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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.

Ecological production functions (EPFs) link ecosystems, stressors, and management actions to ecosystem services (ES) production. Although EPFs are acknowledged as being essential to improve environmental management, their use in ecological risk assessment has received relatively little attention. Ecological production functions may be defined as usable expressions (i.e., models) of the processes by which ecosystems produce ES, often including external influences on those processes. We identify key attributes of EPFs and discuss both actual and idealized examples of their use to inform decision making. Whenever possible, EPFs should estimate final, rather than intermediate, ES. Although various types of EPFs have been developed, we suggest that EPFs are more useful for decision making if they quantify ES outcomes, respond to ecosystem condition, respond to stressor levels or management scenarios, reflect ecological complexity, rely on data with broad coverage, have performed well previously, are practical to use, and are open and transparent. In an example using pesticides, we illustrate how EPFs with these attributes could enable the inclusion of ES in ecological risk assessment. The biggest challenges to ES inclusion are limited data sets that are easily adapted for use in modeling EPFs and generally poor understanding of linkages among ecological components and the processes that ultimately deliver the ES. We conclude by advocating for the incorporation into EPFs of added ecological complexity and greater ability to represent the trade-offs among ES. Integr Environ Assess Manag 2017;13:52-61. © 2016 SETAC.

Uncertainty as to the extent and magnitude of changes in conditions that might occur due to climate change poses a problem for land and resource managers as they seek to adapt to changes and mitigate effects of climate variability. We illustrate using scenarios of projected future conditions on rangelands in the Northern Great Plains and Desert Southwest of the United States. These two regions are different in the ways climate change is projected to affect the regions. Projection of a longer and warmer growing season in the Northern Great Plains could lead to increased forage production and land productivity. Highly uncertain effects on summer monsoons that primarily control rangeland productivity in the Desert Southwest, combined with the possibility of more intense and/or frequent drought events, could present land managers with challenges stemming from decreased forage production and land productivity. Climate projections, though uncertain, provide land managers with basic insight into future conditions they might encounter. They need more. A focus on vulnerability and resilience, with explicit recognition of interactions between ecological and socio‐economic factors, coupled with systematic monitoring and assessment of observable conditions on the land to supplement information based on climate projections, will more effectively provide critical and specific information managers need to adaptively manage rangelands under uncertain climate futures.

Recent increases in capabilities for gathering, storing, accessing, and sharing data are creating corresponding opportunities for scientists to use data generated by others in their own research. Although sharing data and crediting sources are among the most basic of scientific ethical principles, formal ethical guidelines for data reuse have not been articulated in the biological sciences community. This article offers a framework for developing ethical principles on data reuse, addressing issues such as citation and coauthorship, with the aim of stimulating a conversation in the science community and with the goal of having professional societies formally incorporate considerations of data reuse into their codes of ethics.

The need for sound ecological science has escalated alongside the rise of the information age and “big data” across all sectors of society. Big data generally refer to massive volumes of data not readily handled by the usual data tools and practices and present unprecedented opportunities for advancing science and inform- ing resource management through data-intensive approaches. The era of big data need not be propelled only by “big science” – the term used to describe large-scale efforts that have had mixed success in the individual-driven culture of ecology. Collectively, ecologists already have big data to bolster the scientific effort – a large volume of distributed, high-value information – but many simply fail to contribute. We encourage ecologists to join the larger scientific community in global initiatives to address major scientific and societal problems by bringing their distributed data to the table and harnessing its collective power. The scientists who contribute such information will be at the forefront of socially relevant science – but will they be ecologists?

Genetic modification (GM) of microalgae to improve commercial production of biofuels is underway. Inevitable governmental regulations will likely address environmental, economic and human health impacts. Proactive addressing of such regulatory protection goals should begin now, during early development of this new, potentially large and transformative industry. We present strategies for ecological risk assessment of GM algae for commercial mass cultivation assuming that escape of GM algae into the environment is unavoidable. We consider the potential ecological, economic and health impacts of GM algae that persist in and alter natural ecosystems. Horizontal gene transfer with native organisms is of particular concern for certain traits, especially when cultivating GM cyanobacteria. In general, we predict that most target GM algal traits are unlikely to confer a selective advantage in nature, and thus would rapidly diminish, resulting in low but nonzero ecological risk. Genetic and mechanical containment, plus conditional matching of GM algal traits to unnatural cultivation conditions, would further reduce risk. These hypothetical predictions must be verified through rigorous ongoing monitoring and mesocosm experiments to minimize risk and foster public and regulatory acceptance.

