SEDIMENT TRANSPORT AND CHANNEL MORPHOLOGY OF SMALL,FORESTED STREAMS1

This paper reviews sediment transport and channel morphology in small, forested streams in the Pacific Northwest region of North America to assess current knowledge of channel stability and morphology relevant to riparian management practices around small streams. Small channels are defined as ones in which morphology and hydraulics may be significantly influenced by individual clasts or wood materials in the channel. Such channels are headwater channels in close proximity to sediment sources, so they reflect a mix of hillslope and channel processes. Sediment inputs are derived directly from adjacent hillslopes and from the channel banks. Morphologically significant sediments move mainly as bed load, mainly at low intensity, and there is no standard method for measurement. The larger clastic and woody elements in the channel form persistent structures that trap significant volumes of sediment, reducing sediment transport in the short term and substantially increasing channel stability. The presence of such structures makes modeling of sediment flux in these channels — a potential substitute for measurement — difficult. Channel morphology is discussed, with some emphasis on wood related features. The problem of classifying small channels is reviewed, and it is recognized that useful classifications are purpose oriented. Reach scale and channel unit scale morphologies are categorized. A “disturbance cascade” is introduced to focus attention on sediment transfers through the slope channel system and to identify management practices that affect sediment dynamics and consequent channel morphology. Gaps in knowledge, errors, and uncertainties have been identified for future research.     

Novel dimensionless index for physically based assessment of thermal refugia characterizes off-channel habitat on gravel bed river

In the Willamette River, OR, main channel temperatures can be too warm for cold water fishes, causing fish to concentrate in secondary channel features that provide thermal refugia. However, temperature regimes vary among and within features. Improved understanding of physical processes controlling thermal regimes is needed. This study developed a dimensionless index for assessment of thermal refugia on the upper Willamette River. The novel hyporheic insolation (HIN) index uses minimal field measurements to predict thermal refugia resulting from buffering. Continuous water temperature measurements at one side channel, eight alcoves, and six beaver ponds provided data to ground truth calculated ${ℍ}_{\text{in}}$ predictions. Water temperature records were first used to characterize stratification at sites. Calculation of the Richardson number, an index of stability, showed two well-mixed sites and 13 stratified sites. At stratified sites, calculated ${ℍ}_{\text{in}}$ values characterized the ratio of cooling flux from hyporheic discharge to heat flux from incoming solar radiation. As ${ℍ}_{\text{in}}$ increased, measured temperatures at sites decreased. Despite overall scatter, a logarithmic fit to bin-averaged ${ℍ}_{\text{in}}$ values showed R² = 0.91. Calculations suggest that secondary channel features characterized by stratification and cool hyporheic discharge can provide thermal refugia. Accordingly, the HIN index may serve as a practical tool grounded in physical processes governing temperature across a floodplain.     

ON PRECIPITATION SENSOR NETWORK DENSITIES FOR EVALUATING WINTERTIME OROGRAPHIC CLOUD SEEDING EXPERIMENTS1

Principal component analysis is used to investigate density requirements of wintertime orographic cloud seeding experiment precipitation sensor networks. Three passes in the vicinity of Climax, Colorado are studied. The eighteen or more evenly spaced precipitation sensors of each pass are almost completely described by three principal components. These three principal components appear to represent (i) mean precipitation, (ii) slope orientation to storm systems, and (iii) elevation. Evaluation of these principal components is implemented with two distribution-free tests, a proportionality test and the runs test. The results of this study suggest that the loss of experimental information caused by low density precipitation sensor networks may be of little consequence.     

Making sense of public values: Environmental controversies for corporate decision makers

Every year I try to choose the “word of the year”—that is, the word that will be the most topical and overused in the news, politics, and business. Past “words of the year” were leadership, excellence, quality, and so on. This year's, without a doubt, must be values. Just listen to any political speech and you'll be sure to hear it! Magazine article after magazine article makes reference to values—family values, social values, public values, personal values, etc. Business is beginning to experience first-hand the power of this word and the controversy it engenders, especially in the area of environmental issues. Corporations already heavily scrutinized by the public on operational issues like facility expansion, pollution, emissions, product acceptance, etc., are struggling to assess how best to manage competing public values. What do we do when the public has one value and business has another? Or, how can choices be made between two operating needs that compete for the same budget? It is the dilemma posed by values in conflict that this article explores. Once the domain of scholars and philosophers, this timely topic is now demanding the consideration and awareness of everyone in the business world.     

