Karen S. Baker

Optical properties of the clearest natural waters (200-800 nm)

A new UV submersible spectroradiometer has been employed to determine the diffuse attenuation coefficient for irradiance in the clearest natural waters [K(w)(lambda)] with emphasis on the spectral region from 300 to 400 nm. K(w)(lambda) can be related to the inherent optical properties of pure water, in particular the total absorption coefficient a(w)(lambda) and the molecular scattering coefficient b(m)(lambda), by means of equations derived from radiative transfer theory. We present an analysis showing that limiting values of K(w)(lambda) can be estimated from a(w)(lambda) and vice versa. Published a(w)(lambda) data, which show discrepancies much larger than their estimated accuracies, are briefly reviewed and then compared, via our analysis, with K(w)(lambda) data (our own new and previously published data as well as relevant data of others). This comparative analysis and new data allow a consistent and accurate set of optical properties for the clearest natural waters and for pure fresh water and saltwater to be estimated from 300 to 800 nm.

Marine pelagic ecosystems: the West Antarctic Peninsula

The marine ecosystem of the West Antarctic Peninsula (WAP) extends from the Bellingshausen Sea to the northern tip of the peninsula and from the mostly glaciated coast across the continental shelf to the shelf break in the west. The glacially sculpted coastline along the peninsula is highly convoluted and characterized by deep embayments that are often interconnected by channels that facilitate transport of heat and nutrients into the shelf domain. The ecosystem is divided into three subregions, the continental slope, shelf and coastal regions, each with unique ocean dynamics, water mass and biological distributions. The WAP shelf lies within the Antarctic Sea Ice Zone (SIZ) and like other SIZs, the WAP system is very productive, supporting large stocks of marine mammals, birds and the Antarctic krill, Euphausia superba. Ecosystem dynamics is dominated by the seasonal and interannual variation in sea ice extent and retreat. The Antarctic Peninsula is one among the most rapidly warming regions on Earth, having experienced a 2°C increase in the annual mean temperature and a 6°C rise in the mean winter temperature since 1950. Delivery of heat from the Antarctic Circumpolar Current has increased significantly in the past decade, sufficient to drive to a 0.6°C warming of the upper 300 m of shelf water. In the past 50 years and continuing in the twenty-first century, the warm, moist maritime climate of the northern WAP has been migrating south, displacing the once dominant cold, dry continental Antarctic climate and causing multi-level responses in the marine ecosystem. Ecosystem responses to the regional warming include increased heat transport, decreased sea ice extent and duration, local declines in ice-dependent Adélie penguins, increase in ice-tolerant gentoo and chinstrap penguins, alterations in phytoplankton and zooplankton community composition and changes in krill recruitment, abundance and availability to predators. The climate/ecological gradients extending along the WAP and the presence of monitoring systems, field stations and long-term research programmes make the region an invaluable observatory of climate change and marine ecosystem response.

PENETRATION OF UV-B AND BIOLOGICALLY EFFECTIVE DOSE-RATES IN NATURAL WATERS*

Abstract— Spectral irradiance measurements. from 310 to 650 nm. have been made in low and modcrately productive ocean waters. These new data and selected earlier clear ocean water data are used as a basis for extrapolating the diffuse attenuation coefficient for irradiance into the 280 nm region. This allows a quantitative calculation of the penetration of UV‐B (280–340 nm) and of biologically (DNA) effective dose‐rates as a function of depth into various ocean water types. The model of Green et al. (1974a) for various atmospheric ozone thicknesses has been used to obtain input surface irrddiancc for this calculation. Our purpose is to provide a basis for estimating the penetration of possible increased UV‐B into natural waters due to possible changes in the ozone concentration of the stratosphere. Given appropriate biological data, this method allows a quantitative evaluation of radiation effects on aquatic organisms as a function of depth. As a specific example, our results have been graphically compared with the dosage‐response results on anchovy larvae obtained by Hunter et al. (1978).

