Structural change and sustainable development

In this paper, we show that the commonly observed decline in primary (natural resource using) sector output and employment shares, often termed structural change, can be explained as an endogenous response to the presence of nature's constraint. Structural change takes place even if consumer preferences are homothetic, and technological progress does not discriminate against the primary sector. Under certain conditions, structural change allows an open economy to grow with natural resource sustainability. Sustained and environmentally sustainable economic growth is possible even if the natural resource is exploited under open access. Well-defined property rights are neither necessary, nor sufficient for sustainable growth. We show that there is no unique relationship between natural resource endowment and the rate of economic growth over the long run. Resource-rich economies may grow faster or slower than resource-poor ones.     

On the gains of committing to inefficiency: Corruption, deforestation and low land productivity in Latin America

We present a new explanation and empirical evidence showing that rural subsidies to large farmers tend to be associated with low land productivity and excessive deforestation. We develop a lobbying model where wealthy farmers trade bribes or political contributions to government politicians in exchange for subsidies; farmers are able to tilt the terms of the bargaining game with policy makers in their favor by pre-committing to an inefficient choice of semi-fixed inputs. Government proneness to accept political contributions or bribes and its willingness to provide subsidies cause farmers to adopt inefficient modes of production as a mechanism to capture such subsidies. Our predictions are consistent with stylized facts on land use in Latin America, and suggest that subsidy schemes have been counterproductive—distorting and constraining development, and triggering excessive depletion of natural resources. We validate some of the predictions of the model through econometric analyses using a new data set for nine countries in Latin America.     

Environmental behavior of antibiotic monensin: preliminary studies in Argentina

The increase of intensive bovine production systems in Argentina involves the use of therapeutic agents and growth promoters that reach the environment through animal excreta. The growth promoter most widely used in Argentina is monensin, an ionophore polyether antibiotic produced by Streptomyces cinnamoniensis. Here, the behavior of monensin in different solid environmental matrices is analyzed, and preliminary results that suggest a strong dependence of monensin retention with the organic matter content of the matrix are discussed.     

Population structure and historical demography of the thorny skate (<Emphasis Type="Italic">Amblyraja radiata</Emphasis>, Rajidae) in the North Atlantic

Population genetic structure of the thorny skate (Amblyraja radiata) was surveyed in >300 individuals sampled from Newfoundland, Iceland, Norway, the Kattegat and the central North Sea. A 290-bp fragment of the mt cytochrome-b gene was first screened by SSCP. Sequences of SSCP haplotypes revealed 34 haplotypes, 14 of which were unique to Iceland, 3 to Newfoundland, 1 to Norway and 3 to the Kattegat. The global F _ST was weak but significant. Removal of the two Kattegat locations, which were the most differentiated, resulted in no significant genetic differentiation. Haplotype diversity was high and evenly distributed across the entire Atlantic (h = 0.8) with the exception of the North Sea (h = 0.48). Statistical parsimony revealed a star-like genealogy with a central widespread haplotype. A subsequent nested clade analysis led to the inference of contiguous expansion with evidence for long distance dispersal between Newfoundland and Iceland. Historical demographic analysis showed that thorny skates have undergone exponential population expansion that started between 1.1 million and 690,000 years ago; and that the Last Glacial Maximum apparently had little effect. These results strongly differ from those of a parallel study of the thornback ray (Raja clavata) in which clear structure and former refugial areas could be identified. Although both species have similar life history traits and overlapping ranges, the continental shelf edge apparently does not present a barrier to migration in A. radiata, as it does for R. clavata.     

Functional responses of copepod nauplii using a high efficiency gut fluorescence technique

To investigate copepod nauplii ingestion rates on phytoplankton, we have adapted the traditional gut fluorescence technique as it can be used with lower gut pigment concentrations. With the improved technique, laboratory experiments were performed to estimate functional responses for nauplii of Calanus helgolandicus and Centropages typicus. Nauplii were raised from eggs to copepodites and the experiments were performed with stages NIV-NV. Gut evacuation rates and ingestion rates were measured on Isochrysis galbana at different concentrations. Specific ingestion rates ranged between 0.038–0.244 μg C μg⁻¹ nauplii C d⁻¹ for C. typicus and 0.041–1.412 μg C μg⁻¹ nauplii C d⁻¹ for C. helgolandicus. Both species showed a type III functional response, reaching a saturation concentration at around 600 μgC l⁻¹ for C. typicus and 800 μgC l⁻¹ for C. helgolandicus. An erratum to this article can be found at     

Reproduction and life-cycle of the beachflea (<Emphasis Type="Italic">Orchestia gammarellus</Emphasis> (Pallas) (Crustacea: Amphipoda) at thermal and non-thermal sites in the intertidal of Iceland: how important is temperature?

