Acclimatization patterns in tropical reptiles: uncoupling temperature and energetics

The physiological compensation of animals in changing environments through acclimatization has long been considered to be of minor importance in tropical ectotherms due to more stable climatic conditions compared to temperate regions. Contrasting this assumption are reports about a range of metabolic adjustments in tropical species, especially during the last two decades from field acclimatized animals. Metabolic rates are strongly linked to temperature in ectotherms but they also reflect energetic requirements and restrictions. We therefore postulate that the observed variety of acclimatization patterns in tropical reptiles results from an interaction of multiple influences, including food and water availability, rather than from thermal constraints alone. We present new data from two sympatric Malagasy lizards with contrasting acclimatization patterns and, complemented with an extensive literature search, discuss the variety of acclimatization patterns in tropical reptiles with regard to thermal and energetic influences. This broad consideration of constraints allows a rearrangement of apparently controversial patterns into a scheme of decreasing metabolic costs, including two new categories for selective and selective inverse acclimatization, where metabolic shifts are restricted to body temperatures below those preferred during activity.     

Climate variability and spruce beetle (Dendroctonus rufipennis) outbreaks in south-central and southwest Alaska

We used tree ring data (AD 1601-2007) to examine the occurrence of and climatic influences on spruce beetle (Dendroctonus rufipennis) outbreaks in south-central and southwest Alaska and found evidence of regional-scale outbreaks dating from the mid-1700s, related to climate variability at multiple temporal scales. Over interannual time scales (approximately 1-3 years), El Ni?o years, combined with severe late-summer drought, appeared to contribute significantly to spruce beetle outbreaks in the study area. Over multidecadal time scales (up to approximately 40 years), cool-phase Pacific Decadal Oscillation (PDO) conditions tended to precede beetle outbreaks, regardless of the phase of El Ni?o-Southern Oscillation (ENSO). All sites showed low-severity disturbances attributed to spruce beetle damage, most notably during the 1810s. During other major periods of disturbance (i.e., 1870s, 1910s, 1970s), the effects of spruce beetle outbreaks were of moderate or higher severity. The highly synchronized timing of spruce beetle outbreaks at interannual to multidecadal scales, and particularly the association between cool-phase PDO conditions and beetle disturbance, suggests that climate (i.e., temperature, precipitation) is a primary driver of outbreaks in the study area. Our disturbance chronologies (mid-1700s to present) suggest that recent irruptions (1990s to present) in south-central and southwest Alaska are within the historical geographic range, but that outbreaks since the 1990s show greater spatiotemporal synchrony (i.e., more sites record high-severity infestations) than at any other time in the past approximatly 250 years.     

Integrating climate change adaptation into Dutch local policies and the role of contextual factors

Moving towards a more sustainable adaptation process requires closer integration of policies related to the environment. An important actor in this is the local government. This paper examines to what extend adaptation is currently being integrated into Dutch local policies, and what the role is of a municipality's size, risk and experience in the encountered manifestations of adaptation. First, it was determined that adaptations taking place only anticipate currently perceivable weather extremes – mostly increasing precipitation. Second, it was determined that the realisation of further adaptations is hindered by a strongly sectoral divided reality. Adaptation is now heavily dominated by the water department, while spatial planning and the environment are only limitedly involved. Finally, it was observed that the contextual factor size proved to most important for horizontal policy integration, whereas the contextual factor extreme-weather experience was the most definite for the realisation of adaptations. We conclude that a more sustainable adaptation should first tackle the sectoral divides which requires administrative efforts, for example, professional training. These would preferably be initiated from a vertical direction.     

Species-specific dinoflagellate vertical distribution in temperature-stratified waters

Thermal stratification is increasing in strength as a result of higher surface water temperature. This could influence the vertical distribution of vertically migrating dinoflagellates. We studied the diel vertical distribution of the dinoflagellates Heterocapsa triquetra and Prorocentrum minimum using stratified laboratory columns with two thermoclines of different strength (ΔT° = 10 or 17 °C), with below cline temperature of 8 °C. Above the thermocline, nutrient depletion simulated the natural summer conditions in the Baltic Sea. Our study shows that H. triquetra and P. minimum can behave differently in terms of their vertical occurrence, both in space and in time when subjected to thermoclines of different strength. Also, both dinoflagellate species showed species-specific distribution patterns. In the ΔT° = 10 °C treatment, H. triquetra cells performed a diel vertical migration (DVM) behavior just above the thermocline, but not in the ΔT° = 17 °C. In the ΔT° = 17 °C, the cells did not migrate and cell densities in the water column decreased over time. Opposing results were observed for P. minimum, where a DVM pattern was found exclusively below the thermocline of ΔT° = 17 °C, while in the ΔT° = 10 °C treatment, no clear DVM pattern was observed, and the highest number of cells were found in the cold bottom water. These results indicate that an increase in thermal stratification can influence species-specific dinoflagellate distribution, behavior, and survival.     

Development of a new hydrocarbon index for oil-in-water

A new robust method for determination of hydrocarbons in water without use of Freon^™ or other halogenated solvents has been validated and subjected to an interlaboratory exercise. The method is based on extraction with a light hydrocarbon (boiling point in the 39–69°C range), followed by cleanup for removal of polar components and detection by gas chromatography (GC) with flame ionisation (FID) detection. The performance characteristics of the method are comparable with that of the previous Freon-IR method with recoveries in the 60–80% range and reproducibility (between laboratory variations) of about 30%.

A screening method for hydrocarbons in the range 5 ppm and above based on infrared spectroscopy (IR), and a promising method for detection of low levels based on solid phase extraction (SPE) has been tested and validated.     

Controls on coarse wood decay in temperate tree species: birth of the LOGLIFE experiment

Dead wood provides a huge terrestrial carbon stock and a habitat to wide-ranging organisms during its decay. Our brief review highlights that, in order to understand environmental change impacts on these functions, we need to quantify the contributions of different interacting biotic and abiotic drivers to wood decomposition. LOGLIFE is a new long-term 'common-garden' experiment to disentangle the effects of species' wood traits and site-related environmental drivers on wood decomposition dynamics and its associated diversity of microbial and invertebrate communities. This experiment is firmly rooted in pioneering experiments under the directorship of Terry Callaghan at Abisko Research Station, Sweden. LOGLIFE features two contrasting forest sites in the Netherlands, each hosting a similar set of coarse logs and branches of 10 tree species. LOGLIFE welcomes other researchers to test further questions concerning coarse wood decay that will also help to optimise forest management in view of carbon sequestration and biodiversity conservation.     

Controls on Coarse Wood Decay in Temperate Tree Species: Birth of the LOGLIFE Experiment

Dead wood provides a huge terrestrial carbon stock and a habitat to wide-ranging organisms during its decay. Our brief review highlights that, in order to understand environmental change impacts on these functions, we need to quantify the contributions of different interacting biotic and abiotic drivers to wood decomposition. LOGLIFE is a new long-term ‘common-garden’ experiment to disentangle the effects of species’ wood traits and site-related environmental drivers on wood decomposition dynamics and its associated diversity of microbial and invertebrate communities. This experiment is firmly rooted in pioneering experiments under the directorship of Terry Callaghan at Abisko Research Station, Sweden. LOGLIFE features two contrasting forest sites in the Netherlands, each hosting a similar set of coarse logs and branches of 10 tree species. LOGLIFE welcomes other researchers to test further questions concerning coarse wood decay that will also help to optimise forest management in view of carbon sequestration and biodiversity conservation.