Research outlined here is a continuation of a study initiated in 1991 on the barren, upland plateau on Devon Island, Canada. This research focuses upon the interactive roles of soil development, and cryptogamic crust and vascular plant establishment and function in the formation of polar deserts. Research on the macroscale landscape features of crusted and non-crusted sites will continue. This study will be expanded to include the mesoscale features of stone nets and stripes and the role these features play in soil weathering processes, the establishment and nitrogen fixation of cryptogamic crusts, and the transfer of nitrogen from crusts to soils and vascular plants. The physiological and biomechanical adaptations of root systems to cold, nutrient-poor, frosty disturbed soils, and the role of carbon accumulation and water relations of seedlings and adults will be studied as these aspects relate to the limited role of vascular plants within vast areas of polar desert. The large year-to-year variability provides clues on how this highly stressful system may respond to longer term climate change. Better understanding the response to climate change of extensive, but little understood, polar desert systems will contribute significantly to program goals related to the effect of global changes in the arctic polar environment.
The effects of increased ultraviolet (UV) irradiance on planktonic ecosystems have been studied in some detail for Antarctic waters but comparable studies have not been carried out at high northern latitudes. Recent evidence has documented a thinning of ozone over Arctic seas, suggesting the potential for similar UV effects in northern waters. In this proposal we will determine the effects of present-day UV radiation, as well as the potential effects of increased UV irradiance, on phytoplankton and ichthyoplankton in High Arctic latitudes. Studies of Arctic phytoplankton, to be conducted in Norway, will focus on: (1) the effects of UV radiation on photosynthetic rates and the effect on overall rates of primary production, (2) the extent to which cells can decrease their sensitivity of UV radiation by synthesis of UV-absorbing compounds, (3) species-specific differences in UV resistance and (4) DNA repair capacities which are unknown for northern plankton communities. Studies of UV damage to ichthyoplankton have not been conducted at either pole. Recently developed methods allow us to measure the amount of UV-induced DNA damage in individual free-living eggs and larvae. The results of these studies, done at temperate latitudes, have shown that the diel cycle of damage and repair, the pre-exposure conditions and interspecific differences greatly effect the susceptibility to UV damage. The present study will be the first attempt to measure the impact of UV on early life-stages of important polar fisheries species. The proposal brings the investigators' skills in measuring UV damage together with the unique location, collaborators and technical capabilities of the laboratories in Tromsø, Norway.
Research supported by this grant is under the auspices of the Arctic Systems Science (ARCSS) Global Change Research Program and is jointly sponsored by the Division of Ocean Sciences and the Office of Polar Programs. The research will be centered around a unique and intensive, multidisciplinary research expedition to parts of the Arctic Ocean that have never been extensively studied. The 1994 U.S./Canada Arctic Ocean Section is a collaborative effort that will involve approximately 60 scientists on a Canadian and a U.S. icebreaker during summer 1994. NSF-funded projects will focus on hydrography, biology, paleo- and sea-ice studies. Data collected will be amongst the first ever from several regions of the Arctic Ocean and will be highly relevant to improving our understanding of how the Arctic is an indicator of changing global climate conditions and how it affects the physical, chemical and biological features of the more temperate oceans and regions. This work is a component of the collaborative biology program. Work will be undertaken to examine the fate of organic matter reaching the sea floor and model cycling between the various carbon pools. The fate of carbon fixed in the Arctic Ocean is largely unknown, but it is surmised that a greater portion reaches the bottom than in other oceans. Low abundance and slow feeding rates of zooplankton, and reduced importance of the microbial loop, may explain why the majority of primary productivity falls to the benthos at high-latitudes. Research will focus on some of the possible fates of carbon reaching the benthos by examining patterns of benthic biomass and rates of remineralization, irrigation and particle mixing. Replicate box cores will be collected along the Section. Abundance and biomass of macro- and meio-fauna and depth profiles of Eh and particulate carbon will be determined from these cores. Subcores will be incubated on-board to determine rates of remineralization and bioirrigation. Particle mixing rates will be determined directly from down-core 210Pb distribution and will be compared with mixing estimates obtained from carbon depth-profiles and bioirrigation rates. This study provides insights into the role of benthos in mediating geochemical processes and will provide a model of carbon cycling in Arctic sediments which can be used to make predictions of the consequences of global warming.