The littoral fringe beachflea Orchestia gammarellus (Pallas) is a seasonal breeder over much of its range. Previous studies indicated that temperature was the most important factor initiating breeding while photoperiod appeared inconsequential. We tested the effect of temperature by comparing two populations at non-thermal sites with two populations at thermal sites in Iceland. At the non-thermal sites the species is probably close to its lower temperature tolerance limits, while potentially able to choose optimal temperatures at all times of the year at the thermal sites. The species was a seasonal breeder at all sites, but the breeding season started 2–3 months earlier at thermal sites. Breeding ended at about the same time at all sites. We conclude that photoperiod probably governs breeding season under constant thermal conditions, and this is also supported by observations on laboratory stocks. At the thermal sites the animals became sexually mature in a year or less, as is the case where the species has been studied at lower latitudes, while at the non-thermal sites Icelandic animals, apparently uniquely, need 2 years to become sexually mature.     

Defensive volatile secretions of two diplopod species attract the carrion ball roller scarab <Emphasis Type="Italic">Canthon morsei</Emphasis> (Coleoptera: Scarabaeidae)

Summary. We report field and laboratory evidence indicating that the defensive compounds secreted by the millipedes Amplinus bitumidus (Diplopoda: Polydesmida) and Anadenobolus putealis (Diplopoda: Spirobolida) attract the carrion scarab Canthon morsei (Scarabaeidae: Scarabaeinae). In a Mexican tropical rain forest, C. morsei was mostly caught in pitfall traps baited with the carcasses of both millipede species. Only a few beetles were attracted to fish carrion. Experimental evidence indicates that C. morsei is attracted to freshly dead millipedes. Benzaldehyde and HCN were identified from Amplinus bitumidus; but 2-methyl-1,4-benzoquinone (toluquinone) and 2-methoxy- 3-methyl-1,4-benzoquinone from Anadenobolus putealis. Benzaldehyde attracted significantly more C. morsei individuals than fish meat, or millipedes of both species did after rinsing in hexane. This is the first report of Polydesmida attracting dung beetles.     

The Impact of Biodegradable Plastics in the Properties of Recycled Polyethylene Terephthalate

Journal of Polymers and the Environment - Since biodegradable materials are unwittingly mixed with synthetic materials, this work aimed to study the feasibility of reliably identifying some...     

Resource limitation of bacterial production distorts the temperature dependence of oceanic carbon cycling

Our view of the effects of temperature on bacterial carbon fluxes in the ocean has been confounded by the interplay of resource availability. Using an extensive compilation of cell-specific bacterial respiration (BRi) and production (BPi), we show that both physiological rates respond to changing temperature in a similar manner and follow the predictions of the metabolic theory of ecology. Their apparently different temperature dependence under warm, oligotrophic conditions is due to strong resource limitation of BP, but not of BRi. Thus, and despite previous preconception, bacterial growth efficiency (BGE = BPi/[BPi + BRi]) is not directly regulated by temperature, but by the availability of substrates for growth. We develop simple equations that can be used for the estimation of bacterial community metabolism from temperature, chlorophyll concentration, and bacterial abundance. Since bacteria are the greatest living planktonic biomass, our results challenge current understanding of how warming and shifts in ecosystem trophic state will modify oceanic carbon cycle feedbacks to climate change.     

Fiscal spending and the environment: Theory and empirics

During economic crises, governments often increase fiscal spending to stimulate the economy. While the fiscal spending surge may be temporary, spending composition is often altered in favor of expenditures on social programs and other public goods which may persist over time. We model and measure the impact of fiscal spending patterns on the environment. The model predicts that a reallocation of government spending composition towards social and public goods reduces pollution. However, increasing total government spending without altering its composition does not reduce pollution. We empirically test these predictions for air and water pollutants showing that they are fully supported.