Seasonal activity and thermoregulation in Meriones unguiculatus: A gerbil's choice

Summary Mongolian gerbils were observed over seasonal changes in day length and temperature in an outdoor enclosure containing an extensive burrow system. Animals could choose between the stable environment of their burrow and the daily and seasonal flunctuations aboveground. Surgically implanted radio transmitters provided body temperature and location of animals.Gerbils avoided temperature extremes by emerging from their burrow when ambient temperature fell below burrow temperature in hot weather and rose above burrow temperature in cold weather. They delayed emergence in the winter until several hours after sunrise and emerged before or after sunset in summer (Fig. 1).Circadian changes in core-body temperature corresponded to increases and decreases in behavioral activity. Emergence from the burrow was predictable by an increase in body temperature, as a warm-up period preceded emergence (Fig. 3).We conclude that gerbils, when subjected to extreme temperatures in the wild, probably time their activity to correspond to preferred ambient temperatures and thus shift from diurnal activity in the winter to nocrurnal activity in the summer (Fig. 2). This desert rodent's exceptional thermoregulatory capacity adapts it for synchronizing its daily activity to temperature.     

Computer simulation of barren-ground caribou dynamics

This paper describes a simulation model of a Canadian caribou population. The model was constructed by an interdisciplinary team of field biologists, managers, and systems ecologists. Population dynamics are represented in terms of age structure, with age-dependent survival and fecundity. Biomass dynamics of the major food species are also simulated, and the food dynamics interact with the caribou population through a foraging submodel that explicitly considers snow depth, seasonal migrations, and total area of useable winter habitat. The model was used to examine two hypotheses regarding the abundance of barren-ground caribou. It was shown that there is no reason to suspect that food supply currently limits the population size; instead, hunting pressure appears to be the critical variable. The implications of this finding for population management are discussed.     

Applying DOE's Graded Approach for assessing radiation impacts to non-human biota at the INL

In July 2002, The US Department of Energy (DOE) released a new technical standard entitled A Graded Approach for Evaluating Radiation Doses to Aquatic and Terrestrial Biota. DOE facilities are annually required to demonstrate that routine radioactive releases from their sites are protective of non-human receptors and sites are encouraged to use the Graded Approach for this purpose. Use of the Graded Approach requires completion of several preliminary steps, to evaluate the degree to which the site environmental monitoring program is appropriate for evaluating impacts to non-human biota. We completed these necessary activities at the Idaho National Laboratory (INL) using the following four tasks: (1) develop conceptual models and evaluate exposure pathways; (2) define INL evaluation areas; (3) evaluate sampling locations and media; (4) evaluate data gaps. All of the information developed in the four steps was incorporated, data sources were identified, departures from the Graded Approach were justified, and a step-by-step procedure for biota dose assessment at the INL was specified. Finally, we completed a site-wide biota dose assessment using the 2002 environmental surveillance data and an offsite assessment using soil and surface water data collected since 1996. These assessments demonstrated the environmental concentrations of radionuclides measured on and near the INL do not present significant risks to populations of non-human biota.     

Erratum to: Prey selection by resident common bottlenose dolphins (Tursiops truncatus) in Sarasota Bay, Florida

Prey selection was investigated in wild, resident common bottlenose dolphins, Tursiops truncatus, during the summer months in Sarasota Bay, Florida, USA. Stomach content analyses of 15 dolphins with extensive sighting histories and well-documented distributions were used to determine prey use. Prey availability was assessed by purse seine surveys. We compared the relative abundances of prey available to estimates of prey use at closely matching spatial and temporal scales. G-tests determined that dolphins in this study significantly selected for prey at the species, family, and soniferous/non-soniferous prey levels (G _adj  = 753.98–1,775.93, df = 1–21, p ≤ 0.01). While comprising only 6.3% of the total available prey, soniferous fishes accounted for 51.9% of the total prey consumed. Manly’s standardized forage ratios and 95% Bonferroni confidence intervals determined significant positive selection for soniferous prey and against non-soniferous prey (β^S = 0.9461 vs. β^NS = 0.0539). Dolphins selected against Gerridae, Clupeidae, and Sparidae (β ≤ 0.0014), as well as against all the species within those families (β ≤ 0.0190). It is likely that passive listening for soniferous prey provides an ecological or energetic advantage to cetaceans utilizing this specific foraging technique.     

Application of the analytic hierarchy process to compare alternatives for the long-term management of surplus mercury

This paper describes a systematic method for comparing options for the long-term management of surplus elemental mercury in the US, using the analytic hierarchy process as embodied in commercially available Expert Choice software. A limited scope multi-criteria decision analysis was performed. Two (2) general types of treatment technologies were evaluated (stabilization/amalgamation and selenide), combined with four (4) disposal options: (a) hazardous waste landfill; (b) hazardous waste monofill; (c) engineered below-ground structure; and (d) mined cavity. In addition, three storage options for elemental mercury were considered: (a) aboveground structure; (b) hardened structure; and (c) mined cavity. Alternatives were evaluated against criteria that included costs, environmental performance, compliance with current regulations, implementation considerations, technology maturity, potential risks to the public and workers, and public perception. Considering non-cost criteria only, the three storage options rank most favorably. If both cost and other criteria are considered, then landfill options are preferred, because they are the least expensive ones. Storage options ranked unfavorably on cost because: (a) even relatively small per annum costs will add up over time; and (b) storage is a temporary solution and, sooner or later, a treatment and disposal technology will be adopted, which adds to the cost. However, the analysis supports continued storage for a short period (up to a few decades) followed by permanent retirement when treatment technologies have matured. Suggestions for future work include: (a) involving additional stakeholders in the process, (b) evaluating alternatives for mercury-containing wastes rather than for elemental mercury only, (c) revisiting the analysis periodically to determine if changes are required, (d) conducting uncertainty analyses utilizing Monte Carlo-based techniques.     

