Identifying phenological functional types in savanna trees

Savannas are notable for the varied patterns of leaf display in the tree layer. Characterising this variation, and assessing the range of phenological strategies apparent in savanna ecosystems will be helpful for understanding savanna tree life-histories and their response to global change. We recorded leaf phenological metrics on a monthly basis for 28 woody species for one year in a semi-arid savanna at Nylsvley Nature Reserve, South Africa. Using these metrics four plant functional types were described: (1) evergreen species, which retained full canopy throughout the year; (2) semi-evergreen species, which lost a significant amount of canopy during the dry season, but not less than 60%; (3) obligate deciduous species in which the canopy was leafless for about 3 months during the dry season; and (4) rain-stimulated species, in which canopy flushing was driven by rainfall patterns. Of the 28 species, 18% were evergreen, 18% obligate deciduous, 32% semi-evergreen and 32% were rain-stimulated species. These results confirm that phenological strategies are variable in savannas, and highlight that there are numerous cues controlling the timing of leaf out and leaf drop. By defining distinct phenological strategies we can predict which plant functional types will have phenological cues that will be vulnerable to shifting climates.     

Butterfly dispersal in farmland: a replicated landscape genetics study on the meadow brown butterfly (<Emphasis Type="Italic">Maniola jurtina</Emphasis>)

Context

Anthropogenic activities readily result in the fragmentation of habitats such that species persistence increasingly depends on their ability to disperse. However, landscape features that enhance or limit individual dispersal are often poorly understood. Landscape genetics has recently provided innovative solutions to evaluate landscape resistance to dispersal.

Objectives

We studied the dispersal of the common meadow brown butterfly, Maniola jurtina, in agricultural landscapes, using a replicated study design and rigorous statistical analyses. Based on existing behavioral and life history research, we hypothesized that the meadow brown would preferentially disperse through its preferred grassy habitats (meadows and road verges) and avoid dispersing through woodlands and the agricultural matrix.

Methods

Samples were collected in 18 study landscapes of 5 × 5 km in three contrasting agricultural French regions. Using circuit theory, least cost path and transect-based methods, we analyzed the effect of the landscape on gene flow separately for each sex.

Results

Analysis of 1681 samples with 6 microsatellites loci revealed that landscape features weakly influence meadow brown butterfly gene flow. Gene flow in both sexes appeared to be weakly limited by forests and arable lands, whereas grasslands and grassy linear elements (road verges) were more likely to enhance gene flow.

Conclusion

Our results are consistent with the hypothesis of greater dispersal through landscape elements that are most similar to suitable habitat. Our spatially replicated landscape genetics study allowed us to detect subtle landscape effects on butterfly gene flow, and these findings were reinforced by consistent results across analytical methods.

     

Micromechanical "Trampoline" magnetometers for use in large pulsed magnetic fields

A silicon micromechanical magnetometer was constructed and successfully used in 60-tesla pulsed magnetic fields of less than 100-millisecond duration. The device is small, inexpensive to fabricate, and easy to use. It features a fast mechanical response (up to 50,000 hertz) and extremely high sensitivity yet is relatively robust against electrical and mechanical noise. Quantum oscillations in the magnetization of a 1-microgram sample of an organic superconductor, kappa-[bis(ethylenedithio)tetrathiafulvalene]2Cu(NCS)2, have been observed with this device.     

Major compositional units of the moon: lunar prospector thermal and fast neutrons

Global maps of thermal and fast neutron fluxes from the moon suggest three end-member compositional units. A high thermal and low fast neutron flux unit correlates with the lunar highlands and is consistent with feldspathic rocks. The South Pole-Aitken basin and a strip that surrounds the nearside maria have intermediate thermal and fast neutron flux levels, consistent with more mafic rocks. There appears to be a smooth transition between the most mafic and feldspathic compositions, which correspond to low and high surface altitudes, respectively. The maria show low thermal and high fast neutron fluxes, consistent with basaltic rocks.     

Lunar Fe and Ti abundances: comparison of lunar prospector and clementine data

The Lunar Prospector neutron spectrometer data correlate well with iron and titanium abundances obtained through analysis of Clementine spectral reflectance data. With the iron and titanium dependence removed, the neutron spectrometer data also reveal regions with enhanced amounts of gadolinium and samarium, incompatible rare earth elements that are enriched in the final phases of magma crystallization. These regions are found mainly around the ramparts of the Imbrium impact basin but not around the other basins, including the much larger and deeper South Pole-Aitken basin. This result confirms the compositional uniqueness of the surface and interior of the Imbrium region.     

