Diatom analysis of three Norwegian cores

The purpose of this project is to supply diatom data to the Norwegian Institute of Water Research for cores from three Norwegian lakes: Steinsfjorden, Lyseren and Gjersjøen. The data will feed into a palaeolimnological project which also includes analysis of algal pigments and radiometric dating of the cores. The study aims to assess shifts in the diatom assemblages and to determine the nature of the baseline assemblages. Additionally the project aims to apply an existing diatom-phosphorus (P) transfer function to the diatom data in order to infer the trophic histories of the lakes

Diatom analysis of Polish cores

The purpose of this project is to supply high resolution diatom data to the Norwegian Institute of Water Research for cores from three Polish lakes: Lakes Rumian, Kiełpińskie and Lidzbarskie, and lower resolution diatom data from a further seven Polish lakes: Dąbrowa Wielka, Dąbrowa Mała, Grądy, Tarczyńskie, Zwiniarz, Zarybinek and Hartowieckie. The data will feed into a palaeolimnological project which also includes analysis of algal pigments and radiometric dating of the cores. The study aims to assess shifts in the diatom assemblages and to determine the nature of the baseline assemblages. Additionally the project aims to apply an existing diatom-phosphorus (P) transfer function to the diatom data in order to infer the trophic histories of the lakes

A palaeolimnological study of Loch Shin, Scotland. Final report to SEPA and the Forestry Commission

This project reports on analysis of a sediment core collected from the lower basin of Loch Shin in Sutherland, Scotland on 24 August 2015, spanning a total sediment depth of 31.5 cm. Palaeoecological techniques, principally diatom analysis of a dated core, were employed to assess environmental change at the loch since 1850 AD. The project aims to determine the reference conditions of the loch and to establish the onset, rate and magnitude of any changes in the diatom flora. The Scottish Environment Protection Agency are particularly interested in any changes in the loch that may have occurred in association with fish farming and forestry practices and whether the hydropower scheme has had any impact. Radiometric methods were applied to the core in order to date the recent sediments, revealing that the 31.5 cm core dates back to ~1850 AD. There is an increase in sedimentation rates before the 1920s, followed by small changes around a mean value of 0.026 g cm-2 yr-1 until the 2000s, after which the sedimentation rates increase slightly again in recent years to 0.038 g cm-2 yr-1. Diatom analysis was carried out on 21 samples distributed throughout the core and a diatom-total phosphorus (TP) transfer function was applied to the diatom data to reconstruct trophic status. There were marked changes in the diatom assemblages during the 160 year period represented by the core and cluster analysis revealed four major zones with the most significant split, reflecting floristic change, at 7.75 cm which corresponds to 1994. In the period from 1860 to 1930 (Zone 1), the sedimentary diatom assemblages of Loch Shin were very stable with a diatom flora typical of nutrient-poor, deep lakes and the diatom-inferred TP concentrations were low and stable at 5 μg L−1 indicating oligotrophic conditions. The diatom reference conditions of Loch Shin can thus be described as a community of oligotrophic, acidophilous-circumneutral taxa, particularly Cyclotella kuetzingiana, Achnanthidium minutissimum and Brachysira vitrea. The diatom assemblages began to change from ~1930 with the arrival of taxa more typically associated with mesotrophic waters, namely Aulacoseira subarctica and Asterionella formosa, marking an initial enrichment phase (Zone 2). The progressive and gradual nature of the shifts suggests a response to the cumulative effect of increasing pressures in the catchment during the mid to late twentieth century including dam construction and the consequent water level rise in the 1950s, as well as forestry plantation and fertilisation which took place from the 1960s. A more pronounced enrichment phase was evident from the mid-1990s with the expansion of Aulacoseira subarctica, the arrival of Fragilaria crotonensis and the decline, and in some cases the loss, of numerous taxa seen in the early part of the record (Zone 3). The diatom-inferred TP concentrations increased to 16 μg L−1. While the exact causes of these shifts cannot be established, the most marked changes in the diatoms are coincident with the arrival of the fish farms on the loch in 1994-1995 suggesting that aquaculture may have played a role. Since 2009 Fragilaria crotonensis has disappeared although the reasons for this are not clear (Zone 4). A. subarctica remains the dominant species and the planktonic component of the assemblages remains high at 50-60%. The diatom-inferred TP concentrations decreased to 11 μg L-1 at the core surface, indicating that there may be a recent phase of reduction in trophic status. However, given that there are no reported changes in land use or management since 2009 and that diatoms respond to a host of factors in addition to nutrient concentrations, it would be unwise to suggest that the disappearance of F. crotonensis from the recent sediment record is reflective of improving water quality. Clearly a more detailed study of recent management practices in the catchment and fish farms is required to establish whether there have been any real reductions in nutrient loads to the loch

Compact FBG grating array structure for high spatial resolution distributed strain sensing

We report here an implementation of high-spatial resolution distributed sensors employing compact-grating-array structure, offering advantages of free designing dynamic range and simple interrogation by utilising established wavelength-division-multiplexing technique

Using novel palaeolimnological techniques to define conservation objectives for Hatch Mere: Report for Cheshire Wildlife Trust

