Search

While living collections are critical for biological research, support for these foundational infrastructure elements is inconsistent, which makes quality control, regulatory compliance, and reproducibility difficult. In recent years, the Ecological Society of America has hosted several National Science Foundation-sponsored workshops to explore and enhance the sustainability of biological research infrastructure. At the same time, the United States Culture Collection Network has brought together managers of living collections to foster collaboration and information exchange within a specific living collections community. To assess the sustainability of collections, a survey was distributed to collection scientists whose responses provide a benchmark for evaluating the resiliency of these collections. Among the key observations were that plant collections have larger staffing requirements and that living microbe collections were the most vulnerable to retirements or other disruptions. Many higher plant and vertebrate collections have institutional support and several have endowments. Other collections depend on competitive grant support in an era of intense competition for these resources. Opportunities for synergy among living collections depend upon complementing the natural strong engagement with the research communities that depend on these collections with enhanced information sharing, communication, and collective action to keep them sustainable for the future. External efforts by funding agencies and publishers could reinforce the advantages of having professional management of research resources across every discipline.

A century ago, stewards were responsible for managing estates or for keeping order at public events. Today, the Earth is one global estate, and improved stewardship is vital for maintaining social order and for preserving life on Earth. In this paper, we describe Earth Stewardship, a social–ecological framework for sustaining life in a rapidly changing world. The paper defines the components of Earth Stewardship, characterizes the scientific needs for its agenda, and discusses initial efforts to engage multiple disciplines and segments of society in its application. As a beginning, new knowledge for global stewardship must be generated by teams of physical, biological, and social scientists. However, other stakeholders are needed for generating and applying such knowledge, including people in communities of faith, professions involved in design, planning and restoration, and policymakers and managers. Communicating environmental problems and solutions must take into account the psychology of how people perceive problems, promoting positive stances toward the actions needed for an adaptive approach to Earth Stewardship. Successful long-term stewardship of the Earth will require a global partnership linking researchers, managers, policymakers, and citizens.

Fixed-point sampling of a shallow tidal estuary was performed hourly for 14 d in summer of 1982 and again in winter of 1983. This sampling regime was of statistically appropriate duration to allow characterization of the variability between periods of 2 to 96 h by spectral analysis of the time-series. The project (PULSE) took place in the Newport River Estuary, located behind the Outer Banks of North Carolina, USA. In all, twentyeight parameters were monitored, encompassing the meteorology, hydrology, water chemistry and phytoplankton-production physiology. Although the annual cycle was monitored, only the winter and summer seasons are compared here, i.e., the lowest water temperatures with the highest water temperatures. The physics, chemistry and biology of the estuary at the hourly scale were highly variable and non-random. The estuary is riverine in winter; growth-limiting nitrogen is supplied as nitrate (NO 3 - ) and ammonium (NH 4 + ) by runoff from the drainage basin. In summer, the estuary is lagoonal; nitrogen is supplied as NH 4 + by biological regeneration. Chlorophyll a biomass varies primarily at the ∼4 d period in winter and at the diel period in summer. Although finely tuned to environmental variability, phytoplankton abundances were at equilibrium insofar as daily chlorophyll production was balanced by losses, i.e., grazing, export and deposition. Most important, high-frequency processes, here periods at the scale of cell-division times, can be very important in phytoplankton ecology.

Two-dimensional electrophoresis was carried out on fractions of the cyanobacteriumSynechocystis 6308 (ATCC 27150). Phycobilisomes isolated fromSynechocystis in 0.75M potassium phosphate buffer, pH 6.8, (KPi) plus Triton X-100 showed 5 prominent polypeptides when examined by two-dimensional electrophoresis. Ultracentrifugation of cells broken in KPi lacking Triton yielded three fractions, a membrane-containing pellet, a green supernatant, and a less dense yellow supernatant. The three fractions yielded a total of 272 polypeptides visualized by silver staining of two-dimensional gels. Fourteen polypeptides were found only in the yellow fraction, 14 polypeptides were found only in the green fraction, and 16 polypeptides were found only in the membrane fraction; 23 polypeptides were found in all three fractions. The crude Triton-containing KPi extract contained 62, and a 50 mM HEPES extract contained 55, of the 272 polypeptides visualized in these fractions. Two-dimensional electrophoresis combined with subcellular fractionation may be useful tools for examining changes in polypeptide composition caused by nitrogen starvation.

Ulva curvata (Kutz.) de Toni growing in shallow estuaries experiences a highly variable supply of dissolved inorganic N, which can limit growth rates. The effects of N supply variability and annual temperature and light variation on growth rates and chemical composition were assessed in plants grown in outdoor tanks supplied with running seawater and either pulsed or continuous N additions for 8 d. Environmental variables were measured every 12 h, growth rates every 2 d, and plant nitrogenous constituents every 4 d. The experiment was repeated 7 times over the course of a year. The slopes of growth rate-tissue N and growth rate-N supply plots increased with temperature and varied at periods at least as short as 2 d. Temperature explained 44% of variation in growth rate, and temperature, light, and N supply together explained 53% of variation in growth rate. N-limitation occurred only above 20°C, the approximate temperature for the maximum growth rate. Growth rate and tissue N were not affected by N supply frequency. Tissue N, ribulose-bisphosphate carboxylase activity, and chlorophyll contents were correlated with each other and with environmental variables but not with growth rate. U. curvata thus does not maintain balanced growth in the strict sense, but rather stores nutrients supplied as pulses for use when they become growth-limiting. Since the relative importance of any single growth-limiting factor is highly dynamic, assessing the importance of multiple limiting factors requires longterm, high-frequency sampling of principal limiting factors and seaweed growth rates.