Overview of the Brazilian Citriculture Certification

This study aims to characterize the different types of certification in the Brazilian citriculture as well as analyze the major changes in the market. The paper also has the objective to discuss how social and environmental factors influence the demand for food certifications and the sustainability and ethics aspects in the field. Therefore, a literature review on the subject was carried out as well as a qualitative research using interviews with certifiers, governmental institutions, farmers, cooperatives and producer associations. The certification is becoming mandatory for those working in foreign markets and for those working nationally; it can be a competitive differential. The organic certification in citriculture shows the highest number of growers. Companies with large areas of citrus and the orange juice processing industry are adhering to this certification in order to maintain themselves competitive in the market. There is an enormous potential of Brazilian citriculture certification, because the certified area is still less than 6 % of the total area. Certification reduces the asymmetry of information and consists of an important step towards sustainability although incapable of solely guaranteeing it.     

Heat warnings and avoidance behavior: evidence from a bike-sharing system

Environmental Economics and Policy Studies - Governments throughout the globe usually implement early warning systems to prevent health-related costs from exposure to extreme heat. In a warming...     

Sea-level rise in Indonesia: on adaptation priorities in the agricultural sector

Adaptation to climate-change impacts requires understanding of where impacts are to be expected and what their magnitude may be. Adaptation funds are only a limited resource for helping affected parties in coping with climate-change impacts. The application of suitable methods helps to determine the recipients of adaptation aid. A quantification of impacts based on different impact analyses can aid in taking on various perspectives on the same problem in order to identify the appropriate perspective for the given decision-making context or for identifying impact patterns. Once executed, this prioritizes adaptation needs and finding a suitable allocation rule, given the policy makers perception of the decision-making context. The study introduces a set of methods of spatially explicit, sub-national (province level), and country-wide impact analyses regarding inundation impacts on agricultural areas for four important food crops in Indonesia. These methods are applied to a 1 and 2 m sea-level rise scenario and include a novel approach for impact analyses, data envelopment analysis, which is not widely used in environmental studies as of yet. Based on the given case study, the paper demonstrates the applicability of these methods and identifies impact patterns.     

Humans use social information to adjust their quorum thresholds adaptively in a simulated predator detection experiment

Quorum sensing is used in many biological systems to increase decision accuracy. In quorum sensing, the probability that an individual adopts a behavior is a nonlinear function of the number of other individuals adopting this behavior. From an optimal decision-making perspective, individuals should adjust their quorum threshold to the particulars of the decision problem. Recent work predicts that a key factor here is the quality of social information. In particular, it is predicted that individuals should adjust their quorum thresholds such that it lies in between the average true and false positive rate of the other group members. We here test this prediction with a predator detection experiment. First, human groups observed a group of animals (projected on a white screen) in which a predator was present or absent, and each individual made an independent decision to escape or not. Second, individuals received social information on the decisions of their group members, after which individuals decided again. This social information, however, did not represent their own decisions but consisted of responses that either came from a high-performing group (i.e., many individuals detecting the predator) or from a low-performing group (i.e., few individuals detecting the predator). We found that individuals adaptively adjust their quorum threshold to the quality of the social information: when receiving social information from high-performing groups, individuals employed higher quorum thresholds than when receiving information from low-performing groups. Our study demonstrates that humans can quickly evaluate the quality of publicly available information and adaptively adjust their decision rules.     

Coral mucus stable isotope composition and labeling: experimental evidence for mucus uptake by epizoic acoelomorph worms

Mucus released by scleractinian corals can act as an important energy and nutrient carrier in coral reef ecosystems, and a distinct isotopic signature would allow following the fate of this material. This study investigates the natural C and N stable isotopic signatures of mucus released by four scleractinian coral genera (Acropora, Fungia, Pocillopora and Stylophora) in comparison with those of suspended particulate organic matter (POM) in seawater of a Northern Red Sea fringing coral reef near Aqaba, Jordan. The natural δ¹³C and δ¹⁵N signatures of coral mucus differed significantly from seawater POM for the majority of seasonal comparisons, but were inappropriate for explicit tracing of mucus in the coral reef food web. Thus, a labeling technique using stable isotope tracers (¹³C and ¹⁵N) was developed that produced δ¹³C values of up to 122 ± 5‰ (mean ± SE) and δ¹⁵N of up to 2,100 ± 151‰ in mucus exuded by Fungia corals. ¹³C and ¹⁵N-enriched compounds were rapidly (within 3 h) and light-dependently transferred from the endosymbiotic zooxanthellae to the mucus-producing coral host. The traceability of ¹⁵N-labeled mucus was examined by evaluating its uptake and potential utilization by epizoic acoelomorph Waminoa worms naturally occurring on a range of scleractinian coral taxa. This tracer experiment resulted in uptake of coral mucus by the coral-associated acoelomorphs and further demonstrated the possibility to trace stable isotope-labeled coral mucus by revealing a new trophic pathway in coral reef ecosystems.     

