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Displaying: 161 - 180 of 383 Next
161. Global Climate Change, Faunal Invasion And Succession In High arctic Ecosystems : Implications For Ecosystem Function.

Prof. I.D. Hodkinson Dr. S.J. Coulson School of Biological & Earth Sciences, Liverpool John Moores University, Byrom St., Liverpool L3 3AF, UK (Contact details: Tel. 0151 2312030 Fax. 0151 207 3224 email; Prof. N.R. Webb NERC Centre for Ecology & Hydrology, Winfrith Technology Centre, Dorchester, Dorset, DT2 8ZD, (Contact details: email Objectives and Hypotheses Our main objectives are to:  describe, measure and model patterns and rates of invertebrate community development and succession following glacial retreat in the high Arctic using known chronosequences.  cross-relate rates of community change to known climatic shifts.  relate invertebrate community development to rates of key ecological processes such as decomposition of organic matter.  evaluate the potential for more southerly species successfully to invade existing Arctic invertebrate communities.  develop descriptive and predictive models of community development under conditions of climatic amelioration. We are testing the following hypotheses:  that dispersal of particular functional groups of invertebrates in response to climate warming is a rate-limiting factor for invertebrate succession and community development in the high Arctic.  that invertebrate community development in response to climatic warming is deterministic and directional, and therefore predictable.  that the magnitude and stability of key ecosystem processes, such as decomposition, in the high Arctic are linked to biotic complexity, which can be suitably characterised by the invertebrate community composition.  that natural succession provides a useful model for predicting rates of invasion by colonising species following climatic amelioration. Study sites Studies on two contrasting but complementary chronosequences on west Spitsbergen commenced in June 2000, an oligotrophic succession on t he glacial foreland of Midtre Lovénbre and a relatively eutrophic succession on Lovénøyene, a series of islands in Kongsfjord. A 1.5 km transect was established, extending from the foot of the Midtre Lovénbre to the terminal moraines and across the sandur. Seven equally spaced sampling sites (approx 20 x 40 m) were established at right angles to the main transect line). Each site was chosen to represent the most mature vegetation type present at each point. By contrast, each Lovénøy was viewed as a separate sample site. The chronology of glacial 'retreat' was established from vertical and oblique aerial and ground based photographs held by the Norsk Polarinstitutt Archive, Tromsø, from historical records and ground photographs and, for the oldest site, by radiocarbon dating of the soil. Results Ages of sites: The ages of the sites from the Midtre Lovénbre sequence vary between 2 years (site one) to 1900 (site seven), while the islands vary between 100 (Leirholmen) to 1800 (Storholmen). Plant community description and soil formation A detailed description has been made in the changes in the plant community (18 taxa) from site 1-7 on the Lovénbre - from unconsolidated parent to almost 100% ground cover. The presence, abundance and dynamics of each species have been described. Species have been characterised as early, mid or late successional. Parallel trends occur in soil characteristics including increasing depth, increasing organic matter and water content, decreasing clast size and a lowering of pH. Animal community description The soil fauna comprise primarily Collembola, mites, Enchytraeidae and chironomid larvae. Herbivores (one aphid and sawfly larvae) are few but hymenopteran parasitoids and predators (spiders and gamasid mites) are abundant. The distribution patterns of species and their abundances have been quantified for both the Lovénbre and Lovénøyene chronosequnces. The very first colonisers of bare moraines are Linyphiid spider species (predators). Other early soil colonisers are generally the surface active species such as the collembolan Isotoma anglicana. The poorest colonisers are the deep soil dwelling species. Experiments are thus underway examining wind blown dispersal and survival on seawater. A cellular automaton model, using absolute density and pitfall trap is being used to simulate diffusion dispersal of soil animals. A set of unusual weather conditions in late July produced a mass immigration of a small moth Plutella xylostella into Svalbard. This chance event has allowed us to track in detail the movement of associated weather systems and to reconstruct the direction and source of immigrants. Such events are rare but may become increasingly frequent as climate changes, opening a closed gateway for animals from further south to move into the Arctic. Continuing work Current visit (late July/early August) is aimed at collecting supporting information on the plant cover and microhabitat characteristics for manuscripts in preparation.

Climate change
162. Quality signalling, parasites and sexual selection: gobies as a model system

The main objective of the project was to investigate yje reproductive dynamics of the two-spotted goby, a small semi-pelagic fish abundant along rocky shores of Northern Europe.

163. Lipids, Buoyancy and vertical distribution of calanoid copepods

To measure overall densities of overwintering copepods from Gullmarsfjorden in order to understand the role of lipids in their vertical distribution and buoyancy.

164. Investigation of the ontogeny and phylogeny of certain glial cells in Bilateria

In secretory cells of the vertebrate floor plate and subcommissural organ are descendant of an ontogenetically ancient type of radial glial cells.

