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Displaying: 161 - 180 of 328 Next
161. Greenland Right Whale

The ecology of the Greenland Right Whale is studied using the historical information from written sources from Dutch archives. The Spitsbergen and Davis Strait populations of the Greenland Right Whale were so heavily hunted that they are almost exterminated now in the northern waters. The whale bones on the beaches of Arctic islands are the archaeological evidences of this exhausting hunt. Very often whaling logbooks, crew statements and lists of catch figures are the only sources of information preserved of this animal in these regions. In this project recent biological information of the animal in the seas around Alaska and historical information of the whale in the North Atlantic and Davis Strait is used to reconstruct the migration, distribution and ecological behaviour of the Greenland Right Whale in the North Atlantic Ocean.

whaling Biology whales Populations Biodiversity Marine mammals
162. UV/marine macrophytes

The overall objective is to assess the influence of increased UV radiation and temperature on photosynthesis, nutrient uptake and primary production of microphytes. In order to do this, the existence and nature of strategies against potential UV damage in marine macrophytes of different climatic regions will be investigated. Research activities Measurement of photosynthesis using oxygen exchange and variable fluorescence (PAM); determination of oxidative stress (Gluthation, SOD, CLSM) and nutrient uptake under different UV-regimes

Biological effects nutrient uptake UV radiation photosynthesis Exposure production
163. Ecological energetics of Arctic breeding birds