The U.S. Culture Collection Network was formed in 2012 by a group of culture collection scientists and stakeholders in order to continue the progress established previously through efforts of an ad hoc group. The network is supported by a Research Coordination Network grant from the U.S. National Science Foundation (NSF) and has the goals of promoting interaction among collections, encouraging the adoption of best practices, and protecting endangered or orphaned collections. After prior meetings to discuss best practices, shared data, and synergy with genome programs, the network held a meeting at the U.S. Department of Agriculture (USDA)-Agricultural Research Service (ARS) National Center for Genetic Resources Preservation (NCGRP) in Fort Collins, Colorado in October 2015 specifically to discuss collections that are vulnerable because of changes in funding programs, or are at risk of loss because of retirement or lack of funding. The meeting allowed collection curators who had already backed up their resources at the USDA NCGRP to visit the site, and brought collection owners, managers, and stakeholders together. Eight formal collections have established off-site backups with the USDA-ARS, ensuring that key material will be preserved for future research. All of the collections with backup at the NCGRP are public distributing collections including U.S. NSF-supported genetic stock centers, USDA-ARS collections, and university-supported collections. Facing the retirement of several pioneering researchers, the community discussed the value of preserving personal research collections and agreed that a mechanism to preserve these valuable collections was essential to any future national culture collection system. Additional input from curators of plant and animal collections emphasized that collections of every kind face similar challenges in developing long-range plans for sustainability.

Natural and managed ecosystems provide food, water, and other valuable services to human societies. Unnoticed by many in the scientific community, the values associated with ecosystem services have been integrated into U.S. government policy. A recent administration memo ([ 1 ][1]) put U.S. federal

More diverse sources of energy are needed for countries to progress toward energy independence and to meet future food production needs. The US Task Force on Strategic Unconventional Fuels concluded that to achieve this objective it is essential to develop a domestic unconventional fuels industry. Rangelands, which cover 50% to 70% of the earth’s terrestrial surface and dominate much of the western half of the United States, represent a major source of alternative energy resources. A framework to systematically identify biophysical-socioeconomic links that influence the delivery of ecosystem services affected by alternative uses of rangelands has been lacking. The Integrated Social, Economic, and Ecological Conceptual framework was developed by the Sustainable Rangeland Roundtable to address this deficiency. We apply this framework to demonstrate how the effect on ecosystem services of exploiting rangeland-based biofuel, natural gas, and wind energy resources can be systematically compared. We also demonstrate the use of this framework for selecting suitable indicators to monitor changes in the biophysical-socioeconomic links affected by the development of these unconventional energy sources. This type of approach can potentially enhance coordination between federal, state, and local agencies that are attempting to set polices and regulations for the sustainable development of unconventional energy resources on rangelands.

Rangeland Ecosystem Goods and Services: Values and Evaluation of Opportunities for Ranchers and Land Managers DOI:10.2458/azu_rangelands_v33i5_maczko

To maximize the utility of research to decisionmaking, especially given limited financial resources, scientists must set priorities for their efforts. We present a list of the top 40 high-priority, multidisciplinary research questions directed toward informing some of the most important current and future decisions about management of species, communities, and ecological processes in the United States. The questions were generated by an open, inclusive process that included personal interviews with decisionmakers, broad solicitation of research needs from scientists and policymakers, and an intensive workshop that included scientifically oriented individuals responsible for managing and developing policy related to natural resources. The process differed from previous efforts to set priorities for conservation research in its focus on the engagement of decisionmakers in addition to researchers. The research priorities emphasized the importance of addressing societal context and exploration of trade-offs a...

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.

