Electroshock was a viable and efficient means of euthanizing adult spring Chinook salmon or sorting the fish and collecting their gametes. However, equipment settings must be optimized based on site-specific (e.g., water conductivity) and species-specific (e.g., fish size and seasonal state of maturation) factors.

Optimizing Models of the North Atlantic Spring Bloom Using Physical, Chemical and Bio-Optical Observations from a Lagrangian Float

The North Atlantic spring bloom is one of the main events that lead to carbon export to the deep ocean and drive oceanic uptake of CO(2) from the atmosphere. Here we use a suite of physical, bio-optical and chemical measurements made during the 2008 spring bloom to optimize and compare three different models of biological carbon export. The observations are from a Lagrangian float that operated south of Iceland from early April to late June, and were calibrated with ship-based measurements. The simplest model is representative of typical NPZD models used for the North Atlantic, while the most complex model explicitly includes diatoms and the formation of fast sinking diatom aggregates and cysts under silicate limitation. We carried out a variational optimization and error analysis for the biological parameters of all three models, and compared their ability to replicate the observations. The observations were sufficient to constrain most phytoplankton-related model parameters to accuracies of better than 15 %. However, the lack of zooplankton observations leads to large uncertainties in model parameters for grazing. The simulated vertical carbon flux at 100 m depth is similar between models and agrees well with available observations, but at 600 m the simulated flux is larger by a factor of 2.5 to 4.5 for the model with diatom aggregation. While none of the models can be formally rejected based on their misfit with the available observations, the model that includes export by diatom aggregation has a statistically significant better fit to the observations and more accurately represents the mechanisms and timing of carbon export based on observations not included in the optimization. Thus models that accurately simulate the upper 100 m do not necessarily accurately simulate export to deeper depths.

Lessons from Ellen: A Case Study Investigation of Comprehension Strategy Instruction in Action

In the past ten years, reading comprehension instruction has received significant attention from educational researchers. Drawing on studies from cognitive psychology, reader response theory, and language arts research, current best practice in reading comprehension instruction is characterized by a strategies approach in which students are taught to think like proficient readers who visualize, infer, activate schema, question, and summarize as they read. Studies investigating the impact of comprehension strategy instruction on student achievement in reading suggest that when implemented consistently the intervention has a positive effect on achievement. Research also shows, however, that few teachers embrace this approach to reading instruction despite its effectiveness, even when the conditions for substantive professional development (i.e. prolonged engagement, support, resources, time) are present. The interpretive case study reported in this dissertation examined the year-long experience of one fourth grade teacher, Ellen, as she leanled about comprehension strategy instruction and attempted to integrate the approach in her reading program. The goal of the study was to extend current understanding of the factors that support or inhibit an individual teacher's instructional decision making. The research explored how Ellen's academic preparation, beliefs about reading comprehension instruction, and attitudes toward teacher-student interaction influenced her efforts to employ comprehension strategy instruction. Qualitative methods were the basis of this study's research design. The primary methods for collecting data included pre- and post-interviews, field notes from classroom observations and staff development sessions, infonnal interviews, e-mail correspondence, and artifacts such as reading assignments, professional writing, school newsletters, and photographs of the classroom. Transcripts from interviews, as well as field notes, e-mail, and artifacts, were analyzed according to grounded theory's constant-comparative method. The results of the study suggest that three factors were pivotal in Ellen's successful implementation of reading strategy instruction: Pedagogical beliefs, classroom relationships, and professional community. Research on instructional change generally focuses on issues of time, resources, feedback, and follow-through. The research reported here recognizes the importance of these components, but expands contemporary thinking by showing how, in Ellen's case, a teacher's existing theories, her relationship with her students, and her professional interaction with peers impact instructional decisions.