Large numbers of birds breed each summer on the tundra of the northern hemisphere. Two prominent groups in the Arctic bird fauna are waders and waterfowl (ducks, geese and swans). Breeding, which is an energetically costly activity (Drent & Daan 1980), is especially costly in the high Arctic. This is mainly due to low temperatures and high wind speeds in an open landscape (Piersma & Morrison 1994, Wiersma & Piersma 1994). In addition, the summer period is very short. This leaves little time for necessary pre-breeding, breeding and post-breeding activities. Thus, costs are high and available time is short. In order to reach their breeding grounds, arctic birds have to migrate over vast distances between their Arctic breeding sites and temperate or tropical wintering grounds. Migration is also an energetically costly event. This generally high rate of living puts high demands on the birds and we may expect the birds to have evolved a wide range of physiological and behavioural adaptations. Given the inaccessibility of most tundra areas and the necessity of relatively advanced techniques, ecological energetic studies of wader and waterfowl are relatively scarce (with the notable exception of tundra breeding Nearctic geese). With this project we aim at measuring and describing some important energy turnover processes of waders and waterfowl during the short and hectic Arctic summer and to evaluate them in an evolutionary context. We will pay particular attention to the importance of energy and nutrient stores with which the birds arrive at the breeding grounds for egg production, energy turnover of breeding birds in relation to species and microclimate, and the fat deposition and basal metabolism of birds preparing for autumn migration. The project is partly a continuation of work carried out during the Swedish-Russian Tundra Ecology Expedition 1994 (TE-94). Research activities: Capital vs. income breeders Since the favourable season is short for Arctic breeding birds, they are hard pressed to start egg laying immediately after arrival at the breeding grounds. However, upon arrival food availability is often low. It is thought that female birds planning to start a family on the tundra are forced to produce a clutch using, at least to some degree, body reserves accumulated prior to or during their migratory journey. Birds using such a strategy are called capital breeders, in contrast to income breeders' that only use resources obtained during the reproductive period (Drent & Daan 1980). We seek to investigate how commonly the capital breeder strategy is on the Nearctic tundra and how its use varies with: - Species: large species are expected to be more dependent on this - Strategy as their breeding seasons are longer and they are thus more time stressed. - Site: birds at sites where circumstances allow an early start of the breeding season may not be equally dependent on capital breeding than birds using late sites. - Timing: early arriving birds are more pressed to use the capital breeding strategy than late arriving birds, the latter being able to produce eggs from the food available upon arrival. The different potential food sources to birds often have distinct isotopic ratios of C12/C13 and N14/N15 depending on environment and metabolic characteristics. Isotopic ratios of C and N can therefore serve as a kind of fingerprint for these food stuffs. These specific ratios will ultimately also be reflected in the isotopic composition of the consumers tissues; especially with regard to C12/C13 ratios (Hobson & Clark 1992). Distinct differences may therefore also be expected in tissue isotope ratios of newly hatched young from capital and non-capital breeders. Such differences may also appear within nests in case the female has used a mixed strategy. Although in developing tissues these differences may rapidly fade away, isotope differences between young may be fixed in down feathers already present at hatching. Comparing the isotope ratios in down samples within broods with isotope ratios in potential food sources at the breeding ground thus provides a clue to the extend the mother made use of the capital breeding strategy. We will collect down, feathers and blood from all birds trapped. We will concentrate on waders, yet, also waterfowl are of high interest (although the chances to trap birds are smaller). Of highest priority will be down from chicks and blood from parent birds. In likely foraging areas of parents and chicks that we have sampled, we will collect insects and plants and other possible food sources. At the NIOO the samples will be analysed for C12/C13 and N14/N15 ratios using mass spectrometry. The fact that we will visit many different habitats with different climate, foraging conditions and phenology is a major prerequisite for successfully conducting this part of the project. Energy turnover of brooding birds The few available measurements of daily energy expenditure (DEE) of incubating waders in tundra regions, using the doubly labelled water (DLW) method, have shown that breeding in the High Arctic is indeed costly (Piersma & Morrison 1994, Piersma et al. unpublished data from Siberia). The high cost stems from the combined effects of low temperatures and high wind speeds in an open landscape, but may also be affected by the birds own intense foraging activities. However, the measurements that have become available up till now do not cover the whole "climate space" that arctic breeding waders encounter, due to the bias in study sites and the particularities of weather conditions during the few studies that have been carried out. We would like to extend the series of measurements using DLW in incubating waders of more species than hitherto available and under more environmental conditions. Field measurements of DEE involve initial capture of a bird on the nest, loading it with DLW and recapturing the bird after a certain period of time, usually 24-48 hours. There is room for improvement over the earlier studies in monitoring the loaded birds activity budget (using transponders, small radiotags and/or nest/egg temperature recorders) and in assaying the birds physiological status. Apart from mass and size variable, birds could probably be assayed for the thickness of the breast muscle (a heat generating part of the body) and the size of the stomach (as an indicator of the digestive apparatus) using ultrasound. These techniques are under development at NIOZ and the University of Groningen at the moment. Equally, body composition in terms of fat and lean components could be estimated from dilution factors after quantitative DLW injections. It is crucial to simultaneously measure the meteorological variables air temperature, wind speed and global solar radiation, and hence a weather station has to be brought to the study sites to this effect. Fat deposition and basal metabolism of birds preparing for autumn migration Waders need high-performing bodies to cope with their energetically high rate of living. This is reflected in their basal metabolic rate (BMR). The BMR of an animal is the energy it spends at rest (i.e., at night for day-active animals), in thermoneutral conditions, without processing food, and when it is not involved in productive activities like reproduction, moult or growth. The BMR of a bird may be compared with the fuel consumption of a car engine that is running idle. A Formula-One car, that operates at an incredibly high rate also has a high cost of running idle. A standard car with a less impressive engine takes less energy to keep running. As the cost of running idle reflects the potential power of an engine, the BMR reflects the potential rate of work of an animal body. Waders have comparatively high BMR compared to other non-passerine birds (Kersten & Piersma 1987). Moreover, studies of captive Knots have shown that they vary their BMR over the year (Piersma et al. 1995). In addition, waders trapped during the first part of their autumn migration in Arctic Eurasia were found to have higher BMR than their conspecifics at tropical wintering grounds in Africa (Kersten et al. in press, Lindström in press a). This all suggests that waders can adjust the size of their engine which makes sense, since the best solution would be to have a strong engine when circumstances so demand, and a smaller engine during more relaxed parts of the year (for example at wintering grounds in Africa; Klaassen et al. 1990). Although we are actually most interested in the long-term maximum rate of energy expenditure as a measure of adaptations to a high rate of living, this is very difficult to measure, and especially so in a comparable way. Instead, the BMR, which is supposed to reflect the maximum energy turnover potential, is fairly easy to measure, and figures from different investigations can be compared. During TE-94, 24 juvenile waders of five different species were measured for their BMR in a respirometer (Lindström in press a). We want to continue this work by including birds of new species, and of the same species but from another breeding area. Juvenile birds will be caught during the first parts of the autumn migration (mainly August) in portable and walk-in traps. They are then brought to the ship where they will be measured in the respirometer. The BMR values will be compared to those obtained during TE-94 and with data from the migration and the wintering grounds in America and Europe to look for inter- and intra-specific patterns. Whereas it is fairly well known that many (most ?) wader species put on huge energy reserves prior to migration to the Arctic, almost nothing is known about the size of reserves carried by waders prior to departure from the Arctic. This is necessary to know in order to understand the migration strategies adopted (Alerstam & Lindström 1990) and when analysing migration routes. During TE-94 almost 300 juvenile waders were trapped during August, most of them being Little Stints Calidris minuta. It was revealed that also when migrating from the Arctic, substantial energy reserves were put on (Lindström in press b). We now want to collect corresponding data from the Nearctic. Whereas much is known about the size of energy reserves of migration waders further south in America (for example, McNeil & Cadieux 1972, Thompson 1974, Johnson et al. 1989, Driedzic et al. 1993), we know of no such data from the Nearctic region.