The first Workshop on Agricultural Air Quality: State of the Science was held at the Bolger Center in Potomac, Maryland from 4 to 8 June 2006. This international conference assembled approximately 350 people representing 25 nations from 5 continents, with disciplines ranging from atmospheric chemistry to soil science. The workshop was designed as an open forum in which participants could openly exchange the most current knowledge and learn about numerous international perspectives regarding agricultural air quality. Participants represented many stakeholder groups concerned with the growing need to assess agricultural impacts on the atmosphere and to develop beneficial policies to improve air quality. The workshop focused on identifying methods to improve emissions inventories and best management practices for agriculture. Workshop participants also made recommendations for technological and methodological improvements in current emissions measurement and modeling practices. The workshop commenced with a session on agricultural emissions and was followed by international perspectives from the United States, Europe, Australia, India, and South America. This paper summarizes the findings and issues of the workshop and articulates future research needs. These needs were identified in three general areas: (1) improvement of emissions measurement; (2) development of appropriate emission factors; and (3) implementation of best management practices (BMPs) to minimize negative environmental impacts. Improvements in the appropriate measurements will inform decisions regarding US farming practices. A need was demonstrated for a national/international network to monitor atmospheric emissions from agriculture and their subsequent depositions to surrounding areas. Information collected through such a program may be used to assess model performance and could be critical for evaluating any future regulatory policies or BMPs. The workshop concluded that efforts to maximize benefits and reduce detrimental effects of agricultural production need to transcend disciplinary, geographic, and political boundaries. Also, such efforts should involve natural and social scientists, economists, engineers, business leaders, and decision makers. The workshop came to the conclusion that through these collaborative efforts improvements in air quality from agricultural practices will begin to take effect.

Through the work of international public health organizations and advancements in the biological and technological sciences, substantial progress has been made in our ability to prevent, control, locally eliminate, and in one case eradicate infectious diseases. Yet each successful control or local elimination has been met with the emergence of new pathogens, the evolution of novel strains, or different epidemiological circumstances that have limited or reversed control methods. To respond to the increasing threat of emerging infectious diseases and bioterrorism it is vital that we design and implement efficient programs that prevent and control infectious pathogen transmission. The theoretical tools of ecology and epidemiology may be the cornerstone in constructing future programs aimed at preventing and controlling infectious diseases throughout the world. Reprinted with permission from Frontiers in Ecology and the Environment, Vol 3, Issue No 1, page 4–11, issue of February 2005. Copyright © 2005 by The Ecological Society of America. Himalayan Journal of Sciences 3(5) 2005 p.25-32

The massive investment of resources devoted to monitoring and assessment of economic and societal indicators in the United States is neither matched by nor linked to efforts to monitor and assess the ecosystem services and biodiversity that support economic and social well-being. Although national-scale assessments of biodiversity ( 1 ) and ecosystem indicators ( 2 ) have been undertaken, nearly a decade has elapsed since the last systematic assessment ( 2 ). A 2011 White House report called for a national biodiversity and ecosystem services assessment ( 3 ), but the initiative has stalled. Our aim here is to stimulate the process and outline a credible framework and pathway for an ongoing assessment of ecosystem functioning (see the photo). A national assessment should engage diverse stakeholders from multiple sectors of society and should focus on metrics and analyses of direct relevance to policy decisions, from local to national levels. Although many technical or science-focused components are in place, they need to be articulated, distilled, and organized to address policy issues.

Heterocapsa triquetra is an important bloom-forming dinoflagellate found in estuaries and nearshore regions worldwide. In an initial time-intensive study, the shallow, tidally mixed Newport River estuary, North Carolina, USA, was sampled from a fixed point located in the middle of the estuary every 2 h for 2 wk during the development of an H. triquetra bloom. The objective of this study was to investigate how short-term, high-frequency changes in temperature, light and salinity affected diel and interday cell division patterns and in situ growth rates of H. triquetra. During this study, phytoplankton samples were preserved in buffered formaldehyde and mitotic indices determined by acridine orange staining. The diel division pattern showed a nocturnal maximum between 23:00 and 05:00 h with reduced division during the day, a pattern characteristic of most dinoflagellates. The relative proportion of binucleate cells present during the day was influenced by interday variations in total irradiance, increasing during 2 of the 3 periods when there were 3 or more consecutive high light days (>28 E m -2 d -1 ). Approximately 40 % of the overall variation in interday division rates could be accounted for by differences in daily irradiance. The interday light differences were largely due to well-developed atmospheric frontal systems that brought increased cloud cover to the study area at regular 3 to 4 d intervals. The initial study, however, was of insufficient length to determine if the transient day-to-day light limitation could significantly affect seasonal bloom formation. A second longer-term, spatially intensive study was therefore undertaken to assess the relative importance of the incident light levels and nutrient inputs in controlling H. triquetra bloom initiation. During the second study, the estuary was monitored for photosynthetically active radiation (PAR), salinity, temperature, inorganic nutrients and cell densities of H. triquetra at 9 locations every wk from 23 December 1997 to 27 March 1998. Maximal H. triquetra bloom formation occurred during a 2 wk period when daily incident light levels were at or near the annual low. This suggested that H. triquetra is well adapted for utilizing low light levels and that variation in in situ growth rates in response to daily changes in PAR had little effect on bloom development. Instead, bloom initiation began with inputs of nitrogen-rich water following a runoff event, indicating that nutrient inputs are much more important in controlling bloom development than is light.