Marine Ecosystem Sensitivity to Climate Change

393 M ounting evidence suggests that the earth is experiencing a period of rapid climate change. Never before has it been so important to understand how environmental change influences the earth’s biota and to distinguish anthropogenic change from natural variability. Long-term studies in the western Antarctic Peninsula (WAP) region provide the opportunity to observe how changes in the physical environment are related to changes in the marine ecosystem. Analyses of paleoc limate records (MosleyThompson 1992, Peel 1992, Domack et al. 1993, Thompson et al. 1994, Dai et al. 1995, Domack and McClennen 1996, Leventer et al. 1996) have shown that the WAP region has moved from a relatively cold regime between approximately 2700 BP and 100 BP, to a relatively warm regime during the current century. Air temperature records from the last half-century show a dramatic warming trend, confirming the rapidity of change in the WAP area (Sansom 1989, Stark 1994, Rott et al. 1996, Smith et al. 1996). Significantly, polar ecosystem research over the last few decades (Fraser et al. 1992, Trivelpiece and Fraser 1996) and paleoecological records for the past 500 years (Emslie 1995, Emslie et al. 1998) reveal ecological transitions that have occurred in response to this climate change. In this article, we summarize the available data on climate variability and trends in the WAP region and discuss these data in the context of long-term climate variability during the last 8000 years of the Holocene. We then compare the available data on ecosystem change in the WAP region to the data on climate variability. Both historical and paleoenvironmental records indicate a climate gradient along the WAP that includes a dry, cold continental regime to the south and a wet, warm maritime regime to the north. The position of this climate gradient has shifted over time in response to the dominant climate regime, and it makes the WAP region a highly sensitive location for assessing ecological responses to climate variability. Our findings show that this century’s rapid climate warming has occurred concurrently with a shift in the population size and distribution of penguin species.

PHOTOINHIBITION OF PHOTOSYNTHESIS IN NATURAL WATERS

Abstract— A quantitative analysis of the wavelength‐dependent influence of solar irradiance on natural phytoplankton photosynthesis has been made. The effect on productivity due to several different UV radiation regimes has been measured. In the course of this analysis, it has been shown that the biological weighting function for photoinhibition of chloroplasts (Jones and Kok, 1966) allows the calculation of a biologically effective dose which is consistent with the measured photoinhibition in natural phytoplankton populations. The ecological implications of a change in available UV radiation, possibly due to anthropogenic altering of the ozone layer, are explored and it is found that the present static bottle l4C technique of measuring in situ phytoplankton productivity does not lend itself to assessing accurately the potential ecological consequences of possible increased MUV (middle ultraviolet radiation in the 280–340 nm region) on phytoplankton populations. A small change in MUV has a relatively minor effect on photoinhibition dose rates whereas it has a large potential effect on DNA dose rates.

Infrastructure Time: Long-term Matters in Collaborative Development

This paper addresses the collaborative development of information infrastructure for supporting data-rich scientific collaboration. Studying infrastructure development empirically not only in terms of spatial issues but also, and equally importantly, temporal ones, we illustrate how the long-term matters. Our case is about the collaborative development of a metadata standard for an ecological research domain. It is a complex example where standards are recognized as one element of infrastructure and standard-making efforts include integration of semantic work and software tools development. With a focus on the temporal scales of short-term and long-term, we analyze the practices and views of the main parties involved in the development of the standard. Our contributions are three-fold: 1) extension of the notion of infrastructure to more explicitly include the temporal dimension; 2) identification of two distinct temporal orientations in information infrastructure development work, namely ‘project time’ and ‘infrastructure time’, and 3) association of related development orientations, particularly ‘continuing design’ as a development orientation that recognizes ‘infrastructure time’. We conclude by highlighting the need to enrich understandings of temporality in CSCW, particularly towards longer time scales and more diversified temporal hybrids in collaborative infrastructure development. This work draws attention to the manifold ramifications that ‘infrastructure time’, as an example of more extended temporal scales, suggests for CSCW and e-Research infrastructures.