ducks Biology waders Populations breeding success energetics swans Biodiversity geese survival strategies Reproduction wildfowl migration
164. Bewick's Swan ecology of migration and reproduction in the Pechora Delta, Russia

International cooperative research program (field work in 1992-1996) on Bewick's Swans, on ecological limitations in the annual cycle, mainly during periods of high energy expenditure, i.e. breeding and migration. Relates to feeding ecology (both terrestrial and aquatic (pondweed tubers) vegetation, annual variation in climatic conditions. Aims at: 1. understanding limiting factors for population size (production of young and survival) 2. understanding migratory behaviour in this large species 3. protecting crucial areas for breeding, moulting and migrating for this vulnerable swan population Research activities: - Field expeditions (2-5 months) to the Arctic, covering the entire breeding season, including moult and pre-migratory fattening - Running a ringing project with over 1,000 individually marked birds - Data analysis and publications

Biology Populations breeding success survival swans Biodiversity Reproduction migration behaviour
165. UV-radiation and its impact on genetic diversity, population structure and foodwebs of arctic freshwater

The aim of this international project is to measure and model arctic UV-radiation and assess the effects on freshwater planktonic organisms and foodwebs. The fieldwork and experiments are conducted at Ny-Alesund, Spitsbergen. The specific aim of our participation is to study the food web effects of UV-B stress by means of in-situ enclosure studies. In the laboratory we found that UV-B stressed algal cells may increase in volume and form a thicker cell wall. These changes in the algal cells may reduce their digestibility by zooplankton. Further the role of photopigments (like melanin and carotenoids), present in some zooplankters, will be studied in relation to the survival of these animals at high UV-B exposure. Research activities Grazing experiments with Daphnia pulex (melanic and hyaline) are performed in in-situ enclosures (under different UV exposures) in the Brandal Lagune during July. The green alga Chlamydomonas will be incubated in-situ under different UV exposures to assess the potential use of this alga as a biodosimeter for UV-B. Further the survival of melanic and hyaline daphnids will be tested in-situ.

Biological effects UV radiation survival photopigments Exposure Food webs Reproduction phytoplankton zooplankton
166. Goose breeding ecology: overcoming successive hurdles to raise goslings

Determining ecological constraints for Barnacle Geese during the Arctic summer to understand individual breeding success. Geese are individually marked, measured and observed over their lifetime in order to study individual reproductive strategies and their consequences. Also the interaction between the geese and their food plants is studied in detail. Research activities Every year, during summer, fieldwork in Ny Ålesund, every two years counting geese along Norden-skioldkysten. Both areas are located on Spitsbergen.

