Scaling mass and morphology in leaves: an extension of the WBE model

Recent advances in metabolic scaling theory have highlighted the importance of exchange surfaces and vascular network geometry in understanding the integration and scaling of whole-plant form and function. Additional work on leaf form and function has also highlighted general scaling relationships for many leaf traits. However, it is unclear if a common theoretical framework can reveal the general rules underlying much of the variation observed in scaling relationships at the whole-plant and leaf level. Here we present an extension of the general model introduced by G. B. West, J. H. Brown, and B. J. Enquist that has previously been applied to scaling phenomena for whole plants to predict scaling relationships in leaves. Specifically, the model shows how the exponents that describe the scaling of leaf surface area, length, and petiole diameter should change with increasing leaf mass (or with one another) and with variation in leaf dimensionality. The predictions of the model are tested and found to be in general agreement with a large data set of leaves collected from both temperate and arid sites. Our results demonstrate that a general model based on the scaling properties of biological distribution networks can also be successfully applied to understand the diversity of leaf form and function.     

Efficient energy use and well being

This paper reviews the evolution of energy use in Sweden since the early 1970s to shed light on the future, with emphasis on the role of energy efficiency. Between 1973 and 1989 improvements in end-use energy efficiency saved 8% of Sweden's primary energy use and 24% of Sweden's delivered energy use. These savings were concentrated in the residential and manufacturing sectors, with important savings also occurring in air travel and the heating of commercial buildings. Despite these accomplishments, we found that Sweden was well behind Denmark, FRGermany, Japan and the USA in energy savings during this period. At the beginning of the 1990s Sweden exhibited one of the most energy intensive economic structures in the OECD. Sweden now faces many dilemmas that will influence future energy use: the role of nuclear power, pricing and taxation policies for fuels and electricity, the future of subsidies for housing and travel, the role of Sweden's energy intensive exports, and indeed the very lifestyle of the Swedes.     

Project appraisal and planning for overdeveloped countries: I. The costing of nonrenewable resources

In cost-benefit analysis, natural resources, like other factors of production, should be costed as a mixture of marginal social cost of exploiting additional resources and lost marginal social benefit of forgone alternative uses, according to the way in which extra resources are made available to a project. For a nonrenewable resource, changes in future marginal social cost and marginal social benefit are likely to add significantly to the immediate elements of cost, as successively less tractable resource stocks are exploited. Of the several reasons given for ignoring these future costs, the most plausible is that technological advance justifies a heavy discount on the future. However, neither historical nor logical arguments demonstrate the inevitability of efficacious technological advance.     

Evaluation of chlorophyll fluorescence, in vivo spectrophotometric pigment absorption and ion leakage as biomarkers of UV-B exposure in marine macroalgae

The photosynthetic fluorescence ratio F_v:F_m, in vivo absorption spectra and ion leakage were evaluated as biomarkers of ambient and elevated UV-B (280 to 320 nm) exposure of the intertidal alga Enteromorpha intestinalis (Chlorophyta) and the sublittoral alga Palmaria palmata (Rhodophyta). Measurements of thallus growth were also used to assess adverse biological effects. Ambient and elevated UV-B significantly inhibited photosynthesis in both species. It was shown that the F_v:F_m ratio is a sensitive, non-specific general biomarker of UV-B exposure in both species. Moreover, the in vivo absorption of what was tentatively identified as chlorophylls a and b as well as phycoerythrin and/or carotenoids, phycoerythrobilin and phycocyanin decreased in a dose-response dependent manner and was associated with a decrease in growth rate in P. palmata. The intertidal alga E. intestinalis showed a greater degree of tolerance to UV-B exposure. These results indicate that changes in the F_v:F_m ratio together with reductions in in vivo pigment absorption could provide an early quantitative warning of the detrimental effects of UV-B in marine macroalgae. Received: 16 May 1997 / Accepted: 16 July 1997     

Patterns of growth,energy utilization and reproduction in some meso- and bathypelagic fishes off Southern California