The recipient has been chosen for an NSF Presidential Faculty Fellow Award. The recipient will continue his research in the transport of carbon, nitrogen, phosphorus and sulfur through Arctic tundra ecosystems to include both physical and geochemical transport mechanisms and pathways. These studies will lead to a better understanding of broad environmental problems such as acid rain, eutrophication, species introductio ns and climate change. The research will lead to a predicative capability for ecosystem function to show how organisms react to each other and to human-imposed change. Fundamental questions about geochemical cycling within organisms at both the regional and global scales will be examined. A novel technique involving the use of stable isotopes will be applied at the scale of entire ecosystems and will be used to estimate the current carbon balance in arctic ecosystems. Determination of the processes controlling the current carbon balance will allow the PI to predict the changes that may occur during forecasted climate change in the Arctic.
Depletion of stratospheric ozone, particularly in the polar regions, is causing increased concern over the effects of harmful UV radiation (mainly UVB, 280320 nm). UVB is damaging to many biological processes, and in plants, specifically targets photosynthesis. Large increases in the penetration of solar UVB in the Southern Ocean during the austral spring from ozone depletion is known to have significant effects on phytoplankton productivity. The phenomenon is less severe in the Arctic, but ozone related increases in incident UVB have accelerated over the last three years. This proposal addresses the question of the effects of increased UVB on large benthic marine macroalgae (kelp) and the levels of UVB that penetrate into the coastal water of the Arctic. Little is known about the sensitivity of kelp photosynthesis to UVB. Assessment of UV effects (280400 nm) in an environmental context can be made by weighting the spectrum of UV irradiance with a biological weighting function (BWF; similar to an action spectrum). The investigators will measure detailed BWFs and the kinetics of UV effects on photosynthesis of macroalgae in High Arctic, emphasizing the kelps Laminaria saccharina and L. solidungula, which are distributed throughout the circumpolar Arctic. Both laboratory cultured plants and sporophytes collected during two spring and one summer field season, in the Canadian High Arctic (Resolute, 79°30'N; 95°W) will be measured. Plants exposed to different natural light environments during the nine-month ice covered period will be examined for differences in their sensitivity to UV radiation; the importance of the nitrogen status of the plants in recovery processes that counteract UV-induced damage will also be investigated. The results will enable the first quantification of potential UV exposure in kelp habitats and the biological effects of such exposure in terms of kelp productivity in arctic coastal systems.
Freezing resistance in polar fishes is usually attributed to noncolligative peptide antifreezes. In 1991, it was found that some arctic fishes increase the freezing point depression of their body fluids by producing high concentrations of glycerol in winter. Subsequent studies of this phenomenon have led to a realization that other inorganic ions and organic osmolytes have important roles in freezing resistance in many polar fishes, and possibly other roles as well. Prominent among these solutes are trimethylamine oxide (TMAO) and urea, which are more widely distributed in polar fishes than glycerol. These studies have lead to several unusual findings concerning the synthesis, roles, conservation and distribution of these osmolytes. Therefore, the overall objective of this study is to better understand the biochemistry and physiology of glycerol, TMAO and urea in arctic fishes. Previous studies have shown that significant glycerol losses occur in smelt and that these losses are compensated for by a synthetic pathway (via pyruvate) that appears to differ from that in other cold-hardy, glycerol-producing animals. New studies will focus on various amino acid substrates that may be involved in this pathway, and the seasonal variation in activity of three key enzymes that also are thought to be involved. The unexpected occurrence of high serum TMAO levels in many arctic fishes also raises several questions. TMAO is usually acquired by teleosts through the diet, but in the smelt family it appears to be synthesized in response to cold. TMAO synthesis will be tested by an assay for TMAO oxidase in warm- and cold-acclimated fishes. Inorganic ion concentrations in polar fishes are high enough to interfere with intracellular processes, such as enzyme activities.
