Kin recognition in rainbowfish (Melanotaenia eachamensis): sex, sibs and shoaling

Living with relatives can be beneficial to individuals via the evolution of kin-directed altruism, but this is tempered by the increased risk of inbreeding. Therefore, in social species, the ability to recognise relatives can be highly advantageous. This study focuses on kin discrimination in the Lake Eacham rainbowfish, Melanotaenia eachamensis, an endangered freshwater species from north-east Queensland, Australia. First, I examined kin recognition abilities when a combination of both chemical and visual recognition cues was available. When given a choice of shoaling with same-sex groups, females spent significantly longer with full-sibs rather than half-sibs, full-sibs rather than non-relatives and half-sibs rather than non-relatives. Males spent significantly longer shoaling with full-brothers versus half-brothers, but showed no other shoalmate preferences. Second, in the presence of only chemical cues, females did not discriminate among groups of different levels of relatedness, but males showed a non-significant tendency to associate with full-sibs rather than non-relatives. Male shoaling behaviour seemed to be more influenced by factors other than relatedness, e.g. intra-sexual competition. Finally, I found that the shoaling preferences of females changed when exposed to groups of males. Females preferred to associate with non-relatives rather than half-brothers and non-relatives rather than full-brothers. There was no significant difference in the time spent with half-brothers versus full-brothers. Taken together, my results suggest that females have very good kin recognition abilities. They prefer to shoal with female relatives but avoid male relatives, and so are able to balance the benefits of nepotism and the costs of incest. Received: 2 May 2000 / Revised: 26 July 2000 / Accepted: 30 July 2000     

Non-linear incentives,plan design,and flood mitigation: the case of the Federal Emergency Management Agency's community rating system

A basic proposition of ‘agency theory’ is that output-based performance incentives encourage greater effort. However, studies find that incentive schemes can distort effort if rewards for performance are discrete or non-linear. The Federal Emergency Management Agency's (FEMA) Community Rating System (CRS) is a flood mitigation programme with a non-linear incentive design. Under this programme, localities are incentivised to implement a mix of 18 flood mitigation activities. Each activity is performance scored, with accumulated scores corresponding to a percent discount on flood insurance premiums for residents that hold National Flood Insurance policies. Discounts range from 0 to 45% and increase discretely in increments of 5%. With multivariate statistical and Geographic Information Systems analytic techniques, tests are made to find whether observed changes in annual CRS scores for participating localities in Florida are explained by non-linear incentives, adjusting for hydrologic conditions, flood disaster histories, socio-economic and human capital controls that can plausibly account for local mitigation activity scores over time. Results indicate that local jurisdictions are discount-seeking, with mitigation efforts partially driven by the non-linear incentive design of the CRS programme. The paper ends with recommendations to improve the operation FEMA's flood mitigation programme.     

Effects of dissolved oxygen and iron aging on the reduction of trichloronitromethane, trichloracetonitrile, and trichloropropanone

Iron metal (Fe(0)) is a potent reductant capable of reducing a wide variety of halogenated organic compounds including disinfection byproducts (DBPs). These reduction reactions may play a role in DBP fate in iron water mains and potentially could be exploited to remove DBPs from drinking water or wastewater in a packed-bed configuration. Oxidants (i.e., dissolved oxygen (DO) and chlorine) present in the water, however, may decrease the DBP degradation rate by competing for reactive sites and rapidly aging or corroding the iron surface. Thus, batch experiments were performed to investigate the effect of DO on the degradation rates of selected DBPs by Fe(0). Experiments were performed under anaerobic conditions, in initially oxygen saturated buffer without DO control, and under controlled DO (approximately 4.0 or 8.0 mg l⁻¹) conditions. The effect of short-term (25–105 min) iron aging in DO-containing buffer on DBP degradation rate also was investigated in separate experiments. For fresh Fe(0), the degradation rates of trichloronitromethane (TCNM) and trichloroacetonitrile (TCAN) in initially oxygen saturated buffer were similar to their respective rates under anaerobic conditions. The degradation rate of 1,1,1-trichloropropanone (1,1,1-TCP), however, decreased significantly in the presence of DO and the effect was proportional to DO concentration in the controlled DO experiments. For a DO concentration of 4 mg l⁻¹, the degradation rate of the three DBPs was greater for longer aging times as compared to their respective rates after 25 min, suggesting the formation of a mineral phase that increased reactivity. For a DO concentration of 8 mg l⁻¹, the effects of increasing aging time were mixed. TCNM degradation rates were stable for all aging times and comparable to that under anaerobic conditions. The TCAN and 1,1,1-TCP degradation rates, however, tended to decrease with increasing aging time. These results suggest that the reduction of highly reactive DBPs by Fe(0) will not be affected by the presence of DO but that the reaction rates will be slowed by DO for DBPs with slower degradation kinetics.     

Ecological responses to variation in seasonal snow cover

Seasonal snow is among the most important factors governing the ecology of many terrestrial ecosystems, but rising global temperatures are changing snow regimes and driving widespread declines in the depth and duration of snow cover. Loss of the insulating snow layer will fundamentally change the environment. Understanding how individuals, populations, and communities respond to different snow conditions is thus essential for predicting and managing future ecosystem change. We synthesized 365 studies that examined ecological responses to variation in winter snow conditions. This research encompasses a broad range of methods (experimental manipulations, measurement of natural snow gradients, and long-term monitoring), locations (35 countries), study organisms (plants, mammals, arthropods, birds, fish, lichen, and fungi), and response measures. Earlier snowmelt was consistently associated with advanced spring phenology in plants, mammals, and arthropods. Reduced snow depth often increased mortality or physical injury in plants, although there were few clear effects on animals. Neither snow depth nor snowmelt timing had clear or consistent directional effects on body size of animals or biomass of plants. However, because 96% of studies were from the northern hemisphere, the generality of these trends across ecosystems and localities is also unclear. We identified substantial research gaps for several taxonomic groups and response types; research on wintertime responses was notably scarce. Future research should prioritize examination of the mechanisms underlying responses to changing snow conditions and the consequences of those responses for seasonally snow-covered ecosystems.