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Displaying: 141 - 160 of 206 Next
141. Interactions between meiofauna and mat-forming microbes at the sediment-water interface - implications for benthic-pelagic coupling in coastal systems

The project investigated small-scale biotic interactions between laminated microbial communities and meiofauna at light-exposed sediment-water boundaries of estuarine lagoons. The production and biological structure of these systems is mainly determined by complex processes at the sediment-water interface which depend on finely scaled patterns, requiring appreciation of how the biota interact within these scales. We tested whether changing light conditions and active emergence of the harpacticoid species Mesochra lilljeborgi and Tachidius discipes are mediated by the activity of benthic oxygenic and anoxygenic phototrophic microbes. Two hypotheses were tested which addresses to the question of causality between changing light conditions and active emergence of the harpacticoid copepods. (1)The harpacticoid copepods T. discipes and M. lilljeborgi will enter the bottom water during daylight when oxygenic photosynthesis of cyanobacteria and eukaryotic algae is blocked and conditions at the sediment-water interface have turned anoxic. (2)Both species will not emerge during dark exposures when transferred to sterilized sediments.

Biological effects Biology copepod microbial communities interactions Sediments Ecosystems
142. Structure and function of shallow marine coastal communities

Shallow coastal areas on the Swedish west coast are generally considered highly productive and important nursery grounds for both invertebrates and fish. Several commercial important coastal fish species utilize the abundant food resources in the shallow bays during their juvenile life history stages. In my research, trophic relationships are characterized among a guild of epibenthic fish and crustaceans in some shallow embayments along the Swedish west coast. I focus principally on the influence of physical factors (temperature, salinity, exposure, sediment type, oxygen level and habitat structure) on predator-prey dynamics which are quantified in a multi-level approach involving laboratory experiments and field sampling. My intention is to study biotic regulation of populations within the limits set by naturally occurring abiotic factors in coastal areas. The general hypothesis is that habitat structure (sediment and vegetation) in a coastal area has a decisive importance for community structure and function. The structure of the habitat influence the carrying capacity of the area and set the limits within which population size may fluctuate. Population dynamic, production and consumption of epibenthic fauna and fish has been estimated quantitatively in some shallow soft bottom bays, and energy flow models have been constructed for both a sandy habitat and an eelgrass bed. Interactions between habitat structure (sediment and vegetation) and the structure of epibenthic fauna has been evaluated in several types on coastal environments in the Skagerrak and the Kattegat. For example, changes in macrovegetation in shallow coastal areas and its effects on recruitment and population structure of associated crustaceans and fish has been investigated. Distribution of filamentous algae has been assessed by aerial photo documentation, and interactions between vegetation and fauna has been studied in laboratory experiments and field investigations. Structure of fish assemblages has been related to vegetation type in both rocky and soft bottom communities. In shallow sandy bays recruitment mechanisms in flatfish has been studied. Further, the structuring role of hypoxia on demersal fish communities has been investigated in SE Kattegat and York River, Chesapeake Bay, including studies of species structure, biomass, growth, migrations and food selection.

Biology Ecosystems
143. 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
144. 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
145. Environmental sensitivity of cold water corals

Distribution • What is the current distribution of coral colonies in the North Sea? • Where are coral colonies located on the structures? • Do any colonies show evidence of exposure to drill cuttings? Monitoring & Environmental Recording • What hydrodynamic regime and levels of suspended particulate material are coral colonies exposed to? • Does the coral skeleton retain an archive of any past contamination? • Does skeletal growth vary over time and does this correlate with any past contamination? • How variable is the rate of coral growth and does this correlate with any environmental variables? Environmental Sensitivity • What effect does increased sediment load have on coral behaviour and physiology? • What effect does exposure to discharges (e.g. cuttings and produced water) have on coral behaviour and physiology? • Are such exposures realistic in the field?

Shelf seas Biological effects Pollution sources Environmental management Contaminant transport Petroleum hydrocarbons Oceanography Biodiversity Local pollution Ecosystems
146. Phosphorus Cycling in the Cryosphere

This project will construct detailed phosphorus budgets for polar catchments occupied by glaciers and freshwater systems undergoing rapid response to climate warming. These are Midre Lovenbreen, Svalbard; Jebsen Creek, Signy Island (maritime Antarctic) and Storglaciaren, northern Sweden. The relationship between meltwater production, pathway and phosphorus liberation from glacial sediments will be examined closely. Emphasis will be given to phosphorus sorption dynamics in turbid glacial streams and their receiving waters (fjords and lakes).

Glaciers Catchment studies Phosphorus Climate change Arctic Geochemistry Ecosystems
147. Bacterial diversity in marine sponges

The aim is to study the diversity and function of marine bacteria closely associated with marine sponges. The special character of life strategy of the community (symbiosis – commensalism), with special emphasis to the identity and the recruitment of bacteria during live cycle of the sponges will be described.