Heterocapsa triquetra is one of the most common bloom-forming dinoflagellates found in estuaries and near shore regions around the world. This work examined the environmental factors associated with 3 separate wintertime H. triquetra blooms in the shallow tidally mixed Newport River estuary, North Carolina, USA. During 2 of the blooms in 1982 and 1983, the estuary was sampled from a fixed, single location every hour for 14 d. During the third study, the estuary was sampled at 9 fixed locations over its entire length each week from late December 1997 through March 1998. This time period included the formation and decline of the H. triquetra bloom. Barometric pressure, precipitation, photosynthetically active radiation, salinity, temperature, nutrient concentrations, and chl a were mea- sured in each study. During the 1997-1998 study, pigments were analyzed using HPLC to characterize the phytoplankton assemblages and the dominant dinoflagellates in each sample were counted. The prevailing environmental conditions associated with the wintertime blooms were largely the result of atmospheric forcing. Low pressure systems moved through the study area at 3 to 4 d intervals and were accompanied by low ambient air temperatures and regular rainfall. Runoff following the rainfall events supplied inorganic nutrients critical for bloom initiation and development. It also created a mesohaline frontal zone in the middle portion of the estuary with salinity and hydrodynamic conditions favorable for H. triquetra growth. Here, the H. triquetra bloom reached its maximal development with chl a levels >100 µg l -1 and cell densities between 1 and 6 × 10 6 l -1 . As the H. triquetra bloom developed, nutrient in- puts from the river became insufficient to meet growth demand and H. triquetra began feeding mixo- trophically, supplementing its nutritional requirements and reducing competition from co-occurring dinoflagellates. Cloud cover associated with the low pressure systems transiently limited H. triquetra growth as did low temperatures. More importantly though, low temperatures limited micro- and macro- zooplankton populations to such an extent that grazing losses were minimal. Hence, in order to bloom, H. triquetra optimizes a suite of factors including low grazing pressure, increased nutrient inputs, alternative nutrient sources, and favorable salinity and hydrodynamic conditions, as well as the nega- tive factors of temperature-limited growth, short day lengths, and periods of transient light limitation.

The authors participated in the NATO Advanced Workshop as ­designated observers, for the purpose of documenting and summarizing the content of the presentations and discussions. This chapter summarizes the participant presentations during sessions A-F as well as the outcomes of three Working Group assessments. The assessments of policy implications, research priorities, and training and education followed the workshop presentations and discussions. The assessments were intended to synthesize and frame future directions and priorities in warfare ecology.

Ready access to data is a key concern in both basic research and problem-solving in the biological sciences, as the scale and scope of the questions that researchers ask expand, and as global problems demand data collected from around the world. With a grant from the National Science Foundation, from 2004 through 2009, the Ecological Society of America (ESA) has led a series of five workshops on data sharing, to help the ecology, evolution, and organismal biology communities find common ground on how to make data more readily discoverable and accessible in their own disciplines. The most recent of these focused in the development of incentives for data sharing, both at the individual and organizational level. This presentation will summarize the workshop recommendations, with a focus on preservation, curation, and access to data; access to analytical and visualization tools; and the need to make data archiving simple and routine. The roles of funders and publishers of research are also key and will be highlighted. Background/Question/Methods Ready access to data is a key concern in both basic research and problem-solving in the biological sciences, as the scale and scope of the questions that researchers ask expand, and as global problems demand data collected from around the world. With a grant from the National Science Foundation, from 2004 through 2009, the Ecological Society of America (ESA) has led a series of five workshops on data sharing, to help the ecology, evolution, and organismal biology communities find common ground on how to make data more readily discoverable and accessible in their own disciplines. The most recent of these focused in the development of incentives for data sharing, both at the individual and organizational level. Results/Conclusions This presentation will summarize the workshop recommendations, with a focus on preservation, curation, and access to data; access to analytical and visualization tools; and the need to make data archiving simple and routine. The roles of funders and publishers of research are also key and will be highlighted.