165. Supply side ecology: the links between larval supply and recruitment for soft sediment benthic communities in the North Sea

The main objective of the project were to collect and process various different populations of selected benthic species to determine, in combination with existing research, the following:

166. Behavioural responses of the nordic krill (Meganyctiphanes norvegica) to light

To examine the effect of light intensity on swimming activity in Krill.

167. The Provenance and Fate of Nitrogen in Arctic Glacial Meltwaters: An Isotopic Approach.

Based upon research previously undertaken at Sheffield University, nutrients released from High Arctic glaciers during the summer ablation season are shown to rarely be in balance with bulk inputs deposited on the glacier surface as winter accumulation. Nutrient budgets suggest glaciers to release an excess of nitrate relative to annual bulk deposition, whilst up to 40% of the Ammonium deposited on the glacier surface appears to be sequestered from the inorganic budget (Hodson., in prep). Contrary to popular understanding, such an imbalance would suggest glaciers to be agents of nutrient storage, release and utilisation. In conjunction with a range of recent research (Sharp, 1999., Skidmore, 2000) this may potentially demonstrate high Arctic glaciers to be dynamic biological systems supporting a plethora of microbial life, rather than biologically inert cryospheric entities as so widely perceived in much of the research literature. Ammonium and Nitrate are nutrients of key importance not only to the maintenance of microbial life in such hostile environments, but also to the primary productivity of ice-marginal freshwater and marine ecosystems. However, as yet, their dynamics have proved difficult to explain. Field research undertaken during summer 2002 used natural isotopes to fingerprint sources and sinks of nutrients within the glacial system, thereby enabling a better understanding of biogeochemical cycling within the glacial environment. Whilst analysis of isotopic samples from this field season is still ongoing, new areas of research have been highlighted. The significance of organic nutrients in biogeochemical cycling has largely been regarded as insignificant, especially with regard to glacier geochemistry (reference). However, large fluxes of organic carbon have been observed emanating from the subglacial drainage of glacier Midre-Lovenbreen (Wynn, unpublished Data) and Dissolved Organic Nitrogen (DON) is now known to represent upto 40-50% of annual nitrogen inputs in glacier snowpacks (Hodson, in prep). Furthermore, bacteria, cysts and algae present within small supraglacial melt pools known as ‘cryoconite holes’, hold the potential to utilise inorganic nutrients and retain them in the organic phase. Consequently, omitting the role of organic nutrients from glacial biogeochemical studies allows only a limited understanding of the chemical and biological interactions occurring within Arctic glaciers. A field study addressing the significance of dissolved organic nutrients within glacial systems is to be undertaken during summer 2003. A new method is currently being investigated which will allow the concentration and subsequent isotopic analysis of dissolved organic nutrients retained on ion exchange resins. Use of environmental isotopes in conjunction with major ion chemistry will help determine the provenance, fate and bioavailability of organic nutrients within the glacial system. Lysimeters inserted into the snowpack will enable the release of organic nutrients into the glacier to be continuously monitored, allowing subsequent changes in meltwater isotopic signatures to be studied relative to this. Particular emphasis shall be given to Nutrient cycling within cryoconite holes and fluxes of organic matter emanating from the subglacial drainage as these represent two possible sites of organic/inorganic interaction. Fieldwork is to be undertaken on Midre-Lovenbreen, Svalbard, a polythermal glacier well known and studied by the author. Initial sample processing shall be accomplished in the laboratory facilities provided in Ny-Alesund, whilst subsequent isotopic analysis is to be undertaken at the British Geological Survey in Nottingham.

168. Tundra Vegetation Composition And Change Over The Past Five Hundred Years.

Please contact Dr Jelte Rozema.

169. Ciliary upstream-collecting in marine filter-feeding invertebrates

The main objective was to study the basic mechanism of ciliary upstream-collecting on a selected marine invertebrate.

170. Variation in primary sex characters in goldsinny and corkwing wrasse in relation to variation in mating system

Variation in primary sex characters of wrasse in relation to reproduction strategy and environmental conditions:

171. Estimating The Contribution Of Deposition Of Ammonia To Bryophytes Utilising The 15N/14N Ratio In Arctic Bryophytes.

Mosses and lichens are important components of arctic ecosystems as well as being an internationally important component of the biodiversity of the British Isles and Scandinavia. They are typically associated with nutrient poor ecosystems and are often eliminated with increased supplies of nitrogen. This study is part of a programme examining the impact of elevated nitrogen in nutrient poor ecosystems on mosses and lichens. This particular study will examine the contribution of airborne nitrogen in the form of ammonia to the growth of mosses in the arctic tundra in Kongsfjord. Breeding colonies of seabirds deposit large quantities of guano, which can be major sources of nitrogen as well as heavy metals (Headley 19xx) and other contaminants in the marine ecosystems. The nitrogen in fish and other organisms high up in the marine food chains have higher concentrations of the heavier stable isotope of nitrogen called 15N. The ratio of this isotope to the usual isotope of nitrogen (14N) can be used as a marker as to the relative contributions of different forms of nitrogen that are being utilised by an organism. By taking samples of moss at different distances from seabird colonies and analysing these and the soil and guano for the concentrations of the two stable isotopes of nitrogen (15N:14N ratio) the relative contributions of nitrogen from the soil and atmosphere can be determined. This can then be utilised along with details of the relative abundance of the mosses along transects away from seabird colonies to ascertain how important atmospheric ammonia is in altering the species composition of moss communities.