Biology breeding success Biodiversity geese
167. The ecological interaction between the Spitsbergen whaling and walrus hunting activities and the marine ecosystem in the 17th and 18th centuries

In the seventeent and eighteenth centuries intensive European whaling and walrus hunting took place in the waters around Spitsbergen, with many stations on the coast of the islands. The hunt was carried out in areas along the edge of pack ice and is therefore very sensitive to changes in the ice situation and climate. When, around 1650, climate and ice distribution changed, whales moved to the north. The whaling stations in the south of Spitsbergen were abandoned when stations in the north were still functioning. When, later, the ice situation deteriorated in the north as well, the stations were abandoned there too. Shore whaling changed into pelagic whaling. Because of these whaling and walrus hunting activities two very numerous large mammals were largely depleted and almost disappeared from the Spitsbergen waters. The pelagically feeding Greenland Right Whale and the bentically feeding walrus, whose initial stocks are estimated at 46,000 Greenland Right Whales and 25,000 walrus, were eliminated. This elimination has caused a major shift in the foodweb. The plankton feeding seabirds and polar cod strongly increased because of the elimination of the Greenland Right Whale, and the eider ducks and bearded seals increased because of the decrease of the number of walruses. This development has led to the enormous amount of seabird rookeries on the West coast of Spitsbergen.

whaling Biology whales Populations hunting Biodiversity Seabirds Food webs Ecosystems walrus Marine mammals
168. Breeding success of the long-tailed Skua

The ecology and breeding success of the Longtailed skua (Stercorarius longicaudus) and the Brown skua (Catheracta lonnbergi) is studied in a longterm programme. The difference in allometric growth between the different species and populations of skuas is interesting when it is related to the ecology and distribution history of these species and populations. Skuas have a dynamic distribution history and an opportunistic way of living. Populations of the same species in different localities have often a different ecology. Therefore, studies on different populations of the same species are carried out.

Biology Populations breeding success skua Biodiversity Seabirds Reproduction
169. Breeding success of the Brown Skua

The ecology and breeding success of the Long-tailed skua (Stercorarius longicaudus) and the Brown skua (Catheracta lonnbergi) is studied in a longterm programme. The difference in allometric growth between the different species and populations of skuas is interesting when it is related to the ecology and distribution history of these species and populations. Skuas have a dynamic distribution history and an opportunistic way of living. Populations of the same species in different localities have often a different ecology. Therefore, studies on different populations of the same species are carried out.

Biology Populations breeding success skua Biodiversity Seabirds Reproduction
170. Entangled Sulphur and Carbon cycles in Phaeocystis dominated Ecosystems (ESCAPE)

The principal aim of the project is to establish a link between the marine carbon and sulphur cycles, for which the marine phytoplankton taxon Phaeocystis sp. was chosen as a model organism. This colony forming alga is an important source of the volatile organic sulphur compound dimethyl sulphide (DMS), and its dense blooms can act as a carbon sink. By combining the expertise of researchers working on the carbon and sulphur cycles a thorough inventory of these chemicals will be made. This should result in a better understanding of the role of Phaeocystis blooms in the escape of DMS in the atmosphere and of carbon from the photic zone, and consequently of its role in climate control.

Sources Biology carbon cycle DMS Climate variability algal blooms Phaeocystis Climate change sulphur cycle
171. Energy balance of the Greenland Ice Sheet

Analysis of the energy balance terms obtained during the measuring campaign in 1991 at Greenland. It deals with profile and turbulence measurements, RASS-SODAR observations and radiation measurments.

mass balance Climate variability Climate Climate change Ice Ice sheets
172. Land ice, climate change and sea level

Land ice forms an important component of the climate system. Sea level variations are closely related to the total ice volume. Purpose of the research project is to obtain a better understanding of how glacier fluctuations and climate change are linked. This is a prerequisite to make more accurate predictions of future sea level.

Glaciers Climate variability Climate Climate change sea-level change Ice Ice sheets
173. Circulation and transports in the Atlantic Ocean

Elaboration of DUTCH-WARP [Deep and Upper Transport, Circulation and Hydrography-WOCE Atlantic Research Programme] in the frame of WOCE: deep circulation of thermal structure of surface water in the Iceland Basin; continuation of the application of ARGOS buoys; implementation of satellite altimetry of the North Atlantic Ocean; eastern boundary current of the North Atlantic Ocean in the Bay of Biscay as contribution to WOCE (1992-1998)

Climate variability remote sensing Climate change Oceanography circulation Ocean currents WOCE
174. Holocene of Nova Scotia and New Brunswick, Canada

Study of the Holocene development in the coastal area of Nova Scotia and New Brunswick (Canada), in relation to sea-level movements, isostatic movements and climate development, particularly for the last 4500 years. Use of stratigraphical and sedimentological methods and of 14C-dating.

