Alien Registration- Byram, Dora (Saint Francis, Aroostook County)

https://digitalmaine.com/alien_docs/32639/thumbnail.jp

Lower food web dynamics in lakes Michigan and Huron: Spatial and temporal responses to recent oligotrophication

Nutrient abatement programs, originally enacted to counter eutrophication have successfully suppressed nutrient loads and relative primary production in marine and freshwater systems. Recently, the additive impacts of invasive filter feeders have further reduced offshore primary production in several aquatic systems throughout the world. It has been hypothesized that the biological activity of these invasive species may sequester nutrients within the nearshore benthic environment, creating steep gradients in primary production between nearshore and offshore habitats. In the Laurentian Great Lakes, past studies of oligotrophication have primarily focused on food web responses in offshore habitats. Organisms at higher trophic levels have been impacted by reduced productivity in offshore waters and may now rely more heavily on nearshore production pathways. This study analyzed long-term changes in surface chlorophyll a concentrations along a nearshore to offshore gradient and the subsequent responses in physiological condition of the secondary consumer Bythotrephes longimanus (hereafter referred to as Bythotrephes). First, we examined long-term (1998-2013) seasonal and regional trends in surface chlorophyll a concentrations in the main basins of lakes Michigan and Huron using satellite imagery. Contrary to the pronounced declines in offshore areas, nearshore chlorophyll a concentrations increased or remained stable throughout time for most seasons. While no regional trends were observed in Lake Huron, nearshore trends were not homogeneous across regions in Lake Michigan. From 1998 to 2013, Chlorophyll a concentrations increased in nearshore areas in the southeast and northwest quadrants of Lake Michigan, most likely due the influence of large adjacent agricultural watersheds and warmer surface water temperatures that characterize these regions. These results were in contrast to the southwest region where nearshore chlorophyll a concentrations declined over the course of 16 years. Increases in nearshore chlorophyll a concentrations and subsequent increase in prey availability, may corroborate the recent reliance of nearshore resources by some fish species in the Great Lakes. The second aspect of this study focused on whether increased nearshore food web subsides would affect the condition of Bythotrephes along a nearshore to offshore gradient and regionally in Lake Michigan. No nearshore to offshore differences in lengths, RNA content, and relative fatty acid content were observed; however, regional differences were, again, prominent. Regional variation in surface water temperature facilitated larger sizes and overall condition of Bythotrephes on the eastern shores of Lake Michigan during the spring and summer. By the fall, surface water had warmed sufficiently lake-wide to allow for comparable size and condition in Bythotrephes across southern Lake Michigan. Overall, responses to oligotrophication at lower trophic levels have differed in both time and space in lakes Michigan and Huron. Further description of how lower trophic levels respond to oligotrophication can help improve our understanding of how nutrient abatement programs and the establishment of invasive filter feeders are influencing food webs across the Great Lakes

Test av portabel röntgenfluorescens (PXRF) för bestämning av jordart, näringsämnen och tungmetaller direkt i fält

Vid markkartering tas matjordsprov som analyseras i laboratorium. Ett stort antal markvariabler kan vara aktuella att analysera. I det här projektet utvärderades möjligheten att använda ett handburet instrument som mäter röntgenfluorescens (PXRF – portable x-ray fluorescence) för att snabbt uppskatta flera sådana variabler direkt i fält. Ett stort antal mätningar med PXRF utfördes på gårdar i Västergötland, där även jordprovtagning med tillhörande kemiska jordanalyser utfördes. De markkarteringsvariabler som undersöktes var ler-, sand- och mullhalt, fosfor (P-AL), kalium (K-AL), calcium (Ca-AL), koppar (Cu-HCl), magnesium (Mg-AL), molybden (Mo-HNO3) och kadmium (Cd-HNO3). Jämförelser mellan insamlade PXRF-data – som gjordes både i fält på markytan och på upptagna jordprover, både före och efter torkning – visade att flera element som bestäms med PXRF var väl korrelerade till flera av markkarteringsvariablerna. Särskilt väl samvarierar textur, Cu, Ca, Mg och Cd med olika ämnen som bestäms med PXRF. Även vid mätning direkt i fält med PXRF finns möjlighet att få fram användbara data. Tekniken kan minska behovet av jordprovtagning och/eller fungera som en snabb metod för kompletterande datainsamling som kan göra det möjligt att kostnadseffektivt ta fram detaljkartor för aktuella markegenskaper