Toward Information Infrastructure Studies: Ways of Knowing in a Networked Environment

This article presents Information Infrastructure Studies, a research area that takes up some core issues in digital information and organization research. Infrastructure Studies simultaneously addresses the technical, social, and organizational aspects of the development, usage, and maintenance of infrastructures in local communities as well as global arenas. While infrastructure is understood as a broad category referring to a variety of pervasive, enabling network resources such as railroad lines, plumbing and pipes, electrical power plants and wires, this article focuses on information infrastructure, such as computational services and help desks, or federating activities such as scientific data repositories and archives spanning the multiple disciplines needed to address such issues as climate warming and the biodiversity crisis. These are elements associated with the internet and, frequently today, associated with cyberinfrastructure or e-science endeavors. We argue that a theoretical understanding of infrastructure provides the context for needed dialogue between design, use, and sustainability of internet-based infrastructure services. This article outlines a research area and outlines overarching themes of Infrastructure Studies. Part one of the paper presents definitions for infrastructure and cyberinfrastructure, reviewing salient previous work. Part two portrays key ideas from infrastructure studies (knowledge work, social and political values, new forms of sociality, etc.). In closing, the character of the field today is considered.

Enriching the Notion of Data Curation in E-Science: Data Managing and Information Infrastructuring in the Long Term Ecological Research (LTER) Network

This paper aims to enrich the current understanding of data curation prevalent in e-Science by drawing on an ethnographic study of one of the longest-running efforts at long-term consistent data collection with open data sharing in an environment of interdisciplinary collaboration. In such a context we identify a set of salient characteristics of ecological research and data that shape the data stewardship approach of the Long Term Ecological Research (LTER) network. We describe the actual practices through which LTER information managers attend to the extended temporal scale of long-term research and data sets both through data care work and information infrastructure development. We discuss the issues of long-term and continuity that represent central challenges for data curation and stewardship. We argue for more efforts to be directed to understanding what is at stake with a long-term perspective and differing temporal scales as well as to studying actual practices of data curation and stewardship in order to provide more coherent understandings of e-Science solutions and technologies.

MIDDLE ULTRAVIOLET RADIATION REACHING THE OCEAN SURFACE

Abstract— Direct measurements of the downwelling spectral irradiance in the middle UV (280–340 nm) have been made for a range of solar zenith angles (20°‐70°). These measurements were made for a marine atmosphere at equatorial latitudes. We fit these data to two semi‐empirical analytic representations, from which quantitative calculations of spectral irradiance in the middle UV incident at the ocean surface can be made. The formulae accommodate variation in wavelength, solar zenith angle, ozone thickness, aerosol thickness and surface albedo. Our purpose is to provide marine photobiologists and photochemists with a basis for estimating middle UV radiation levels reaching the ocean surface and the approximate changes caused by manmade alterations of the ozone layer.

Evolution of a multisite network information system: the LTER information management paradigm.

urban watershed, coastal estuary, eastern deciduous forest, tropical rain forest, tallgrass prairie—these are just a few of the ecosystems represented in the 24 sites of the Long-Term Ecological Research (LTER) Network (Franklin et al. 1990). By combining information from the diverse ecosystems represented in the LTER network, participants have a unique opportunity for large-scale investigations of complex phenomena like climate change, biodiversity, soil dynamics, and environmental policy. In 1996, to facilitate data exchange and synthesis from its multiple sites, LTER launched the LTER Network Information System (NIS), based on an independent site and central office organizational infrastructure. Other organizational partnerships provide examples of earlier efforts also focused on communications and data sharing: the Worm Community System, the Flora of North America Project (FNAP), and the Organization of Biological Field Stations (OBFS). The Worm Community System was developed—before Internet connectivity became available—as a collaborative software environment through which its 1400 widely dispersed researchers could share information on the genetics, behavior, and biology of the soil nematode species Caenorhabditis elegans. Insight into the complexity of a network structure was gained through attention to the design and analysis of both the system’s structure and usability (Star and Ruhleder 1996). The FNAP system, in contrast, was developed with Internet technology. The FNAP, with a goal of identifying and cataloging all plant species, uses online technology to create