Tolerance of juvenile barnacles (Amphibalanus improvisus) to warming and elevated pCO2

We investigated the impacts of warming and elevated pCO₂ on newly settled Amphibalanus improvisus from Kiel Fjord, an estuarine ecosystem characterized by significant natural pCO₂ variability. In two experiments, juvenile barnacles were maintained at two temperature and three pCO₂ levels (20/24 °C, 700–2,140 μatm) for 8 weeks in a batch culture and at four pCO₂ levels (20 °C, 620–2,870 μatm) for 12 weeks in a water flow-through system. Warming as well as elevated pCO₂ hardly affected growth or the condition index of barnacles, although some factor combinations led to temporal significances in enhanced or reduced growth with an increase in pCO₂. While warming increased the shell strength of A. improvisus individuals, elevated pCO₂ had only weak effects. We demonstrate a strong tolerance of juvenile A. improvisus to mean acidification levels of about 1,000 μatm pCO₂ as is already naturally experienced by the investigated barnacle population.     

Effects of ocean acidification, temperature and nutrient regimes on the appendicularian Oikopleura dioica: a mesocosm study

Increasing pCO₂ is hypothesized to induce shifts in plankton communities toward smaller cells, reduced carbon export rates and increased roles of gelatinous zooplankton. Appendicularians, among the most numerous pan-global “gelatinous” zooplankton, continuously produce filter-feeding houses, shortcutting marine food webs by ingesting submicron particles, and their discarded houses contribute significantly to carbon fluxes. We present a first mesocosm-scale study on the effects of temperature, pCO₂ and bloom structures on the appendicularian, Oikopleura dioica. There were effects of temperature and nutrients on phytoplankton communities. No shifts in functional phytoplankton groups, nor changes in particle sizes/morphotypes, known to impact appendicularian feeding, were observed under manipulated pCO₂ conditions. However, appendicularian abundance was positively correlated with increased pCO₂, temperature and nutrient levels, consistent with hypotheses concerning gelatinous zooplankton in future oceans. This suggests appendicularians will play more important roles in marine pelagic communities and vertical carbon transport under projected ocean acidification and elevated temperature scenarios.     

Discounting under uncertainty: Disentangling the Weitzman and the Gollier effect

The uncertainty of future economic development affects the term structure of discount rates and, thus, the intertemporal weights that are to be used in cost benefit analysis. The U.K. and France have recently adopted a falling term structure to incorporate uncertainty and the U.S. is considering a similar step. A series of publications discusses the following concern: a seemingly analogous argument used to justify falling discount rates can also justify increasing discount rates. We show that increasing and decreasing discount rates mean different things, can coexist, are created by different channels through which risk affects evaluation, and have the same qualitative effect of making long-term payoffs more attractive.     

Mineralization of particulate organic matter derived from coral-reef organisms in reef sediments of the Gulf of Aqaba

In situ and laboratory incubation experiments in a fringing reef in the Gulf of Aqaba were performed to study degradation rates of particulate organic matter in reef sediments. Coral mucus, clam eggs, and zooxanthellae were used as model particulate organic compounds for these experiments. Aerobic and anaerobic mineralization rates were calculated by dissolved inorganic carbon (DIC) and O₂ fluxes from the sediments under different particulate organic matter additions. Fast enhancement (approximately twofold) of O₂ and DIC fluxes were found with the addition of coral mucus and clam eggs compared with control incubations without addition. Most of the degradation is believed to have occurred anaerobically rather than aerobically (DIC:O₂ ratios were 4.3–28.1). Higher degradation rates of coral mucus and clam eggs were estimated in carbonate sediment than in silicate sediment (1.2–1.6-fold), which was attributed to the different physical and chemical properties of both sediments. Our study shows the significance of the reef sediment as a suitable site for microbial degradation of particulate organic material excreted from different reef community organisms. This may increase the regeneration of nutrients in the reef environment necessary to sustain high biological productivity.