In order for the Army, and other land managers, to meet responsibilities for sustainable management of natural resources, they must closely monitor the health of those resources and respond to potential threats. A number of recent studies and reviews have suggested there may be declines in the health of southeastern forest ecosystems that support these facilities. These apparent declines involve multiple hardwood and softwood species such as oaks and pines, and appear to have a wide range of potential causes, including fungal and insect pests, air pollutants, and even climate change and the pre-military land use history. As an example, one facility has special concerns about the function of its pine-dominated forests in supporting endangered species, particularly the Red Cockaded Woodpecker (RCW). In their opinion, too many mature Loblolly Pines, which represent the majority of RCW cavity trees on that site, are dying. Younger trees and longleaf pine may also be affected. Other installations have reported concerns with other aspects of pine forest management as well. In a June 2007 workshop, researchers and land managers from several states met to examine the nature and possible causes of the problem from a regional perspective. The questions developed from the workshop by no means cover all the possible issues. Underlying all discussions were concerns that present long-term plans to manage these forest systems to support the recovery needs of the RCW might have to be totally revised. This report represents a summary of several separate reports prepared by groups of workshop participants.

The Publisher regrets that this article was an accidental duplication of an article that has already been published in Atmospheric Environment, Volume 42 (2008), 3195–3208, doi:10.1016/j.atmosenv.2007.07.043 . The duplicate article has therefore been withdrawn.

Within the next 50 to 100 years, the support and maintenance of an extended human family of 8 to 11 billion people will be difficult at best. The authors of this Policy Forum describe changes that are required if we hope to meet the needs and aspirations of humans while improving the health of our planet9s ecosystems. Problems as diverse as disease transmission and global climate change have benefited substantially from advances in ecology. Such advances have set the stage for emergence of a proactive ecological science in which social and political realities are acknowledged and attention is turned decisively toward the future. The ecological sciences must chart an understanding of how ecosystem services can persist given their extensive human use. Innovative research on the sciences of ecosystem services, ecological restoration, and ecological design must be massively accelerated and must be accompanied by more effective communication of ecological knowledge to society.

Human activities affect Earth's life support systems so profoundly as to threaten many of the ecological services that are essential to society. To address this challenge, a new science agenda is needed that integrates people with the rest of nature to help chart a more sustainable trajectory for the relationship between society and the biosphere. This paper describes Earth Stewardship, an initiative of the Ecological Society of America to provide the scientific basis for actively shaping trajectories of social-ecological change to enhance ecosystem resilience and human well-being. Principles for moving toward these goals include simultaneous attention to multiple scales and issues; consideration of both ecological and socioeconomic consequences; alignment of incentives with stewardship behavior; strengthening peoples' connections to valued places; and using demographic transitions as new opportunities for stewardship. Past experience provides guidelines for fostering Earth Stewardship. Early attention to sustainable pathways before problems emerge generally provides more cost-effective solutions than attempting to remediate entrenched problems. Defining sustainable pathways by assessing tradeoffs among alternative options requires careful attention to fine-scale processes, interactions, and feedbacks and to larger-scale controls and constraints. Many opportunities occur locally, through development of practices that match the properties of resources with the needs of their users. Substantial challenges remain at larger scales, including maintaining the diversity, productive capacity, and resilience of nature, which are essential for long-term human welfare. The knowledge needed to inform stewardship requires an interdisciplinary science that draws on the observations, skills, and creativity of a wide range of natural and social scientists, practitioners, and civil society. New questions and solutions will emerge when these groups work together to formulate the issues, design the research, and co-produce the observations, knowledge, and concepts that form the basis for solutions. The goal of Earth Stewardship is not to protect nature from people; rather it is to protect nature for human welfare.