We have studied growth, energy use and reproduction in 4 mesopelagic fishes and 5 bathypelagic fishes living off Southern California (USA). All of the mesopelagic species underwent diurnal vertical migrations, while none of the bathypelagic species did so. The life histories of these pelagic fishes were compared among themselves and with epipelagic sardines and anchovies studied by others. The epipelagic species had the highest growth rates (estimated from otoliths, expressed in standard length or kilocalories), the mesopelagic species had the lowest growth rates and the bathypelagic species had intermediate growth rates. The relatively rapid growth rates of the bathypelagic fishes were achieved by high relative growth efficiencies made possible by low metabolic rates. Of the species studied, the lifespans of the epipelagic and bathypelagic species ranged from 4 to 8 yr and the lifespans of mesopelagic species from 5 to 8 yr. Data on egg diameters suggest that the mesopelagic species first reproduce in their 3rd yr, while the bathypelagic species do so in their last year. Epipelagic fishes generally have a large size, rapid growth, long life and early, repeated reproduction. Mesopelagic fishes are characterized by small size, slow growth, long life and early, repeated reproduction. Bathypelagic fishes generally have large size, rapid growth, somewhat shorter lives and late reproduction, which is possible a single event. The latter pattern is evidently feasible only in a rather stable environment where juvenile survivorship would always display relatively low variability. Many unusual characteristics of deep-living animals have possibly been selected by factors peculiar to the environment; however, such characteristics are just as likely to have been selected by factors equally present in many other environments, but not expressed there due to masking selective forces. In particular, we have in mind the darkness, stability and homogeneity of the bathypelagic realm as phenomena which represent the effective absence of many selective forces.The first two authors contributed equally and their names are listed in alphabetical order     

A Framework for a Delaware Inland Bays Environmental Classification

Since Delaware's coastal bays have been highly eutrophied for at least twenty years and Maryland's coastal bays are not nutrient stressed, dominance of the fish community in Delaware's coastal bays by Fundulus sp. may be an indicator of nutrient stress. Maryland's coastal bays are menhaden, spot, and anchovy dominated. The dominance of Fundulus sp. in a nutrient-stressed system relates to the hardy nature of these fishes, especially in low-oxygen conditions. Submerged aquatic vegetation as seagrasses (SAV) has been absent from the highly nutrient-stressed Delaware coastal bays for about twenty-five years. In contrast, SAV is still found in Maryland's coastal bays. The loss of SAV as a habitat for young fish may also be contributing to the apparent species shift in Delaware's coastal bays.Indian River Bay is less hospitable to macroalgae (seaweeds) than Rehoboth Bay. Dominance of Ulva in Indian River Bay reflects its tolerance to varying salinities, higher nutrient levels, and increased turbidities, and indicates a stressed system. The total volume of macroalgae, especially in Rehoboth Bay, tends to follow the seasonal cycle for phosphorus.Based on an assessment of the ecological condition of the Delaware and Maryland coastal bays conducted by EMAP in 1993 and other related studies, the author offers a conceptual framework for Delaware's inland bays environmental classification, considering the water quality parameters of turbidity, TSS, Chla, DIN, DIP, and O2 as they relate to presence of SAV, seaweed abundance and diversity, benthic invertebrate diversity, and fish sensitivity to low oxygen.     

The lay system in commercial fisheries: Origin and implications

In most commercial fisheries, the crew is remunerated via some form of the lay system. Under the lay system, the crew is paid with a share of revenues or a share of revenues less costs. Naturally, the presence and the functioning of the lay system are well known and accepted as one of fishery's important institutions. Compared with share contracts in agriculture, however, the lay in fisheries has garnered relatively little research. This article has two goals. First, we provide an explanation for the existence of the lay system as an incentive mechanism to alleviate a potential team agency problem. This explanation of the lay system explains anomalies, such as the presence of wages in some fisheries, that are odds with the theory of pure risk sharing. Second we show the implications of the lay system for econometric modeling of fisheries and for understanding firm behavior. In general we conclude that models that fail to account explicitly for the incentive properties of shares are likely to provide poor representations of fishing firm behavior. The thrust of the paper is that the formation and working of the lay system are a fundamental force in fisheries influencing firm behavior and research results in a way that has been largely ignored.     

Maximum likelihood inference for the band-read error model for capture-recapture data with misidentification

Environmental and Ecological Statistics - Misidentification of animals is a common problem for many capture-recapture experiments. Considerably misleading inference may be obtained when traditional...     

Commitment,procedural fairness,and organizational citizenship behavior: a multifoci analysis

Research on commitment, procedural fairness, and organizational citizenship behavior (OCB) suggests that employees maintain distinct beliefs about, and direct behaviors towards, multiple targets in the workplace (e.g., the organization as a whole, their supervisor, and fellow workgroup members). The present studies were designed to test for “target similarity effects,” in which the relationships between commitment, procedural fairness, and OCB were expected to be stronger when they referred to the same target than when they referred to different targets. As predicted, we found that: (1) the positive relationship between commitment and OCB, and (2) the mediating effect of commitment on the positive relationship between procedural fairness and OCB, was particularly likely to emerge when the constructs were in reference to the same target. Support for these target similarity effects was found among layoff survivors (Study 1) and student project teams (Study 2). Theoretical and practical implications are discussed, as are limitations of the studies and suggestions for future research. Copyright © 2008 John Wiley & Sons, Ltd.