Inter-litter competition and communal nursing among Norway rats: advantages of birth synchrony

Summary The effect of inter-litter competition on pup survival was investigated in pairs of female rats (Rattus norvegicus) living and breeding in the same environment. If a female gave birth when a 0- to 14-day-old litter was already present in the environment, her pups had a very high chance of surviving, similar to the situation in which no other litter was present. Moreover, the mother was likely to nurse communally with the mother of the 0- to 14-day-old litter. This communal nursing benefitted the newborn pups as evidenced by their being heavier at weaning than litters that were not nursed communally. In contrast, if a female gave birth when a 15-to 28-day-old litter was already present in the environment, her newborn pups were likely to die within 3 days postpartum, owing to the fact that they were often prevented from suckling at their mother's teats, resulting in milk deprivation, and were often beneath the older pups, resulting in physical trauma. These findings suggest that inter-litter competition is an important source of pup mortality when litters are born 15-28 days apart. The data are discussed in terms of the advantages of birth synchrony.     

The reclamation of worked-out sand and gravel quarries utilising domestic waste — the issue of groundwater pollution

Landfill is the cheapest method of domestic waste disposal but the amount disposed of in this way has declined in recent years. This decline in landfill is due principally to the unavailability of acceptable tipping sites. Up to 30% of land taken for sand and gravel extraction may not be restored to a productive use in the absence of fill material. Domestic waste is often available to reclaim derelict sand and gravel quarries, but unsubstantiated fears of tip leachate polluting groundwaters has prevented its use for this purpose.     

Predatory behavior and prey selection by army ants in a desert-grassland habitat

Summary Colonies of Neivamyrmex nigrescens conduct extensive nocturnal raids on other ants and termites in the desert-grassland of Arizona-New Mexico. We collected quantitative data on several aspects of raiding to pinpoint differences due to colony size and behavioral phase. In the nomadic phase, colonies began raiding at sunset and continued until dawn. Larger colonies covered more area, discovered more prey sites, and collected more booty than smaller colonies, but there were no systematic changes in raid intensity over the course of the nomadic phase. In the statary phase, raiding occurred less frequently and was less intense when it occurred; however, at the end of this phase, raiding was similar to nomadic phase raids in extent, duration, and booty captured. N. nigrescens preyed exclusively on termites and ants, and appeared to select certain species of Pheidole in preference to other ants. Pheidole was the most abundant genus, but was preyed upon twice as often as expected based on relative colony density. Pheidole attempted to avoid predation by fleeing or defending their nest, but rarely succeeded. Because they are about the same size as army ants and lack defensive chemicals, Pheidole made comparatively easy prey. N. nigrescens ignored or was repelled by other ants (Pogonomyrmex, Novomessor, Iridomyrmex, Myrmecocystus) during the early summer, when Pheidole was abundant; however, in late summer when Pheidole was less available, the army ants preyed upon Novomessor cockerelli. N. harrisi raided in close proximity to N. nigrescens, but preyed exclusively on Solenopsis xyloni. Selection of prey and partitioning of resources are now indicated in several army ant species; these processes have probably been important factors in the evolution of the ants' predatory behavior.     

Field observations on the emergence rhythm of the Norway lobsterNephrops norvegicus,using different methods

The emergence ofNephrops norvegicus (L.) from their burrows was studied on several fishing grounds around Scotland at 28 to 62 m depth. Various methods were used: sampling by trawl and baited creels, observations by television and time-lapse cameras. Peak emergence generally occurred around dusk and dawn. In shallow water (30 m) there was also a significant level of activity during the intervening night period. Day/night variations in the size composition of catches suggest that relatively more time is spent out of the burrow with increasing size. There was good agreement between the various methods employed, suggesting that trawl and camera avoidance has little influence on the pattern of emergence observed. The use of bait in some experiments confirmed that emergence is essentially a feeding activity.     

Wave Enhancement of Diffusivities within Surficial Sediments

The enhancement of solute diffusivities within coastal surficial sediments as a result of wave action is examined. Fluctuating pressure gradients associated with passing waves cause interstitial water motions leading to enhanced diffusivities through the mechanism of shear dispersion. Wave amplification of diffusivities is likely to be greatest for waves of period 10 s, in shallow water, over a bottom of coarse grain. Diffusivity enhancement of hundreds of times molecular diffusivity is achievable. The mechanism is distinct from, but complements, the mechanism of rotational dispersion which has been previously described. Other mechanisms that enhance solute transport within surficial sediments rely on the interaction between wave-driven or steady flow over bottom obstructions such as biogenic structures or sand ripples. It is suggested that while the resulting advective flows may dominate solute transport within the top few 10 s of centimeters of the sediment column, shear dispersion may be more important deeper within the sediment. In any event, in contrast to these other mechanisms, shear dispersion is operative even when the seabed is flat. Application of the theory to sediments of the South Atlantic Bight would suggest that shear dispersion is capable of explaining a major part of the interstitial transport inferred from measurements.     