Shelf seas Biological effects Biodiversity Ecosystems
148. Bacterial diversity in echinodermata

Little is known about the consistency or phylogenetic affiliation of accociated intra- or extracellular bacterial populations in Echinodermata. Because certain taxa harbour bacteria and other not, these associations are presumably originated by coevolution and not by ecological circumstances. The intestine of echinodermata is populated by huge amounts of bacteria. Due to the different feeding strategy of echinoderms it is controversly discussed whether these bacteria are passively taken up or if they are permanently present. Hence it will be possible to elucidate if vertical transmission occurs or bacteria are recruted. With the knowledge of phylogenetic affiliations of microbial symbionts and their distribution (or localization) in different hosts, the physiological/biochemical status of the association will be investigated. The main emphasis will be the characterization of the in situ situation by adequate histological techniques (crysectioning) and “passive” (FT-IR) or “active” chemical imaging (confocal imaging, using fluorescent enzyme substrates or physiological dyes). The main experimental work in this WP bases on the creation of 16S-rDNA sequence libraries of echinoderrm associated bacteria (SCB & intestinal). Signature sequences will be analyzed and specific gene probes will be designed and applied.

Shelf seas Biological effects Biodiversity Ecosystems
149. Investigations on the diversity and role of microphytobenthos in marine and freshwater food webs.

The main research goal of this project is focused on trophic interactions within microbenthic communities in aquatic systems. Grazer-microalgae interactions are investigated by conducting field and laboratory experiments in order to get a closer idea of the microphytobenthos community structure itself. Especially the role of morphological and physiological adaptations of microalgae in the presence of specific meio- and macrofaunal predators are of great interest. In addition to that we have devised a new benthic sensor for the quantitative and qualitative assessment in situ of diverse populations of microphytobenthos with high spatial and temporal resolution, enabling rapid evaluation of the community structure and distribution.

microphytobenthos Food webs Sediments chlorophyll fluorescence marine and freshwater sediments Ecosystems benthic algae
150. HIMOM

HIMOM will aim to provide a system of methods, the so-called Hierarchical Monitoring Methods (or HMM), to determine system status and changes which are expressed by biological and physical variations within inter-tidal areas. The HMM will aim to provide a management strategy tailored to the needs of End User involved in activities relating to the sustainable development of tidal flat areas around Europe. The HMM system will represent a hierarchical suite of activities, ranging from simple ground measurements of biota and physical characteristics to remote sensing of spectral reflectance properties for the analysis of basin scale systems.

Biology Environmental management Biodiversity Ecosystems
151. Helgoland Foodweb Project

To study the organisms involved in phytoplankton succession and the Key factors involved. This includes Bacteria-Algae, Algae-zooplankton and Zooplankton-Fish interactions. Aspects such as algal-grazer defence mechanisms and digestability of alage are core topics.

Biology Environmental management Biodiversity Ecosystems
152. photosynthesis of lichens from lichen-dominated communities in the alpine/nival belt of the alps

The photosynthetic productivity and the factors affecting it are measured in the nival zone of the Alps. Patterns of CO2 exchange for several lichen species are determined whilst recording environmental factors such as light and temperature and lichen water content. Whilst these records will show the lichen response over the year they can most easily be interpreted when the photosynthetic ability of individual lichens is well known. To achieve this the response of each species to light intensity, temperature, thallus water content and humidity will be determined under fully controlled conditions in the laboratory. The final aim is to achieve an initial carbon balance model for the lichen species. This will be aided considerably by the deploying of a continuously recording chlorophyll fluorescence system that will provide activity data for one lichen species on a better than hourly basis throughout the year.

Biological effects Biology microclimate CO2 gas exchange photosynthesis chlorophyll fluorescence ecophysiology lichen Ecosystems alpine environment
153. Effects of UV-B radiation on Microbial communities in Kongsfjorden

Effects of UV-B radiation on microbial communities in Kongsfjorden in relation to metal and dissolved organic matter availabillity.

Biological effects Ozone Biology UV radiation Heavy metals Environmental management Exposure Arctic Model ecosystem Ecosystems
154. Ecological and Physiological Investigations about the Impact of UV Radiation (UVR) on the Succession of Benthic Primary Producers in Antarctica

The succession of macro- and microalgal communities in the Antarctic will be investigated in field experiments under various UV radiation (UVR) conditions and in the absence or presence of grazers. The observed differences in the succession process will be correlated to physiological traits of single species, especially in spores and germlings, which are the most vulnerable stages in their life histories. Photosynthetic activity of the different developmental stages will be measured routinely. Additionally we plan the determination of pigment composition, C:N ratios, content of UV protective pigments and of possible DNA damage. The experiments will start in spring, concomitant to the time of highest UVBR, due to the seasonal depletion of the ozone layer in the Antarctic region. Supplemental laboratory experiments will be conducted to determine the effects of UVR on spores and germlings of individual species. In addition to the above analyses, we plan to examine of UVR induced damage of cell fine structure and of the cytoskeleton. The results of both the field and laboratory experiments will allow us to predict the consequences of enhanced UVR for the diversity and stability of the algal community.