Geology Climate variability isostatic adjustment stratigraphy Climate change sea-level change Holocene Sediments
175. Paleeoecology and (periglacial) eolian sediment transfer in the ice-sheet marginal zone of southwestern Greenland (Kangerlussuaq region)

The project aims at reconstructing the environmental history in the interior Kangerlussuaq region since deglaciation. Focus is placed on the lacustrine and eolian sediments to decipher climate evolution in terms of temperature, evaporation- precipitation balance and phases of high- wind speed events. The overall objectives are to build a high-resolution (decadal-to-century scale) chronostratigraphic framework for past climate variability from the analysis of organic-rich lake sediments and peat filled basins using a variety of sediment analysis techniques (magnetostratigraphy, grainsize, sedimentfractionation techniques, AMS 14C dating, diatom-, pollen- and macrofossil analysis) and sedimentology. Research activities diatom analysis, pollen analysis, magnetic susceptibility, automated correlation techniques, grainsize, organic chemistry, sediment fractionation techniques, AMS radiocarbon dating, sedimentology, mapping, sediment transport and erosion measurements/monitoring, micro-meteorology, vegetation mapping, pollen rain studies, diatom salinity training sets, limnology

Glaciers Geology eolian Climate variability Climate sedimentology Climate change Quaternary geology Ice sheets Geochemistry Sediments paleeoecology geomorphology periglacial paleolimnology
176. Geomorphology, climate and specific phenomena in the periglacial

Periglacial conditions have characterized the geomorphological development of river systems and have activated eolian processes during the Quarternary ice ages in Europe. Frost and melt mechanisms have also caused deformations on micro and macro scale in soil and sediments. Specific periglacial phenomena are indicative for (paleo-) climatic conditions

Geology Climate variability paleoclimatology Climate Climate change geomorphology periglacial
177. Health effects of increased UV exposure

Besides some beneficial effects of UV exposure, i.e. skin tanning and vitamin D production, UV ex-posure can have deleterious effects on human health. Deleterious effects are a.o. skin cancer, skin aging, wrinkling, cataract, snow blindness, and effects on the immune system. The objectives of this project are especially aimed at the detection of UV effects on the human immune system and as a consequence of the UV induced immunomodulation effects on the resistance to infections and tumors. Research activities Research activities are focussed at laboratory animal studies, studies with human volunteers, epidemiology and mathematical modelling.

Biological effects epidemiology UV radiation immunology Exposure Human health
178. Prediction of extreme offshore structure response

The development of methods for the accurate prediction of the extreme response of non-linear dynamic systems which use less computer time than presently commom methods.

structure response technology Modelling offshore
179. Palaeobotany and palynology