172. Feast or famine: how to be a successful marine benthic consumer

Five French Scientists orginating from the Observatoire Océnologique de Banyals, stayed at the Kristineberg Marine Station during two weeks.

173. Direct and Plant Mediated Responses of Biodiversity and Ecosystem Function of Decomposer Fungi to Nitrogen Enrichment in a High arctic Ecosystem

Please contact Dr Clare Robinson

174. Adaptation of Higher Plants and Snow Algae to the Arctic Environment

Please contact Dr Cornelius Lutz

175. Dissolved Organic Nitrogen in Tundra Ecosystems

In 2001 we were granted an LSF award for work on dissolved organic nitrogen in arctic ecosystems. In collaboration with Bjorn Solheim and Christina Wegener of the University of Tromso, we studied (a) the DON and DIN content of a range of soils around Ny Alesund and (b) the relative uses of nitrogen fixation and DON in a defined range of communities. We established a long term experiment at Stuphallet on dry tundra, where we made additions of nitrogen to fixed quadrats. The nitrogen additions were of nitrate, ammonium, glycine and glutamate at 10 kg ha-1. This is the first long-term experiment where organic N additions have been made to tundra. Our hypothesis is that DON is a preferred N source for tundra angiosperms. Within 10 days of application of the N in 2001, there were no significant changes in plant chlorophyll content or N content, not surprisingly as the plants were fruiting and end-of-season N retranslocation and leaf loss were in progress. This application is to make measurements on these plots to test the hypothesis after one year, and to make further applications.

176. Proximate ecological controls on the swimming behaviour of coastal euphausiids

To examine the way in which light intensity and spectrum affects the swimming behaviour and activity of the pelagic euphausiid Meganyctiphanes norvegica.

177. Cell lineage and gene expression during cleavage and larval development of Meganyctiphanes norvegica (Crustacea, Malacostraca, Euphausiacea)

The project is part of a large comparative study on the evolution of the development of crutaceans, mainly malacostracans (higher crustaceans).

178. UFTIR: Time Series of Upper Free Troposphere observations from a European ground-based FTIR network

The main specific objectives of UFTIR are: (1) To revise and homogenise the analyses of available experimental data for providing consistent time series of distinct tropospheric and stratospheric abundances of the target gases using new inversion algorithms. A common strategy for retrieval and characterisation of the vertical distributions of the target gases from FTIR ground-based measurements will be established. (2) To provide quantitative trends and associated uncertainties for the target gases over about the last decade, as a function of latitude throughout Western Europe, focusing on the troposphere. (3) To integrate the data in model assessments of the evolutions of tropospheric abundances. The measured burden and changes of the tropospheric gases will be compared with 3D model simulations, in order to help developing the latter, assist in explaining potential causes for the observed changes and to assess the consistencies between the trends at the surface to the free troposphere and lowermost stratosphere, and the agreement with known evolutions of emissions. UFTIR will make the community prepared to deliver tropospheric data for validation and synergistic exploitation of new satellite experiments like ENVISAT.

Atmospheric processes Sources Ozone FTIR Climate variability Spatial trends Pollution sources Climate change Modelling Emissions Atmosphere Temporal trends profile inversions
179. Climate Change and Competitive Interactions

The effects of climate change in a dynamic competitive interaction between two or more species can be bought about either as direct responses of species to change or indirectly through effects on competing species. Intertidal barnacles are ideal model organisms to test these alternative causal mechanisms, being easily censussed and directly competing for space. Single- and multi- species models will be developed for barnacles in SW England to determine whether direct or indirect mechanisms better predict responses to change. The models will include functions for space-limitation, environmental influence and, in the latter models, functions for interspecific competition. Historical data from a network of sites collected over a 40-year period will be used to develop and test the models.

Climate variability Spatial trends Climate change Biodiversity Temporal trends Ecosystems
180. Reducing the environmental impact of sea cage fish farming through the cultivation of seaweeds

Although the most visible effect of fish cage aquaculture is the output of particulate organic waste, 80% of the total nutrient losses from fish farming are plant-available as potentially eutrophicating substances. This project will assess the ability of commercially important seaweeds, cultivated in the immediate vicinity of caged fish, to reduce the impact of such nutrient releases. The algae cultivated in high nutrient sites will be tested as a food source for humans and for cultivated shellfish, and a model of the distribution of dissolved contaminants from sea-cage fish farms will be developed to predict the impact of introducing algal cultivation at any site.

Pathways Biological effects Fish Spatial trends Environmental management Contaminant transport Food webs Sediments Pesticides Temporal trends Ecosystems