Synechocystis sp. strain PCC6308 cells were starved for nitrogen for 5 days. The polypeptide compositions of whole cell extracts and washed membranes of nitrogen-replete and nitrogen-starved cells were compared by one- and two-dimensional electrophoresis. Immunoblotting of one-dimensional gels indicated that pelletable ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) was depleted in cells starved for nitrogen, while levels of soluble Rubisco were comparable in nitrogen-starved and nitrogen-replete cells. This is consistent with the hypothesis that pelletable Rubisco may serve as a nitrogen reserve in Synechocystis 6308. Other polypeptides were differentially enriched in the membrane or soluble fractions of nitrogen-replete cells or nitrogen-starved cells, suggesting nitrogen starvation may alter partitioning of polypeptides into soluble and membrane fractions. Degradation of abundant polypeptides during nitrogen starvation appeared to cause an effective magnification of less abundant polypeptides in the molecular mass range of 20 to 40 kilodaltons, as shown by two-dimensional electrophoresis. A 42-kilodalton thylakoid carotenoid protein identified by immunoblotting was conserved in membranes from nitrogen-starved cells. This may be functional for cells depleted of pigment and thus exposed to higher light levels because of decreased self-shading.

The Board of Scientific Counselors (BOSC) of the Office of Research and Development (ORD) of the U.S. Environmental Protection Agency (USEPA) was established to provide advice, information, and rec...

Concentrations of phosphadenylates ATP, ADP and AMP were measured in foot muscle tissue of the Asian clam, Corbicula fluminea Muller, by the luciferin‐luciferase bioluminescence technique. Total adenylate concentration μM · g‐ 1, dry weight and adenylate energy charge [AEC = (ATP+1/2ADP)/(ATP + ADP + AMP] were calculated. The effects of laboratory acclimation, starvation and exposure to 0.005, 0.05, 0.5 and 5.0mgCd · l‐1 were investigated. We observed no significant difference between the AEC of clams collected from the Savannah River Channel below Augusta, Georgia and those collected from Clark Hill reservoir on the Savannah River above Augusta. When C. fluminea, collected from the Savannah River were taken to the laboratory and fed and maintained in aerated water at 21°C, the AEC increased from 0.76±0.06 to 0.95±0.01 (x±95% CI, n = 8). This indicates that C. fluminea in the Savannah River were living under sub‐optimal conditions. Starvation for 10 and 20 days did not significantly decrease the AEC. Howe...

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.

Phycobilisomes isolated from actively growing Synechocystis sp. strain 6308 (ATCC 27150) consist of 12 polypeptides ranging in molecular mass from 11.5 to 95 kilodaltons. The phycobilisome anchor and linker polypeptides are glycosylated. Nitrogen starvation causes the progressive loss of phycocyanin and allophycocyanin subunits with molecular masses between 16 and 20 kilodaltons and of two linker polypeptides with molecular masses of 27 and 33 kilodaltons. Nitrogen starvation also leads to enrichment of four additional polypeptides with molecular masses of 46, 53, 57, and 61 kilodaltons and a transient enrichment of 35- and 41-kilodalton polypeptides in isolated phycobilisomes. The 57-kilodalton additional polypeptide was identified by immunoblotting as the large subunit of ribulosebisphosphate carboxylase/oxygenase. Proteins with the same molecular weights as the additional polypeptides were also coisolated with the 12 phycobilisome polypeptides in the supernatant of nitrogen-replete Synechocystis thylakoid membranes extracted in high-ionic-strength buffer and washed with deionized water. These observations suggest that the additional polypeptides in phycobilisomes from nitrogen-starved cells may be soluble or loosely bound membrane proteins which associate with phycobilisomes. The composition and degree of association of phycobilisomes with soluble and adjacent membrane polypeptides appear to be highly dynamic and specifically regulated by nitrogen availability. Possible mechanisms for variation in the strength of association between phycobilisomes and other polypeptides are suggested.