Arctic breeding birds arrive on their nesting grounds at a time when weather conditions may still be extreme (low temperature, snow). However, the brief arctic summer requires that they begin nesting as early as possible to take advantage of the ephemeral abundance of food to feed young. Failure to adhere to this rigid schedule results in drastically reduced reproductive success. Hormone-behavior adaptations that maximize survival and reproductive success under the extreme conditions of the Arctic are the focus of this proposal. It has been shown that the interrelationships between testosterone and territorial aggression are diverse, especially as birds arrive on the arctic breeding grounds. In some species territoriality is extremely brief, following which birds apparently become refractory to the effects of testosterone. Others are territorial throughout the breeding season, but the dependence of these behaviors upon testosterone activation remains unclear. Aggressive behavior of between four and seven arctic breeding passerines displaying different types of territoriality will be compared. Temporal patterns of testosterone in relation to patterns of aggressive behavior and the effects of manipulating testosterone level will also be determined. Additionally, these species will be compared with their closest relatives breeding at mid-latitudes (i.e., matched pairwise comparisons to avoid confounding issues relating to phylogenetic relationships). In this way it is possible to determine the ecological bases of different types of territorial behavior and interrelationships with testosterone, as well as indicate potential specialization of arctic breeding birds. The same spectra of species in the Arctic and at mid-latitudes will be used to compare adrenocortical responses to stress.
This program focuses on population and ecosystem level questions within the framework of succession. It capitalizes on a substantial existing base of information and preliminary results from past research to address hypothesized controls of structure and function of successional forest communities. These processes previously have not been examined in a comprehensive manner in the North American taiga. Results of this research will greatly improve understanding of the links between resource supply (moisture, light, nutrients) and plant growth as influenced by herbivores and soil microbial activity. Researchers in interior Alaska have demonstrated their commitment to long-term studies of ecological processes. Several studies have been pursued, essentially by the same scientists for 20 to 25 years. For example, a series of plots in various successional stages on the floodplain of the Chena and Tanana Rivers, established in 1964, are still being monitored for growth and changes in species composition. The U.S. Department of Agriculture Forest Service also is committed to long-term experimentation and encourages these activities through their management of Bonanza Creek Experimental Forest, the principal site of this research. The hypotheses put forth in this proposal address important long-term aspects of forest ecosystem structure and function only initially evaluated in earlier research efforts.
During the first five years of the Arctic (LTER) at Toolik Lake, Alaska, systematic measurements of climate, of tundra plant distribution and productivity, and of lake and stream physics, chemistry and biology were begun. Whole system experiments were set up on the tundra, in streams, and in lakes to examine the ecological effects of changes in environmental and biological factors such as air temperature, added nutrients and changes in the density of the top predators and grazers. These measurements and long-term experiments are designed to help reach the overall goal: to understand how tundra, streams and lakes function in the Arctic and to predict how they respond to human-induced changes including climate change. Under this broad goal there are three specific goals: (1) determine year-to-year ecological variability in these systems and measure long-term changes; (2) understand the extent of control by resources (bottom-up control) or by grazing and predation (top-down control); and (3) measure rates and understand the controls of the exchange of nutrients and organic matter between land and water. Long-term experiments are the heart of the Arctic (LTER) program. It has been found that arctic systems often do not respond for many years, and that long-term responses are often not predictable from short-term responses. Changes in the responses of both streams and terrestrial vegetation to nutrient amendments are still being documented after nineyears. Lake trout manipulations take many years to show effects as these long-lived fish may change their diet from invertebrates to fish when they reach a certain size. As a result, most long-term experiments and measurements for determining ecological variability will be continued. The results of the long-term experiments will continue to be measured as more is discovered about long-term ecosystem controls by resources and predation. New research on the controls of the exchange of nutrients between land and water will be started. A major watershed experiment will be carried out to measure the movements of water and dissolved gases through the groundwater and into the streams.