Cooperative breeding by the Galápagos mockingbird,Nesomimus parvulus

Summary The costs and benefits of helping behavior were analyzed for 36 pairs of the Galápagos mockingbird, Nesomimus parvulus, and their associates. Helping at the nest is usually done by sons or males suspected to be offspring of the breeders. Costs and benefits to breeders were assessed by comparison of pairs with and without helpers, and costs and benefits to helpers were assessed by comparison of birds which help and those which establish themselves as novice breeders.Helping behavior benefits breeders by increasing fledging success and by reducing the adult energy load in territory defense and feeding of nestlings. Breeders assisted by helpers may also benefit by decreased nest predation. Helpers enhance their inclusive fitness by helping, and gain directly by increasing their chances of securing a territory. Helpers do not appear to gain any fitness advantage from the experience of assisting, nor do they increase their survivorship by remaining on natal territory.Ecological and demographic features such as saturated territories and low territory turn-over rates due to high adult survival may be primarily responsible for the evolution of the helping behavior, with kinselection reinforcing it. Associated features of this system are a male-biased population sex ratio, a greater energetic benefit to breeding males than to breeding females in having helpers, earlier dispersal and breeding by females than by males, and much more frequent helping by males than by females. These are interpreted as consequences of brothersister aggression that indirectly minimizes the chances of inbreeding.     

Defensive chemistry of lycid beetles and of mimetic cerambycid beetles that feed on them

Summary.  Beetles of the family Lycidae have long been known to be chemically protected. We present evidence that North American species of the lycid genera Calopteron and Lycus are rejected by thrushes, wolf spiders, and orb-weaving spiders, and that they contain a systemic compound that could account, at least in part, for this unacceptability. This compound, a novel acetylenic acid that we named lycidic acid, proved actively deterrent in feeding tests with wolf spiders and coccinellid beetles. Species of Lycuscommonly figure as models of mimetic associations. Among their mimics are species of the cerambycid beetle genus Elytroleptus, remarkable because they prey upon the model lycids. We postulated that by doing so Elytroleptus might incorporate the lycidic acid from their prey for their own defense. However, judging from analytical data, the beetles practice no such sequestration, explaining why they remain relatively palatable (in tests with wolf spiders) even after having fed on lycids. Chemical analyses also showed the lycids to contain pyrazines, such as were already known from other Lycidae, potent odorants that could serve in an aposematic capacity to forestall predatory attacks. David Utterback: Deceased     

Sensory complementation and the acquisition of predator recognition by salmonid fishes

Following disturbance, some aquatic prey species release chemicals that act as a warning cue and increase vigilance in nearby conspecifics. Such disturbance cues evoke consistent low intensity anti-predator responses. In contrast, alarm cues from injured conspecifics often evoke stronger intensity responses in prey animals. In this study, we test the sensory complement hypothesis, which suggests that multiple cues act in an additive or synergistic fashion to provide additional information for risk assessment by prey. In the first experiment, we showed that juvenile rainbow trout pre-exposed to disturbance cues respond to a given concentration of damage-released alarm cues with a higher intensity of response than the trout that were pre-exposed to cues from undisturbed conspecifics. The two cues acted in an additive fashion. In the second experiment, we demonstrated that disturbance cues alone were not enough to elicit a conditioned response to the odour of a novel predator. We also showed that while disturbance cues elicit an increase in the response of trout to alarm cues, this increase does not translate into a stronger learned response to the predator when the predator odour is paired with alarm cues. Future studies should take into account sensory complementation to avoid underestimating the responses of prey to predators.     

A Review of the Northern Ecosystem Initiative in Arctic Canada: Facilitating Arctic Ecosystem Research Through Traditional and Novel Approaches

The Canadian Arctic is undergoing considerable social and environmental change. Anthropogenic stressors on this sensitive environment include climate change, contaminants, resource extraction, tourism and increasing human populations. The Northern Ecosystem Initiative (NEI) is a program aimed at supporting the sustainability of northern communities, and at improving our understanding of how northern ecosystems respond to these environmental stressors. A key element of the NEI is to establish partnerships between all levels of government, non-governmental environmental agencies, and northern residents. The NEI is an important source of financial support critical for social and environmental scientists as well as northern residents and their community and regional organizations. Initiated in 1998, the NEI has supported numerous northern scientific and capacity-building projects, and has evaluated the information gained from this work to refine and focus its future support to address key information gaps and northern needs.     

Marine Birds as Indicators of Arctic Marine Ecosystem Health: Linking the Northern Ecosystem Initiative to Long-Term Studies

Marine birds are sensitive indicators of the condition of marine ecosystems in the Arctic, partly because they feed at the top of the arctic food chain. The Northern Ecosystem Initiative (NEI) recently supported four separate studies that investigated aspects of Arctic marine bird science which simultaneously addressed goals of the NEI to better understand northern ecosystems and their response to environmental stressors. The projects used both scientific and traditional knowledge to examine the relationship between sea-ice, contaminants, and the ecology of marine birds, and to transfer environmental knowledge to students. Results from these investigations confirm that changes are occurring in Arctic environments, and that these are captured through marine bird research. Collectively these studies provided new data that supported NEI objectives of monitoring the health of the Arctic ecosystem, and contributed to Canada's international obligations for Arctic science.