Biological effects Biology UV radiation Environmental management Climate change Biodiversity Arctic Ecosystems Seaweeds
155. Detection of UV-B induced DNA damage

Detection of UV-B induced DNA damage on zoospores of brown algae

Biological effects Biology UV radiation CPD Temporal trends Ecosystems
156. Helgoland Foodweb Project

The aim of this project is to investigate and understand those factors that play a role in the seasonal dynamics of different functional groups in the pelagic zone of coastal seas. We investigate the interactions between bacteria, phytoplankton, zooplankton and juvenile fish in order to assess the importance of biological interactions in the seasonal succession.

Biology Fish Plankton Bacteria Food webs Ecosystems
157. Macroalgal secondary metabolites from Arctic waters

The aim of this project is to investigate natural products from polar macroalgae. As arctic waters represent an extreme habitat, formation of secondary metabolites is limited - besides other factors - by light conditions. Therefore, the influence of light, particularly different photon fluence rates and UV radiation, on secondary metabolism and on regulation of associated genes will be studied.

polar macroalgae Biological effects UV radiation Ecosystems
158. Physiological response of growth, photosynthesis and nutrient uptake of marine macrophytes in a UV- and CO2 - enriched environment

As a result of the increasing atmospheric CO2 levels and other greenhose gases due to anthropogenic activities, global and water temperature is rising. The objectives of our project might be summarized as follows: I. To measure the activity of the enzymatic systems involved in carbon, nitrogen and phosphorus uptake (carbonic anhydrase, nitrate reductase and alkaline phosphatase) in selected macroalgae. To assess the optimal concentration of inorganic nitrogen and phosphorus for growth and photosynthesis. To study the total concentration of carbon and nitrogen metabolites in the macroalgae (proteins, total carbohydrates, and lipids) in order to define the possible existence of nutrient limitation. II. To simulate the conditions of climate change, represented as CO2 enrichment and increasing UV radiation, on the activity of carbon, nitrogen and phosphorus uptake mechanisms. III. To screen the activity of the enzymatic systems previously detailed in macroalgae from the Konjsfjord, in order to know their nutritional state.

Biological effects nutrient uptake UV radiation Climate change Macroalgae eutrophycation Ecosystems
159. Detection of spatial, temporal, and spectral surface changes in the Ny-Ålesund area 79 N, Svalbard, using a low cost multispectral camera in combination with spectroradiometer measurements.

Changes in surface reflection at the arctic tundra at Ny-Ålesund, Svalbard (79 N) were monitored during the melting season 2002 using a low cost multispectral digital camera with spectral channels similar to channels 2, 3, and 4 of the Landsat Thematic Mapper satellite sensor. The camera was placed 474 m above sea level at the Zeppelin Mountain Research Station and was programmed to take an image automatically every day at solar noon. To achieve areal consistency in the images (which is necessary for mapping purposes) the images were geometrically rectified into multispectral digital orthophotos. In contrast to satellite images with high spatial resolution the orthophotos provide data with high spatial and high temporal resolution at low cost. The study area covers approximately 2 km2 and when free of snow, it mainly consists of typical high arctic tundra with patchy vegetation and bare soil in between. The spectral information in the images was used to divide the rectified images into maps representing different surface classes (including three subclasses of snow). By combining classified image data and ground measurements of surface reflectance, a model to produce daily maps of surface albedo was developed. The model takes into account that snow-albedo decreases as the snow pack ages; and that the albedo decreases very rapidly when the snow pack is shallow enough (20-30 cm) to let surface reflectance get influenced by the underlying ground. Maps representing days with no image data (due to bad weather conditions) were derived using interpolation between pixels with equal geographical coordinates. The time series of modeled albedo-maps shows that the time it takes for the albedo to get from 80% to bare ground levels varies from less than 10 days in areas near the coast or in the Ny-Ålesund settlement till more than 70 days in areas with large snow accumulations. For the entire study area the mean length of the 2002 melting period was 28.3 days with a standard deviation of 15.1 days. Finally, the duration of the snowmelt season at a location where it is measured routinely, was calculated to 23 days, which is very close to what is the average for the last two decades.

Digital camera Hydrography Mapping Geophysics Climate variability Orthophotograph Spatial trends Remote sensing Orthophoto Modelling Arctic GIS Spectral Temporal trends Ecosystems
160. Physiological adaptations of the arctic fox to high Arctic conditions

To investigate arctic foxes physiological adaptations to life at high latitudes. Resting and running metabolic rates, body weight, food intake, body core temperature, heart rate, and blood parameters were examined during different seasons and during periods of food deprivation.

Biological effects Biology Climate Arctic Ecosystems