Freshwater systems are a major feature of the arctic landscape, despite the low precipitation, because permafrost prevents drainage and evaporation is low. Their relative biotic simplicity offers advantages to researchers attempting to sort out the various controls and interactions of arctic lakes and streams. An understanding of the ecological processes is a necessary part of the long-term goal of this project: prediction of the effect of changes in land use and climate on arctic stream and lake ecosystems. This project will be based at an (LTER) site, Toolik Lake, on the North Slope of Alaska, and will make use of long-term experiments of stream and lake fertilization and manipulations of the dominant predator in lakes, the lake trout. These manipulations are maintained by the (LTER) group. The project also will use (LTER)-produced data on basic environmental conditions including climate, lake physics and chemistry, nutrient concentrations in streams and lakes and stream flow. The project will move strongly towards synthesis and use data derived from all the past studies plus data from recent manipulations on streams and lakes. The long-term goal of the synthesis and modeling is to understand the movements and transformations of water, nutrients and organic matter through an entire watershed in the High Arctic.
Over the last several decades many populations of pinnipeds and seabirds have undergone significant declines. Many hypotheses to explain the declines have been made and numerous studies have been undertaken to search for the underlying causes. Juvenile survival, however, may be one of the most critical factors influencing the growth and recovery of depleted populations of pinnipeds. Maternal resources imparted to offspring prior to weaning are important for a successful transition from nutritional dependence to independence and subsequent survival. This may be particularly so of species whose life histories are constrained by rearing young at high latitudes and species which wean their young abruptly. Growth and recovery of depleted populations at high latitudes are further constrained when life-history fecundity schedules limit individuals to producing one offspring per year. Thus, the quantity and quality of maternal investment to the young are a critical determinant of post-weaning survival. This research will examine the relationship between foraging behavior and maternal investment in northern fur seals. The research will be conducted in the Pribilof Islands, Alaska, where lactating northern fur seals have been shown to have three distinct foraging patterns (shallow, deep and mixed). The location of the Pribilof Islands, near the edge of an extensive continental shelf, fortuitously gives animals breeding there two distinct foraging environments, one on the continental and one off. Each environment has a distinct assemblage of prey species. Previous studies show the deep diving foraging pattern to be associated with foraging over the continental shelf. We will quantify the foraging costs and total investment in pups associated with the different foraging strategies observed in northern fur seals. This will be done by comparing the maternal investment in terms of both the actual energy and material delivered to the pup and the energetic cost to the mother. These data will be used to determine if one foraging strategy is energetically more efficient or beneficial and if this is so, does it allow the mother to make a greater investment in her young?
This project will investigate the relationship between bacterioplankton community composition and community metabolic capabilities in the Arctic Ocean. They will examine the patterns of spatial variation in these properties of Arctic Ocean bacterioplankton communities and attempt to relate them to sources of organic matter fueling heterotrophic production. The investigation will be conducted using samples collected from a U.S. Navy submarine from MarchMay 1995, which then will be dedicated to Arctic oceanography. Collected samples will be analyzed in the laboratory after the cruise. Community composition will be analyzed using a method developed at San Francisco State University based on separating partial sequences of the 16S rRNA gene. Community metabolic capabilities will be assessed by the ability of bacteria to grow on 95 different organic carbon sources. They will analyze water samples chemically to determine the concentrations of amino acids, carbohydrates and dissolved organic carbon, and conduct bioassays using native bacteria to determine directly the proportion of dissolved organic carbon that they can metabolize.