This is the final report to Natural England on the project ‘Using novel palaeolimnological techniques to define lake conservation objectives for Hatch Mere’. The aim is to use existing and recently developed palaeoecological techniques to define reference conditions and assess the condition of Hatch Mere Special Scientific Interest (SSSIs) in the Cheshire meres, and thereby assist in the setting of conservation objectives and management goals. Two sediment cores (one open water and one marginal), approximately 1 m in length, were collected from Hatch Mere in August 2011. The cores were sampled at 1 cm intervals throughout and approximately ten samples from each site were analysed for diatoms, Cladocera, macrofossils, geochemistry (XRF) and pigments. The cores were dated using radiometric techniques in order to place the fossil remains within a known time frame. An existing diatom-total phosphorus (TP) transfer function was applied to the diatom data to reconstruct the nutrient history of the mere. The dating results suggest that the open water core (HAT3) extends back to ~1800 AD and the marginal core extends back beyond ~17o00 AD. The palaeoecological data indicate that the site has been a moderately enriched lake for the whole of the period represented by the cores with diatom-inferred TP concentrations of ~30 μg L-1 in the lower part of the record. However, there were marked changes across a range of indicators from the early 1800s indicative of enrichment, which has continued through the twentieth century. The key changes were the expansion of the eutrophic diatom species Cyclostephanos dubius and hence an increase in diatom-inferred TP to ~84 μg L-1, a steady increase in pigment concentrations from all algal groups, and shifts in the zooplankton community indicative of increased pelagic productivity. Eutrophication has resulted in marked changes in the aquatic plant community from a structurally diverse flora with abundant Charophytes, nymphaeids and taxa with a mix of seasonalities to the current state with no submerged flora and only Nuphar lutea. The most notable changes in the macrofossil record have occurred from the mid-1800s and are, therefore, coincident with the main phase of enrichment. The dominance of the upper sediments by planktonic zooplankton and abundant Daphnia ephippia towards the top of the core, lends further weight to a plankton dominated system. This study provides information on the plant and animal communities that were present in the lake prior to the major eutrophication phase and this significantly alters the generic target previously set for the lake and will be valuable for setting targets for future management of the site

Integrating Habitats Directive and Water Framework Directive Monitoring: Baseline Survey of Natura 2000 Standing Water Habitats in Wales

This report was commissioned by the Environment Agency (EA) on behalf of the Countryside Council for Wales (CCW) in 2004. It brings together data collected in 2003 and 2004 from 28 Welsh lakes in 11 Special Areas of Conservation (SACs). The report • collates and presents limnological data collected for the Environment Agency in 2003 for the purposes of site condition assessment, • presents limnological data collected for CCW in 2004 for the purposes of site condition assessment, • provides a series of lake data reports on each of the 11 specifies SACs. Sampling and analytical methods are described and the data presented in the report include; • site information (catchment geology, land use and lake characteristics and bathymetries), • water chemistry, temperature and oxygen profiles, • macrophyte survey data presented as DAFOR rated species lists, • short core analysis for diatoms (required for 19 of the 28 sites)

Application of long period gratings sensors to respiratory function monitoring

A series of in-line curvature sensors on a garment are used to monitor the thoracic and abdominal movements of a human during respiration. These results are used to obtain volumetric tidal changes of the human torso showing reasonable agreement with a spirometer used simultaneously to record the volume at the mouth during breathing. The curvature sensors are based upon long period gratings written in a progressive three layered fibre that are insensitive to refractive index changes. The sensor platform consists of the long period grating laid upon a carbon fibre ribbon, which is encapsulated in a low temperature curing silicone rubber. An array of sensors is also used to reconstruct the shape changes of a resuscitation manikin during simulated respiration. The data for reconstruction is obtained by two methods of multiplexing and interrogation: firstly using the transmission spectral profile of the LPG's attenuation bands measured using an optical spectrum analyser; secondly using a derivative spectroscopy technique

Understanding the Mechanism of Human P450 CYP1A2 Using Coupled Quantum-Classical Simulations in a Dynamical Environment

The reaction mechanism of the human P450 CYP1A2 enzyme plays a fundamental role in understanding the effects of environmental carcinogens and mutagens on humans. Despite extensive experimental research on this enzyme system, key questions regarding its catalytic cycle and oxygen activation mechanism remain unanswered. In order to elucidate the reaction mechanism in human P450, new computational methods are needed to accurately represent this system. To enable us to perform computational simulations of unprecedented accuracy on these systems, we developed a dynamic quantum-classical (QM/MM) hybrid method, in which ab initio molecular dynamics are coupled with classical molecular mechanics. This will provide the accuracy needed to address such a complex, large biological system in a fully dynamic environment. We also present detailed calculations of the P450 active site, including the relative charge transfer between iron porphine and tetraphenyl porphyrin

Sedimentary macrofossil records reveal ecological change in English lakes: implications for conservation

Aquatic macrophytes play a key role in providing habitat, refuge and food for a range of biota in shallow lakes. However, many shallow lakes have experienced declines in macrophyte vegetation in recent decades, principally due to eutrophication. As changes in macrophyte composition and abundance can affect overall ecological structure and function of a lake, an assessment of the timing and nature of such changes is crucial to our understanding of the wider lake ecosystem. In the typical absence of historical plant records, the macro-remains of macrophytes preserved in lake sediments can be used to assess long-term changes in aquatic vegetation. We generated recent (150–200 years) plant macrofossil records for six English lakes subject to conservation protection to define past macrophyte communities, assess trajectories of ecological change and consider the implications of our findings for conservation targets and strategies. The data for all six lakes reveal a diverse submerged macrophyte community, with charophytes as a key component, in the early part of the sedimentary records. The stratigraphies indicate considerable change to the aquatic vegetation over the last two centuries with a general shift towards species more typically associated with eutrophic conditions. A common feature is the decline in abundance of low-growing charophytes and an increase in tall canopy-forming angiosperms such as fine-leaved Potamogeton species, Zannichellia palustris and Callitriche species. We hypothesise, based on findings from long-term datasets and palaeoecological records from enriched shallow lakes where plants are now absent, that the observed shifts provide a warning to managers that the lakes are on a pathway to complete macrophyte loss such that nutrient load reduction is urgently needed. It is the sound understanding of present-day plant ecology that affords such reliable interpretation of the fossil data which, in turn, provide valuable context for current conservation decisions