In the wake of topical research issues such as global change and energy resources, one can recognize two priority targets for the study of fossil plant remains: - insight into the role of land plants and phytoplankton as monitors, recorders, motors and moderators of climatic and environmental change; -insight into the predictive value of organic remains with respect to genesis, composition, occurrence, quality and quantity of fossil fuel reserves. In harmony with these targets, current research at the Laboratory of Palaeobotany and Palynology (LPP) is aimed to provide for basic contributions to the palaeoecological study and interpretation of Palaeozoic, Mesozoic and Cenozoic plant life. Four interconnected areas of scientific emphasis are currently distinguished: - biotic change: documentation and causal analysis of changes of past plant biota in terrestrial and marine environments, both at short and long time-scales; - selective preservation: identification of the biological, physical and chemical factors that determine selective preservation of organic matter during transport, sedimentation and burial; - methodology: development and introduction of new analytical methodology relevant to the study and interpretation of fossil plant remains; - systematics: generation and compilation of systematic data aimed at the accurate identification and classification of fossil plant remains. Overview of results LPP strives after a balance between the study of land plant remains and organic-walled marine phytoplankton (mainly dinoflagellates). Research objectives are related to both short (latest Pleistocene-Holocene) and long time-scales (late Palaeozoic-Cenozoic). Short time-scales Modern land plant communities can be understood only in the light of their history since the onset of the last deglaciation (15,000 yr BP). In western and southern Europe this history is governed by the climatically induced spread of forest communities and their subsequent recession as man's influence expanded. Through fine-scale analysis (temporal and spatial, as well as systematic), of assemblages of microscopic and macroscopic plant remains, research concentrates on the accurate discrimination between autogenic, climatically induced, and anthropogenic vegetational change in contrasting physiographic entities: (1) crystalline mountains in France and the Iberian peninsula; (2) landscapes characterized by Pleistocene-Holocene eolian (sand, loess) deposition in the Netherlands and Germany; (3) fluvial plains in the Netherlands; (4) littoral landscapes in Portugal, and (5) Arctic landscapes of Spitsbergen, Jan Mayen and Greenland. Following earrlier research experiences with respect to the palaeoecological analysis of pollen assemblages from the Vosges (France), in the research period special attention was given to deciphering the complex, altitude related, late Pleistocene-Holocene pollen signals from other low mountain ranges. Results have demonstrated that the spatial distribution of vegetation patterns can be followed through time by recognizing: (1) common time-proportionate trends in pollen values, and (2) local pollen components characteristic for altitudinal vegetation zones and lake/mire development. Long time-scales For the recognition and evaluation of biotic change on long time-scales, LPP concentrates on the study of land plant and phytoplankton records from sedimentary successions that contrast with respect to: (1) time of formation (selected late Palaeozoic, Mesozoic and Cenozoic intervals); (2) paleotectonic and palaeogeographic history (intracratonic; passive and active plate margins); (3) depositional environment (terrestrial to deep-marine); and (4) biogeographic provinciality. Temporal and spatial distribution patterns of plant remains are explored for proxy variables indicative of terrestrial and marine environmental change. Investigated variables include land temperature, humidity, precipitation, runoff, sea-level, sea surface temperature, salinity, nutrient supply, productivity, organic burial rate and CO2 level. In the review period particular attention has been given to the development of palaeoecological models of dinoflagellate cyst distribution in marine sediments. It has been shown that: (1) the potential of dinoflagellates in Mesozoic and Cenozoic time-resolution may frequently exceed that of planktonic foraminifera and calcareous nannoplankton, and (2) dinoflagellates can be applied in novel ways to further the environmental understanding of depositional sequences and sedimentary cycles defined by physical (seismic, sedimentological) analysis. Although research related to global change programmes is generally restricted to the Late Tertiary-Quaternary, there is one notable exception. It is recognized that a better understanding of the patterns and processes of past mass extinctions can contribute to an understanding of present and future man-induced extinction processes. Work by LPP concentrates on the profound biotic crises at the Permian/Triassic (P/Tr) and Cretaceous/Tertiary (K/T) junctions. Study of the P/Tr land plant record has now revealed ecosystem collapse in the terrestrial biosphere. At the K/T junction, it has been demon-strated that dinoflagellates have remained immune to extinction. Independent of configurations predicted by meteorite-impact or massive volcanism, therefore, palynological studies enable high-resolution reconstruction of environmental change, both during pre-crisis times and the phases of K/T ecosystem decline and recovery.

Geology palaeobotany Climate variability Climate Climate change palynology Sediments
180. Tundra

Overall objective is to obtain net fluxes for carbon and freshwater water from an Arctic catchment under base-case and global change scenarios. Objective of the Vrije Universiteit Amsterdam is to study the temporal and patial variability in floodplain sediment balance over the last 2000 years. Research activities: Selected areas in the Usa basin will be studied in detail, both in the zones of continuous and discontiunous permafrost. Fieldwork was and will be conducted in the summers of 1998 and 1999. At selected field sites, the present day processes of river erosion and deposition will be evaluated and the natural evolution and variation of amount and rate of erosion and deposition will be determined for the last 2000 years.

Pathways erosion sediment balance Soils Hydrography Catchment studies carbon flux Climate variability freshwater flux Discharges Spatial trends Climate change Geochemistry Sediments Temporal trends