Larval competition in weevils Revena rubiginosa (Coleoptera: Curculionidae) preying on seeds of the palm Syagrus romanzoffiana (Arecaceae)

Inter- and intraspecific local resource competition may lead to the selection of specific adaptive individual characteristics to overcome interference competition. A highly selective scenario is predictable for interference competition among seed preying weevil larvae that live in and feed upon a single host seed. This scenario is found in Syagrus romanzoffiana palm seeds which are predated by Revena rubiginosa (Curculionidae) larvae. Although multiple infestation of one seed by weevil larvae can occur, invariably only one individual survives and develops in each host seed. A strong competition between the first instar larvae in a restricted window of host fruit development stages leads to physical interactions of conspecifics by ovicide or direct fighting using falcate mandibles. The occurrence of this type of mandible is synchronized with fruit development and restricted to instars with probable competition, as infestation occurs only while the endocarp is soft. Only after lignification of the endocarp the larva changes into the next instar. Mandibles of subsequent instars differ markedly from those of the first instar. The new mandibles can scrape the solid endosperm but are unable to perforate and kill conspecifics. These findings give strong evidence for the selective pressure of intraspecific competition, where special behaviour, mandible morphology and synchronization of its changes with the seed development contribute to individual benefit that involves the killing of conspecifics, since one host seed can only maintain a single larva throughout its complete development.     

Transient dynamics of pelagic producer-grazer systems in a gradient of nutrients and mixing depths

Phytoplankton-grazer dynamics are often characterized by long transients relative to the length of the growing season. Using a phytoplankton-grazer model parameterized for Daphnia pulex with either flexible or fixed algal carbon:nutrient stoichiometry, we explored how nutrient and light supply (the latter by varying depth of the mixed water column) affect the transient dynamics of the system starting from low densities. The system goes through an initial oscillation across nearly the entire light-nutrient supply space. With flexible (but not with fixed) algal stoichiometry, duration of the initial algal peak, timing and duration of the subsequent grazer peak, and timing of the algal minimum are consistently accelerated by nutrient enrichment but decelerated by light enrichment (decreasing mixing depth) over the range of intermediate to shallow mixing depths. These contrasting effects of nutrient vs. light enrichment are consequences of their opposing influences on food quality (algal nutrient content): algal productivity and food quality are positively related along a nutrient gradient but inversely related along a light gradient. Light enrichment therefore slows down grazer growth relative to algal growth, decelerating oscillatory dynamics; nutrient enrichment has opposite effects. We manipulated nutrient supply and mixing depth in a field enclosure experiment. The experimental results were qualitatively much more consistent with the flexible than with the fixed stoichiometry model. Nutrient enrichment increased Daphnia peak biomass, decreased algal minimum biomass, decreased the seston C:P ratio, and accelerated transient oscillatory dynamics. Light enrichment (decreasing mixing depth) produced the opposite patterns, except that Daphnia peak biomass increased monotonously with light enrichment, too. Thus, while the model predicts the possibility of the "paradox of energy enrichment" (a decrease in grazer biomass with light enrichment) at high light and low nutrient supply, this phenomenon did not occur in our experiment.     

One century of hydrological monitoring in two small catchments with different forest coverage

Long-term data on precipitation and runoff are essential to draw firm conclusions about the behavior and trends of hydrological catchments that may be influenced by land use and climate change. Here the longest continuous runoff records from small catchments (<1 km(2)) in Switzerland (and possibly worldwide) are reported. The history of the hydrological monitoring in the Sperbel- and Rappengraben (Emmental) is summarized, and inherent uncertainties in the data arising from the operation of the gauges are described. The runoff stations operated safely for more than 90% of the summer months when most of the major flood events occurred. Nevertheless, the absolute values of peak runoff during the largest flood events are subject to considerable uncertainty. The observed differences in average, base, and peak runoff can only partly be attributed to the substantial differences in forest coverage. This treasure trove of data can be used in various ways, exemplified here with an analysis of the generalized extreme value distributions of the two catchments. These distributions, and hence flood return periods, have varied greatly in the course of one century, influenced by the occurrence of single extreme events. The data will be made publicly available for the further analysis of the mechanisms governing the runoff behavior of small catchments, as well as for testing stochastic and deterministic models.     