The relationships between morphology and environmental history will be investigated. The plan of research is aimed at: (1) refining and advancing promising, but nascent, techniques for extracting a record of the past life history and environmental conditions encountered by individual fish from otolith carbonate and archival tags, and (2) exploring a fresh approach to investigate the influence of environmental conditions upon morphology and life history plasticity by applying experimentally validated otolith techniques to individuals from a multitude of natural conditions. The goals are to establish retrospective and predictive relationships between the chemical structure of otoliths and environmental factors: to understand interactions among environmental factors that affect chemical structure; and to combine the environmental information encoded in otoliths with field observations to evaluate the importance of biotic and abiotic parameters to the establishment of divergent life history patterns in Arctic charr. Daily growth increments, the ratios of elements in the otolith and archival tag information will be used to back-calculate environmental and somatic changes for individual fish. Techniques will be applied to: (1) assess life history data (i.e., growth rates, age structure, hatch date distribution, timing of spawning, etc.) in terms of life history strategies; (2) establish the importance of critical life-history transitions, conditions affecting their onset, and derive migrational schemes (whether an individual is a migrant or a resident, age at first migration, whether a former migrant individual will resume a resident life history strategy and the events leading and following migration) by investigating the structural and elemental composition of fish otoliths; (3) detect differences in growth and life histories between different geographical areas as related to hydrographic, trophic or habitat conditions; (4) precisely time the occurrence of several pivotal life history transitions and correlate them with environmental variables. The results of the proposed research will provide a paradigm to the study of fish life histories. Such knowledge is vital to our understanding of the processes fundamental to adaptable life history patterns and would make it possible to link growth and migration to environmental occurrences. This would provide insight into the ecological process of interactions between a species and its environment.
The environment of the High Arctic imposes two critical limits to the existence of many forms of life. One includes the extreme physical conditions of the environment: cold temperatures, high wind velocities and low precipitation. The other is the briefness of the growing season. This environment is especially stringent for sandpipers (Scolopacidae), which occupy their arctic breeding grounds for as little as two months, and whose chicks are among the smallest of warm-blooded animals. This research project will utilize detailed measurements of the growth and development, energetics, thermal environment, food supply and parental care of scolopacid chicks to discover how these birds exploit the arctic environment so successfully. Cold temperatures require a high capacity for generating metabolic heat; short breeding seasons require rapid growth. Therefore, the combined stresses of low temperature and short season would seem to push small homeotherms to the limit in the High Arctic. The problem of resolving compromises between the conflicting functions of growth rate and heat generation is an excellent model for understanding how the design of the organism relates to its environmental setting. Field and laboratory measurements will be used to determine the forms of relationships and quantify the coefficients in a mathematical model of the scolapacid chick. The essential elements of the model encompass the internal organization of the chick and the relationship of the chick to its environment. The model changes continuously as the chick grows, and growth is simulated by expressions relating growth rate to functional capacity of tissues, and functional capacity to the proportion of adul t size achieved. Laboratory and field work will provide data to evaluate the scolapacid chick model. Laboratory investigation will focus on components of energy budgets; capacity of chicks to generate heat in response to cold stress; loss of heat from the body, including that caused by evaporation from the respiratory surfaces; and tolerance of body cooling. Observations of free-ranging chicks in natural family groups, using radio-tagged individuals where practical, will help to validate the results from penned birds. Conditions of the thermal environment and the availability of food items will be monitored continuously to provide data on the range and temporal variability of these factors.
Clonality is an extremely important phenomenon in plants. Clonal plant species comprise up to 90% of the higher plant species in alpine and Arctic communities, 60% or more of temperate floras, and even in tropical habitats, the majority of woody species possess the ability to sucker, crown sprout or develop adventitious roots. Clonality is found in trees, shrubs and herbs, under terrestrial, aquatic and arboreal conditions, and in both autotrophic and parasitic groups, yet much about this widely successful growth mode remains poorly understood. In clonal plants, sugars and other nutrients are transported from "mother" plants to "daughter" offshoots (ramets). Using greenhouse experiments to test theory, the research proposed will examine how variation in resource allocation among ramets affects the life history and contributes to the success of different genetic individuals of the clonal plant dodder (Cuscuta exaltata). Clonal plants have broad economic importance as both crop plants (e.g., strawberries, blueberries, raspberries and asparagus) and noted crop pests such as dodder, which parasitizes crops including alfalfa in both temperate and tropical agriculture. The information provided by this study may prove useful for both crop growth and pest control, offering the data needed to create better schemes for timing and distribution of fertilizers in clonal crops, and reducing the dependence on chemical control of clonal pests.