The main effects and interactions between light (Io, full incident sunlight to 0.07 Io) and NO3− loading (0.4 to 4.3 mmol · g dry weight−1· d−1) on growth rate, photosynthesis and biochemical constituents of Gracilaria tikvahiae McLachlan were studied using a factorial design experiment in outdoor, continuous-flow seawater cultures. Incipient nitrogen limitation in the low NO3− loading, Io and 0.57 Io treatments occurred after 2.5 weeks of growth under the experimental conditions and resulted in decreased tissue NO3− and R-phycoerythrin. Tissue NO3− and R-phycoerythrin accounted for up to ca. 15 and 20%, respectively, of the total N in G. tikvahiae suggesting a N reserve role for these N pools. Under light and NO3− limitation, growth rate was a parabolic function of the C:N ratio. As light limitation increased, growth rate and the C:N ratio decreased as levels of Chl-a, R-phycoerythrin, percent N and percent protein increased. As NO3− limitation increased, growth rate and levels of Chl-a, R-phycoerythrin, percent N and percent protein all decreased with parallel increases in the C:N ratio. In contrast to the inverse relationship between pigment content and light, ribulose bisphosphate carboxylase (RuBPCase) activity (on both a protein and dry weight basis) varied directly with light. This biochemical acclimation of G. tikvahiae to light and N availability appears to be a process directed towards maximizing photo synthetic capacity and growth.

(1981). Phosphoadenylate concentrations and energy charge in two freshwater crustaceans: Responses to physical and chemical stressors. SIL Proceedings, 1922-2010: Vol. 21, No. 1, pp. 205-220.

Nitrogen uptake rates of Ulva curvata (Kutz.) de Toni (Ulvales) and Codium decorticatum (Woodw.) Howe (Caulerpales) grown under several N addition regimes were determined by perturbation and continuous mode techniques, and as N demand, by the product of growth rate and tissue N. Uptake rates are reported as the slope of rate vs. concentration curves in each case. N uptake rates of U. curvata were inversely correlated with tissue N and affected only slightly by temperature. There was no correlation of N uptake rate with tissue N in C. decorticatum. N uptake rates of C. decorticatum were affected by temperature but to a lesser degree than were growth rates. Neither N addition per se nor light affected N uptake capacity of either species. The proximal mechanism for seaweeds accumulation of N at low light and temperatures may be that N uptake is less limited by light and temperature than is growth. This in turn may partially compensate for the effects of reduced light and temperature on growth by increasing pigment and enzyme levels. Perturbation uptake rates were higher than continuous mode or N demand rates in Ulva but not in Codium. N uptake rates of Ulva were higher than those of Codium, but N storage capacities were lower. These two observations suggest that Ulva experiences a fundamentally more variable N supply than does Codium. This is consistent with the clarification of Ulva as an ephemeral form and of Codium as persistent. A seaweed's functional form therefore appears to influence the spectrum of resource variability available to it as well as its ability to persist in the environment.

Seasonal variation in ribulosebisphosphate carboxylase (RuBPCase) activity and cellular N allocation in Ulva curvata (Kutz.) De Toni and Codium decorticatum (Woodw.) Howe was followed over two annual cycles. Because apparent seasonal variation may result from random sampling of a coherent pattern of shorter-term variation, estimating the magnitude of seasonal variation in seaweed N allocation requires sampling over a range of time scales. Such sampling reveals annual ranges of variation in N allocation to be greater than those measured at time scales of hours to days. RuBPCase activity in both U. curvata and C. decorticatum peaks in winter and summer, with fall and spring lows. Total N and C exhibit pronounced winter highs and summer lows in C. decorticatum , with less predictable variation in U. curvata . Growth is controlled by temperature in both species, while N uptake is only loosely coupled to temperature or light. Seasonal variations in N allocation are driven by interactive effects of N supply, temperature, and light on growth and N uptake. These effects are largely independent of morphological and genetic differences between species.

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.

The effects of light on growth, RuBPCase activity, and chemical composition of Ulva curvata (Kutz.) De Toni and U.Lactuca L. were examined at a range of temperatures and N-supply levels. Groeth of Ulva speices becomes more light-dependent with increasing temperature and N. The effect of light on RuBPcase is N-dependent, with a positive correlation under N-sufficient and a negative correlation under N-limited conditions. Light effects on pigment levels and ratios may be independent of effects on growth rate. These interactions uncouple growth rate from RuBPCase and pigments, and thus from tissue%N. The limits of variability of the growth-%N relationship can be described by a parabola. Under relative light or temperature-limitation, %N is negatively, growth increase with increasing %N. Tight coupling of seaweed wrowth and chemical composition may therefor be relatively rare in natural waters where growth can be simultaneously limited by light, temperature, and N.