Alien Registration- Stadig, Susie T. (Saint Francis, Aroostook County)

https://digitalmaine.com/alien_docs/23430/thumbnail.jp

Remote sensing and on-farm experiments for determining in-season nitrogen rates in winter wheat – Options for implementation, model accuracy and remaining challenges

Optimised nitrogen (N) fertilisation can be used to increase farm profits, to realise the achievement of quality goals for produce, and to reduce environmental risks in the form of leaching and/or volatilisation of N compounds from the fields. This study examined options and challenges for remote sensing-based variable rate supplemental N fertilisation in winter wheat (Triticum aestivum L.). The models were based on data from ten field trials conducted in different regions across Sweden over three years. A two-step approach for modelling optimal N rates, suitable for practical implementation in precision agriculture, was developed and evaluated. The expected accuracies for new sites and years were assessed by leave-one-entire-trial-out cross-validation. In a first step, the average N rate was modelled from site-specific information, including data that can be obtained from on-farm experiments, i.e. N uptake in plots without N fertilisation (zero-plots) and N uptake in plots with non-limiting N supply (max-plots). In the second step, additions or subtractions from this average N rate was modelled based on vegetation indices (VIs) mapped by remote sensing. Mean absolute error of the best prediction was 14 kg N ha−1. In a practical application, however, there will be additional uncertainty from several sources, e.g. uncertainty in the assessment of yield potential. The best mean N rate model was based on geographical region, cultivar, N uptake in zero-plots and yield potential, while the best model of relative N rate within the field used a new multispectral index (d75r6), which was designed to give a standardized measure of the steepness of the red edge of reflectance of a crop canopy spectrum. Several other multispectral VIs also performed well but red-green-blue indices were less useful. We conclude that remote sensing (to capture within-field spatial variation patterns), on-farm experiments (to determine the field mean N rate), and the farmers’ experience and knowledge on local conditions (e.g. to assess the yield potential), is a useful combination of information sources in decision support systems for variable rate application of N. Options and remaining research needs for the setup of such a system are discussed

Evaluation of physical dysfunction in cats with naturally occurring osteoarthritis

Osteoarthritis (OA) is a common cause of chronic pain and physical dysfunction in cats. Clinical signs are often subtle and lameness is rarely the chief complaint. The main clinical features consist of gradual changes in the cat’s behaviour and everyday living. The changes are often misinterpreted as part of normal ageing. In a clinical setting, the diagnosis is based on information from the owner, physical examination and radiography. However, conflicting physical and radiographic signs makes feline OA challenging to diagnose. Improved tools are needed as diagnostic aid and to evaluate treatment efficacy. The overall aim of the thesis was to improve methods for diagnosis and evaluation of treatment in cats with naturally occurring OA. Since chronic pain can only be measured indirectly, physical dysfunction caused by OA was measured. The alteration in physical dysfunction was evaluated using physical examination, objective pressure mat technique and subjective owner assessment questionnaires. The specific aims were to: establish reference values from gait analysis in sound cats, compare kinetic data from sound cats walking on the pressure mat with results from OA cats, evaluate four different questionnaires regarding validity and reliability, and in a clinical pilot study evaluate the effects of pain relieving treatment in OA cats using the pressure mat and the questionnaires. The acquired reference values from sound cats confirmed that cats have a similar gait symmetry and front-hind asymmetry as dogs. Peak vertical force and vertical impulse were reliable gait parameters to analyse. Cats with OA and cranial cruciate ligament injury were compared to sound control cats. The cats with OA put load on their paws more unevenly and had a different behaviour in the home environment, compared to sound cats. The four questionnaires that were evaluated all had sound validity and reliability. The clinical pilot study comparing meloxicam and robenacoxib, showed that osteoarthritic cats that received pain-relieving drugs improved significantly. The thesis contributes to evaluation of physical dysfunction in osteoarthritic cats by using objective pressure mat technique and subjective questionnaires. This leads to improved management of chronic pain in cats with OA and improved feline welfare

Rita B. Stadig Correspondence

Entry is a handwritten biographical sketch of Rita Stadig author of Our Maine Heritage, a history of Maine