How does elemental composition ("stoichiometry") of animals vary among species? How might differences in body elemental composition affect how food webs function? This project will test the hypothesis that differences among species in body stoichiometry of the nutrients nitrogen (N) and phosphorus (P) reflect differences among species in specific growth rate. It is predicted that rapidly growing organisms must have high ribosome concentrations in their bodies. Ribosomes are P-rich (low N:P ratio) cellular structures responsible for protein synthesis and thus growth. Therefore, rapidly growing organisms are predicted to have lower N:P ratios in their bodies than slower growing species. We will test this hypothesis by studying elemental and biochemical composition and body growth rates of zooplankton species at high latitudes versus mid-latitudes. Natural selection along latitudinal gradients is hypothesized to select for differing growth rates among similar planktonic species. We will study ecological and evolutionary determinants of a parameter, animal N:P stoichiometry, that is likely to be a key factor influencing food webs of lake and ocean ecosystems.
The proposed research investigates the impact of plant chemical inputs on soil microbial processes in the Alaskan taiga forest. Studies will focus on tannins produced by alder and balsam poplar, two species that form part of the successional sequence in the flood plain forests of Alaska. Tannins of varying chemical structure will be isolated from these species and added to soils from both alder and poplar sites. Their effects on a suite of microbial processes including respiration, nitrogen mineralization and enzyme activities will be measured. The specific structure of the chemicals will be linked with their biological activities to improve our understanding of the ecological function of these chemicals. Tannins will be applied from each species to each soil to determine whether the microbial communities can adapt to the chemicals coming in. These studies will greatly improve our understanding of how plants affect the soil processes that control nutrient availability and therefore plant succession in the Alaskan taiga. We will improve our understanding of forest community dynamics, controls on litter quality and decomposition, plant-microbe interactions and the role of microbial community composition in ecosystem function.
Global general circulation models suggest that the greatest future temperature increases of 48ºC will occur in boreal and tundra biomes. An understanding of the future dynamics of these systems is important in determining their role as negative or positive feedback to the global carbon cycle, especially in peatlands containing permafrost, which may undergo dramatic change with climate warming. Permafrost peatlands are a potential example of systems that do not respond in equilibrium with climate. The PIs suggest that both local and regional factors influence the dynamics of boreal permafrost peatland systems, and that the transient dynamics of these landscapes will not correspond to climatic warming in an equilibrial fashion due to local constraints serving as negative feedback to change. The goal of this study is to identify the relative contributions of regional climatic versus local autogenic processes to the successional dynamics in permafrost peatland landscapes. With this information, spatial cellular automata models will be developed to test the degree of landscape disequilibrium with climate by sequentially adding local feedback responses. The peat accumulation potential of permafrost peatlands versus melted peatlands will be measured to determine carbon source-sink shifts as landscapes change.