Life history demographic parameter synthesis for exploited Florida and Caribbean coral reef fishes

Age‐ or length‐structured stock assessments require reliable life history demographic parameters (growth, mortality, reproduction) to model population dynamics, potential yields and stock sustainability. This study synthesized life history information for 84 commercially exploited tropical reef fish species from Florida and the U.S. Caribbean (Puerto Rico and the U.S. Virgin Islands). We attempted to identify a useable set of life history parameters for each species that included lifespan, length at age, weight at length and maturity at length. Key aspects of the life history synthesis were development of: (a) a database that characterized study details including sampling region, biological and statistical methods, length range of sampled individuals, sample size, capture gears and sampling time frame; (b) reproducible procedural criteria for parameter identification for a given species; and (c) a reliability metric for each parameter type. Complete life history parameter sets were available for 46 species analysed. Of these, only 16 species had parameter sets meeting the highest standards for reliability, highlighting future research needs.     

Assessing the suitability of a non-lethal biopsy punch for sampling fish muscle tissue

Samples for the analysis of stable isotopes, genetics and other tissue sampling methods of small fish are often taken via lethal techniques. The aim of this study was to determine the suitability of a non-lethal sampling method for removing muscle tissue from fish under 30 cm total length (TL). A 4-mm biopsy punch was used to remove muscle tissue from two different species, Lutjanus russelli (Lutjanidae) and Lethrinus laticaudis (Lethrinidae). Several scales were removed from the sampling location, and then the biopsy punch was inserted to remove the muscle tissue. Immediately following this, a mixture of Fish Bandage? and three drops of Betadine? antiseptic solution was applied to the wound to reduce the chance of infection. The biopsy punch removes an average of 8 mg of muscle tissue from the fish, more than is required for stable isotope and genetic analyses (1 mg). The condition of fish subjected to our three treatments, biopsied fish, a handling controls and a tank control, was compared via gill beat counts at the time of biopsy and 3, 6, 9, 12 and 24 h after treatment. Overall, no instances of mortality were recorded across the study for all species and all treatments. This method has been found to be a suitable non-lethal method in the removal of muscle tissue from these two fish species, potentially also other species under 30 cm TL, by eliminating mortality and minimising stress responses in sampled fishes.     

Investigating patterns of straying and mixed stock exploitation of sea trout,Salmo trutta,in rivers sharing an estuary in south‐west England

For effective management, information on the stock composition of a fishery is essential. Here, the utility of a resident trout, Salmon trutta L, microsatellite baseline to determine the origins of sea trout entering the rivers Tamar, Tavy and Lynher in south‐west England is highlighted – all share a common estuary and have major runs of sea trout. There is a high degree of geographical structuring of the genetic variation in the baseline rivers. Testing with simulated and real data sets showed fish can be assigned to reporting group with a high degree of accuracy. Mixed stock analysis of >1000 sea trout showed that fish entering the Tamar and Tavy constituted mixed stocks. Significantly, in the Tamar, non‐natal origin sea trout are restricted to the lower catchment. As well as providing insight into sea trout behaviour, this study also has important implications for the management of recreational rod and line fisheries.     

Measuring Soil and Tissue Potassium with a Portable Ion-Specific Electrode in Cotton

Most laboratories make potassium (K) fertilizer recommendations based on field research calibrated with soil K from atomic absorption spectroscopy, flame emission spectroscopy, or inductively coupled plasma mass spectrometry. Information is needed to interpret readings from K⁺ meters on cotton. The objective was to compare soil and cotton plant sap potassium content from a Laqua Twin? K⁺ meter to results from standard tests. Aluminum sulfate solution was used with the meter to extract K from 10 soil samples from the North America Proficiency Testing program. A linear relationship (R² = 0.86) was found between K measured with a K⁺ meter and K measured with 138 labs using ammonium acetate or Mehlich-3. Using a factor of 1.4754 to adjust readings, fertilizer recommendations with the K⁺ meter were similar to results from atomic absorption spectroscopy. A linear relationship was found between petiole K measured in the lab and petiole sap measured with the K⁺ meter.