Adaptation Options Strategies for Hazards and Vulnerability Mitigation: An International Perspective

The broad objective of this special issue of Mitigation and Adaptation Strategies for Global Change is to address some of the gaps in our knowledge and understanding of the policies, programs, and measures that might be applied to natural hazards and their impacts in an era of climate change. Given the global impacts of climate change and world-wide pattern of increasing losses from natural hazards we necessarily adopt an international perspective. The specific goals of the special issue are to: (a) encompass experiential aspects, emphasizing current practice of mitigation and its associated measures, and their results; and (b) explore primary or root causes of alarming shifts in human and economic costs of environmental extremes. Special emphasis is placed on how human activities are playing a key role in enhancing vulnerability to NTEE (nature-triggered environmental extremes), quite independently from the anthropogenic causes of climate change. The goals are also (c) to examine costs, risks, and benefits (of all kinds including social, political, ecological) of mitigation, and adjustment and adaptation measures; and (d) analyze policy implications of alternative measures. These components are expected to make significant contributions to policy considerations – formulation, implementation and evaluation. There is much uncertainty about the rate of climate change; however, the fact of increase of the atmospheric temperature in the last century is no longer a subject of scientific or policy debate. Due to such changes in the geophysical parameters, certain types of nature-triggered environmental extreme events are likely to continue to increase. How global warming will affect regional climates and pertinent variables is not well known, limiting our ability to predict consequential effects. This factor poses serious constraints against any straightforward policy decisions. Research findings of the work of this volume reaffirm that human dimensions, specifically our awareness and decision-making behavior, are powerful explanatory factors of increasing disaster losses. Disaster mitigation through addressing human, social, and physical vulnerability is one of the best means for contributing to ‘climate change adaptation plans’, and sustainable development goals. Recent lessons from various countries have depicted that the formulation of mitigation strategies cannot be exclusively top-down as it requires social, political, and cultural acceptance and sense of ownership. An interactive, participatory process, involving local communities, produces best expected outcomes concerning mitigation, preparedness, and recovery. An emerging consensus is that there is a need to move towards the ‘mission’ of the International Strategy for Disaster Reduction which aims at building disaster resilient communities by promoting increased awareness of the importance of disaster reduction as an integral component of sustainable development, with the goal of reducing human, social, economic and environmental losses due to natural hazards and related technological and environmental disasters. Sharing of best practices and lessons globally is certain to produce more efficiency and understanding in policy and decision making.     

Horizontal and vertical distribution of organic contaminants in deep-sea fish species

Polychlorobiphenyls (PCBs) and pesticides are persistent, semivolatile contaminants whose global circulation is now well established. One of their ultimate sink is the bio- and geo-phases in the deep-sea. We have investigated the distribution of selected PCBs and pesticides with depth and longitude in various deep-sea fish, namely black scabbardfish (Aphanopus carbo), orange roughy (Hoplostethus atlanticus), roundnose grenadier (Coryphaenoides rupestris) and Bathysaurus ferox from Madeira, Sesimbra, the Meriadzec Terrace and Rockall Trough in the North Eastern Atlantic at 1000 m depth, and at 2000 m depth where available. In most species, males presented higher levels of contamination than females. This pattern was probably due to the females eliminating contaminants through egg production. Roundnose grenadier presented higher levels of contamination (mainly p,p'-DDE, CB 153, 138, 180, sigmaCB(24) and p,p'-DDT) in fish caught at 2000 m than at 1000 m depth. Similarly, B. ferox, which is found deeper than the other species studied, showed much higher levels of most CBs and pesticides (lipid normalised) than the other species. Concentrations were up to 10 times higher, and showed differences between water masses.     

MIRABEL: models for integrated review and assessment of biodiversity in European landscapes

In this paper, we present the methodology and some results from the application of an integrating conceptual framework, MIRABEL, to analyze the consequences of environmental change for biodiversity. For 28 European countries, MIRABEL tabulates changes in the status of threatened habitats predicted to result from 10 environmental pressures. Regional variations in the severity of the pressures and impacts are taken into account by compiling separate impact tables for each of 13 Ecological Regions. Results suggest that agricultural intensification is one of the main threats, however, differences recorded by MIRABEL in the intensity of the pressures, their rate of change and their past and expected impacts on biodiversity in the various Ecological Regions is telling evidence of Europe's biogeographical variety, and of the need to take this into consideration when assessing environmental change.