Northern sphagnum-dominated wetlands are complex, nutrient-poor ecosystems that are major sources of atmospheric methane and store tremendous quantities of organic carbon. These systems can emit unusually large amounts of dimethylsulfide (DMS) into the atmosphere, and this efflux is often greater than emissions from marine habitats that contain much more sulfur. Ongoing studies reveal that rapid fluxes of DMS occur in oligotrophic areas of wetlands rather than in more nutrient-rich sites. This peculiarity may to be due to the fact that the methanogenic demethylation of DMS does not occur in oligotrophic peats, whereas it does occur in minerotrophic ones and also in neutral lake sediment. The present study will investigate the production, consumption and emission of DMS in wetlands of varying trophic status to elucidate the role of terminal decomposition processes in controlling DMS release. Several hypotheses will be tested: (1) DMS emissions are most rapid in oligotrophic (ombrotrophic) regions of wetlands, and this phenomenon is ubiquitous; (2) DMS emissions (and accumulation) are faster in oligotrophic regions because DMS is not decomposed by methanogenic bacteria; (3) chemical conditions (i.e., pH, mineral content) are responsible for the lack of DMS consumption in oligotrophic peats; (4) methylotrophic methanogens are sparse in oligotrophic areas; (5) Methylated sulfides are produced in all anoxic freshwater systems The project will combine: (1) field experiments measuring emissions of reduced gases and distribution of pertinent chemical species along trophic gradients within a wetland, and in separate wetlands of different trophic status; (2) field manipulations in which wetland plots will be amended with selected nutrients and/or trace elements; (3) laboratory experiments to investigate pathways of organic matter transformations and relationships with trace gas production; (4) investigations of the relative distribution and abundance of selected microorganisms using molecular biotechnology techniques. The results will elucidate important aspects of bacterial metabolic pathways for the production and consumption of methylated S compounds in wetlands, and in freshwaters in general. Since DMS transformations are conducted primarily by microorganisms situated at the important terminal end of decomposition, these data will provide insight into what controls decomposition in sites that tend to accumulate large quantities of organic matter, and how methanogenesis, acetogenesis, anaerobic metabolism and methylation and demethylation activity vary in response to changes in trophic status.
The objective of the proposed research is to explore the effects of biodiversity in plant species and of plant growth forms on ecosystem cycling of C and N in arctic tundra. In addition, it will test whether or not functional groups of plants are an adequate approximation for detailed physiological information on all species in understanding vegetation controls over ecosystem processes, and the response of ecosystems to perturbations. Effort will be focused on arctic tundra, a high priority ecosystem. An integrated program of modeling and experimentation is proposed. Experimentally, diversity in the tundra will be manipulated by removing different growth forms of tundra plants (which represent functional groups in the tundra), and all possible combinations of the species from two growth forms, and effects on ecosystem C and N cycling will be measured. Simulation models will be developed to compare the effects of growth of individual plant species on ecosystem-level resource supply and cycling with those of functional groups constructed by averaging the characteristics of the different species in the growth form. Plant growth for each of the major species and competitive interactions during growth will be modeled. Model predictions of the distribution and net productivity of species or functional groups, ecosystem net primary productivity and nutrient cycling under current climatic conditions will be compared. Effects of removing or introducing species or functional groups from the models, and of perturbations caused by herbivory or variable climate will also be examined, and will be compared with experimental results of removing species and growth forms. This research is novel because it is the first experimental test of the effects of species and growth form diversity on ecosystem processes in the tundra, and it is the first attempt to model the impact of plant species and their competitive interactions on ecosystem processes in arctic tundra. This is critical to understanding the role of species and functional group diversity in ecosystem processes.
The development of a fisheries management Geographical Information System (GIS) for the Bering Sea/Aleutian Islands (BSAI) of Alaska is proposed. During Phase I, a needs assessment will be conducted, data collection and analysis will begin, requirements analysis for the fisheries managers in the BSAI region will be conducted and a fisheries management BSAI (GIS) specification will be produced. Phase II will complete the data collection and analysis process and implement the (GIS) designed during Phase I.
Ice scouring is the most disruptive and widespread physical disturbance to marine bottom communities in polar waters. At high-latitudes, ice pressure ridges scour the sea floor to depths of 60 m, and larger ice bergs ground as deep as 400 m. This project will explore the ecological implications of this disturbance to arctic benthic populations and communities. It is a multidisciplinary CanadianU.S. program involving two major components. The first is to characterize and model the physical disturbance regime over a three-year period by repetitive mapping the study areas with high resolution side-scan sonar, and to quantify the scour recovery process by divers. This approach will enable us to identify newly formed scours each season, and to generate quantitative and ecologically relevant data on disturbance coverage, frequency, intensity and physical recovery. The second component is to investigate benthic population and community responses to ice scour, documenting the successional stages of biotic recovery. They will test whether observed widespread patterns of zonation and larger spatial and temporal community mosaics are correlated to this key disturbance. This combined physical and biotic approach will enable them to develop a conceptual model of scour aging and recovery, and to evaluate the impact of this disturbance on benthic production and diversity.