FLUSHING CHARACTERISTICS OF A MISSISSIPPI DEAD-END CANAL SYSTEM1

ABSTRACT: A study of residential canal system on the Mississippi Gulf Coast and adjacent natural water bodies was conducted to determine the relationship in flushing characteristics between man-made and natural systems. The comparison was based on measurements of temperature, salinity, conductivity, coliform, pH, transparency, biological oxidation demand, dissolved oxygen, bathymetry, tides, water velocity, and Rhodamine dye concentrations. The results indicate that coliform bacteria increase with increasing distance of stations from St. Louis Bay and dissolved oxygen decreases in a similar manner. Biological oxidation demand was low at all stations; showing no differences between natural and man-made systems. The canal system Studied was shallower than adjacent water bodies and water velocities in the canal system are a function of tidal amplitude while velocities in the river are affected by both tides and runoff. The other parameters measured show little or no differences between natural and man-made systems, but reflect overall seasonal changes. Flushing rates between the residential canal systems and an adjacent natural system are equivalent on the basis of decline in dye concentrations measured over a five-day period.     

RUNOFF AND WATER QUALITY FROM THREE SOIL LANDFORM UNITS ON MANCOS SHALE1

ABSTRACT: Relative yields of water, sediment, and salt (as indexed by electrical conductivity) were determined using simulated rainfall plots on three soil landform units on Mancos shale in the Price River Basin, Utah. Final infiltration rates on residual shale derived soils were between 0.13 and 0.50 cm/hr. No runoff was generated on cracked soils derived from aeolian deposits. Suspended sediment concentrations and elehcal conductivities were 180 and 68 times greater, respectively, for a steep dissected Mancos shale upland than for a low relief shale pediment and recent alluvial surface. Riling accounted for approximately 80 percent of the sediment produced on the steep, dissected shale surface. Channel scow and soil creep also produced measurable mounts of sediment. A survey of sediment basins in steep, dissected shale up lands indicated that an average of 1.25 Mg/ha/year of sediment is produced by that landform unit Carefully designed and located basin plugs can be used effectively to trap sediment, water, and salt from dissected shale uplands.     

BIOLOGICAL AND ECONOMIC IMPLICATIONS OF SACRAMENTO WATERSHED MANAGEMENT OPTIONS1

ABSTRACT: This paper brings together spatially and temporally explicit mechanistic models of hydrodynamic, water quality, and ecological processes with an economic model to examine water management alternatives for California's Sacramento River and Delta ecosystem, a large‐scale watershed. Overallocated water supplies in most years, combined with increasing demand for water for environmental purposes, have created a politically charged atmosphere and a need for quantitative assessment of the implications of policy alternatives. By developing and analyzing a common set of policy scenarios, this integrated framework allows us to consider tradeoffs between agricultural economic factors, water quality, and population dynamics for two at‐risk fish species. We analyze two rather extreme types of policy options; one involves structural modifications to change the flow of water within the watershed but no change in water diversions, while the other reallocates water from agricultural users to fish and wildlife. Results suggest that substantial environmental improvements could be made at a relatively modest cost to farmers (1 to 4 percent reductions in revenues) but that those costs could be significant locally. In addition to tradeoffs between farmers and environmental interests, results suggest that policy makers may need to balance competing environmental objectives.     

Objectives for management of socio-ecological systems in the Great Barrier Reef region,Australia

A wide range of goals and objectives have to be taken into account in natural resources management. Defining these objectives in operational terms, including dimensions such as sustainability, productivity, and equity, is by no means easy, especially if they must capture the diversity of community and stakeholder values. This is especially true in the coastal zone where land activities affect regional marine ecosystems. In this study, the aim was firstly to identify and hierarchically organise the goals and objectives for coastal systems, as defined by local stakeholders. Two case study areas are used within the Great Barrier Reef region being Mackay and Bowen–Burdekin. Secondly, the aim was to identify similarities between the case study results and thus develop a generic set of goals to be used as a starting point in other coastal communities. Results show that overarching high-level goals have nested sub-goals that contain a set of more detailed regional objectives. The similarities in high-level environmental, governance, and socio-economic goals suggest that regionally specific objectives can be developed based on a generic set of goals. The prominence of governance objectives reflects local stakeholder perceptions that current coastal zone management is not achieving the outcomes they feel important and that there is a need for increased community engagement and co-management. More importantly, it raises the question of how to make issues relevant for the local community and entice participation in the local management of public resources to achieve sustainable environmental, social, and economic management outcomes.     

Application of Aerial Photography and Photogrammetry in Environmental Forensic Investigations

Historical aerial photography can be a powerful tool in environmental forensic investigations. Historical aerial photography is available for many sites from the 1930s on. It is researched and obtained from both public and private sources. Most of the photography consists of vertical stereoscopic film annotated with the date of the photomission. A current photomission can be flown using airborne GPS for precise registration of the photomosaics. The photography is scanned at a very high resolution and registered in a coordinate system using a digital stereoplotter that removes terrain distortion and allows the precise measurement of objects. The digital stereoplotter is used to produce photomosaics and to interpret environmentally significant features in the photography. The accuracy of the environmental interpretations is dependent on the skill and experience of the interpreter as well as the resolution of the photography and quality of the equipment used. The photomosaics are then registered in a geographic information system along with the interpretations of environmentally significant features. In a similar manner, historic maps are scanned and registered into the same coordinate system. The interpreted images and maps form a significant part of the expert report. A computer projection system is used to show the interpreted images at trial.