Barriers and guidelines for public policies on climate change adaptation: A missed opportunity of scientific knowledge‐brokerage

Progress in formulating and implementing effective adaptation policies is often hampered by a wide variety of barriers that are well documented in the literature. Among the barriers are lack of awareness, certainty, resources and political commitment. Since these and other barriers can be overcome (e.g., by raising awareness, closing knowledge gaps, and increasing resources), numerous decision‐support frameworks (mainly written guidelines) have been developed for this purpose. The present paper takes stock of both the barriers in adaptation policymaking, as documented in the literature, and the guidelines that aim to facilitate public policies on climate change adaptation. It then compares to what degree selected adaptation guidelines serve as knowledge‐brokerage tools that provide guidance on how to overcome the barriers addressed in the scientific literature. The comparison shows that adaptation guidelines address barriers of adaptation policymaking neither comprehensively nor systematically. Since most adaptation guidelines focus on (subjective) experiences with good practices than on empirical research findings, we conclude that they represent a missed opportunity of scientific knowledge‐brokerage in climate change adaptation.     

Market-based approaches and tools for improving water and air quality

Nitrogen (N) losses from agriculture are negatively impacting groundwater, air, and surface water quality. National, state, and local policies and procedures that can mitigate these problems are needed. Market-based approaches where waste treatment plants (point sources) can purchase nutrient credits from upstream agricultural operations (non-point sources) to meet their National Pollutant Discharge Elimination System permit requirements within the Clean Water Act are being explored. This paper reviews these market-based approaches for enhancing air and water quality at a lower cost than simple command-and-control regulation, and describes new tools that are being developed, such as Nitrogen Trading Tool (NTT), that can be used to assess nitrogen losses to the environment under different management scenarios. The USDA-NRCS, EPA and several other state and local agencies are interested in these new tools. The NTT, though primarily designed for water quality markets, also estimates savings in nitrous oxide (N₂O) emissions that can be traded in carbon markets. For example, an analysis using NTT shows that for 100 ha of crop land, a C sequestration equivalent of approximately 25–38 Mg C y^?1 for a farm in Ohio, and 13–21 Mg C y^?1 for a farm in Virginia could be achieved with better nitrogen management practices. These numbers across a watershed could be much larger with improved N and conservation management practices that contribute to better water quality and lower global warming potential. There is a need to further develop, calibrate, and validate these tools to facilitate nitrogen and carbon trading future markets around the globe to increase environmental conservation across agro-ecosystems worldwide.     

Presence of hydrocarbon-degrading bacteria in the gills of mussel Mytilus galloprovincialis in a contaminated environment: a mesoscale simulation study

A number of previous studies have shown that the relationships of symbiosis existing between mussels and microorganisms are directly dependent on the environmental conditions. However, little is known about existing relationships between mussels and bacteria in hydrocarbon-impacted marine environments. The aim of this preliminary study is to investigate the presence of oil-degrading bacteria in the mussel Mytilus galloprovincialis during growth in polluted ecosystems. All the experiments were carried out in a mesocosm system designed to simulate chronic pollution and to enable direct exposure of mussels to chemicals. Quantitative (4′,6-diamidino-2-phenylindole, colony-forming units, Most Probable Number) analyses and screening (presence/absence) of metabolic functional genes were performed to analyse bacterial populations inside the gills of mussels exposed and not exposed to hydrocarbons. The data obtained show that the presence of hydrocarbons affected the abundance of bacteria inside the gills of specimens and determines selection for specific (hydrocarbon-degrading) bacteria (i.e. Alcanivorax sp. and Marinobacter sp.). However, is not yet clear whether the presence of such genera of bacteria inside the mussel is due to symbiosis or as a result of filtration.